JP2004003613A - Fluid bearing for spindle motor, spindle motor and disk drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid bearing for a spindle motor having the minimum size and capable of being manufactured at reasonable cost. <P>SOLUTION: The fluid bearing for the spindle motor is equipped with a shaft 62 and a bearing bush 60a which surrounds the shaft 62 in a state of having very narrow radial clearance. A groove is formed to form a pressure formed area on the outer surface of the shaft 62 and/or inner surface of the bearing bush 60a. The bearing bush 60a is constituted by a single member along with a flange 60, a base plate or the other stationary body members of the spindle motor. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a brushless DC motor used as a spindle motor in a disk drive, and more particularly to a fluid bearing for such a spindle motor.
[0002]
[Prior art]
Disk drive systems have been used for storing digital information in computers and other electronic devices for many years. The information is recorded on concentric recording tracks of the magnetic disk, where the actual information is stored in the form of magnetic transitions in the disk coating. The disk itself is rotatably mounted on a motor-driven spindle, where information is accessed by a transducer located on a swivel arm that moves radially across the surface of the disk. In order to ensure a faultless exchange of information, the read / write head or transducer needs to be precisely positioned with respect to the recording tracks of the disc. Consequently, a prerequisite for reliable data transfer is a stable and accurate rotary bearing for the spindle.
[0003]
In brushless DC motors of the type described above used as spindle motors in disk drives, conventionally the rotating spindle comprises a roller bearing according to the prior art. Accurate running and accuracy are achieved by tightly mounting the bearing under a given preload without play. In addition, roller members and bearing rings with limited dimensional tolerances are used. The drawbacks from this system, such as disturbing rotational noise and limited shock resistance, have been accepted and tolerated.
[0004]
Fluid or hydrodynamic bearings have significant improvements over conventional ball bearings in spindle motors. In this type of system, a lubricating fluid (gas or liquid) acts to separate the bearing surface between the stationary substrate or housing and the rotating spindle or hub of the motor. For example, fluid lubricants including oil and complex ferromagnetic or air are used in hydrodynamic bearing systems.
[0005]
Fluid bearings have the advantage over ball bearings of improved running accuracy, greater impact resistance and lower noise formation.
[0006]
Spindle motors for data-bearing disks, in which the shaft fixed to the rotor has a hydrodynamic bearing system, are known in the art. Prior art hydrodynamic bearing systems include, for example, a bearing bush that can be closed at one end by an opposing plate. Within this bearing bush is a shaft that is wrapped in a fluid, preferably oil. One or more groove patterns are formed on the inner surface of the bearing bush or the outer surface of the shaft and serve to generate hydrodynamic bearing pressure.
[0007]
Further, a fluid bearing having an axial pivot bearing in a low-power spindle motor is also known, and by supporting the bearing at the center of rotation, an axial bearing load is received in one direction on an opposed plate, and Directional opposing loads are generated magnetically, for example, by the interaction of the rotor and the stator. However, these types of hydrodynamic bearings have very low axial stiffness and are problematic, for example, for use in hard disk drives. Because such applications require axial stiffness in both axial directions. On the other hand, hydrodynamic bearings with axial pivot bearings have the advantage of very low friction losses and consequently very low power consumption.
[0008]
An example of a fluid bearing corresponding to the above-described conventional technology can be known from Patent Document 1 below.
[0009]
[Patent Document 1]
U.S. Pat. No. 4,948,836
[0010]
[Problems to be solved by the invention]
The invention particularly relates to a hydrodynamic bearing for a spindle motor for a disk drive such as a hard disk drive having very small dimensions, for example as used for laptop computers. Spindle motors for small size disk drives and with hydrodynamic bearings need to have low power consumption, especially when equipped in portable, battery powered devices.
[0011]
Conventionally, spindle motors with hydrodynamic bearings usually consist of an assembly of separate components. Specifically, in particular, the bearing bush is non-rotatably mounted on a flange, a base plate, a frame, a support, or a member of such a spindle motor, and the shaft is held in the bearing bush. In order to mount the bearing bush to the flange or the base plate, these members usually comprise a flange tube in which the bearing bush is held non-rotatably. The bearing bush and the flange tube are permanently joined together by joining, welding, pressing or any other method.
