JP2006325329A - Spindle motor and disk drive device using this spindle motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle motor in which deformation of a bearing member in assembling a fluid dynamic pressure bearing is suppressed to stabilize bearing performance to improve reliability and to reduce size and thickness, and a recording disk driving device using the spindle motor. <P>SOLUTION: The disk driving device is constituted in such a manner that the bearing retaining member 11 fitted with the bearing member 8 is fixed to a chassis 15 via the bearing member. As a base material for the bearing member 8, the bearing retaining member 11 and the chassis 15, materials having different linear expansion coefficients with the linear expansion coefficient of the bearing retaining member 11 as a center are used. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a spindle motor having a dynamic pressure bearing mounted on, for example, an HDD device, an optical disk device, a magneto-optical disk device, a magnetic disk device, a polygon mirror, and the like, and a disk drive device using the spindle motor.

  In a spindle motor bearing used in a disk device that rotates a disk-shaped recording medium such as a hard disk, in order to support the shaft and the bearing member in a relatively rotatable manner, lubrication with oil or the like interposed between the two is provided. Various dynamic pressure bearings using fluid pressure of fluid have been proposed.

  With respect to a spindle motor using such a dynamic pressure bearing, while maintaining a simple structure and desired bearing rigidity, it is possible to prevent negative pressure from being generated in the oil, and to further reduce the thickness and cost. A spindle motor and a disk drive using the spindle motor have been proposed.

  On the other hand, in order to make the device thinner, the chassis material tends to be changed to a martensitic steel material for the purpose of improving the chassis strength and at the same time providing the chassis with electromagnetic shielding properties.

  In a spindle motor using a hydrodynamic bearing, in order to secure a fastening strength with a large and small variation in bonding the bearing member and the housing (chassis), an adhesive gap is set according to the viscosity of the adhesive. The bearing member and the housing (chassis) are set by providing an adhesive groove in the adhesive gap, applying or filling the adhesive with the adhesive groove being 0.4 mm or less and the total adhesive groove width ratio being 0.4 or less. A structure in which is attached is shown. As a result, the adhesive strength can be increased and variations can be reduced (see, for example, Patent Document 1).

In addition, in a spindle motor having a hydrodynamic bearing having a full-fill structure in which the entire bearing gap is filled with oil, the bearing member that rotatably supports the rotor is fixed to the bearing member and the upper outer peripheral surface of the bearing member. Also shown is a structure comprising a plate-shaped member and a substantially cup-shaped bearing housing that holds the bearing member and the plate-shaped member, and the bearing member and the plate-shaped member are bonded to the bearing housing. Thereby, it is said that the perpendicularity of the radial bearing portion and the thrust bearing portion can be kept good, and the spindle motor can be reduced in size, thickness and power consumption (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 11-250562 (page 7, FIG. 1) JP 2004-316680 A (page 11, FIG. 2)

In the first example, when the linear expansion coefficients of the bearing member and the housing (chassis) are substantially the same, no significant problem occurs. For example, when the bearing member is made of brass and the housing is made of aluminum, the coefficient of linear expansion is 20.9 × 10 ⁻⁶ / ° C. for brass and 23.9 × 10 ^{−6 for} aluminum. Since it is / ° C., when the bearing member and the housing are bonded, there is no problem even if a thermosetting adhesive is used because the difference in coefficient of linear expansion is small.

However, in recent years, an example in which a martensitic steel material is employed as the material of the bearing member is increasing. Furthermore, in order to increase the strength even if the housing thickness is the same to make the disk device thin, and to obtain great rigidity even if the housing thickness is reduced, the housing material is adopted from aluminum to martensitic steel material There are an increasing number of examples. Here, in the case of a martensitic steel material, the linear expansion coefficient is 10.4 × 10 ⁻⁶ / ° C., so in order to increase the adhesive strength, an adhesive gap is set in accordance with the viscosity of the adhesive. The conventional configuration has the following problems. That is, for example, when the material of the bearing member is brass and the housing material is a martensitic steel material, if the bearing member and the housing are fixed with a thermosetting adhesive, the coefficient of linear expansion is Since the difference is large, the gap between the bearing member and the housing becomes large, and there is a problem that the adhesive strength is lowered.

  On the other hand, when the material of the bearing member is a martensitic steel material and the housing is aluminum, similarly, if the bearing member and the housing are fixed with a thermosetting adhesive, the outer peripheral portion of the bearing member is fixed after heat curing. Since the contraction of the inner peripheral portion of the housing is larger than the contraction, the inner peripheral diameter of the bearing member is reduced and the rotational load is increased. Therefore, the current value must be increased. For this reason, there existed a subject that power consumption became large.

  Furthermore, at the position in the height direction of the outer peripheral portion of the bearing member and the inner peripheral portion of the housing, for example, when the height position of the outer peripheral portion of the bearing member is higher than the housing, the height facing the housing Since the inner diameter of the shaft hole of the bearing member at the position portion is reduced, the inner peripheral diameter of the shaft hole of the bearing member changes in the height direction, and there is a problem that the pressure balance in the radial bearing is lost.

  Similarly, in the second example, the bearing housing material is a thin metal plate made of aluminum alloy, copper, copper alloy, etc., and the bearing member material is a porous sintered body impregnated with oil. Therefore, when the material of the boss part (chassis) is a martensitic steel material, there is a problem that the adhesive strength between the boss part and the bearing housing is lowered.

  Furthermore, in this second example, a plate-like member, which is a thrust bearing, is fixed to the outer periphery of one end of the bearing member in order to provide a communication groove. However, especially when the device is made thin, the thickness of the plate-like member becomes thin and sufficient adhesive strength cannot be obtained, and it is difficult to obtain the perpendicularity between the inner peripheral surface of the bearing member and the plate-like member. There was also a problem that the axial runout component of the motor deteriorated.

  The present invention solves the above-described problems, suppresses the occurrence of distortion of the bearing portion caused by the adhesion and fixing of the bearing member, the bearing holding member, and the chassis, and increases the adhesion strength and has a stable bearing performance, and the spindle motor It is an object of the present invention to provide a disk drive device using the disk.

