JP2005117713A - Fluid bearing motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid bearing motor capable of attaining a sufficient angular rigidity even when a thin hard disc is employed by using a fluid bearing part having a plurality of kinds of bearing including a gas bearing employing a gas as a working fluid and a liquid bearing employing a liquid as a working fluid. <P>SOLUTION: A dynamic pressure generating groove is formed in at least any one of the outer circumferential surface of a shaft 5 and the inner circumferential surface of a sleeve 3, and the gap between the outer circumferential surface of the shaft 5 and the inner circumferential surface of the sleeve 3 is filled with a liquid as a working fluid to constitute a radial liquid bearing 8 as a liquid bearing. A dynamic pressure generating groove is formed in at least any one of the inner circumferential side bottom face 6a of the rotor 6 of a motor and the surface of a thrust flange 2 facing the inner circumferential side bottom face 6a thus constituting a thrust gas bearing 9 as a gas bearing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fluid dynamic bearing motor suitable for a spindle motor for a hard disk device.

  Along with the recent increase in capacity of hard disk drives, as a bearing used in spindle motors of hard disk drives, instead of the conventional ball bearings, the rotation accuracy is superior to that of ball bearings and the noise is also excellent. Many fluid bearings are being used.

  Hard disk devices are conventionally used as external storage devices for computers, but recently, they are also used as recording media for portable players that reproduce music information and video information and as recording media for car navigation devices that display map information. It has become like this. However, since such portable players and car navigation devices are used in an environment subject to vibrations, if a hard disk device is to be made to cope well with such applications, as a hard disk device, it will be more than ever. In addition, it is required to have durability against sudden posture changes and vibrations, and it is desired to be miniaturized so that it is convenient to carry. Since it is used in a limited state, it is important to have low power consumption.

  By the way, oil such as lubricating oil is generally used as a working fluid of a fluid dynamic bearing used in a spindle motor of a hard disk device. However, motors incorporating fluid bearings using oil are often adversely affected by the characteristics of the oil. In other words, when used in a low temperature environment, the viscosity of the oil increases, so the power consumption increases with this, and there is a disadvantage that the usable time is extremely reduced. In addition, when the motor rotates at high speed, oil is likely to leak due to the bearing portion rotating at high speed, and there is a risk that oil deterioration due to higher temperatures may be accelerated.

As a technique for solving such a problem, it is conceivable to use a gas such as air instead of a liquid such as oil as the working fluid of the fluid bearing.
However, when a gas bearing in which the working fluid is a gas such as air is used, in a state where the motor is driven to rotate, the fixed portion and the rotating portion of the motor are supported by the gas bearing through which the gas is interposed. Therefore, when the magnetic disk or the like is rotated in the air, static electricity generated in the rotating part cannot be released to the fixed part, which may cause various kinds of static electricity troubles.

  As a countermeasure against such a problem, a motor using a fluid bearing portion having a plurality of fluid bearings of a gas bearing using a gas such as air as a working fluid and a liquid bearing using a liquid such as oil as a working fluid. Are proposed in Patent Document 1, Patent Document 2, and the like.

  In the motor disclosed in Patent Document 1, as shown in FIG. 12, a fixed shaft 51 having a first portion 51a having a small diameter and a second portion 51b having a large diameter is erected on a base 50 serving as a base. Thus, a fixed portion is configured, and a rotor hub 52 that is a rotating portion is disposed on the second portion 51b of the fixed shaft 51 via a fluid bearing portion. The stator 53 is fixed to the outer periphery of the cylindrical portion 50 a of the base 50 that fixes the first portion 51 a of the fixed shaft 51, and the rotor 54 is attached to the rotor hub 52 so as to face the stator 53.

  A rotating shaft 55 is fixed at the center of the rotor hub 52, and a thrust plate 56 is attached to an end of the rotating shaft 55. The thrust plate 56 is connected to a second portion 51b having a large diameter on the fixed shaft 51. The interior is in the hole formed in the inner periphery of the. Further, a thrust cover 57 that also functions as a retaining member for the fixed shaft 51 is fixed to the upper inner peripheral surface of the second portion 51 b of the fixed shaft 51 so as to cover the thrust plate 56 from above.

  The fluid bearing portion of the motor includes a radial air bearing 58 in which the working fluid is air and a thrust liquid bearing 59 in which the working fluid is a liquid such as oil. Here, the radial air bearing 58 is formed between the outer peripheral surface of the large-diameter second portion 51b of the fixed shaft 51 and the inner peripheral surface of the rotor hub 52 opposed thereto, and the radial air bearing 58 is fixed. The second portion 51b of the shaft 51 is provided at both ends of the second portion 51b at a predetermined distance in the direction of the rotation axis. On the other hand, the thrust liquid bearing 59 is provided between one disk-shaped surface of the thrust plate 56 and the inner peripheral bottom surface of the second portion 51b of the fixed shaft 51 facing the disk-shaped surface, or the other of the thrust plate 56. Are formed between at least one of the disk-shaped surface and the thrust cover 57 opposed to the disk-shaped surface.

