WO2005001300A1 - 動圧軸受装置及びそれを用いた回転装置 - Google Patents
動圧軸受装置及びそれを用いた回転装置 Download PDFInfo
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- WO2005001300A1 WO2005001300A1 PCT/JP2004/008885 JP2004008885W WO2005001300A1 WO 2005001300 A1 WO2005001300 A1 WO 2005001300A1 JP 2004008885 W JP2004008885 W JP 2004008885W WO 2005001300 A1 WO2005001300 A1 WO 2005001300A1
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- WO
- WIPO (PCT)
- Prior art keywords
- magnetic fluid
- magnetic
- sleeve
- dynamic pressure
- thrust plate
- Prior art date
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Classifications
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
- G11B19/20—Driving; Starting; Stopping; Control thereof
- G11B19/2009—Turntables, hubs and motors for disk drives; Mounting of motors in the drive
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C17/00—Sliding-contact bearings for exclusively rotary movement
- F16C17/10—Sliding-contact bearings for exclusively rotary movement for both radial and axial load
- F16C17/102—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure
- F16C17/107—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure with at least one surface for radial load and at least one surface for axial load
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/02—Parts of sliding-contact bearings
- F16C33/04—Brasses; Bushes; Linings
- F16C33/06—Sliding surface mainly made of metal
- F16C33/10—Construction relative to lubrication
- F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
- F16C33/103—Construction relative to lubrication with liquid, e.g. oil, as lubricant retained in or near the bearing
- F16C33/1035—Construction relative to lubrication with liquid, e.g. oil, as lubricant retained in or near the bearing by a magnetic field acting on a magnetic liquid
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/02—Parts of sliding-contact bearings
- F16C33/04—Brasses; Bushes; Linings
- F16C33/06—Sliding surface mainly made of metal
- F16C33/10—Construction relative to lubrication
- F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
- F16C33/106—Details of distribution or circulation inside the bearings, e.g. details of the bearing surfaces to affect flow or pressure of the liquid
- F16C33/107—Grooves for generating pressure
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
- H02K7/08—Structural association with bearings
- H02K7/085—Structural association with bearings radially supporting the rotary shaft at only one end of the rotor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2370/00—Apparatus relating to physics, e.g. instruments
- F16C2370/12—Hard disk drives or the like
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
- H02K7/08—Structural association with bearings
- H02K7/09—Structural association with bearings with magnetic bearings
Definitions
- the present invention relates to a hydrodynamic bearing device, and relates to a hydrodynamic bearing device which prevents leakage and scattering of a magnetic fluid, and eliminates a problem caused by an unstable phenomenon of fluid bombing due to imbalance of dynamic pressure, and a dynamic pressure bearing device. It relates to the spindle motor used.
- a thrust plate is fixed to an end of a shaft, and a thrust hydrodynamic bearing portion is formed by an axial surface of the thrust plate and an opposing surface of a convex cylindrical portion of a fitted sleeve.
- a radial dynamic pressure bearing portion is formed by the outer peripheral surface of the shaft and the facing surface of the convex cylindrical portion of the fitted sleeve.
- Lubricating oil is held in the dynamic pressure bearing portion, and dynamic pressure is generated by rotation of the rotor. Things were known. In such a hydrodynamic bearing device, it is necessary to effectively prevent leakage and scattering of the lubricating oil filled in the hydrodynamic bearing portion.
- the lubricating oil which is a medium of the magnetic fluid, evaporates into the atmosphere with time, the service life of the bearing is limited, or maintenance such as refilling is required.
- the dynamic pressure bearing device there is a problem that the rotation of the sleeve or the like is not stabilized due to the unstable flow of the magnetic fluid due to the bombing generated in the dynamic pressure bearing portion.
- the unstable flow of the magnetic fluid due to such bombing is caused by the dynamic pressure generated by the dynamic pressure bearing being imbalanced in the upper and lower directions in the axial direction, and the magnetic fluid flowing in one direction.
- a magnetic circuit is formed using a magnetic member and a magnetic fluid, and the end of the magnetic fluid is magnetically sealed by a seal gap portion.
- Devices are known (for example, see Patent Documents 1 and 2). However, since these devices need to hold both ends of the magnetic fluid with a strong magnetic flux, it is necessary to form a magnetic circuit incorporating a strong permanent magnet or the like in the sleeve and the shaft.
- a taper seal utilizing the balance between surface tension and external pressure is also known (for example, see Patent Document 3).
- the taper seal has a function as a reservoir that stores the lubricating oil while maintaining the capillary phenomenon by gradually increasing the height of the tapered portion, but the taper seal utilizes the capillary phenomenon To retain the lubricating oil It is necessary to narrow the gap.
- the degree of freedom in the shape design of the taper seal is extremely limited, and high component processing accuracy such as mirror finishing is required.
- the cost of manufacturing parts increases.
- Patent Document 1 Japanese Patent Application Laid-Open No. 6-33941 (Page 3, FIG. 1 and FIG. 3)
- Patent Document 2 U.S. Pat.No. 4,694,213 (pages 3-5, FIG. 1)
- Patent Document 3 JP 2001-112214A (Pages 4-5, Fig. 1)
- a first object of the present invention is to hold a magnetic fluid by a magnetic field when stationary and hold the magnetic fluid mainly by centrifugal force during rotation as means for holding a magnetic fluid.
- a magnetic fluid with a high saturation magnetization value or a magnet with a strong magnetic force In order to maintain the magnetic fluid during rotation mainly by a magnetic field, it is necessary to use a magnetic fluid with a high saturation magnetization value or a magnet with a strong magnetic force.
- magnetic fluids having a high saturation magnetization generally tend to have a high viscosity, and the higher the viscosity of the magnetic fluid, the greater the tonnolek loss of the dynamic pressure bearing.
- strong magnets such as samarium cobalt or neodymium iron boron are very expensive.
- the magnetic fluid is held mainly by centrifugal force during rotation, so that it is sufficient if the magnetic fluid can be held by the magnetic field only at rest. It is an object of the present invention to make it possible to use inexpensive magnets with weak magnetic force, such as ferrite and ferrite.
- a second object of the present invention is to provide a reservoir for a magnetic fluid to provide a reserve capacity for a magnetic fluid used for a dynamic pressure bearing portion.
- a third problem of the present invention is that centrifugal force and a communication hole provided in a sleeve prevent the bearing performance from deteriorating during rotation, and can be caused by the unstable phenomenon of bombing of the dynamic pressure bearing. Leakage and scattering of the conductive magnetic fluid can be prevented.
- the present invention has adopted the following configurations.
- the thrust plate and a sleeve having a convex cylindrical portion to be fitted into the shaft are relatively rotatably fitted on a shaft fitted with an annular thrust plate, and the thrust plate is axially mounted on the shaft.
- a gap for generating thrust dynamic pressure is formed by the axially outer surface of the convex cylindrical portion facing the inner surface
- a gap for generating radial dynamic pressure is formed by the outer peripheral surface of the shaft facing the inner peripheral surface of the convex cylindrical portion of the sleeve.
- an annular cover made of a non-magnetic member is formed on the sleeve through an air gap outside the thrust plate in the axial direction.