  In order to achieve this object, a spindle motor of the present invention comprises a rotating shaft, a hub having a disk receiving portion, and the rotating shaft fixed to the central portion of the rotating shaft, and a rotating magnet fixed to the hub concentrically with the rotating shaft. And a bearing member that pivotally supports the rotating shaft, an armature that faces the rotating magnet and generates a rotational force around the central axis of the rotating shaft, and the bearing member. In a configuration comprising a bearing holding member and a chassis for fixing the armature and the bearing holding member, each of the respective materials of the bearing member, the bearing holding member, and the chassis, each centering on the value of the linear expansion coefficient of the bearing holding member In this case, materials having different linear expansion coefficients are used.

  Further, in the above configuration, the rotating shaft further includes a thrust plate that closes the lower portion of the bearing member and is fixed to the lower portion of the bearing member so as to face one end surface of the rotating shaft. And a groove for generating dynamic pressure is provided on at least one of the inner peripheral surfaces of the bearing member facing it, and at least one of the thrust plate and one end surface of the rotating shaft facing the thrust plate. In addition, a dynamic pressure generating groove having a shape that applies pressure acting on the inner side in the radial direction with respect to the oil when the rotating body rotates may be provided.

  With this configuration, the bearing member and the bearing holding member when assembling the spindle motor, and the distortion of the bearing member that occurs after adhesion and hardening in the adhesion between the bearing holding member and the chassis are reduced, and the bearing performance of the radial bearing and the thrust bearing is stabilized. And deterioration of the adhesive strength between the chassis and the bearing holding member can be suppressed. Further, it is possible to reduce the deterioration of the adhesive strength due to a change in storage temperature and the like, and the change in the shape of the bearing member due to a change in use temperature.

  The spindle motor of the present invention includes a rotating shaft, a rotating body having a disc receiving portion and a rotating magnet fixed to the hub concentrically with the rotating shaft. A bearing member that pivotally supports the rotating shaft; an armature that faces the rotating magnet and generates a rotational force around the central axis of the rotating shaft; and a bearing holding member that holds the bearing member; In the configuration composed of the armature and the chassis for fixing the bearing holding member, the bearing holding member and the bearing member are made of materials having substantially the same linear expansion coefficient values.

  Further, in the above configuration, the rotating shaft further includes a thrust plate that closes the lower portion of the bearing member and is fixed to the lower portion of the bearing member so as to face one end surface of the rotating shaft. And a groove for generating dynamic pressure is provided on at least one of the inner peripheral surfaces of the bearing member facing it, and at least one of the thrust plate and one end surface of the rotating shaft facing the thrust plate. In addition, a dynamic pressure generating groove having a shape that applies pressure acting on the inner side in the radial direction with respect to the oil when the rotating body rotates may be provided.

  With this configuration, the bearing member and the bearing holding member when assembling the spindle motor, and the distortion of the bearing member that occurs after adhesion and hardening in the adhesion between the bearing holding member and the chassis are reduced, and the bearing performance of the radial bearing and the thrust bearing is stabilized. And deterioration of the adhesive strength between the chassis and the bearing holding member can be suppressed. Further, it is possible to reduce the deterioration of the adhesive strength due to a change in storage temperature and the like, and the change in the shape of the bearing member due to a change in use temperature.

  The spindle motor of the present invention is a rotating body comprising a rotating shaft, a hub having a disk receiving portion, the rotating shaft being fixed to the center thereof, a rotating magnet fixed concentrically with the rotating shaft, and a retaining member. A bearing member that pivotally supports the rotating shaft, an armature that faces the rotating magnet and generates a rotational force around the central axis of the rotating shaft, and faces the end surface of the rotating shaft in the axial direction In the configuration comprising a bearing holding member that has a one-side opening shape that has a closed end surface that holds the bearing member, and a chassis that fixes the armature and the bearing holding member, the outer peripheral surface of the rotating shaft faces the outer surface. At least one of a radial bearing in which a groove for generating dynamic pressure is provided on at least one of the inner peripheral surfaces of the bearing member, and a plane of the hub facing the upper end surface and the upper end surface of the bearing member, When rotating the rotating body It has a configuration which is disposed a fluid dynamic bearing comprising a thrust bearing hydrodynamic groove shape applying pressure acting on the radially inward side with respect to the oil is provided.

  In the above configuration, an annular ring member is integrally formed on the hub, and the inner peripheral portion of the annular ring member and the outer peripheral portion of the bearing holding member face each other with a predetermined distance in the radial direction. The outer peripheral portion of the bearing holding member has a curved surface facing the inner peripheral portion of the annular ring member at a predetermined distance, and the tapered surface has a tapered surface so that the outer diameter becomes smaller toward the closed end surface in the lower portion of the curved surface. The oil may be filled up to a part of the formed portion where the annular ring member and the tapered surface face each other.

  Furthermore, in the above-described configuration, a material may be used in which the values of the linear expansion coefficients of the bearing holding member are the center, and the materials of the bearing member, the bearing holding member, and the chassis are different from each other.

  With this configuration, it is possible to increase the facing area between the upper end surface of the bearing member constituting the thrust bearing and the flat portion of the hub facing the bearing member, and the position of the thrust bearing is separated from the axis of the rotary shaft in the radial direction. The bearing rigidity can be increased. Further, the oil surface tension and the external pressure are balanced at the inner peripheral portion of the annular ring member of the hub and the tapered surface of the bearing holding member, and an interface is formed between the oil and air. By ascertaining the position of the interface, it is possible to confirm that the bearing unit is filled with oil after oiling when assembling the bearing unit. Therefore, process management and performance management are facilitated.

  Furthermore, the bearing member and the bearing holding member when assembling the spindle motor, and the distortion of the bearing member that occurs after the adhesive hardening in the adhesion between the bearing holding member and the chassis are reduced, and the bearing performance of the radial bearing and the thrust bearing is stabilized. It becomes possible. Further, the deterioration of the adhesive strength between the chassis and the bearing holding member is reduced. Furthermore, the deterioration of the adhesive strength due to a change in storage temperature or the like, and the change in the shape of the bearing member due to the change in use temperature can be reduced.