  As shown in FIG. 13, the motor disclosed in Patent Document 2 is configured such that a rotating portion 73 including a rotating shaft 71 and a cylindrical hub 72 is fixed to a fixed portion including a base 77 and a fixed shaft 78. A thrust liquid bearing (denoted as a thrust fluid bearing in Patent Document 2) 74 and a radial gas bearing 75 are rotatably supported. That is, a thrust collar 76 provided at one end of the rotating shaft 71 is supported by a thrust liquid bearing 74, and a rotating portion is provided by a radial gas bearing 75 configured between a fixed shaft 77 facing the inner diameter surface of the hub 72. 73 is held. A motor composed of a rotor 79 and a stator 80 is disposed inside the radial gas bearing 75.

According to these techniques, since gas is used as the working fluid of the radial bearing, the working fluid of the radial bearing is used in a low temperature environment as compared with the case where a liquid such as oil is used. The increase in power consumption due to the influence of viscosity can be suppressed, and only the thrust liquid bearings 59 and 74 can use a small amount of liquid as a working fluid, so that they can be used in environments subject to vibrations or rotated at high speed. Oil leakage is less likely to occur.
JP 2000-337363 A Japanese Patent Laid-Open No. 11-275807

  However, in the configuration shown in FIGS. 12 and 13, the radial air bearing 58 and the radial gas bearing 75 are formed on the large diameter portion of the inner peripheral surface of the rotor hub 52 and the inner diameter surface of the hub 72. Since the ratio of the length to the diameter in the radial air bearing 58 and the radial gas bearing 75 is small, when the motor having such a structure is applied to a thin hard disk device incorporated in a portable player or a car navigation device, these radial air bearings 58 and radial gas bearings 75 The ratio of the length to the diameter in the air bearing 58 or the radial gas bearing 75 becomes extremely small. As a result, the bearing rigidity generated per unit length is lowered, and further, the bearing length (distance between the radial bearings) is shortened. As a result, the bearing pitch is shortened, which causes a problem that the angular rigidity is lowered.

  In addition, since the thrust liquid bearings 59 and 74 use a liquid such as oil as the working fluid, the thrust liquid bearings 59 and 74 have a large vertical bearing rigidity with a small thrust bearing diameter compared to the case where gas is used as the working fluid. There are advantages that can be generated. However, as shown in FIGS. 12 and 13, the thrust liquid bearing 59 is provided on the inner peripheral side of the fixed shaft 51, and the thrust liquid bearing 74 is formed by a small diameter thrust collar 76 provided at one end of the rotating shaft 77. In any structure, since the thrust bearing diameter is small, a large angular rigidity cannot be expected.

  Therefore, if a hydrodynamic bearing motor using a hydrodynamic bearing as shown in FIGS. 12 and 13 is employed in a thin hard disk device, the bearing may come into contact due to insufficient angular rigidity when there is vibration or a sudden change in posture. In the worst case, the motor may be locked.

  The present invention solves the above-mentioned problem, when a thin hard disk or the like is used using a fluid bearing portion having a plurality of types of bearings, a gas bearing using gas as a working fluid and a liquid bearing using liquid as a working fluid. However, an object of the present invention is to provide a fluid dynamic bearing motor capable of obtaining sufficient angular rigidity.

  In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that the rotating part is fixed to the fixed part via a fluid bearing part having a gas bearing in which the working fluid is gas and a liquid bearing in which the working fluid is liquid. The hydrodynamic bearing motor is supported in a freely rotatable manner, wherein the radial bearing is a liquid bearing and the thrust bearing is a gas bearing.

  According to a second aspect of the present invention, the fixed portion includes a base, a hollow cylindrical sleeve erected on the base, and a thrust flange, and the rotating portion has an outer periphery on the inner peripheral surface of the sleeve. A cylindrical shaft whose surface is fitted with a gap, and a bottomed cylindrical motor rotating body coupled to the shaft and having an inner peripheral bottom surface facing the thrust flange, the outer periphery of the shaft A dynamic pressure generating groove is formed on at least one of the surface and the inner peripheral surface of the sleeve, and a liquid as a working fluid is filled in a gap between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve. A radial liquid bearing, and a dynamic pressure generating groove is formed on at least one of the inner peripheral side bottom surface of the motor rotating body and the opposing surface of the thrust flange facing the inner peripheral side bottom surface. Construct thrust gas bearing Characterized in that was.