[0012]
Precise machining and an assembly of perfectly aligned components are the keys to the efficient functioning of hydrodynamic bearings. In order to assemble the current hydrodynamic bearings, a certain minimum wall thickness is required for each component, on the one hand stipulated by the manufacturing technology, and on the other hand, those required for sufficient mechanical stability Derived from
[0013]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a fluid bearing for a spindle motor used in particular in a hard disk drive, said fluid bearing having a minimum dimension suitable for use in a small disk drive and having a reasonable It can be manufactured at a low cost.
[0014]
[Means for Solving the Problems]
This object is achieved by a hydrodynamic bearing having the features of claim 1.
[0015]
In accordance with the present invention, the bearing bush and flange, base plate or other stationary member of the spindle motor are configured as a single member, so that additional space is formed within the motor. In the prior art, for rigidity and manufacturing purposes, a minimum wall thickness of about 1 mm for the bearing bush and a minimum wall thickness of about 0.3 mm for the flanged tube, for a total of 1 While a minimum wall thickness of .3 mm is required, in the hydrodynamic bearing according to the invention it is possible to achieve a wall thickness of less than 1 mm for the bearing bush integrated in the flange. In practice, in a two-part configuration for a hydrodynamic bearing having a separate bearing bush and, as mentioned above, a housing for the bearing bush such as a flange, it is not possible to form such a wall thickness. Impossible. A configuration corresponding to the invention allows a considerable space to be reserved within the diameter of the bearing bush. This increases the expectation that the hydrodynamic bearings described in the present invention will be used for very small size spindle motors.
[0016]
The fluid bearing according to the present invention is particularly suitable as a rotary bearing for a rotor of a spindle motor used in a hard disk drive, and has a shape of 2.5 inches, 1.8 inches and smaller with respect to a power magnetic disk. Have a factor.
[0017]
The invention has the additional advantage that the hydrodynamic bearing for a spindle motor can be made up of fewer parts than used in the prior art. This allows reducing costs, simplifying the assembly process, and minimizing the total number of bearing parts and bearing tolerances. The bearings used in the present invention also require less finishing steps after assembly of the components than required in the prior art.
[0018]
A bearing according to the invention comprises a shaft and a bearing bush surrounding the shaft with very narrow radial clearance. Grooves are formed on the outer surface of the shaft and / or the inner surface of the bearing bush to form a pressure generating region. The fluid bearing according to the present invention is characterized in that the bearing bush is formed integrally with the flange, the base plate or another stationary body member of the DC motor.
[0019]
A radial bearing is formed between the shaft and the bearing bush. For the formation of an axial bearing according to the invention, a pivot bearing is preferably formed between the bottom sealing the bearing bush and the bottom of the shaft. In one embodiment of the invention, this bottom surface can be formed by an opposing plate sealing one end of the bearing bush. Instead, the bearing bush integrated with the flange is constructed with a closed end face. In the hydrodynamic bearing according to the invention, the bearing bush has at least one open end from which the shaft projects. An annular stop is preferably mounted on the open end of the bearing bush and is non-rotatably connected to the bearing bush. In a preferred embodiment of the present invention, the shaft has a shoulder portion, and a hydrodynamic axial bearing is formed between the shoulder portion and an opposing surface of the stopper. The hydrodynamic axial bearing formed between the shoulder and the opposing surface of the stopper has a function as a thrust bearing, and receives an axial load in the direction of the open end of the bearing bush. At the same time, this axial bearing design according to the present invention prevents the shaft from deviating from the bearing bush. An axial load applied in the opposite direction is received by the pivot bearing.
[0020]
When constructed according to the present invention, the hydrodynamic bearing is formed with minimal dimensions, good axial stiffness, and low power loss, and can be used when mounting in various locations It is.
[0021]
In one embodiment of the invention, the stopper can take the form of an annular cap and is fitted into the open end of a bearing bush from which the shaft end located at the stopper projects, The shaft end protrudes from the bearing through the central opening of the shaft. In another embodiment, the stop is formed in an annular disk and is attached to the open end of the bearing bush.
[0022]
The groove pattern is formed on the shoulder and / or the opposing surface of the stopper to form a hydrodynamic axial bearing. Depending on the configuration, one or two groove patterns can be formed, in particular, on the inner surface of the shaft and / or the bearing bush, forming one or two radial bearings.