  Furthermore, in the above configuration, a brass material may be used as the material of the bearing member, an austenitic steel material as the material of the bearing holding member, and a martensitic or ferritic steel material as the material of the chassis.

  Alternatively, a martensitic or ferritic steel material may be used as the material of the bearing member, an austenitic steel material as the material of the bearing holding member, and an aluminum material as the material of the chassis.

  Alternatively, a brass material may be used as the material of the bearing member, a brass aluminum material as the material of the bearing holding member, and a martensitic or ferritic steel material as the material of the chassis.

  Alternatively, a martensitic or ferritic steel material may be used as the bearing member material, a martensitic or ferritic steel material may be used as the bearing holding member material, and an aluminum material may be used as the chassis material.

  With this configuration, without increasing the number of parts constituting the spindle motor, the magnetic attraction force generated between the rotating magnet and the chassis facing the rotating magnet allows the thrust bearing as a fluid dynamic pressure bearing between them. A necessary thrust force can be generated, and a spindle motor having stable bearing performance can be realized.

  Furthermore, in the said structure, it is good also as a structure which provided the magnetic attraction board which consists of a martensitic steel material in the position of the chassis facing a rotating magnet.

  With this configuration, a magnetic attraction force can be generated between the rotating magnet and the chassis facing the rotating magnet by the magnetic attraction plate fixed to the chassis with respect to the chassis formed of the aluminum material. A thrust force necessary for a thrust bearing as a fluid dynamic pressure bearing can be generated between them by the magnetic attraction force, and a spindle motor having stable bearing performance can be realized.

  Further, the disk drive device of the present invention is a device in which a disk-shaped recording medium capable of recording information is mounted, a housing, a spindle motor fixed inside the housing and rotating the disk-shaped recording medium, and the disk-shaped recording medium And an information access means for writing or reading information at a required position, wherein the spindle motor is a spindle motor described in any of the above.

  With this configuration, it is possible to realize a disk drive device that has high reliability and is reduced in size and thickness.

  The spindle motor of the present invention uses a material having different values of linear expansion coefficients for the bearing member, the bearing holding member, and the chassis material, centering on the value of the linear expansion coefficient of the bearing holding member. The holding member and the chassis are formed, or the bearing holding member and the bearing member are formed using a material in which the linear expansion coefficients of the bearing holding member and the bearing member are substantially equal.

  With such a configuration, the bearing member and the bearing holding member when assembling the spindle motor, and the distortion of the bearing member that occurs after adhesion hardening in the adhesion between the bearing holding member and the chassis are reduced. Therefore, the bearing performance of the radial bearing and the thrust bearing can be stabilized, and the deterioration of the adhesive strength between the chassis and the bearing holding member is reduced. In addition, there is a great effect that the deterioration of the adhesive strength due to changes in storage temperature and the like, and the change in the shape of the bearing member due to the change in operating temperature can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same element and description may be abbreviate | omitted.

(First embodiment)
1 to 4 are diagrams for explaining a spindle motor and a disk drive device using the spindle motor according to the first embodiment of the present invention. FIG. 1 is a cross-sectional view showing the configuration of the spindle motor. FIG. 2 is an enlarged sectional view showing the vicinity of a bearing portion in the spindle motor shown in FIG. FIG. 3 is a schematic diagram showing the configuration of the disk drive device. FIG. 4 is an enlarged cross-sectional view showing the vicinity of the bearing portion of the spindle motor in another example of the present embodiment.

  1 and 2, a hub 2 having a disc receiving portion 2u composed of a cylindrical surface and a flat portion on the outer periphery thereof, and one end portion of the rotating shaft 4 is outside at the center portion of the hub 2. It is fitted and fixed. The rotating shaft 4 is rotatably supported, the hollow cylindrical bearing member 8 made of brass and the lower portion of the bearing member 8 are closed, and the hub 2 is rotated on a surface facing one end face 4w of the rotating shaft 4. A thrust plate 40 in which a pump-in spiral groove (not shown), which is a dynamic pressure generating groove for inducing pressure inward in the radial direction with respect to the oil, is formed as a dynamic pressure generating groove is sometimes used as a means for adhesion or the like. Thus, it is fixed to the lower portion of the bearing member 8. A thrust bearing 23 is constituted by the end face 4 w of the rotating shaft 4 and the thrust plate 40.

  Here, the gap distance between the plane including the stepped portion 4v of the rotating shaft 4 and the upper end surface of the bearing member 8 is larger than the distance between the end surface 4w of the rotating shaft 4 and the surface on which the spiral groove of the thrust plate 40 is formed. It is comprised so that it may become.

  Further, the rotating magnet 16 is fixed to the hub 2 by means such as adhesion so that the outer periphery thereof is concentric with the outer periphery of the rotating shaft 4, and the rotating body 13 is attached by the rotating shaft 4, the hub 2 and the rotating magnet 16. It is composed.

  A bearing holding member 11 is fixed to the outer periphery of the bearing member 8 by means such as adhesion. The lower end portion of the bearing holding member 11 is inserted into a hole provided in the chassis 15, and the bearing holding member 11 is fitted to the chassis 15 by means of machining such as caulking or bonding. Further, the armature 14 is opposed to the outer peripheral surface of the rotating magnet 16 via a predetermined gap in the radial direction and generates a rotating force with respect to the rotating magnet 16 around the central axis of the rotating shaft 4. Is fixed to the chassis 15.

  Between the outer peripheral surface of the rotating shaft 4 and the inner peripheral surface of the bearing member 8 and between the end surface 4w of the rotating shaft 4 continuous therewith and the surface on which the spiral groove of the thrust plate 40 is formed, a series of minute A gap is formed, and oil is continuously held in the minute gap without interruption, so that a hydrodynamic bearing having a so-called full-fill structure is formed.