  According to a fourth aspect of the present invention, the fixed portion includes a base, a shaft erected on the base, and a thrust flange, and the rotating portion has a gap between the inner peripheral surface and the outer peripheral surface of the shaft. A cylindrical sleeve that fits and has a bottomed cylindrical motor rotating body coupled to the sleeve and having a bottom surface facing the thrust flange, the outer peripheral surface of the shaft and the inner periphery of the sleeve A radial liquid bearing is formed by forming a dynamic pressure generating groove on at least one of the surfaces and filling the gap between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve as a working fluid. The thrust gas bearing is configured by forming a dynamic pressure generating groove on at least one of the inner peripheral side bottom surface of the motor rotating body and the opposing surface of the thrust flange facing the inner peripheral side bottom surface. It is characterized by .

  According to a sixth aspect of the present invention, the fixed portion includes a base, a hollow cylindrical sleeve erected on the base, and a thrust flange, and the rotating portion has an outer periphery on the inner peripheral surface of the sleeve. A cylindrical shaft whose surface is fitted with a gap, a bottomed cylindrical motor rotating body coupled to the shaft and having an inner peripheral bottom surface facing the thrust flange, and an inner surface of the motor rotating body A thrust plate attached to the periphery, and a dynamic pressure generating groove is formed on at least one of the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve, and the outer peripheral surface of the shaft and the inner surface of the sleeve A radial liquid bearing is formed by filling a liquid as a working fluid in a gap between the peripheral surface and at least one of a bottom surface of the motor rotating body and a facing surface of a thrust flange facing the bottom surface. And said thrust flange and to form the dynamic pressure generating grooves on at least one side of the surface facing each other with the thrust plate, and characterized by being configured to thrust gas bearing.

  According to these configurations, since the radial liquid bearing is formed between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve, even when the length of the motor in the direction of the rotation axis can be reduced only, The ratio of the length of the liquid bearing to the axis of rotation and the bearing length (distance between the radial bearings) can be made sufficiently large. As a result, a decrease in bearing rigidity can be suppressed, and a good angle Rigidity can be ensured. Further, since the thrust gas bearing can be formed to have a large diameter along the inner peripheral side bottom surface of the motor rotating body, it is possible to obtain a large angular rigidity. Furthermore, since gas is used as the working fluid for the thrust bearing, the thrust bearing fluid is also affected by the viscosity even when used in a low temperature environment compared to the case where a fluid such as oil is used. An increase in power consumption can be suppressed, and the amount of liquid working fluid used can be reduced.

  As described above, according to the above configuration, since the radial liquid bearing is formed between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve, it is possible to suppress a decrease in bearing rigidity in the radial liquid bearing, which is favorable. Angular rigidity can be ensured, and the thrust gas bearing can be formed to have a large diameter along the inner peripheral side bottom face and outer peripheral side bottom face of the motor rotor, so that a large angular rigidity can be obtained. Is possible. As a result, the motor structure can be adapted to a thin hard disk device, and the bearing rigidity can be sufficiently obtained even when there is vibration or a sudden change in posture. In addition, since gas is used as the working fluid for thrust bearings, an increase in power consumption due to the influence of viscosity can be suppressed, and the amount of liquid working fluid used can be reduced, and the environment is susceptible to vibration. Oil leaks are less likely to occur even when used at high speeds or when rotated at high speeds.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a longitudinal sectional view of a fluid dynamic bearing motor according to a first embodiment of the present invention. The fluid dynamic bearing motor is used in a spindle motor of a thin hard disk device built in a portable player or a car navigation device, but is not limited thereto.

  As shown in FIG. 1, in this fluid dynamic bearing motor, a rotating portion is supported rotatably with respect to a fixed portion via a fluid bearing portion. The fluid bearing portion includes a gas bearing in which the working fluid is a gas and a liquid bearing in which the working fluid is a liquid.

  The fixing portion is composed of a base 1 and a hollow cylindrical sleeve 3 which is erected in a state of being press-fitted or bonded to the base 1 and has a thrust flange 2. A stator coil 4 is attached to the outer periphery of the cylindrical portion 1a supporting the sleeve 3 in the base 1 directly or via another member. In addition, although the case where the bottom part of the sleeve 3 is integrally formed is shown in FIG. 1, the structure by which another thing is being fixed may be sufficient.

  The rotating portion has a cylindrical shaft 5 whose outer peripheral surface is fitted to the inner peripheral surface of the sleeve 3 with a gap, and an inner peripheral bottom surface 6 a that is coupled to the shaft 5 and faces the thrust flange 2. And the bottomed cylindrical motor rotating body 6. A magnet 7 is bonded and fixed directly or via a back yoke made of a magnetic material to the inner periphery of the motor rotating body 6 away from the inner peripheral bottom surface 6a so as to face the stator coil 4. ing. The upper surface of the shaft 5 is provided with a screw hole 5a for clamping for holding a disk (not shown) that is a magnetic recording medium.