[0023]
In one preferred embodiment of the invention, the end of the shaft located at the stopper projects from the central opening of the stopper, and an annular conical slope is provided between the inner surface of the central opening of the stopper and the shaft. A (tapered) space is formed and connected by a radial bearing gap between the shaft and the bearing bush to the capillary annular gap to form a so-called capillary seal. The basic principle of such a “capillary seal” is described, for example, in US Pat. No. 5,667,309. This conical space (tapered region) forms an expansion volume and reservoir and is connected to a radial bearing gap, where the bearing fluid can rise as the fluid level rises with increasing temperature It is. This prevents bearing fluid from escaping from the radial bearing gap. Further, when the bearing fluid evaporates, the bearing fluid can be sequentially supplied to the bearing gap.
[0024]
The annular tapered region is preferably formed by an inclined shaft located at the stopper, or by a chamfer at the center of the stopper and in the internal opening.
[0025]
In one preferred embodiment of the invention, the pivot bearing is accommodated by a bearing bush. At the location of the pivot bearing, a small groove pattern can be formed on the curved shaft end and / or on the opposing surface of the bearing bush, to avoid contact between the shaft and the bearing bush during operation. Further, the curved shaft end and / or the opposing surface of the bearing bush can be provided with a very hard coating to minimize wear and breakage of the bearing bush and shaft upon contact. . By forming the second axial bearing as a pivot bearing, the overall power loss to the hydrodynamic bearing will be kept to a minimum.
[0026]
Various patterns have been proposed for forming grooves in radial bearings and axial bearings, for example, spiral or symmetric or asymmetric herringbone patterns.
[0027]
According to the present invention, the entire wall thickness of the bearing bush integrated with the flange or the base plate is 1.2 mm or less, depending on the embodiment, and the aspect ratio (l / d) is 2 or less. Then, it is preferably smaller than 0.8 mm. Here, l is the length of the bearing bush measured from the upper end of the flange to the open end of the bearing bush, and d represents the inner diameter of the bearing bush.
[0028]
In a special embodiment of the invention, the shaft projecting from the open end of the bearing bush has a smaller diameter than the shaft portion remote from the open end surrounded by the bearing bush, the diameter of the shaft being Gradually increases along the axial direction of the shaft portion away from the open end of the bearing bush in the direction of the bottom surface of the bearing bush. In particular, the shaft portion and the bearing bush surrounding the shaft portion are configured complementarily to each other such that the bearing bush receives radial and axial loads from the shaft.
[0029]
The present invention also provides a spindle motor having a fluid bearing having the above-described configuration, and a disk device having such a spindle motor. In one embodiment, the shaft end is non-rotatably connectable to or mountable within a hub of a spindle motor, the hub supporting a recording disk of a disk drive.
[0030]
To form a hydrodynamic axial bearing, the hydrodynamic bearing according to the invention can comprise a thrust washer which is non-rotatably mounted on the shaft. The thrust washer interacts with the opposing plate within the bearing bush to form an axial hydrodynamic thrust bearing.
[0031]
The present invention also provides a spindle motor having the above-described fluid bearing, and a disk drive having such a spindle motor. In one embodiment, the shaft end is fixed within the hub of the spindle motor or non-rotatably coupled to the hub.
[0032]
The present invention will be described in detail below based on preferred embodiments with reference to the drawings.
[0033]
BEST MODE FOR CARRYING OUT THE INVENTION
The spindle motor shown in FIG. 1 includes a flange or a base plate 10 for mounting on a disk device (not shown). The flange 10 is non-rotatably connected to the bearing bush 12 for the shaft 14 of the bearing device. The rotor 16 is non-rotatably connected to the shaft 14 and rotates with respect to the flange 10 and the bearing bush 12. Stator 18 is non-rotatably coupled to flange 10.
[0034]
The rotor 16 includes a hub 20 and a shaft 14 fixed to the center of the hub 20. The rotor magnet 22 is coupled to the inner peripheral wall of the hub 20, that is, pressed or joined. The outer peripheral wall of the hub 20 is formed in a shape capable of holding one or a plurality of magnetic disks (not shown).
[0035]
The stator 18 includes a stack 24 and a stator winding 26 in which a coil is wound around the stack 24. The annular permanent magnets 22 mounted on the stator 18 and the rotor 16 or the hub 20 are separated from each other by a small coaxial gap, an air gap 28.