- An opening is formed at the radially inner end of the annular cover, and at least two of a gap between the thrust plate and the annular cover and a radially inner gap of the sleeve opposed to the radially outside of the thrust plate.
- a gap between the thrust plate forming the reservoir and the annular cover holds an end of the magnetic fluid, and a radial direction from the end of the magnetic fluid.
- the end of the magnetic fluid is held by the magnetic field of a magnetomotive member such as a permanent magnet.
- a magnetomotive member such as a permanent magnet.
- the centrifugal force accompanying the rotation of the sleeve or shaft is applied, and the magnetic fluid is stably held at the end, so that leakage and scattering of the magnetic fluid are reliably prevented, and the magnetic fluid is always held in the bearing. be able to.
- a magnet for generating a magnetic field it is sufficient to mainly hold a magnetic fluid at rest, so it is not necessary to use a relatively expensive magnet with a strong magnetic force such as samarium cobalt or neodymium iron boron.
- a weak magnetic force such as a ferrite magnet and the use of an inexpensive magnet can be used.
- the strong magnetomotive member is integrally molded or fixed to a sleeve, an annular cover, a thrust plate, or the like so as to be located radially outside the end of the magnetic fluid.
- the sleeve includes all that are integrally fixed to the thrust plate and the convex cylindrical portion rotatably fitted to the shaft. Therefore, even if the rotor hub and the member having the convex cylindrical portion are physically different, as long as they rotate integrally, they are all regarded as sleeves in the present invention.
- the magnetization direction of the magnetomotive member is not limited to the axial direction but may be the radial direction.
- the shape of the annular cover may be parallel to the facing thrust plate, or may be a shape that expands toward the opening.
- the thrust plate may be formed integrally with the shaft.
- the sleeve includes all that are integrally fixed to the protruding cylindrical portion rotatably fitted to the thrust plate and the shaft.
- the part provided with the annular cover is regarded as a sleeve.
- the case where the annular cover and the sleeve are integrally formed is also included in the scope of the present invention.
- the annular cover may be fixed to the sleeve via a magnetomotive member such as a permanent magnet.
- the reservoir needs a sufficient volume to store the magnetic fluid.
- a volume varies depending on the size of the hydrodynamic bearing device, the material used for the parts of the hydrodynamic bearing device, and the filling amount of the magnetic fluid, but the reservoir according to the present invention uses the magnetic fluid and the centrifugal force to store the magnetic fluid.
- the space and the length of the reservoir have a margin, and the reservoir space can be designed in any shape, and the design flexibility is extremely high.Sufficient volume can be easily secured and high Since component processing accuracy is not required, it is possible to reduce the cost of component production.
- the dynamic pressure bearing device according to the present invention can be used for any rotating device having a rotor that is fitted around a shaft and rotates.
- any rotating device having a rotor that is fitted around a shaft and rotates.
- bearings for multimedia products such as CDs, DVDs, MOs, optical discs, etc., and various small precision motors such as fans
- medium-sized motors such as household appliances, housing equipment, automotive equipment, and industrial use
- Bearings for machinery bearings for medical equipment, bearings for industrial equipment such as turbines, reels, Bearings for vehicles such as cars, trains, ships, and aircraft, and bearings for manufacturing equipment such as semiconductors, 'electronic devices, and' electrical products' and other machines.
- a sleeve having a convex cylindrical portion that fits into the seal plate and the shaft is relatively rotatably externally fitted to the shaft on which the annular seal plate is fitted, and the convex cylinder of the sleeve is
- the hydrodynamic bearing device in which a radial dynamic pressure is generated by the outer peripheral surface of the shaft facing the inner peripheral surface of the shaft and a magnetic fluid is sealed in the gap, a gap is formed axially outward of the seal plate.
- An annular cover made of non-magnetic material is formed on the sleeve via
- a radially inner end of the annular cover as an opening, at least a gap between the seal plate and the annular cover and a radially inner gap of a sleeve opposed to a radially outer side of the seal plate.
- the two gaps serve as reservoirs for storing the magnetic fluid, and the ends of the magnetic fluid are held in the gaps between the seal plate and the annular cover forming the reservoir, and are radially outward from the ends of the magnetic fluid.
- the pole piece has the function of concentrating the lines of magnetic force from the pole face of the permanent magnet to a position radially outward from the end of the magnetic fluid in the reservoir.
- the hydrodynamic bearing device according to the present invention can be used in any rotating device having a rotor that fits around a shaft and rotates similarly to (1) and the like.
- a magnetic circuit is formed through a sleeve made of a magnetic material.
- the hydrodynamic bearing device according to the present invention can be used in any rotating device having a rotor that fits around a shaft and rotates similarly to (1) and the like.
- the magnetic fluid flowing by bombing and the like is returned through the upper and lower communication holes, so that the amount of magnetic fluid retained in the axial upper and lower thrust bearings, radial bearings, and the reservoir is kept constant. Further, by preventing the generation of a local negative pressure, deterioration of bearing performance and leakage and scattering of the magnetic fluid do not occur.
- the hydrodynamic bearing device according to the present invention can be used in any rotating device having a rotor that fits around a shaft and rotates similarly to (1) and the like.
- the magnetic fluid By forming the horizontal communication holes, the magnetic fluid always returns during rotation, so that there is no partial deterioration of the magnetic fluid.
- the mixed air bubbles can be efficiently discharged to the outside. As a result, the bearing function is not impaired.
- the hydrodynamic bearing device according to the present invention can be used in any rotating device having a rotor that fits around a shaft and rotates similarly to (1) and the like.
- An annular step for suppressing capillary action is formed on the open end of the annular cover and / or on the axially outside of the thrust plate or the seal plate and radially inward.
- a dynamic pressure bearing device according to any one of (7).
- the annular step is formed, for example, by providing a step having an annular R-shape at an intermediate portion of the annular cover facing the thrust plate or the seal plate.
- the magnetic fluid is held by a magnetic force in a gap between the thrust plate or the seal plate and the annular cover opposed thereto.
- the capillary action due to the intermolecular force between the thrust plate or the seal plate, the annular cover and the magnetic fluid, and the intermolecular force of the magnetic fluid acts.
- the direction in which the intermolecular force acts between the thrust plate or seal plate, the annular cover, and the magnetic fluid changes at the R-shape, and the gap is expanded toward the opening of the annular cover By doing so, the capillary action is suppressed, so that the end of the magnetic fluid is held at the rising portion of the step.
- the step of the annular cover The shape of the difference is not limited to the R shape, and may be, for example, a ridge line.
- the shape of the step may be formed by providing a concave ring portion radially inside and outside the thrust plate or seal plate in the axial direction, or by forming a concave ring portion on the thrust plate or seal plate. It may be formed by combining the R shapes of the annular cover.
- the hydrodynamic bearing device according to the present invention can be used in any rotating device having a rotor that fits around a shaft and rotates similarly to (1) and the like.
- rotating device means any rotating body having a rotor that is fitted around a shaft and rotates.
- multimedia products such as computer hard disk drives, fans, CD's, DVD's, optical discs, etc., various small precision motors such as fans, household appliances, residential equipment, etc.
- machine tools, medical equipment, turbines, reels, vehicles such as automobiles, trains, ships, aircraft, etc., semiconductors' electronics' electrical products', and other machines and other manufacturing equipment.