  A dynamic pressure generating groove is formed on at least one of the outer peripheral surface of the shaft 5 and the inner peripheral surface of the sleeve 3. The gap between the outer peripheral surface of the shaft 5 and the inner peripheral surface of the sleeve 3 is filled with liquid and conductive oil as a working fluid to constitute a radial liquid bearing 8 as a liquid bearing. ing. FIG. 1 shows a case where radial liquid bearings 8 are respectively provided at the upper part and the lower part between the shaft 5 and the sleeve 3, but the present invention is not limited to this. The dynamic pressure generating groove may be formed continuously.

  A dynamic pressure generating groove is also formed on at least one of the inner peripheral bottom surface 6a of the motor rotor 6 and the opposing surface 2a of the thrust flange 2 facing the inner peripheral bottom surface 6a. Between these, liquid such as oil is not filled, but air is simply a gap, and a thrust gas bearing 9 is formed as a gas bearing (air bearing). Note that at least one of the inner peripheral bottom surface 6a of the motor rotating body 6 and the opposing surface 2a of the thrust flange 2 constituting the radial liquid bearing 9 is provided with a surface such as plating, DLC (diamond-like carbon), or ion nitriding. In this case, the wear resistance and the friction coefficient can be reduced.

  The dynamic pressure generating grooves of the radial liquid bearing 8 and the thrust gas bearing 9 may be in a herringbone shape or a spiral shape, but are not limited to this and may have other shapes.

  In the above configuration, when a rectified current is passed through the stator coil 4, electromagnetic force is generated between the stator coil 4 and the magnet 7, and the motor rotating body 6 and the shaft 5 that are integral with the magnet 7 rotate. When the motor rotator 6 and the shaft 5 rotate, the oil and air as the working fluid are pumped in the radial liquid bearing 8 and the thrust gas bearing 9 to increase the internal pressure, and the motor rotator 6 and the shaft 5 The thrust flange 2 and the sleeve 3 are rotated in a state of being supported with high accuracy without contact.

  In this case, since the radial liquid bearing 8 is formed between the outer peripheral surface of the shaft 5 and the inner peripheral surface of the sleeve 3, the fluid bearing motor is used for a spindle motor of a thin hard disk device or the like. Even if the length in the direction of the rotating shaft in the shaft can only be made smaller, the ratio of the length in the direction of the rotating shaft of the liquid bearing to the diameter of the bearing portion and the bearing length (distance between the radial liquid bearings 8) should be made sufficiently large. As a result, a decrease in bearing rigidity can be suppressed, and good angular rigidity can be ensured.

  Further, the thrust gas bearing 9 composed of the inner peripheral side bottom surface 6a of the motor rotating body 6 and the opposed surface 2a of the thrust flange 2 is formed to have a large diameter along the inner peripheral side bottom surface 6a of the motor rotating body 6. Therefore, a large angular rigidity can be obtained.

  As a result, this hydrodynamic bearing motor is used as a spindle motor for thin hard disk drives built in portable players and car navigation systems, and has sufficient bearing rigidity to withstand vibrations and sudden changes in posture. Can be obtained.

  Furthermore, since gas (air) is used as the working fluid for the thrust bearing, the viscosity of the thrust bearing working fluid is lower when used in a low temperature environment as compared with the case where a fluid such as oil is used. The increase in power consumption due to the influence of the liquid can be suppressed, and the amount of liquid working fluid used can be reduced, so that oil leakage is less likely to occur even when used in environments subject to vibrations or when rotating at high speed. .

  In addition, since conductive oil is used as the working fluid of the radial liquid bearing 8, static electricity generated in the rotating part during motor rotation is released to the fixed part side through the oil, thereby improving static electricity removal. It can be carried out.

  When this fluid bearing motor is used as a fluid bearing motor having a standard disk inner diameter of about 25 mm in a 3.5-inch hard disk device, the diameter of the portion of the shaft 5 where the radial liquid bearing 8 is provided is 2 mm to 6 mm. Preferably, the strength of the motor rotor 6 is increased by setting the diameter of the thrust gas bearing 9 of the thrust flange 2 to 15 mm to 23 mm, preferably 18 mm, preferably about 4 mm, bearing length 6 mm to 12 mm, preferably about 9 mm. Large bearing rigidity and angular rigidity can be generated in a secured state.

  Further, in a fluid bearing motor having a standard disk inner diameter of about 20 mm in a 2.5 inch hard disk device, the diameter of the portion where the radial liquid bearing 8 of the shaft 5 is provided is 2 to 5 mm, preferably about 3 mm, and the bearing length. Is set to 5 mm to 10 mm, preferably about 7 mm, and the diameter of the thrust gas bearing 9 of the thrust flange 2 is set to 12 mm to 18 mm, preferably 15 mm. Stiffness can be generated.

  As a result, the height of the motor can be reduced to about ½ of that of the conventional one, but oil leakage is difficult to occur, and the static electricity of the rotating part can be satisfactorily removed during motor rotation. It is possible to obtain a hydrodynamic bearing motor having bearing rigidity that can sufficiently withstand even when the posture changes.