[0036]
The shaft 14 is divided into two parts, a shaft portion 30 having a larger diameter and a shaft portion 32 having a smaller diameter. The bearing bush 12 is a cylindrical member in which a cylindrical hole 34 is formed so as to fit the shaft 14. In order to form an annular conical inclined space (tapered region) called a so-called capillary seal portion between the inner surface of the bearing bush 12 and the shaft 14, a cylindrical hole 34 at an open end of the bearing bush 12 is formed. The portion has a radius that is slightly larger than the other portions of the cylindrical bore 34.
[0037]
A cap portion 36 is formed at the open end of the bearing bush 12 and is fitted to the bearing bush 12. The cap portion 36 is annular and has an opening inside the central portion having a smaller diameter than the cylindrical hole 34. The cap portion 36 is fitted to the shaft portion 32 having a small diameter, and is provided when the spindle motor receives an impact due to a radial overlap with the shaft portion 30 having a large diameter or when the spindle motor is in an inverted position. In operation, the shaft 14 is prevented from deviating from the bearing bush 12.
[0038]
The shaft 14 is housed in a cylindrical hole 34 of the bearing bush 12. The portion of the shaft 14 inserted into the cylindrical hole 34 includes the shaft portion 30 having a large diameter. At the shaft end 38 received by the bearing bush 12, the radius, together with the opposing inner surface of the bearing bush 12, is configured to form a pivot bearing. Grooves are formed in the shaft end 38 and / or the opposing inner surface of the bearing bush 12 to prevent physical contact during operation.
[0039]
The radial bearing gap 40 between the bearing bush 12 and the shaft 14 is filled with a bearing fluid, preferably a lubricating oil. In order to form a radial bearing, a pressure-forming groove is formed either on the outside of the shaft 14, preferably on the shaft part 30 with a large diameter, or on the inside surface of the bearing bush 12. One or two aggregated grooves can be formed and, if necessary, one or two radial bearings.
[0040]
A shoulder or step 44 is formed in the shaft 14 between the large diameter shaft portion 30 and the small diameter shaft portion 32 and interacts with the cap portion 36. The cap portion 36 also functions as a stopper, and forms a hydrodynamic axial bearing between the surface of the cap portion 36 facing each other and the shoulder portion 44 of the shaft 14. Grooves can be formed in these opposing surfaces to form an axial bearing.
[0041]
A preload back yoke 42 is mounted on the flange 10. The preload back yoke 42 interacts with the rotor magnet 22 to apply a force to the rotor 16 to pull the rotor 16 toward the flange 10.
[0042]
As seen in FIG. 1, the bearing bush 12 is held by the tubular portion 50 of the flange 10 so that the overall wall thickness is comprised of the bearing bush 12 and the wall thickness of the flange tubular portion 50. It is formed as follows.
[0043]
To reduce the size of the hydrodynamic bearing, the present invention provides a bearing bush to be integrated into a flange, a base plate of a spindle motor or the like as a single piece. Preferred embodiments of various assemblies for a spindle motor having a hydrodynamic bearing according to the present invention are shown in FIGS. Further elements of a spindle motor, such as a rotor, can be configured in a similar manner as shown in FIG. 1, which illustrates only one exemplary configuration of the spindle motor, and the invention is not limited thereto. .
[0044]
FIG. 2 shows an assembly for a spindle motor having a hydrodynamic bearing according to the first embodiment of the present invention. This assembly consists of a flange 60 having an integrated bearing bush 60 a surrounding a shaft 62 with a narrow radial clearance forming an air gap 64. Together with the opposing inner surface 66, the shaft 62 forms a pivot bearing at one end received by the flange 60. At the other end, the shaft 62 protrudes from the opening end of the bearing bush 60 a of the flange 60. The shaft 62 has a step or shoulder 68 that interacts with the stopper 70. In the embodiment shown in FIG. 2, the stopper 70 is formed as a cap for the open end of the bearing bush 60a.
[0045]
A radial bearing is formed by the groove 72 formed on the outer surface of the shaft 62 or the inner surface of the bearing bush 60a. To form a hydrodynamic axial bearing, a groove is formed in the shoulder 62 and / or the opposing surface of the stopper 70 of the shaft 62. The axial bearing formed between the shoulder portion 68 and the stopper 70 functions as an auxiliary bearing that receives an axial load opposite to the load acting on the pivot bearing. The illustrated configuration allows the spindle motor to be operated in various installation positions. In reality, of course, the motor further comprises a rotor and a stator component, as shown in FIG.