  Further, by using a martensitic or ferritic steel material for the chassis 15, the magnetic attraction force generated between the chassis 15 and the rotating magnet 16 facing the rotating magnet 16 causes a thrust between them. The thrust force required for the bearing 23 is generated.

  Here, the inner peripheral surface of the bearing member 8 is connected to a pair of spiral grooves that incline in opposite directions with respect to the rotational direction, inducing fluid dynamic pressure in the oil when the hub 2 rotates. A “<”-shaped herringbone groove (not shown) is formed as a dynamic pressure generating groove, and a radial bearing 22 is formed between the outer peripheral surface of the rotary shaft 4.

  Further, a retaining member 19 is bonded to the upper end portion of the bearing member 8 so as to face the stepped portion 4v provided on the rotating shaft 4 so as to prevent the rotating body 13 from coming off in the axial direction of the rotating shaft 4. It is fixed by means such as press fitting.

  In the radial bearing 22, the pumping force by the herringbone groove is increased with the rotation of the rotating body 13, and fluid dynamic pressure is generated. The rotating shaft 4 is pivotally supported by the bearing member 8.

  Similarly, with the rotation of the rotating body 13, a pressure directed radially inward is induced in the oil by the spiral groove of the pump-in. This radially inward pressure promotes oil flow, increases the oil internal pressure, and causes fluid dynamic pressure acting in the floating direction of the hub 2 between the end face 4w of the rotating shaft 4 and the thrust plate 40. appear.

Here, the linear expansion coefficient of the typical material of the elements constituting the bearing member 8, the bearing holding member 11, and the chassis 15 is 20.9 × 10 ⁻⁶ / ° C. for brass, and 17 for the austenitic steel material. The martensitic steel material is 10.4 × 10 ⁻⁶ / ° C. at 3 × 10 ⁻⁶ / ° C. Therefore, the inner peripheral diameter of the bearing member 8 when the combination of the respective materials is changed for each component of the bearing member 8, the bearing holding member 11 and the chassis 15 and each component is fixed with a thermosetting adhesive. Table 1 shows the results obtained by structural analysis of changes in Here, the shape of the bearing member 8 is such that the outer peripheral diameter is 4.1 mm, the inner peripheral diameter is 3 mm, the total length is 1.1 mm, the adhesive temperature is 95 ° C., the adhesive is cured at 95 ° C., and then at room temperature (25 ° C. ), The change (difference) in the radius of the lower end with respect to the radius of the upper end of the inner peripheral diameter of the bearing member 8 as the radial bearing 22 is calculated. Here, the radius difference shown in (Table 1) is a difference in radius between the upper end portion and the lower end portion of the radial bearing 22, and when the radius difference is a positive value, the radius of the lower end portion is larger. Is shown.

  As apparent from Table 1, when the material of the bearing member 8 is brass and the material of the chassis 15 is martensite, the material of the bearing holding member 11 causes the upper end of the radial bearing 22 of the bearing member 8 to be It can be seen that the amount of change (difference) in the radius of the lower end relative to the radius changes.

  Due to the downsizing and thinning of the disk device, the radial gap between the outer peripheral surface of the rotating shaft 4 and the inner peripheral surface of the bearing member 8 is normally set to 2 μm to 3 μm. When the material of the bearing member 8 is brass, the material of the chassis 15 is martensite, the material of the bearing holding member 11 is a martensitic steel material, and the design center value of the radial gap is 3 μm, the radial bearing 22 Since the difference in the radial gap between the upper end and the lower end of the bearing changes by 1 μm, the radial gap at the upper end of the radial bearing 22 becomes 2.5 μm, and the radial gap at the lower end of the bearing becomes 3.5 μm. The dynamic pressure at the lower part of the bearing 22 becomes lower than the design value, and a desired value cannot be obtained as the bearing rigidity.

  On the other hand, as in the present embodiment, the material of the bearing holding member 11 is centered on the value of the linear expansion coefficient, and the materials of the bearing member 8, the bearing holding member 11 and the chassis 15 are different from each other. For example, when the material of the bearing holding member 11 is an austenitic steel material, the material of the bearing member 8 is brass, and the chassis 15 is a martensitic steel material, the bearing member 8 and the bearing holding member 11 It can be seen from Table 1 that the difference in the radial gap between the upper and lower ends of the radial bearing 22 generated by curing the chassis 15 with a thermosetting adhesive can be made very small. Further, when the linear expansion coefficients of the bearing holding member 11 and the bearing member 8 are made of the same or substantially the same material, for example, the bearing holding member 11 is made of brass, and the bearing member 8 is made of brass. Even in this case, the difference in the radial gap between the upper end portion and the lower end portion of the radial bearing 22 generated by curing the bearing member 8, the bearing holding member 11, and the chassis 15 with a thermosetting adhesive is extremely small. it can.

  Therefore, the bearing member 8 and the bearing member 8 are made of materials having different values of the linear expansion coefficients of the bearing member 8, the bearing holding member 11, and the chassis 15, respectively. A structure in which the bearing holding member 11 is bonded and the bearing holding member 11 to which the bearing member 8 is bonded is bonded to the chassis 15, or the bearing member 8 and the bearing holding member 11 are made of the same material or the bearing member 8 and the bearing holding member 11. The spindle motor, in particular, the hydrodynamic bearing is assembled by adhering materials having substantially the same linear expansion coefficient as the material of the material and adhering the bearing holding member 11 to which the bearing member 8 is adhered to the chassis 15. The distortion of the bearing member 8 that occurs at the time is suppressed, and the bearing performance is stabilized. Furthermore, strong adhesive strength is obtained between the chassis 15 and the bearing holding member 11. Furthermore, the adhesive strength does not deteriorate even with a temperature change such as a storage temperature or a temperature rise during operation. Moreover, the change of the shape as the radial bearing 22 can also be suppressed.