In the above embodiment, the case where the thrust flange 2 is fixed to the sleeve 3 has been described. However, the cylindrical portion 1a of the base 1 is extended, and the thrust flange 2 is fixed to the extended portion. Further, the thrust flange 2 may be formed integrally with the sleeve 3 or the extending portion of the cylindrical portion 1a in the base 1. That is, the thrust flange 2 may be provided on the fixed portion side.
(Embodiment 2)
FIG. 2 is a longitudinal sectional view of a fluid dynamic bearing motor according to the second embodiment of the present invention. As shown in FIG. 2, in this fluid dynamic bearing motor, a separate back yoke 10 is provided on the motor rotating body 6, and a flange having an inner diameter smaller than the outer diameter of the thrust flange 2 is provided at the upper end of the back yoke 10. A portion 10a is provided.

According to this configuration, in addition to the function and effect of the first embodiment, there is an advantage that the motor rotating body 6 can be prevented from being detached by the back yoke 10. Further, the material of the motor rotating body 6 can be changed to a non-magnetic material such as SUS304 and the material of the back yoke 10 can be changed to a magnetic material, and an optimum material corresponding to the use application of the fluid bearing motor is used. There are also advantages that can be made.
(Embodiment 3)
FIG. 3 is a longitudinal sectional view of a fluid dynamic bearing motor according to a third embodiment of the present invention. As shown in FIG. 3, this hydrodynamic bearing motor is a (tide) type in which the shaft 5 is fixed at both ends of the base 1 and the upper lid 11, and is excellent in vibration characteristics because it is supported at both ends. Yes. The thrust flange 2 is attached not to the sleeve 3 but to a cylindrical portion 1a provided on the base 1 so as to surround the sleeve 3 from the outside.

  Further, at both ends of the radial liquid bearing 8, at least one of the shaft 5 and the sleeve 3 is provided with a taper 8 a having a wider bearing gap toward the end, thereby preventing oil as a working fluid from leaking. Yes.

In addition, as shown in FIG. 4, you may comprise in the cantilever shape in which the shaft 5 is fixed only to the base 1. FIG.
(Embodiment 4)
FIG. 5 is a longitudinal sectional view of a fluid dynamic bearing motor according to a fourth embodiment of the present invention. As shown in FIG. 5, in this fluid dynamic bearing motor, a thrust yoke 21 as an inner peripheral side thrust member, which is a separate member from the main body portion of the motor rotating body 6, is provided at a position on the inner peripheral side bottom surface of the motor rotating body 6. Attached and fixed. A thrust gas bearing 9 is configured as a gas bearing by forming a dynamic pressure generating groove on at least one of the thrust yoke 21 and the facing surface 2a of the thrust flange 2 facing the thrust yoke 21. . Reference numeral 10 denotes a back yoke attached to the inner peripheral surface of the motor rotating body 6.

  According to this configuration, since one side of the thrust gas bearing 9 is configured by the thrust yoke 21 which is a separate member from the main body portion of the motor rotating body 6, even when an aluminum material is used as the main body portion of the motor rotating body 6. As the thrust yoke 21 as the inner circumferential side thrust member, an optimum material such as a stainless material can be used as a member constituting the thrust gas bearing 9, and as a result, the bearing life and reliability can be improved.

In addition, you may use what integrated the thrust yoke 21 and the back yoke 10. FIG.
(Embodiment 5)
FIG. 6 is a longitudinal sectional view of a fluid dynamic bearing motor according to the fifth embodiment of the present invention. As shown in FIG. 6, in the fluid dynamic bearing motor, as in the first embodiment, the sleeve 3 is fixed to the base 1, the motor rotating body 6 is fixed to the shaft 5, and the shaft 5 and the motor are rotated. Although the body 6 rotates integrally, a thrust plate 12 is attached to the inner periphery of the motor rotating body 6, and the thrust flange 2 is connected to the inner peripheral side bottom surface 6 a of the motor rotating body 6 and the thrust plate. 12 to be sandwiched from above and below via a minute gap. Then, dynamic pressure generating grooves are formed in any of the upper surface of the thrust flange 2 and the inner peripheral bottom surface 6a of the motor rotor 6, and the lower surface of the thrust flange 2 and the upper surface of the thrust plate 12, respectively. Thus, a thrust gas bearing 9 as a gas bearing (air bearing) is formed on the upper surface side and the lower surface side of the thrust flange 2 (that is, at two locations).

  Note that surface treatment such as plating, DLC (diamond-like carbon), or ion nitriding may be performed on at least one of the upper and lower surfaces of the thrust flange 2 or the inner peripheral bottom surface 6a of the motor rotor 6 and the upper surface of the thrust plate 12. In this case, the wear resistance and the friction coefficient can be reduced.