- a sleeve and a rotor hub are simply formed integrally, and an annular cover and a magnetomotive force member are fixed.
- the rotor hub is fixed to the sleeve, and an annular cover and the like are further attached to the rotor hub.
- the magnetic fluid is held by a magnetic field when stationary, and the magnetic fluid is held mainly by centrifugal force during rotation, so that it is not necessary to hold the magnetic fluid during rotation by a strong magnetic field. This has the effect.
- the present invention provides a dynamic pressure bearing unit by providing a reservoir for storing a magnetic fluid.
- the storage capacity of the magnetic fluid used can be given a margin, the service life of the hydrodynamic bearing device can be extended by evaporating the lubricating oil that is the medium of the magnetic fluid, and the volume of the magnetic fluid due to the temperature rise of the hydrodynamic bearing It can sufficiently cope with expansion.
- the present invention prevents a decrease in bearing performance during rotation by a centrifugal force and a communication hole provided in a sleeve, and a magnetic fluid which may be caused by an unstable phenomenon of bombing of a dynamic pressure bearing. This has the effect of preventing leakage and scattering of water.
- FIG. 1 is a longitudinal sectional view showing an example of an embodiment according to the present invention.
- FIG. 2 is a plan view taken along the line IV-IV of FIG. 1 showing a dynamic pressure groove of the thrust plate according to the present invention, and a partial cross-sectional view showing a positional relationship with the sleeve.
- FIG. 3 is an analysis diagram of lines of magnetic force in the dynamic pressure bearing device of FIG. 1.
- FIG. 4 is an analysis diagram of lines of magnetic force in another hydrodynamic bearing device according to the present invention.
- FIG. 5 is a longitudinal sectional view showing an example of another embodiment according to the present invention.
- FIG. 6 is a longitudinal sectional view showing an example of another embodiment according to the present invention.
- FIG. 7 is a longitudinal sectional view showing an example of another embodiment according to the present invention.
- FIG. 8 is an analysis diagram of lines of magnetic force in the dynamic bearing device of FIG. 6.
- FIG. 9 is a longitudinal sectional view showing an example of another embodiment according to the present invention.
- FIG. 10 is a longitudinal sectional view showing an example of another embodiment according to the present invention.
- FIG. 11 is an analysis diagram of lines of magnetic force in the dynamic bearing device of FIG. 9.
- FIG. 12 is a longitudinal sectional view showing an example of another embodiment according to the present invention.
- FIG. 13 is a longitudinal sectional view showing an example of another embodiment according to the present invention.
- FIG. 14 (a) is a longitudinal sectional view showing an example of another embodiment according to the present invention. (b) of (a)
- FIG. 15 is a longitudinal sectional view showing an example of another embodiment according to the present invention.
- FIG. 16 is a longitudinal sectional view showing an example of another embodiment according to the present invention.
- FIG. 17 is a longitudinal sectional view showing an example of the production method according to the present invention.
- FIG. 18 is a longitudinal sectional view showing an example of the DC motor according to the present invention.
- FIG. 19 is a longitudinal sectional view showing an example of another DC type motor according to the present invention.
- FIG. 20 is a longitudinal sectional view showing an example of another DC motor according to the present invention.
- a force will be described by taking as an example a dynamic pressure bearing device of a spindle motor used in a computer hard disk drive.
- the present invention is not limited to the following embodiments.
- FIG. 1 is a longitudinal sectional view schematically showing an embodiment of the invention according to claim 1.
- the hydrodynamic bearing device rotatably fits a sleeve 3 made of a non-magnetic member having a convex cylindrical portion 17 to a fixed shaft 1 to which an annular thrust plate 2 made of a magnetic member is fixed.
- Radial dynamic pressure is generated by the thrust bearing portion 5 that generates thrust dynamic pressure by the axial inner surface of the thrust plate 2 and the axial outer surface of the convex cylindrical portion 17, and the outer peripheral surface of the shaft 1 that faces the inner peripheral surface of the convex cylindrical portion 17.
- a radial bearing portion 7 that generates a magnetic field is formed, and a magnetic fluid 12 is sealed in these bearing portions 5 and 7.
- a thrust dynamic pressure groove 6 is formed on the radial bearing portion 7 and a radial dynamic pressure groove 8 is formed on the radial bearing portion 7.
- dynamic pressure grooves 6 and 8 face the axial inner surface of the thrust plate 2 or the axial outer surface of the convex cylindrical portion 17 of the sleeve 3 and the radial outer surface of the shaft 1 facing each other. It is provided on the radially inner surface of the convex cylindrical portion 17 of the sleeve 3.
- a dynamic pressure groove having a spiral shape or a herringbone shape is used as the dynamic pressure groove.
- FIG. 2A is a plan view of the thrust plate 2 showing the spiral dynamic pressure groove 6 in FIG. 1 taken along the line IV-IV, and a partial cross-sectional view showing the relative position of the thrust plate 2 to the sleeve 3. .
- the outer peripheral portion of the spiral dynamic pressure groove 6 in the present embodiment is provided on the opposed surface on the thrust plate side of the concave portion 14 formed radially outward of the thrust bearing portion formed on the axially outer surface of the convex cylindrical portion of the sleeve 3.
- the projecting surplus portion S is formed.
- the recess 14 is a groove that forms a part of the reservoir 10, and stores the magnetic fluid 12. Since a large amount of the magnetic fluid 12 is stored in the concave portion 14, compared with the case where the concave portion 14 is not formed, a larger amount of magnetic fluid is generated due to the surplus portion S on the opposing surface of the concave portion 14 on the thrust plate side. Fluid 12 flows to thrust bearing 5. The dynamic pressure of the thrust bearing is more effectively generated by this flow.
- the thrust dynamic pressure groove 6 is formed on the outer surface in the axial direction of the convex portion of the sleeve 3, the outer surface in the axial direction of the convex portion of the sleeve 3 is formed flat, and the thrust dynamic pressure grooves 6 face each other so that the reservoir and the surplus portion S are provided.
- a recess 14 is formed on the inner surface of the thrust plate 2 in the axial direction.
- an annular cover 4 made of a non-magnetic member is fixed to the sleeve 3 through a gap of 0.3 mm filled with a magnetic fluid 12 outside the thrust plate 2 in the axial direction.
- the gap formed by the thrust plate 2 and the annular cover 4, the gap having a gap of 0.2 mm and the radial direction of the thrust bearing portion are formed by a radially inner surface of the sleeve 3 facing the radially outer surface of the thrust plate 2.
- a reservoir 10 for storing the magnetic fluid is formed by a gap having a gap of 0.1 mm, which is formed radially outside of the convex cylindrical portion of the sleeve 3 and outward in the axial direction, and forms the reservoir 10.
- the two ends of the magnetic fluid 12 are held in the gap between the thrust plate 2 and the annular cover 4 to be fixed.
- An annular permanent magnet 15 magnetized in the axial direction is sandwiched between the sleeve 3 and the annular cover 4 at a position radially outward from the ends 13 and 13.
- the specific interval is not limited to this.
- the material of the shaft 1 is SUS (stainless steel) 304
- the material of the thrust plate 2 is SUS420
- the sleeve 3f is SUS304
- the annular cano 4f is SUS304
- the permanent magnet is 15 is made of ferrite pramag.