  FIG. 3 is a schematic diagram for explaining the configuration of the disk drive device 50 using the spindle motor according to the embodiment of the present invention. The interior of the housing 51 forms a clean space with extremely little dust and the like, and a spindle motor 52 on which a disk-shaped disk plate 53 for storing information is mounted is installed. In addition, a head moving mechanism 57 serving as information access means for reading and writing information from and to the disk plate 53 is disposed inside the housing 51. The head moving mechanism 57 includes a head 56 that reads and writes information on the disk plate 53, an arm 55 that supports the head 56, and an actuator 54 that moves the head 56 and the arm 55 to a required position on the disk plate 53. Has been.

  By using a spindle motor as shown in FIG. 1 as the spindle motor 52 of such a disk drive device 50, desired rotational accuracy can be obtained, and at the same time, the disk drive device 50 can be made thinner and lower in cost. it can.

  In the above-described embodiment, the chassis 15 is made of a martensitic steel material, but the chassis 15 may be made of aluminum. In this case, as shown in FIG. 4, a magnetic attraction plate 17 made of martensitic steel material is fixed to a position facing the rotating magnet 16 of the chassis 15 by adhesion or the like, and between the rotating magnet 16 and the chassis 15. It is configured to generate a thrust force.

  When the material of the chassis 15 is aluminum and the material of the bearing member 8 is composed of martensitic or ferritic steel material, the results of structural analysis under the same conditions as in the above (Table 1) are shown in (Table Shown in 2).

  As apparent from Table 2, the material of the bearing member 8 is made of martensitic steel, the material of the chassis 15 is made of aluminum, and the material of the bearing holding member 11 is made of brass. When the design center value of the radial clearance on the inner peripheral surface of the member 8 is 3 μm, the difference in radial clearance between the upper end and the lower end of the radial bearing 22 changes by −1.1 μm. The radial clearance at the upper end is 3.55 μm, the radial clearance at the lower end of the bearing is 2.45 μm, and the dynamic pressure at the top of the radial bearing 22 is lower than the design value, making it impossible to obtain a desired value for the bearing stiffness. .

  On the other hand, as can be understood from the results of (Table 2), the values of the linear expansion coefficients of the materials of the bearing member 8, the bearing holding member 11, and the chassis 15 are centered on the values of the linear expansion coefficients of the materials of the bearing holding member 11. For example, when the bearing holding member 11 is made of an austenitic steel material, the bearing member 8 is made of a martensitic or ferritic steel material, and the chassis 15 is made of aluminum. The radial gap between the upper end portion and the lower end portion of the radial bearing 22 generated by curing the bearing member 8, the bearing holding member 11, and the chassis 15 with a thermosetting adhesive can be made extremely small.

  Alternatively, when the linear expansion coefficients of the bearing holding member 11 and the bearing member 8 are made of the same or substantially the same material, for example, the material of the bearing holding member 11 is a martensitic steel material and the material of the bearing member 8 is a martensite type. Even when the steel material and the chassis 15 are made of aluminum, the upper and lower ends of the radial bearing 22 generated by curing the bearing member 8, the bearing holding member 11, and the chassis 15 with a thermosetting adhesive. The radial gap can be made very small.

  Therefore, the bearing member 8 and the bearing member 8 are made of materials having different values of the linear expansion coefficients of the bearing member 8, the bearing holding member 11, and the chassis 15, respectively. A structure in which the bearing holding member 11 is bonded and the bearing holding member 11 to which the bearing member 8 is bonded is bonded to the chassis 15, or the bearing member 8 and the bearing holding member 11 are made of the same material or the bearing member 8 and the bearing holding member 11. As shown in FIG. 1 of the above-described embodiment, the bearing holding member 11 to which the bearing member 8 is bonded is bonded to the chassis 15 by using materials having substantially the same linear expansion coefficients as the material of the above. As in the spindle motor shown in FIG. 5, the distortion of the bearing member 8 is suppressed, the bearing performance is stabilized, and the strong contact between the chassis 15 and the bearing holding member 11 is achieved. Strength can be obtained. Furthermore, the adhesive strength does not deteriorate even with a temperature change such as a storage temperature or a temperature rise during operation. Moreover, the change of the shape as the radial bearing 22 can also be suppressed.

  In the above-described embodiment, the radial bearing 22 and the thrust bearing 23 are described as fluid dynamic pressure bearings using a fluid such as oil. However, as is well known, a rotary bearing member such as two ball bearings spaced apart from each other by a predetermined distance in the axial direction of the rotary shaft is provided between the rotary shaft 4 and the bearing member 8. The rotary shaft may be pivotally supported on the bearing member via the rotary bearing member. Even in such a configuration, the change in the axial direction of the inner peripheral diameter of the bearing member when the components of the bearing member, the bearing holding member, and the chassis are fixed with a thermosetting adhesive is the above-described embodiment. Will be the same. That is, by reducing the change in the inner peripheral diameter of the bearing member, the force with which the inner peripheral diameter of the bearing member tightens the upper rotary bearing member and the lower rotary bearing member does not change significantly, and the bearing performance Will not adversely affect

  As described above, according to the present embodiment, when assembling a spindle motor, especially when assembling by bonding the bearing member and the bearing holding member constituting the radial bearing and bonding the bearing holding member and the chassis, the bearing member Is suppressed, the bearing performance is stabilized, and a strong adhesive strength is obtained between the chassis and the bearing holding member. Furthermore, the adhesive strength does not deteriorate even with a temperature change such as a storage temperature or a temperature rise during operation. Further, a change in shape as a radial bearing can be suppressed, and a spindle motor having high stability and reliability can be realized.

  Further, by mounting such a spindle motor, it is possible to realize a disk drive device that is highly reliable, small and thin.

(Second Embodiment)
FIGS. 5-7 is a figure for demonstrating the spindle motor concerning the 2nd Embodiment of this invention. FIG. 5 is a cross-sectional view showing the configuration of the spindle motor. FIG. 6 is an enlarged sectional view showing the vicinity of the bearing portion in the spindle motor shown in FIG. FIG. 7 is an enlarged cross-sectional view showing the vicinity of a bearing portion in a spindle motor of another example.