  Reference numeral 13 denotes a screw hole for inserting a screw for fixing a disk as a recording medium. A plurality of screw holes are received on the outer peripheral side of the outer diameter portion of the thrust flange 2 in the motor rotating body 6. The thrust plate 12 closes the lower surface side of the screw hole 13.

  According to this configuration, since the thrust gas bearing 9 is provided at two locations on the upper surface side and the lower surface side of the thrust plate 12, the angular rigidity can be further improved, and the adverse effects caused by the motor posture can be further reduced.

Further, since the thrust plate 12 is also used as a member for closing the screw hole 13, the number of parts can be reduced as compared with the case where a member for closing the screw hole 13 is provided separately.
Also in this embodiment, the cylindrical portion 1a in the base 1 may be extended, and the thrust flange 2 may be attached and fixed to the extended portion.
(Embodiment 6)
FIG. 7 is a longitudinal sectional view of a fluid dynamic bearing motor according to the sixth embodiment of the present invention. As shown in FIG. 6, in this hydrodynamic bearing motor, no thrust flange is provided, and the outer peripheral side bottom surface 6 b of the motor rotating body 6 is opposed to the base side thrust member 22 fixed to the base 1. A gas bearing is formed by forming a dynamic pressure generating groove on at least one of the outer peripheral side bottom surface 6b of the motor rotating body 6 and the opposing surface of the base side thrust member 22 with a gap therebetween. The thrust gas bearing 23 is configured as follows.

  According to this configuration, since the thrust gas bearing 23 is configured at the position of the outer peripheral side bottom surface 6b of the motor rotating body 6, the thrust flange is used to thrust the gap between the motor rotating body 6 and the inner peripheral side bottom surface 6a. The thrust bearing diameter can be made larger than when the gas bearing 9 is configured, and as a result, the bearing rigidity can be further improved.

  Although the base side thrust member 22 is not provided, it is possible to configure the thrust gas bearing 23 by making the base 1 itself face the outer peripheral side bottom surface 6b of the motor rotor 6, but the base side thrust member Providing separately as 22 has an advantage that a material suitable for the thrust gas bearing 23 can be selected, and the bearing life and reliability can be improved.

  Further, as shown in FIG. 8, a thrust yoke 24 as an outer peripheral side thrust member, which is a separate member from the main body portion of the motor rotating body 6, is attached and fixed to the outer peripheral bottom surface 6 b of the motor rotating body 6. The thrust gas bearing 23 may be configured as a gas bearing by forming a dynamic pressure generating groove on at least one of the thrust yoke 24 and the opposing surface of the base-side thrust member 22. Reference numeral 10 denotes a back yoke attached to the inner peripheral surface of the motor rotating body 6.

  According to this, since one side of the thrust gas bearing 23 is constituted by the thrust yoke 24 which is a separate member from the main body portion of the motor rotor 6, even when an aluminum material is used as the main body portion of the motor rotor 6, As the thrust yoke 24 as the outer peripheral side thrust member, an optimum material such as a stainless material can be used as a member constituting the thrust gas bearing 23. As a result, the bearing life and reliability can be further improved.

In addition, you may use what integrated the thrust yoke 24 and the back yoke 10. FIG.
(Embodiment 7)
FIG. 9 is a longitudinal sectional view of a fluid dynamic bearing motor according to a seventh embodiment of the present invention. As shown in FIG. 6, in this fluid dynamic bearing motor, a pivot portion 5 b is formed at the lower end portion of the shaft 5 as a convex portion protruding toward the bottom surface portion of the sleeve 3.

  With this configuration, when the hydrodynamic bearing motor is stationary, the thrust flange 2 and the bottom surface 6a of the motor rotating body 6 do not contact each other, but the pivot portion 5b of the shaft 5 and the bottom surface portion of the sleeve 3 have a small area. Will come in contact. Therefore, the contact area at the time of starting the motor is reduced, and as a result, the starting torque can be reduced.

  Further, the fluid dynamic bearing motor shown in FIGS. 10A and 10B has a configuration similar to that of the fluid dynamic bearing motor shown in FIG. 9. In this fluid dynamic bearing motor, a sleeve is provided at the lower end portion of the shaft 5. 3 has a small-diameter convex portion 5c protruding toward the bottom surface portion side, and a thrust liquid bearing 14 is formed between at least one surface of the convex portion 5c of the shaft 5 and the bottom surface portion of the sleeve 3. .

  According to this configuration, it is possible to obtain the same effect as when the pivot portion 5b is formed on the shaft 5 as described above. Moreover, since the thrust liquid bearing 14 is formed in addition to the thrust gas bearing 9 provided on the bottom surface 6a of the motor rotor 6 and the opposed surface 2a of the thrust flange 2 facing the bottom surface 6a, the angular rigidity is further increased. It is possible to improve and reduce adverse effects caused by the motor attitude.