- the material is not limited to this.
- the shaft 1 may be formed of SUS420 or the like.
- FIG. 3 is a magnetic force line analysis diagram showing the flow of the magnetic force lines. Since the annular cover 4 and the sleeve 3 are made of a non-magnetic material, they do not affect the sealing mechanism.
- the lines of magnetic force form a magnetic circuit that reaches the permanent magnet 15 through the magnetic fluid 12 held by the thrust plate 2 and the reservoir 10 that are magnetic members.
- the lines of magnetic force are concentrated mainly at two points indicated by A, and a magnetic gradient is formed around the portion where the force is applied, and the magnetic fluid 12 is held.
- Fig. 4 is a magnetic field line analysis diagram showing the flow of the magnetic field lines when the permanent magnet is magnetized in the radial direction.
- the annular cover 4 and the sleeve 3 are made of a non-magnetic member, and the shaft 1 thrust plate 2 and the like are made of a magnetic member.
- the lines of magnetic force reach the thrust plate 2 and the shaft 1 through the magnetic fluid 12 held in the reservoir 10.
- the lines of magnetic force concentrate radially outward from the end 13 of the magnetic fluid 12 and hold the end 13 of the magnetic fluid 12.
- the gap between the thrust plate 2 and the annular cover 4 in the reservoir 10 is relatively large with a gap of about 0.3 mm, and the peripheral members constituting the gap do not require high-precision machining and are easy to manufacture. is there. Furthermore, since there is almost no influence of the capillary phenomenon, the magnetic fluid 12 moves from the opening 11 where the magnetic fluid 12 cannot move to the radial inner opening. There is no leakage or scattering.
- the dynamic pressure bearing device is constituted by the fixed shaft and the rotating sleeve.
- the present invention is not limited to this, and the dynamic pressure bearing device may be constituted by the rotating shaft and the fixed shaft.
- FIG. 5 is a longitudinal sectional view showing a partial outline of one embodiment of the invention according to claim 3.
- an annular thrust plate 2 made of a magnetic material is fixed to a fixed shaft 1
- a sleeve 3 made of a nonmagnetic material having a thrust plate 2 and a convex cylindrical portion fitted into the shaft 1.
- an annular force bar 4 made of a non-magnetic member is fixed to the sleeve 3 outside the thrust plate 2 in the axial direction through a gap filled with the magnetic fluid 12.
- An annular permanent magnet 16 is fixed radially outside the end 13 of the magnetic fluid 12 and axially outside the annular cover 4.
- the end 13 of the magnetic fluid 12 is held radially outward from the opening 11.
- the end 13 of the strong magnetic fluid 12 is held by a magnetic field by a permanent magnet 16.
- a centrifugal force is generated in the hydrodynamic bearing device during rotation, and the end portion 13 of the magnetic fluid 12 is stably held.
- the magnetic fluid 12 moves from the opening 11 where the magnetic fluid 12 does not move to the radially inner opening 11. There is no.
- FIG. 6 is a longitudinal sectional view showing an example of another embodiment of the invention according to claim 3.
- a hydrodynamic bearing device has a fixed shaft 1 on which an annular thrust plate 2 made of a magnetic material is fixed, and a sleeve 3 made of a nonmagnetic material having a thrust plate 2 and a convex cylindrical portion fitted into the shaft 1.
- an annular force bar 104 made of a non-magnetic member is fixed to the sleeve 3 through a gap filled with the magnetic fluid 12 outside the thrust plate 2 in the axial direction.
- An annular permanent magnet 106 is fixed radially outward from the end 13 of the magnetic fluid 12 and axially outside the annular cover 104.
- the end 13 of the magnetic fluid 12 When stationary, the end 13 of the magnetic fluid 12 is held radially outward from the opening 11. The end 13 of the strong magnetic fluid 12 is held by the magnetic field of the permanent magnet 106. ing. A centrifugal force is generated in the hydrodynamic bearing device during rotation, and the end portion 13 of the magnetic fluid 12 is stably held. As in the first embodiment, the effect of the capillary phenomenon is almost negligible, and therefore, the dynamic pressure bearing device for the magnetic fluid 12 from the opening 11 where the end 13 of the magnetic fluid 12 does not move to the radially inner opening 11. Leakage and scattering to the outside.
- FIG. 7 is a longitudinal sectional view showing a partial outline of an embodiment of the invention according to claim 4.
- a dynamic pressure bearing device has a fixed shaft 1 on which an annular thrust plate 2 made of a magnetic material is fixed, and a thrust plate 2 and a sleeve 3 made of a non-magnetic material having a convex cylindrical portion fitted into the shaft 1.
- an annular force bar 4 made of a non-magnetic member is fixed to the sleeve 3 through a gap filled with the magnetic fluid 12 outward in the axial direction of the thrust plate 2.
- An annular permanent magnet 16 is fixed radially outside the end 13 of the magnetic fluid 12 and axially outside the annular cover 4.
- an annular magnetic member 18 as a pole piece is disposed so as to cover the permanent magnet 16.
- FIG. 8 is a magnetic force line analysis diagram showing the flow of the magnetic force lines in the present embodiment.
- the annular cover 14 is a non-magnetic member and does not affect the sealing mechanism.
- the lines of magnetic force form a magnetic circuit from a magnetic body member 18 as a pole piece to a permanent magnet 16 through a magnetic fluid 12 held in a reservoir 10 and a thrust plate 2 as a magnetic member.
- the lines of magnetic force converge due to the action of the pole pieces, and a magnetic gradient is formed around the converging point where the force is exerted, and the magnetic fluid 12 is retained.
- a centrifugal force is generated in the hydrodynamic bearing device during rotation, and the end portion 13 of the magnetic fluid 12 is stably held.
- the influence of the capillary phenomenon is almost negligible, so that the end 13 of the magnetic fluid 12 does not move to the radially inward opening 11, and the dynamic pressure bearing of the magnetic fluid 12 from the opening 11. Leakage and scattering to the outside of the device.
- FIG. 9 is a longitudinal sectional view showing an example of another embodiment of the invention according to claim 4.
- the dynamic pressure bearing device has an annular thrust plate 2 made of a magnetic member fixed to a fixed shaft 1, and has a convex cylindrical portion fitted into the thrust plate 2 and the shaft 1.
- a sleeve 3 made of a non-magnetic member is rotatably fitted to the outside.
- an annular force bar 4 made of a non-magnetic member is fixed to the sleeve 3 outside the thrust plate 2 in the axial direction through a gap filled with the magnetic fluid 12.
- An annular permanent magnet 116 is fixed to the sleeve 3 radially outward from the end 13 of the magnetic fluid 12 and axially inside the annular cover 4.
- an annular pole piece 108 is arranged so as to cover the permanent magnet 116.
- the end 13 of the magnetic fluid 12 is held radially outward from the opening 11.
- the end 13 of the strong magnetic fluid 12 is held by the magnetic field of the permanent magnet 116.
- the lines of magnetic force generated by the permanent magnet 116 converge due to the action of the pole piece 108, and a magnetic gradient is formed around the convergence point to hold the magnetic fluid 12.
- a centrifugal force is generated in the hydrodynamic bearing device during rotation to stably hold the end portion 13 of the magnetic fluid 12.