[0046]
FIG. 3 shows an improvement of the fluid bearing of FIG. As in FIG. 2, the flange 60 is formed in a single piece with the bearing bush 60a. The bearing bush 60a surrounds the shaft 62 with a narrow radial clearance. The shaft 62 has a shoulder 68 at an end protruding from the open end of the bearing bush 60a. On this end surface, a bearing bush 60 a of the flange 60 is opposed to the shoulder portion 68, and a stopper 60 b surrounding the shaft 62 is formed. This stopper 60b is formed by the end of a bearing bush 60a having a small diameter. A groove can be formed again on the facing surface of the shoulder portion 68 and the stopper 60b in order to form a hydrodynamic axial bearing.
[0047]
The bearing bush 60a is sealed by an opposing plate 74 on the opposite end face. The opposing plate 74, together with the opposing end 76 of the shaft 62, forms a pivot bearing as described with reference to FIG. In the two embodiments shown in FIGS. 2 and 3, an additional groove pattern can be formed on the curved shaft end 76 and / or on the inside facing surface of the bearing bush 60a, and during operation, the physical position in the pivot bearing area is increased. Avoid or minimize contact.
[0048]
In the two embodiments shown in FIGS. 2 and 3, in the region of the open end of the bearing bush 60a, a coaxial tapered region 78 is formed in order to form a capillary seal as described above with reference to FIG. , Formed between the shaft 62 and the bearing bush 60a. In these figures, this is illustrated only in FIG.
[0049]
The two embodiments shown in FIGS. 2 and 3 are particularly suitable for very small spindle motors for disk drives having 2.5 inch, 1.8 inch and smaller form factors.
[0050]
Using the configuration described below with reference to FIGS. 4 and 5 and the configuration shown in FIGS. 2 and 3, it is possible to configure a spindle motor having a fluid bearing that requires a small number of parts. . This allows reducing costs and simplifying the assembly process. Furthermore, only a few finishing steps are required.
[0051]
Furthermore, the illustrated configuration has the advantage of securing space within the motor. In the embodiment shown in FIG. 3, the bearing bush 60a integrated with the flange 60 has a wall thickness of approximately 1.0 mm or less. In the range where the aspect ratio (L / D ratio) is 2 or less, the wall thickness of the bearing bush integrated with the flange is preferably smaller than 0.8 mm. Here, as shown in FIG. 3, L is the length of the bearing bush measured from the upper end of the flange, and D is the inner diameter of the bearing bush.
[0052]
With such a wall thickness, a two-part configuration with separate bearing bushes housed in the flange is virtually impossible to achieve. The arrangement according to the invention increases the expectation of equipping spindle motors with very small dimensions with hydrodynamic bearings.
[0053]
Another embodiment of the bearing described in the present invention is shown in FIG. FIG. 4 shows a flange 60 with an integrated bearing bush 60a. The bearing bush 60a surrounds the shaft 62 with a narrow radial clearance. The inner surface of the bearing bush 60a facing the shaft forms a stop 60b that interacts with the shaft 62. The shaft 62 has a conical portion 62a extending from the open end of the bearing bush 60a to the opposing plate 74. The inner contour of the bearing bush 60a is formed in a complementary manner to the shaft 62 having a conical shape. The conical portion 62a of the shaft 62 and / or the groove inside the bearing bush 60a form a fluid bearing capable of receiving radial and axial load components.
[0054]
In the illustrated embodiment, the bearing bush has a conical recess for receiving a shaft end shaped in a generally complementary manner. The complementary shape of the area inside the bearing bush and the shaft retained therein provide the shaft in the bearing bush with mechanical stability, radially and axially, to the inside of the bearing bush. The conical recess also prevents the shaft from deviating axially from the bearing bush. Opposite axial loads are received by stoppers formed in the bearing bushes.
[0055]
The recess in the bearing bush and the corresponding shaft end are formed such that the bearing bush receives radial and axial bearing loads. By changing the shape of this recess and the end of the shaft, in particular by changing the gradient or curvature on the inner wall of the recess or on the outside of the shaft, the axial and radial loads received by the bearing are limited to their respective limits. Applicable to conditions.