In addition, you may form the same convex part (pivot part 5b and convex part 5c) also in the hydrodynamic bearing motor as shown in FIG.1, FIG.2 or FIG.5-8.
(Embodiment 8)
11 (a) and 11 (b) are longitudinal sectional views of a fluid dynamic bearing motor according to the eighth embodiment of the present invention. As shown in FIG. 11 (a), in this fluid dynamic bearing motor, a suction ring 15 for attracting the magnet 7 magnetically so as to face the magnet 7 bonded to the motor rotating body 6 from below at a predetermined interval. Is provided on the base 1.

  Further, as shown in an enlarged view in FIG. 11 (b), in the middle of the path from the end of the radial liquid bearing 8 on the opening side to the thrust gas bearing 9, specifically, the upper end of the sleeve 3 and the motor A groove-shaped slit 16 is formed as an outflow prevention portion at an inner peripheral surface near the center of the rotating body 6 and at least one location of the sleeve 3 and the thrust flange 2.

  According to this configuration, the motor rotating body 6 is always attracted to the base 1 side by the magnetic attraction force acting between the magnet 7 and the attraction ring 15. Accordingly, when the motor rotates, the motor rotating body 6 is always sucked to the base 1 side, and these are provided by the thrust gas bearing 9 formed on the thrust flange 2 and the inner peripheral side bottom surface 6a of the motor rotating body 6. It is supported in a state where there is a predetermined minute gap between them, and stable rotation is possible.

  Even if oil that is the working fluid of the radial liquid bearing 8 leaks from between the outer peripheral surface of the shaft 5 and the inner peripheral surface of the sleeve 3 where the radial liquid bearing 8 is disposed, The oil is prevented from entering the thrust gas bearing 9 by entering the slit 16, and as a result, the oil does not enter the thrust gas bearing 9 to cause a problem such as loss torque and reliability. Will improve.

In addition, the suction ring 15 may be provided on the base 1 or the slit 16 may be formed in the fluid dynamic bearing motor as shown in FIGS. 1, 2, and 5 to 10.
Further, as the outflow prevention portion, instead of the slit 16, it is also possible to form a protruding portion that dams a working fluid such as oil to flow out.

  The small motor of the present invention is suitable for a hard disk spindle motor, particularly a device used in an environment susceptible to vibration, such as a portable player or a car navigation device. It can also be applied to other motors.

1 is a longitudinal sectional view of a fluid dynamic bearing motor according to a first embodiment of the present invention. A longitudinal sectional view of a fluid dynamic bearing motor according to a second embodiment of the present invention. A longitudinal sectional view of a fluid dynamic bearing motor according to a third embodiment of the present invention. Vertical sectional view of another fluid dynamic bearing motor according to the third embodiment A longitudinal sectional view of a fluid dynamic bearing motor according to a fourth embodiment of the present invention. A longitudinal sectional view of a fluid dynamic bearing motor according to a fifth embodiment of the present invention. A longitudinal sectional view of a fluid dynamic bearing motor according to a sixth embodiment of the present invention. Vertical sectional view of another fluid dynamic bearing motor according to the sixth embodiment A longitudinal sectional view of a fluid dynamic bearing motor according to a seventh embodiment of the present invention. (A) And (b) is a longitudinal cross-sectional view of the other hydrodynamic bearing motor which concerns on the 7th Embodiment, and the bottom view of the shaft (A) And (b) is the longitudinal cross-sectional view and principal part expanded longitudinal cross-sectional view of the hydrodynamic bearing motor which concern on the 8th Embodiment of this invention. Vertical section of a conventional fluid dynamic bearing motor Vertical sectional view of other conventional hydrodynamic bearing motors

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base 2 Thrust flange 3 Sleeve 4 Stator coil 5 Shaft 5b Pivot part (convex part)
5c Convex part 6 Motor rotating body 7 Magnet 8 Radial liquid bearing 9, 14, 23 Thrust gas bearing 10 Back yoke 11 Upper lid 12 Thrust plate 15 Suction ring 16 Slit (outflow prevention part)
21 Thrust yoke (inner circumferential thrust member)
22 Base side thrust member 24 Thrust yoke (outer peripheral side thrust member)

Claims (12)