  The main points that the configuration of the spindle motor according to the present embodiment differs from the spindle motor according to the first embodiment are the following two points. First, in the first embodiment, the thrust bearing 23 is constituted by the end face 4w of the rotating shaft 4 and the thrust plate 40 facing the end surface 4w, whereas in the present embodiment, the hub in the bearing member 63 is provided. The thrust bearing 23 is configured by the upper end surface 63a facing the upper end surface 64a and the flat surface portion 64x of the hub 64 facing the upper end surface 63a of the bearing member 63. Further, in the first embodiment, the thrust plate 40 closes the lower surface of the bearing member 8 and the surface facing the end surface 4w of the rotating shaft 4, whereas in the present embodiment, the bearing holding member 61 is used. The closed end 61w provided on the side closes the lower surface of the bearing member 63 and the surface facing the end surface 62w of the rotating shaft 62.

  Hereinafter, the spindle motor in the present embodiment will be specifically described with reference to FIGS.

  5 and 6, the bearing holding member 61 holds a hollow cylindrical bearing member 63 that rotatably supports the rotating shaft 62, and has a surface facing the lower portion of the bearing member 63 and the end surface 62 w of the rotating shaft 62. Blocked. Further, the outer peripheral upper end portion 61a of the bearing holding member 61 has a predetermined radial distance from the inner peripheral portion 64b of the annular ring member 64a formed integrally with the hub 64 so as to hang down in the axial direction of the rotating shaft 62. Have curved surfaces facing each other. Further, a taper surface 61b is formed in a part of the curved surface, that is, a lower portion so that the outer diameter decreases in the axial direction toward the closed end 61w, and oil is supplied to a part of the taper surface 61b. Filled.

  Further, a notch 61 c is provided at the lower part of the tapered surface 61 b of the bearing holding member 61. By fixing the retaining member 65 to the lower inner peripheral portion of the annular ring member 64a of the hub 64 by means of adhesion or the like so as to face the notch portion 61c and loosely fit in a non-contact state, the hub 64 is fixed. The rotating shaft 62 is prevented from coming off in the axial direction, and the rotating shaft 66, the hub 64, the rotating magnet 16 and the retaining member 65 constitute a rotating body 66.

  Further, a pump-in spiral groove (see FIG. 5) is a dynamic pressure generating groove that induces a pressure inward in the radial direction (on the rotating shaft 62 side) with respect to the oil when the hub 64 rotates. (Not shown) is formed. The hub 64 is urged in the direction of the chassis 15 by the magnetic attractive force acting between the rotating magnet 16 and the chassis 15 made of a magnetic material, and the upper end surface 63a of the bearing member 63 provided with the flat portion 64x of the hub 64 and the spiral groove. Thus, the thrust bearing 23 is formed. The gap distance between the end 62w of the rotating shaft 62 and the closing portion 61w is the gap distance of the thrust bearing 23, that is, the upper end surface 63a of the bearing member 63 in which the flat portion 64x of the hub 64 and the spiral groove are formed. It is comprised so that it may become larger than the space | gap distance.

  Here, a plane between the inner peripheral portion 64 b of the annular ring member 64 a of the hub 64 and the tapered surface 61 b of the bearing holding member 61, a plane facing the upper end surface 63 a of the bearing member 63 and the upper end surface 63 a of the bearing member 63 in the hub 64. Between the outer peripheral surface of the rotating shaft 62 and the inner peripheral surface of the bearing member 63, and between the end surface 62 w of the rotating shaft 62 and the surface of the closed portion 61 w of the bearing holding member 61. A series of minute gaps are formed, and oil is continuously held in the minute gaps without interruption, so that a fluid dynamic pressure bearing having a so-called full-fill structure is formed.

  Here, the radial bearing 22 is formed between the inner peripheral surface of the bearing member 63 in which a herringbone groove (not shown) is formed and the outer peripheral surface of the rotary shaft 62 as in the first embodiment. As the rotary shaft 62 rotates, the pumping force by the herringbone groove, which is a dynamic pressure generating groove, increases, and fluid dynamic pressure is generated between the inner peripheral surface of the bearing member 63 and the outer peripheral surface of the rotary shaft 62. The rotating shaft 62 is supported by a bearing member 63.

  Similarly, as the hub 64 rotates, a pressure directed radially inward is induced in the oil by the spiral groove of the pump-in. Due to the pressure inward in the radial direction, the flow of oil is promoted, the internal pressure of the oil is increased, and a fluid dynamic pressure acting in the floating direction of the hub 64 is generated.

  Accordingly, since the thrust bearing 23 is constituted by the flat surface portion 64x of the hub 64 and the upper end surface 63a of the bearing member 63, the flat surface portion 64x of the hub 64 constituting the thrust bearing 23 and the upper end surface 63a of the bearing member 63 are formed. The facing area can be increased. Further, the position of the thrust bearing 23 can be arranged at a position away from the axis of the rotating shaft 62 in the radial direction. Thereby, bearing rigidity can be enlarged. Further, in the inner peripheral portion 64b of the annular ring member 64a in the hub 64 and the tapered surface 61b of the bearing holding member 61, the surface tension of the oil and the external air pressure are balanced, and an interface (taper seal) exists between the oil and air. It is formed.

  Moreover, when assembling the bearing unit, it is possible to confirm that the bearing unit is filled with oil by confirming the position of the interface after oiling. Therefore, even if the size and thickness are reduced, process management and performance management are facilitated, so that it is possible to stabilize the bearing performance of the disk device incorporating the spindle motor. Thereafter, the retaining member 65 may be fixed to the inner peripheral portion 64 b of the annular ring member 64 a of the hub 64.