- the magnetic fluid 12 flows from the opening 11 where the end 13 of the magnetic fluid 12 does not move to the radially inner opening 11 to the outside of the hydrodynamic bearing device. Leakage and scattering are prevented.
- FIG. 10 is a longitudinal sectional view schematically showing one embodiment of the invention according to claim 5.
- the dynamic pressure bearing device has a convex shaft portion fitted between the two thrust plates 19, 19 on a fixed shaft 1 to which a pair of annular thrust plates 19, 19 made of a non-magnetic member is fixed.
- a sleeve 21 consisting of a magnetic member is rotatably fitted to the outside.
- a pair of annular covers 4 and 4 made of a non-magnetic member are fixed to the sleeve 21 via a gap filled with the magnetic fluid 12 on the outside of the pair of thrust plates 19 and 19 in the axial direction.
- An annular permanent magnet 20 is formed on the thrust plate 19 radially outside both ends 13 and 13 of the magnetic fluid 12, and is formed.
- dynamic pressure grooves are provided on the axial inner surface of the thrust plates 19 and 19 or the axial outer surface of the convex portion of the facing sleeve 21 and the radial outer surface of the shaft 1 or the radial inner surface of the convex portion of the facing sleeve 21. Is common.
- the material of the shaft 1 is SUS304
- the material of the thrust plate 19 is SUS304.
- the sleeve 21 is SUS430
- the annular canopy 4 is SUS304
- the permanent magnet 20 is formed by a ferrite plastic magnet.
- the material is not limited to this.
- FIG. 11 is a magnetic force line analysis diagram showing the flow of the magnetic force lines. Since the annular cover 4 ⁇ thrust plate 19 is made of a non-magnetic material, it does not affect the sealing mechanism. The lines of magnetic force form a magnetic circuit that reaches the permanent magnet 20 through the magnetic fluid 12 held by the sleeve 21 and the reservoir 10 that are magnetic members. A magnetic gradient is formed around the portion where the lines of magnetic force are concentrated, and the magnetic fluid 12 is held.
- a centrifugal force acts on the dynamic pressure bearing device during rotation to stably hold both ends 13, 13 of the magnetic fluid 12.
- the gap between the thrust plate 19 and the annular cover 4 is as large as about 0.3 mm, so that the peripheral members constituting the gap do not require high-precision machining and are easy to manufacture.
- the magnetic fluid 12 held by the magnetic force that prevents the movement of the both ends 13 and 13 of the magnetic fluid 12 to the radially inner opening 11 moves from the opening 11 of the annular cover 4. It will not leak or scatter outside the pressure bearing device,
- FIG. 12 is a longitudinal sectional view showing an example of another embodiment of the invention according to claim 5.
- an annular thrust plate 119 made of a non-magnetic material is fixed to the shaft 1, and a thrust plate 119 and a sleeve 21 made of a magnetic material having a convex cylindrical portion fitted into the shaft 1 are formed. It is rotatably fitted to the outside.
- an annular cover 4 made of a non-magnetic member is fixed to the sleeve 21 via a gap filled with the magnetic fluid 12 outside the thrust plate 119 in the axial direction.
- An annular permanent magnet 120 and a pole piece 118 are formed on a thrust plate 119 radially outside both ends 13, 13 of the magnetic fluid 12.
- the end 13 of the magnetic fluid 12 It is held radially outward.
- the end 13 of the strong magnetic fluid 12 is held by a magnetic field generated by a permanent magnet 120.
- the lines of magnetic force generated by the pole pieces 11 8 fixed to the pole faces of the permanent magnets 120 are concentrated radially outward, and form a magnetic circuit through the magnetic fluid sleeve 12 and the magnetic fluid 12 held by the reservoir 10. I do.
- a magnetic gradient is formed around the portion where the lines of magnetic force are concentrated, and the magnetic fluid 12 is held.
- the centrifugal force acts on the dynamic pressure bearing device during rotation, and the end portion 13 of the magnetic fluid 12 is stably held.
- the magnetic fluid 12 held by the magnetic force that can move the end 13 of the magnetic fluid 12 to the radially inner opening 11 moves from the opening 11 of the annular cover 4. It will not leak or scatter outside the pressure bearing device.
- FIG. 13 is a longitudinal sectional view schematically showing one embodiment of the invention according to claim 6.
- the dynamic pressure bearing device is a non-magnetic member having a convex cylindrical portion fitted between both thrust plates 2 on a fixed shaft 1 having a pair of annular thrust plates 2 made of a magnetic member fixed to upper and lower portions.
- a sleeve 23 is rotatably fitted to the outside. Further, a pair of annular covers 4 made of a non-magnetic member are fixed to the sleeve 23 through a gap filled with the magnetic fluid 12 outside the pair of thrust plates 2 in the axial direction.
- An annular permanent magnet 25 is sandwiched between the sleeve 23 and the annular cover 4 radially outward from both ends of the magnetic fluid 12.
- the sleeve 23 has two upper and lower communication holes 24 formed therein.
- the upper and lower communication holes may be provided at one place, or may be provided at three or more places.
- dynamic pressure grooves are provided on the axial inner surface of the thrust plates 2 and 2 or the axial outer surface of the convex cylindrical portion of the facing sleeve 23 and the radial outer surface of the shaft 1 or the radial inner surface of the convex cylindrical portion of the facing sleeve 23. It is common to open.
- the upper and lower thrust bearings 5, 5' and the radial bearings 7, 7 'and the magnetic fluid holding amount of the reservoir 10 do not become imbalanced or die.
- the magnetic fluid 12 is maintained at a constant level, and there is no reduction in bearing performance and no leakage or scattering of the magnetic fluid 12.
- FIG. 14 (a) is a longitudinal sectional view schematically showing an embodiment of the invention according to claim 7, and FIG. 14 (b) is a sectional view taken along the line X_X in FIG. 14 (a).
- a hydrodynamic bearing device is a non-magnetic member having a convex cylindrical portion fitted between two thrust plates 2 on a fixed shaft 1 having a pair of annular thrust plates 2 made of a magnetic member fixed to upper and lower portions.
- a sleeve 26 is rotatably fitted to the outside.
- a pair of annular covers 4 made of a non-magnetic member are fixed to the sleeve 26 via a gap filled with the magnetic fluid 12 outside the pair of thrust plates 2 in the axial direction.
- An annular permanent magnet 25 is sandwiched between the sleeve 26 and the annular cover 4 at a position radially outward from both ends 13 and 13 of the magnetic fluid 12.
- a vertical communication hole 27 and a horizontal communication hole 28 are formed in the sleeve 26 at two places, and a fluorine rubber ball 29 for sealing is arranged.
- the horizontal communication hole 28 may be formed at one place or a plurality of horizontal communication holes, but it is necessary to connect to the upper and lower communication holes 27.
- Spiral dynamic pressure grooves 6 and 7 are formed on the axial inner surfaces of the thrust plates 2 and 2 and the radial outer surface of the shaft 1.
- the dynamic pressure groove 6 may be formed on the axially outer surface of the convex cylindrical portion of the sleeve 26.
- the dynamic pressure groove 7 may be formed on the radially inner surface of the convex cylindrical portion of the sleeve 26.