[0056]
In the bearing according to the invention, no additional radial and axial bearings are required other than the radial and axial bearings described above. However, if more horizontal stability is required, one or more radial bearings can be formed in the straight section of the shaft.
[0057]
In the embodiment shown in FIG. 4, the shaft 62 has, along with the facing surface of the facing plate 74, a flat end face 80 which forms a hydrodynamic axial thrust bearing. For this purpose, corresponding grooves can be formed in the end face 80 and / or the opposing face of the opposing plate 74. The axial load applied in the opposite direction is received by the inclined inner surface 60c of the bearing bush 60a functioning as a stopper.
[0058]
As an alternative, a pivot bearing can be formed on the shaft end face 80.
[0059]
The hydrodynamic bearing shown in FIG. 4 is also particularly suitable for very small spindle motor applications, especially for disk drives having a 2.5 inch or smaller form factor. Integrating the bearing bush into the flange results in improved use of space. This is because it is not necessary to provide a double member thickness for the bearing bush and a support for the bearing bush in the flange. Furthermore, as a result, fewer parts are required, and there is an advantage that the number of assembly steps can be reduced and the allowable dimension can be matched.
[0060]
Finally, FIG. 5 shows an assembly for a spindle motor having a hydrodynamic bearing according to a fourth embodiment of the present invention. FIG. 5 shows a flange 60 with an integrated bearing bush 60a. The bearing bush 60a surrounds the shaft 62 with a narrow radial clearance. The shaft 62 protrudes from the open end 82 of the bearing bush 60a. At the shaft bottom 84 housed by the bearing bush 60a, a thrust washer 86 is mounted on the shaft 62 and, together with the opposing plate 88, forms an axial thrust bearing, a commonly known technique. The thrust washer also securely holds the shaft 62 against axial movement within the bearing bush 60a. At the open end 82 of the bearing bush 60a in the embodiment shown in FIG. 5, a tapered region 90 is formed between the inner surface of the bearing bush 60a and the shaft 62, forming a so-called capillary seal.
[0061]
Similarly, in this embodiment, the wall thickness of the bearing bush 60a can be reduced at least partially to less than 1.0 mm, and in particular partially to about 0.5 mm. One or more groove patterns 92 are formed on the inner surface of the bearing bush 60a or the outer surface of the shaft 62 to form a pressure-generating region for the hydrodynamic radial bearing.
[0062]
The embodiment shown in FIGS. 2 to 5 corresponding to the invention is, in particular, a flange in which the bearing bush of the hydrodynamic bearing allows the motor to be easily mounted on one of the support plates of the disk drive, Alternatively, the motor is integrated with a base plate, a frame, or a support member of the motor for fixing the motor to the disk device. In other words, the bearing bush forms a single member with these members. A pressure forming groove for a hydrodynamic bearing can be formed in a bearing bush or base plate integrated with the flange. As a result, separate bearing bushes are not required, only few parts are required, leading to reduced costs and reduced man-hours for assembly. At the same time, the fact that no separate bearing bushes are required means that there is more space to form a hydrodynamic bearing on a small size spindle motor. For example, the flange can be manufactured from aluminum or steel and the bearing area can be provided with a hard coating.
[0063]
The hydrodynamic bearing design used in the present invention allows the spindle motor to operate in any desired mounting position, and can receive radial and axial bearing loads for each mounting position. . At the same time, the present invention provides a hydrodynamic bearing having a minimal axial length and sufficient axial stiffness, for example, for use in miniaturized disk drives.
[0064]
The features disclosed in this detailed description, the claims and the drawings are each important, and any combination is possible to realize the invention in various embodiments.
[0065]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the hydrodynamic bearing for spindle motors which has a minimum dimension and can be manufactured at a reasonable cost can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a spindle motor having a fluid bearing, showing an example of an embodiment of the present invention, for describing an environment encompassed by the present invention.
FIG. 2 is a cross-sectional view of a spindle motor assembly having a fluid bearing according to the first embodiment of the present invention.
FIG. 3 is a sectional view of a spindle motor assembly having a fluid bearing according to a second embodiment of the present invention.
FIG. 4 is a cross-sectional view of a spindle motor assembly having a fluid bearing according to a third embodiment of the present invention.