A fluid bearing motor in which a rotating part is rotatably supported with respect to a fixed part via a fluid bearing part having a gas bearing in which the working fluid is gas and a liquid bearing in which the working fluid is liquid,
Radial bearings are liquid bearings,
A fluid dynamic bearing motor, wherein the thrust bearing is a gas bearing. The fixed portion includes a base, a hollow cylindrical sleeve erected on the base, and a thrust flange.
The rotating part is a bottomed cylinder having a cylindrical shaft that is fitted to the inner peripheral surface of the sleeve with a gap between the outer peripheral surface and an inner peripheral bottom surface that is coupled to the shaft and faces the thrust flange. A motor rotating body having a shape,
A dynamic pressure generating groove is formed on at least one of the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve, and a working fluid is formed in a gap between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve. The liquid is filled to form a radial liquid bearing,
The thrust gas bearing is configured by forming a dynamic pressure generating groove on at least one of the inner peripheral bottom surface of the motor rotating body and the opposing surface of the thrust flange facing the inner peripheral bottom surface. The hydrodynamic bearing motor according to claim 1.   The hydrodynamic bearing according to claim 2, wherein a back yoke is provided on an inner peripheral surface of the motor rotating body, and a flange portion having an inner diameter smaller than an outer diameter of the thrust flange is formed at one end portion of the back yoke. motor. The fixed portion includes a base, a shaft erected on the base, and a thrust flange.
The rotating part has a cylindrical sleeve having an inner peripheral surface fitted to the outer peripheral surface of the shaft with a gap, and a bottomed cylindrical motor having a bottom surface coupled to the sleeve and facing the thrust flange. A rotating body,
A dynamic pressure generating groove is formed on at least one of the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve, and a working fluid is formed in a gap between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve. The liquid is filled to form a radial liquid bearing,
The thrust gas bearing is configured by forming a dynamic pressure generating groove on at least one of the inner peripheral bottom surface of the motor rotating body and the opposing surface of the thrust flange facing the inner peripheral bottom surface. The hydrodynamic bearing motor according to claim 1.   An inner circumferential thrust member, which is a separate member from the main body portion of the motor rotating body, is attached to a location on the inner circumferential bottom surface of the motor rotating body, and this inner circumferential thrust member and the thrust flange facing the inner circumferential thrust member 5. The hydrodynamic bearing motor according to claim 1, wherein a thrust gas bearing is configured by forming a dynamic pressure generating groove on at least one of the opposed surfaces. The fixed portion includes a base, a hollow cylindrical sleeve erected on the base, and a thrust flange.
The rotating part is a bottomed cylinder having a cylindrical shaft that is fitted to the inner peripheral surface of the sleeve with a gap between the outer peripheral surface and an inner peripheral bottom surface that is coupled to the shaft and faces the thrust flange. A motor rotating body having a shape, and a thrust plate attached to the inner periphery of the motor rotating body,
A dynamic pressure generating groove is formed on at least one of the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve, and a working fluid is formed in a gap between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve. The liquid is filled to form a radial liquid bearing,
Dynamic pressure is applied to at least one of the bottom surface of the motor rotating body and the facing surface of the thrust flange facing the bottom surface, and at least one of the facing surfaces of the thrust flange and the thrust plate facing each other. The hydrodynamic bearing motor according to claim 1, wherein the generation groove is formed to constitute a thrust gas bearing. The fixed portion includes a base and a hollow cylindrical sleeve erected on the base,
The rotating portion includes a cylindrical shaft that fits with an inner peripheral surface of the sleeve with a gap between the outer peripheral surface, and a base-side thrust member that is coupled to the shaft and attached to the base or the base. A bottomed cylindrical motor rotating body having a bottom surface on the outer peripheral side facing each other,
A dynamic pressure generating groove is formed on at least one of the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve, and a working fluid is formed in a gap between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve. The liquid is filled to form a radial liquid bearing,
A thrust gas bearing is configured by forming a dynamic pressure generating groove on at least one of the outer peripheral side bottom surface of the motor rotating body and the base facing the outer peripheral side bottom surface or the opposing surface of the base side thrust member. The hydrodynamic bearing motor according to claim 1.   The outer peripheral side thrust member, which is a member different from the main body part of the motor rotating body, is attached to the bottom surface of the outer peripheral side of the motor rotating body, and the outer peripheral side thrust member and the base or base side facing the outer peripheral side thrust member 8. The hydrodynamic bearing motor according to claim 7, wherein a dynamic pressure generating groove is formed on at least one of the opposing surfaces of the thrust member to form a thrust gas bearing.   The hydrodynamic bearing motor according to any one of claims 1 to 3 and 5 to 8, wherein a convex portion projecting toward a bottom surface portion of the sleeve is formed on the shaft.   The hydrodynamic bearing motor according to claim 9, wherein a thrust liquid bearing is formed between the convex portion of the shaft and the bottom surface portion of the sleeve.   The hydrodynamic bearing motor according to claim 1, wherein a suction ring that generates a suction force by a magnetic force with respect to the magnet is attached to a portion of the base that faces the magnet.   It is characterized in that an outflow prevention part for preventing the working fluid of the radial liquid bearing from flowing into the thrust gas bearing side is provided at a location in the middle of the path from the opening side end of the radial liquid bearing to the thrust gas bearing side. The hydrodynamic bearing motor according to any one of claims 2, 3, and 6 to 8.

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