  Further, the taper seal portion formed between the inner peripheral portion 64b of the annular ring member 64a and the taper surface 61b functions as an oil reservoir, and the interface formation position is appropriately set according to the amount of oil retained in the taper seal. It is movable. Therefore, when the amount of oil retained decreases, the oil retained by the taper seal is supplied to the respective parts constituting the fluid dynamic pressure bearing by the capillary force. Conversely, when the oil held in each part of the hydrodynamic bearing expands due to temperature rise, etc., the oil interface moves in a direction in which the gap dimension expands from within the tapered space formed in the tapered seal part. To do. Thereby, the oil corresponding to the increased volume is accommodated in the taper seal portion.

  Thus, by configuring the taper seal portion using the surface tension, the taper seal portion can be disposed in a portion having a larger diameter than each portion constituting the hydrodynamic bearing. Furthermore, the axial direction dimension of the taper seal portion can also be made relatively large. Accordingly, the volume in the taper seal portion is increased, and the thermal expansion of the oil retained in a large amount in the fluid bearing having the full-fill structure can be sufficiently followed.

  Here, adhesion or deformation of the bearing surface in the use environment will be described. Since the radial bearing 22 is the same as that of the first embodiment, the description thereof will be omitted, and only the thrust bearing 23 will be described here. Also, the description of the hydrodynamic bearing system and the surface on which the groove is formed is the same as in the first embodiment, and will be omitted.

  As in the first embodiment, the result of structural analysis of the height change of the inner and outer peripheral surfaces of the thrust surface of the bearing member 63 when the components are fixed with a thermosetting adhesive, (Table 3). Here, the shape of the bearing member 63 is such that the outer peripheral diameter of the thrust surface, which is the portion forming the thrust bearing 23 in the upper end surface 63a, is 5.1 mm, the inner peripheral diameter is 3.4 mm, and the thickness of the collar portion at the upper end portion. 0.5 mm, the outer diameter of the notch of the portion that fits into the bearing holding member 61 is 4.1 mm, the inner diameter of the radial bearing 22 is 3 mm, the total length is 1.1 mm, and thermosetting at 95 ° C. The change in height between the inner peripheral portion and the outer peripheral portion of the thrust surface of the bearing member 63 is obtained by structural analysis when it is adhesively cured with an adhesive and then returned to room temperature (25 ° C.). In Table 3, the value when the umbrella shape, that is, the inner peripheral side is high and the outer peripheral side is low is positive. (Table 3) shows a change in the combination of materials for each component of the bearing member 63, the bearing holding member 61, and the chassis 15 in the dynamic pressure bearing, and each component is fixed with a thermosetting adhesive. The height change of the inner peripheral side part and the outer peripheral side part of the thrust surface in the bearing member 63 at this time is shown.

  As can be seen from Table 3, when the material of the bearing member 63 is brass and the material of the chassis 15 is martensite, the inner surface of the thrust surface of the bearing member 63 after the adhesive curing depends on the material of the bearing holding member 61. It can be seen that the height change (height difference) between the peripheral portion and the peripheral portion changes. In addition, the thrust surface of the bearing member 63 after the adhesive curing has an umbrella shape, and the peak value of the pressure generated in the thrust bearing 23 moves to the inner peripheral side. For this reason, in the dynamic pressure in the thrust direction generated in the thrust bearing 23, the position where the dynamic pressure as the design value is generated is on the inner peripheral side from the design value, and the thrust that supports the rotating body 66 by the dynamic pressure generated in the thrust bearing 23 is provided. As the position where the design value of the dynamic pressure in the thrust direction at the thrust bearing 23 moves toward the inner peripheral side, the bearing rigidity increases. Will be reduced.

  Further, as apparent from (Table 3), when the material of the bearing member 63 is made of brass, the material of the chassis 15 is made of martensite, and the material of the bearing holding member 61 is made of a martensitic steel material, The height change (height difference) between the inner peripheral portion and the outer peripheral portion of the thrust surface of the bearing member 63 is a large value of 1 μm, and a desired value cannot be obtained as the bearing rigidity.

  On the other hand, in the present embodiment, the values of the linear expansion coefficients of the bearing member 63, the bearing holding member 61, and the chassis 15 are made of different materials, with the value of the linear expansion coefficient of the bearing holding member 61 as the center. For example, when the material of the bearing holding member 61 is an austenitic steel material, the material of the bearing member 63 is brass, and the chassis 15 is a martensitic steel material, the bearing member 63, the bearing holding member 61, and the chassis 15 are heated. A change in height between the inner peripheral side and the outer peripheral side of the thrust surface in the thrust bearing 23 generated by curing with a curable adhesive can be made extremely small. As a result, a decrease in bearing rigidity as the thrust bearing 23 can be suppressed, and the thrust bearing 23 can be stabilized.

  Alternatively, when the bearing holding member 61 and the bearing member 63 are formed of the same material, or when the linear expansion coefficients of the bearing holding member 61 and the bearing member 63 are substantially equal, for example, the material of the bearing holding member 61 is Similarly, even when the material of the brass and the bearing member 63 is brass, the inner circumference of the thrust surface in the thrust bearing 23 generated by curing the bearing member 63, the bearing holding member 61, and the chassis 15 with a thermosetting adhesive. The change in height between the side and the outer peripheral side can be made very small. As a result, a decrease in bearing rigidity as the thrust bearing 23 can be suppressed, and the thrust bearing 23 can be stabilized.

  In the above-described embodiment, the chassis 15 is made of a martensitic steel material, but the chassis 15 may be made of aluminum. In this case, as shown in FIG. 7, a magnetic attraction plate 17 made of a martensitic steel material is fixed to a position facing the rotating magnet 16 of the chassis 15 by adhesion or the like, and between the rotating magnet 16 and the chassis 15. A thrust force is generated via the magnetic attraction plate 17.

  When the chassis 15 is made of aluminum and the bearing member 63 is made of a martensitic or ferritic steel material, the results of structural analysis under the same conditions as in the above (Table 3) are shown in (Table Shown in 4).

  As can be seen from Table 4, the thrust surface of the thrust bearing 23 in the bearing member 63 after adhesive hardening has a bowl shape, and the peak value of the pressure generated in the thrust bearing 23 moves to the outer peripheral side. It will be. Therefore, in the dynamic pressure in the thrust direction generated in the thrust bearing 23, the position where the dynamic pressure as the design value is generated is on the outer peripheral side from the design value.