FIG. 5 is a sectional view of an assembly part for a spindle motor having a fluid bearing according to a fourth embodiment of the present invention.
[Explanation of symbols]
10 Flange (base plate)
12 Bearing bush
14 shaft
16 rotor
18 Stator
20 hubs
22 Rotor magnet
24 Stator stack
26 Stator winding
28 air gap
30 Shaft section having large diameter
32 Shaft with small diameter
34 Cylindrical hole
36 Cap part
38 Shaft end
40 Radial bearing clearance
42 preload back yoke
44 Shoulder
50 Flange cylindrical part
60 flange
60a bearing bush
60b stopper
62 shaft
62a Conical part of shaft
64 Radial bearing clearance
66 Inner surface of bearing bush
68 Shoulder
70 Stopper
72 grooves
74 Opposing plate
76 Shaft end
78 Inclined space (tapered area)
80 Axial bearing end face
82 Bearing bush open end
84 Shaft bottom
86 Thrust washer
88 Opposing plate
90 Inclined space (tapered area)
92 groove pattern

Claims (12)

A shaft and a bearing bush, wherein the bearing bush surrounds the shaft with a radial clearance, and forms a pressure forming region on an outer surface of the shaft and / or an inner surface of the bearing bush. A fluid bearing for a spindle motor, wherein a groove of
The bearing bush (60a) is configured as a single piece with a flange (60) or a base plate or other stationary body member of the motor;
A fluid bearing for a spindle motor. A pivot bearing is formed between one of the bottom surfaces sealing the bearing bush (60a) and one end surface of the shaft.
The fluid bearing for a spindle motor according to claim 1, wherein: The bottom surface is formed by an opposed plate that seals one end surface of the bearing bush (60a).
The fluid bearing for a spindle motor according to claim 2, wherein: The bearing bush (60a) has an open end from which the shaft (62) projects,
At the open end, an annular stopper (70, 60b) is arranged non-rotatably coupled to the bearing bush (60a),
The shaft (62) has a shoulder portion (68), and a hydrodynamic axial bearing is formed between the shoulder portion (68) and an opposing surface of the stopper (70, 60b).
The fluid bearing for a spindle motor according to any one of claims 1 to 3, wherein: The stopper (60b) is formed as a cap for sealing an end face of the bearing bush (60a) facing the bottom surface of the bearing bush (60a), and is disposed on the stopper (60b) via the stopper (60b). Shaft end protrudes from the bearing bush (60a),
The fluid bearing for a spindle motor according to claim 4, wherein: The stopper (60b) is formed as an annular disk, and is attached to one end surface of the bearing bush (60a) facing the bottom surface of the bearing bush (60a),
A shaft end disposed on the stopper (60b) projects from the bearing bush (60a) via the stopper (60b).
The fluid bearing for a spindle motor according to claim 4, wherein: A groove pattern is formed on the facing surface of the shoulder portion (68) and / or the stopper (60b).
The fluid bearing for a spindle motor according to any one of claims 4 to 6, wherein: A shaft end disposed on the stopper (60b) projects from the bearing bush (60a) through a central opening of the stopper (60b);
An annular conical inclined space is formed between the inner surface of the central opening of the stopper (60b) and the shaft (62) to form a capillary seal.
The fluid bearing for a spindle motor according to any one of claims 4 to 7, wherein: The overall wall thickness of the bearing bush (60a), at least in part of the bearing bush (60a), is less than 1.0 mm, preferably less than about 0.5 mm;
The fluid bearing for a spindle motor according to any one of claims 1 to 8, wherein: The bearing bush (60a) has an open end from which the shaft (62) projects,
The shaft (62) has a smaller diameter at the open end of the bearing shaft (60a) than at a shaft portion remote from the open end, and the shaft (62) is attached to the bearing shaft (60a). Surrounded,
The diameter of the shaft is increased in the direction of the bottom surface of the bearing bush so that the bearing bush (60a) receives radial and axial bearing loads from the shaft (62). As it moves away from the end, it gradually increases along the axial direction of the shaft portion,
The fluid bearing for a spindle motor according to any one of claims 1 to 9, wherein: A spindle motor having a hydrodynamic bearing according to any one of claims 1 to 10. A disk drive comprising the spindle motor according to claim 11.

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