- the dynamic pressure groove 6 is not limited to the spiral dynamic pressure groove as long as it allows the magnetic fluid 12 to flow in the shaft direction.
- the shape may be a herringbone dynamic pressure groove.
- the magnetic fluid 12 flows inward in the radial direction due to a dynamic pressure structure or the like during rotation, and the dynamic pressure bearing portions 5, 7, 5, Through 7
- the fluid flows back from the horizontal communication hole 28 to the dynamic pressure bearing portions 5, 7, 5, and 7 through the upper and lower communication holes 27. Since the magnetic fluid 12 does not stay locally due to this reflux, the magnetic fluid 12 does not partially deteriorate, so that the life of the hydrodynamic bearing device is extended, and stable use over a long period of time is possible.
- air bubbles mixed during the injection of the magnetic fluid may remain or enter between the radial bearings 7 and 7 in the axial direction.
- Such air bubbles may enter the radial bearings 7, 7 as the bearing rotates, which may adversely affect the dynamic pressure generation function.
- the air bubbles between the two radial bearing portions 7, 7 are recirculated through the horizontal communication hole 28 together with the magnetic fluid 12, and only the air bubbles contained in the returned magnetic fluid 12 are removed.
- the bearing function is not impaired by bubbles remaining in the bearing and the like.
- FIG. 15 is a longitudinal sectional view schematically showing an embodiment of the invention according to claim 8.
- the hydrodynamic bearing device includes a fixed shaft 1 in which a pair of annular thrust plates 2 and 2 made of a magnetic material are fixed to upper and lower portions, and a convex cylindrical portion fitted between the two thrust plates 2 and 2.
- a sleeve 3 made of a non-magnetic member is rotatably fitted to the outside.
- a pair of annular covers 30 and 30 made of a non-magnetic member are fixed to the sleeve 3 via a gap filled with the magnetic fluid 12 outside the pair of thrust plates 2 and 2 in the axial direction.
- An annular permanent magnet 25 is sandwiched between the sleeve 3 and the annular cover 30 at a position radially outward from both ends 13 and 13 of the magnetic fluid 12.
- dynamic pressure grooves are formed on the axially inner surface of the thrust plates 2 and 2 or the axially outer surface of the convex cylindrical portion of the facing sleeve 3 and the radially outer surface of the shaft 1 or the radially inner surface of the convex cylindrical portion of the facing sleeve 3. Generally, it is provided.
- annular step is formed at an end of the annular cover 30 on the opening 11 side in the present embodiment so as to hold both ends 13 and 13 of the magnetic fluid 12. Due to the annular step, the distance between the thrust plate 2 and the annular cover 30 is 0.5 mm near the opening 11. However, in the radially outward direction without a step, the diameter becomes as narrow as 0.3 mm.
- the same capillary force acts on the opening 11, so that a gap of at least 0.5 mm or more is required to sufficiently suppress the capillary phenomenon at rest.
- the volume of the magnetic fluid 12 that must be held increases when the reservoir capacity is increased by increasing the distance between the annular cover 30 and the thrust plate 2. Therefore, when an impact or the like is applied from the outside, the magnetic fluid 12 cannot be held by the magnetic force, and the possibility that the magnetic fluid 12 is scattered or leaked increases.
- the intermolecular force between the thrust plate 2 and the annular cover 30 and the magnetic fluid 12 acting on the narrow portion at the time of rest, and the intermolecular force of the magnetic fluid 12 As a result, the direction in which each intermolecular force acts at the annular step of the annular plate changes, thereby suppressing the capillary phenomenon. As a result, it becomes difficult for the magnetic fluid to climb over the step, and together with the magnetic sealing means, the end 13 of the magnetic fluid 12 can be prevented from reaching the annular plate opening 11, and the volume of the reservoir 10 becomes more than necessary. It can be prevented from becoming larger, and the impact resistance against scattering or leakage of the magnetic fluid is improved.
- FIG. 16 is a longitudinal sectional view schematically showing another embodiment of the present invention.
- the hydrodynamic bearing device has a convex cylindrical portion that fits between the thrust plates 2 and 2 on a fixed shaft 31 having a pair of annular thrust plates 2 and 2 made of a magnetic member fixed to upper and lower portions.
- a sleeve 33 made of a non-magnetic member is rotatably fitted to the outside.
- a pair of annular covers 4 and 4 made of a non-magnetic member are fixed to the sleeve 33 via a gap filled with the magnetic fluid 12 outside the pair of thrust plates 2 and 2 in the axial direction.
- Annular permanent magnets 25, 25 are sandwiched between the sleeve 33 and the annular covers 4, radially outward of both ends 13, 13 of the magnetic fluid 12.
- the dynamic pressure grooves are formed on the axially inner surface of the thrust plates 2 and 2 or the axially outer surface of the facing cylindrical portion of the sleeve 33 and the radially outer surface of the shaft 1 or the radially inner surface of the facing cylindrical portion of the sleeve 33.
- radial bearings 7 and 7 are located radially outward from both ends 13 and 13 of magnetic fluid 12 near the opening. The radial bearings 7 and 7 in the present embodiment need to be radially outward from positions substantially the same as both end surfaces of the magnetic fluid 12.
- the internal pressure of the magnetic fluid 12 is increased by the action of the centrifugal force.
- the force and the internal pressure are increased only by the magnetic fluid located radially outward from the magnetic fluid end faces 13 near the opening.
- the internal pressure is reduced.
- the magnetic fluid is injected without magnetically sealing one of the openings having the ends of the magnetic fluid.
- a sleeve 63 having a convex cylindrical portion fitted between the two thrust plates 62, 62 is rotatably fitted to a shaft 61 having a pair of annular thrust plates 62 fixed near both ends in the axial direction.
- Thrust bearing 65 that generates thrust dynamic pressure by the axial inner surface of the shaft and the axial outer surface of the convex cylinder, and radial bearing that generates the radial dynamic pressure by the inner peripheral surface of the convex cylinder and the outer peripheral surface of the shaft.
- a pair of annular covers 64, 64 are fixed to the sleeve 63 via a gap outside the axial direction of the thrust plate 62, and the gap between the thrust plate 62 and the ring cover 64 and A void or the like on the radially inner surface of the sleeve 63 facing the radially outer surface of the thrust plate 62 serves as a reservoir 70 for storing magnetic fluid, and a permanent magnet 75 is provided on the axially outer side of the annular cover 64 on the axially lower side. 'Stick After that, the magnetic fluid 72 is filled through the other annular cover 64 and the opening 11 of the shaft so that both ends 73, 73 of the magnetic fluid 72 are held in the gap between the thrust plate 62 and the annular cover 64.
- a permanent magnet 75 is fixed to the axially outer side of the annular cover 64 on the upper side in the axial direction.
- the magnetic fluid 72 can be injected into the gaps such as the dynamic pressure part and the reservoir 70 without being affected by the magnetic force of the permanent magnet 75.
- the magnetic fluid 72 is injected before the permanent magnets 75 and 75 'are fixed.
- a sleeve 63 having a convex cylindrical portion fitted between the thrust plates 62, 62 is rotatably fitted to a shaft 61 in which a pair of annular thrust plates 62 are fixed near both ends in the axial direction.
- a thrust bearing portion 65 that generates a thrust dynamic pressure by an axial inner surface of the plates 62 and 62 and an axial outer surface of the convex cylindrical portion, and a radial that generates a radial dynamic pressure by an inner peripheral surface of the convex cylindrical portion and an outer peripheral surface of the shaft.
- a bearing portion 67 is formed, and a pair of annular covers 64 is fixed to the sleeve 63 via a gap outside the thrust plate 62 in the axial direction, and the gap between the thrust plate 62 and the annular cover 64 and the thrust plate are formed.
- the space between the radially inner surface of the sleeve 63 and the radially outer surface of the sleeve 62 is used as a reservoir 70 for storing the magnetic fluid, and the magnetic fluid 72 is inserted into the space between the thrust plate 62 and the annular cover 64. After section 73, 73 is filled with magnetic fluid 72 from the opening 11 to be retained, to fix the permanent magnets 75, 75 'in the axial outer side of the annular cover 64.
- the magnetic fluid 72 can be injected into the gaps such as the dynamic pressure part and the reservoir 70 without being affected by the magnetic force of the permanent magnets 75 and 75 '.
- FIG. 18 is a longitudinal sectional view schematically showing a DC motor according to an embodiment of the present invention.
- the spindle motor shown in FIG. 18 includes a bracket 79 to which a stator core 78 is fixed, a shaft 81 having a lower part fixed to a central opening of the bracket 79, and a sleeve rotatably fitted to the shaft 81. 83, and a rotor hub 87 externally fitted to the sleeve 83.
- the upper end of the sleeve 83 is sealed by a counter plate 92, and the lower surface of the counter plate 92 facing the upper surface of the thrust plate 82 and the upper surface of the convex cylindrical portion of the sleeve 83 facing the lower surface of the thrust plate 82 provide a thrust bearing. 85, 85 '.
- the end 93 of the magnetic fluid 90 is fixed to the lower end of the sleeve 83 It is held in a gap between the formed annular cover 84 and a seal plate 97 formed with a magnet 96 fixed near the lower end of the shaft 81.
- a magnetic pole piece 94 is fitted on the annular cover 84.
- the pole piece 94 has a function of controlling the flow of lines of magnetic force in the sealing portion and increasing the magnetic flux density.
- the annular cover 84 and the seal plate 97 are formed of a non-magnetic member, and the pole piece 94 is formed of a magnetic member.
- a vertical communication hole 95 is formed in the sleeve 83.
- the upper and lower communication holes 95 are negatively attached to the side surface of the thrust plate 82. Pressure may be generated, and if a negative pressure is generated, bombing may be hindered or bubbles may be generated in the negative pressure generating portion. In such a case, it is possible to prevent the negative pressure from being generated in the thrust plate 82 by connecting the side surface portion of the thrust plate 82 to the liquid surface in contact with the atmospheric pressure through the upper and lower communication holes 95.
- the upper and lower communication holes 95 in the present embodiment are formed at two opposing locations. It is preferable to provide a plurality of such upper and lower communication holes 95 at equal intervals on the circumference. This is because it is necessary to balance the weight because the sleeve 83 provided with the upper and lower communication holes 95 rotates.
- the sleeve 83 and the rotor hub 87 are formed by external fitting.
- the rotor hub 87 and the sleeve 83 may be formed integrally.
- FIG. 19 is a longitudinal sectional view schematically showing a DC motor according to an embodiment of the present invention.
- the spindle motor shown in FIG. 19 has a bracket 79 to which a stator core 78 is fixed, a sleeve 103 having a lower portion fixed to a central opening of the bracket 79, and a sleeve 103 rotatably fitted in the sleeve 103.
- the shaft 101 to which the thrust plate 102 and the seal plate 117 are fixed, and the rotor hub 107 externally fitted to the shaft 101 also constitute a force.
- the lower end of the sleeve 103 is sealed by a counter plate 112, and the upper surface of the counter plate 112 facing the lower surface of the thrust plate 102, and the lower surface of the convex cylindrical portion of the sleeve 103 facing the upper surface of the thrust plate 102.
- the end 113 of the magnetic fluid 110 is an annular force fixed to the upper end of the sleeve 103. It is held in a gap between the bar 104 and the seal plate 117 on which the magnet 116 is formed.
- a magnetic pole piece 114 is fitted on the annular cover 104. The pole piece 114 has a function of controlling the flow of lines of magnetic force in the sealing portion and increasing the magnetic flux density.
- the annular cover 104 and the seal plate 117 are formed of a non-magnetic member, and the pole piece 114 is formed of a magnetic member.
- a vertical communication hole 115 is formed in the sleeve 103 to prevent the generation of a negative pressure on the side surface of the thrust plate 102.
- the upper and lower communication holes 115 in the present embodiment are formed at one place. This is because the sleeve 103 having the upper and lower communication holes 115 is fixed to the bracket 79 and does not rotate, so that it is not necessary to balance the weight.
- FIG. 20 is a longitudinal sectional view schematically showing a DC motor according to an embodiment of the present invention.
- the spindle motor shown in FIG. 20 has a bracket 36 to which a stator core 38 is fixed, a shaft 41 having an end fixed to a central opening of the bracket 36, and a rotatable outer fit with respect to the shaft 41. It comprises a sleeve 43 to which a permanent magnet 55 is fixed, and a rotor hub (sleeve) 37 to which the sleeve 43 and the rotor magnet 39 are fixed.
- the annular cover 44 is fixed to the rotor hub (sleeve) 37.
- the sleeve 43 and the rotor hub 37 are formed integrally, but the rotor hub 37 and the sleeve 43 may be fixedly formed by separate members.
- a pair of thrust plates 42 are fixed near both ends in the axial direction of the fixed shaft 41, and a thrust bearing portion is formed on the inner surface in the axial direction of the thrust plate 42 and the outer surface in the axial direction of the convex cylindrical portion of the sleeve 43 facing the thrust plate 42.
- Radial bearing portions 47 are formed on the radially inner surface of the convex cylindrical portion of the sleeve 43 and the radially outer surface of the opposite shaft 41.
- Each bearing is filled with a magnetic fluid, and thrust dynamic pressure is generated in the thrust bearings 45 and 45, and radial dynamic pressure is generated in the radial bearings 47.
- the axial inner surface of the thrust plates 42, 42 or the axial outer surface of the convex cylindrical portion of the facing sleeve 43 and Generally, a dynamic pressure groove is provided on the radially outer surface of the shaft 41 or the radially inner surface of the protruding cylindrical portion of the sleeve 43 opposed thereto.
- the magnetic fluid 52 is a reservoir 50 formed by the outer surfaces of the upper and lower surfaces of the convex cylindrical portion of the sleeve 43 in the axial direction, the lower surface of the sleeve 43, the permanent magnet 55, and the annular cover 44, and the surface of the thrust plate 42 that faces each. Filled up to the vicinity of the opening 11 through.
- both ends 53 of the magnetic fluid 52 are held between the annular cover 44 and the thrust plate 42 by the magnetic fluid 52 being attracted to the permanent magnet 55.
- the ends 53 of the magnetic fluid 52 are balanced by centrifugal force. Also, since there is almost no effect of capillary action, leakage and scattering of the magnetic fluid 52 to the outside of the dynamic pressure bearing device from the opening 11 where the end 53 of the magnetic fluid 52 does not move to the radially inner opening 11 Absent.
- the dynamic pressure bearing device holds the magnetic fluid by the magnetic field when stationary, and holds the magnetic fluid mainly by centrifugal force during rotation, and
- the storage capacity of the magnetic fluid used for the magnetic fluid can be given a margin, the service life of the hydrodynamic bearing device can be prolonged by evaporating the lubricating oil that is the medium of the magnetic fluid, and the magnetism due to the temperature rise of the hydrodynamic bearing Capable of sufficiently responding to volume expansion of fluid, preventing bearing performance from deteriorating during rotation, and preventing leakage and scattering of magnetic fluid, which may be caused by the unstable phenomenon of dynamic pressure bearing bombing. it can.
- Such dynamic pressure bearing devices include polygon mirrors, fans, multimedia products such as CD 'DVD' MOs, optical disks, various small precision motors such as fans, home appliances, housing, ⁇ A equipment, automotive, and industrial medium Not only motors, but also machine tools, medical machines, turbines, reels, vehicles such as cars, trains, ships, aircraft, etc., semiconductors' electronics' electrical products', and other machines and other manufacturing equipment can be used.
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- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Power Engineering (AREA)
- Sliding-Contact Bearings (AREA)
- Magnetic Bearings And Hydrostatic Bearings (AREA)
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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JP2005511034A JP4445924B2 (ja) | 2003-06-27 | 2004-06-24 | 動圧軸受装置及びそれを用いた回転装置 |
US10/558,601 US8007176B2 (en) | 2003-06-27 | 2004-06-24 | Dynamic pressure bearing and rotation machine employing same |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003-185075 | 2003-06-27 | ||
JP2003185075 | 2003-06-27 |
Publications (1)
Publication Number | Publication Date |
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WO2005001300A1 true WO2005001300A1 (ja) | 2005-01-06 |
Family
ID=33549640
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2004/008885 WO2005001300A1 (ja) | 2003-06-27 | 2004-06-24 | 動圧軸受装置及びそれを用いた回転装置 |
Country Status (4)
Country | Link |
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US (1) | US8007176B2 (ja) |
JP (1) | JP4445924B2 (ja) |
CN (1) | CN100543324C (ja) |
WO (1) | WO2005001300A1 (ja) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2424385A (en) * | 2005-03-22 | 2006-09-27 | Frank Peter Wardle | Aerostatic device damper |
JP2008298282A (ja) * | 2007-05-31 | 2008-12-11 | Taida Electronic Ind Co Ltd | モーター及びその磁性オイルシール構造 |
US8353630B2 (en) * | 2007-10-09 | 2013-01-15 | Hgst, Netherlands B.V. | Fluid dynamic bearing with a labyrinth seal |
Families Citing this family (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006022931A (ja) * | 2004-07-09 | 2006-01-26 | Matsushita Electric Ind Co Ltd | スピンドルモータ |
US20080211334A1 (en) * | 2004-07-09 | 2008-09-04 | Yasunori Tokuno | Spindle motor |
JP2006064171A (ja) * | 2004-07-28 | 2006-03-09 | Minebea Co Ltd | 流体動圧軸受、該流体動圧軸受を備えたスピンドルモータ並びに記録ディスク駆動装置 |
JP3930874B2 (ja) * | 2004-07-28 | 2007-06-13 | Tdk株式会社 | 磁気記録装置 |
JP2007113705A (ja) * | 2005-10-20 | 2007-05-10 | Minebea Co Ltd | 流体動圧軸受装置、モータおよびディスク記憶装置 |
DE102006054626B4 (de) * | 2006-11-17 | 2014-05-15 | Minebea Co., Ltd. | Spindelmotor mit fluiddynamischem Lagersystem |
KR100997189B1 (ko) * | 2008-11-14 | 2010-11-29 | 삼성전기주식회사 | 모터 |
JP2012193842A (ja) * | 2010-08-09 | 2012-10-11 | Nippon Densan Corp | モータおよびディスク駆動装置 |
US10954597B2 (en) * | 2015-03-17 | 2021-03-23 | Asm Ip Holding B.V. | Atomic layer deposition apparatus |
JP6424783B2 (ja) * | 2015-09-18 | 2018-11-21 | 株式会社オートネットワーク技術研究所 | 端子付き電線、及び配線モジュール |
DE102019213545A1 (de) * | 2019-09-05 | 2021-03-11 | Robert Bosch Gmbh | Gehäuse eines elektrischen Antriebs |
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US4694213A (en) * | 1986-11-21 | 1987-09-15 | Ferrofluidics Corporation | Ferrofluid seal for a stationary shaft and a rotating hub |
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JPH0612128B2 (ja) * | 1988-06-22 | 1994-02-16 | 株式会社日立製作所 | 軸受装置 |
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US5372432A (en) * | 1993-07-16 | 1994-12-13 | Nippon Ferrofluidics Corporation | Dynamic pressure bearing assembly |
JP3541325B2 (ja) * | 1994-04-01 | 2004-07-07 | 株式会社フェローテック | 動圧軸受装置 |
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JP3578948B2 (ja) | 1999-10-01 | 2004-10-20 | 日本電産株式会社 | モータ |
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2004
- 2004-06-24 US US10/558,601 patent/US8007176B2/en not_active Expired - Fee Related
- 2004-06-24 WO PCT/JP2004/008885 patent/WO2005001300A1/ja active Application Filing
- 2004-06-24 JP JP2005511034A patent/JP4445924B2/ja not_active Expired - Fee Related
- 2004-06-24 CN CNB2004800178865A patent/CN100543324C/zh not_active Expired - Fee Related
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US4694213A (en) * | 1986-11-21 | 1987-09-15 | Ferrofluidics Corporation | Ferrofluid seal for a stationary shaft and a rotating hub |
JPH08109923A (ja) * | 1994-10-13 | 1996-04-30 | Hitachi Ltd | 磁性流体供給多孔質含油軸受ユニット |
JPH08210365A (ja) * | 1994-11-29 | 1996-08-20 | Sankyo Seiki Mfg Co Ltd | 軸受のシール装置 |
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JPH11247858A (ja) * | 1998-03-03 | 1999-09-14 | Seiko Instruments Inc | 液体動圧軸受、スピンドルモータ、及び回転体装置 |
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GB2424385A (en) * | 2005-03-22 | 2006-09-27 | Frank Peter Wardle | Aerostatic device damper |
JP2008298282A (ja) * | 2007-05-31 | 2008-12-11 | Taida Electronic Ind Co Ltd | モーター及びその磁性オイルシール構造 |
US8353630B2 (en) * | 2007-10-09 | 2013-01-15 | Hgst, Netherlands B.V. | Fluid dynamic bearing with a labyrinth seal |
Also Published As
Publication number | Publication date |
---|---|
JPWO2005001300A1 (ja) | 2007-04-12 |
CN1813138A (zh) | 2006-08-02 |
US20060273673A1 (en) | 2006-12-07 |
CN100543324C (zh) | 2009-09-23 |
JP4445924B2 (ja) | 2010-04-07 |
US8007176B2 (en) | 2011-08-30 |
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