  As a result, the pressure balance of the dynamic pressure in the thrust direction generated by the rotation of the rotating body 66 is different from the design value. In the case where the shape of the dynamic pressure generating groove provided on the upper end surface 63a of the bearing member 63 constituting the thrust bearing 23 is a spiral groove, the pressure generated in the thrust bearing 23 is inherently toward the central axis of the rotating shaft 62. As a result, sufficient thrust bearing rigidity can be obtained as the thrust bearing 23, and a sufficient flying height can be obtained with respect to the rotating body 66. However, since the shape of the thrust surface on the upper end surface 63a of the bearing member 63 constituting the thrust bearing 23 is a bowl shape, the increase in pressure on the inner peripheral side is reduced, so that sufficient thrust bearing rigidity is obtained. And a sufficient flying height cannot be obtained.

  Therefore, as in the case of the present embodiment shown in (Table 4), each line of each material of the bearing member 63, the bearing holding member 61, and the chassis 15 is centered on the value of the linear expansion coefficient of the bearing holding member 61. For example, in the case where the bearing holding member 61 is made of an austenitic steel material, the bearing member 63 is made of martensite, and the chassis 15 is made of aluminum, the bearing holding member 61 is made of a material having a different expansion coefficient. It is possible to greatly reduce the change in height between the inner peripheral side and the outer peripheral side of the thrust surface of the thrust bearing 23 generated by curing the member 63, the bearing holding member 61, and the chassis 15 with a thermosetting adhesive. Thus, a decrease in bearing rigidity as the thrust bearing 23 can be suppressed, and the thrust bearing 23 can be stabilized.

  Therefore, the bearing member 63, the bearing member 63, the bearing holding member 61, and the chassis 15 are made of materials having different values of the linear expansion coefficient. By adhering the bearing holding member 61 and adhering the bearing holding member 61 to which the bearing member 63 is bonded to the chassis 15, the spindle motor shown in FIG. Occurrence of a height difference between the inner peripheral side and the outer peripheral side of the upper end surface 63a in the bearing member 63 is suppressed, and a decrease in bearing rigidity as the thrust bearing 23 can be suppressed. Thereby, the bearing performance is stabilized, and a strong adhesive strength is obtained between the chassis 15 and the bearing holding member 61. Furthermore, the adhesive strength does not deteriorate even with a temperature change such as a storage temperature or a temperature rise during operation. Moreover, the change of the shape of the upper end surface 63a of the bearing member 63 as the thrust bearing 23 can also be suppressed.

  In the first embodiment and the second embodiment, one embodiment of the spindle motor and the disk drive device according to the present invention has been described. However, the present invention is not limited to such an embodiment. Various changes and modifications can be made without departing from the scope of the invention. For example, in the groove provided on the upper end surface of the bearing member as the thrust bearing or the thrust plate, the means for generating the pressure acting on the oil in the radial direction of the bearing member is the pump-in type in the above description. Instead of a spiral groove, a herringbone groove having an unbalanced shape in the radial direction may be used. In this case, by setting the pumping force by the spiral groove located on the radially outer side to exceed the pumping force caused by the spiral groove located on the radially inner side, the pumping force between these spiral grooves is unbalanced. The amount is the pressure acting radially inward against the oil.

  Moreover, you may form a groove in any surface by the surfaces which face the surface which forms the groove of each bearing. That is, at least one of the outer peripheral surface of the rotating shaft as a radial bearing and the inner peripheral surface of the bearing member, and at least one of the lower end surface of the rotating shaft as a thrust bearing and the surface facing the rotating shaft of the thrust plate Alternatively, a groove may be formed on at least one of the upper end surface of the bearing member and the plane of the hub facing the bearing member.

  As described above, according to the second embodiment, when assembling the spindle motor, particularly when assembling by bonding the bearing member and the bearing holding member constituting the thrust bearing and bonding the bearing holding member and the chassis, The distortion generated in the bearing member is suppressed, the bearing performance is stabilized, and strong adhesive strength is obtained between the chassis and the bearing holding member. Furthermore, the adhesive strength does not deteriorate with respect to temperature changes such as storage temperature or temperature rise during operation, and changes in the shape of the thrust surface as a thrust bearing can be suppressed, resulting in high stability and reliability. It is possible to realize an excellent spindle motor having the characteristics.

  Furthermore, by mounting such a spindle motor, it is possible to realize an excellent disk drive device that is small and thin. For example, it is suitable for a small disk drive device that drives a hard disk having an outer diameter of 1 inch. Furthermore, it can be used not only for a disk drive device such as a hard disk but also for a magneto-optical disk drive device and an optical disk drive device.

  According to the spindle motor according to the present invention, the bearing member, the bearing holding member, and the chassis are made of materials having different values of the linear expansion coefficient, centering on the value of the coefficient of linear expansion of the bearing holding member. A member, a bearing holding member, and a chassis are formed.

  By adopting such a spindle motor configuration, the bearing member and the bearing holding member when assembling the spindle motor, and the distortion of the bearing member that occurs after adhesion hardening in the adhesion between the bearing holding member and the chassis are reduced, and the radial bearing and The bearing performance of the thrust bearing can be stabilized. Furthermore, the deterioration of the adhesive strength between the chassis and the bearing holding member is also reduced. Furthermore, since the deterioration of the adhesive strength due to changes in storage temperature and the like and the change in bearing shape due to changes in operating temperature can be reduced, it is useful in fields such as disk devices and polygon mirror rotating devices.

Sectional drawing which shows the structure of the spindle motor concerning the 1st Embodiment of this invention The spindle motor concerning the embodiment WHEREIN: The expanded sectional view which shows the bearing part vicinity The schematic diagram which shows the structure of a disk drive device in the spindle motor concerning the embodiment The expanded sectional view which shows the bearing part vicinity of the spindle motor in other examples of the embodiment Sectional drawing which shows the structure of the spindle motor concerning the 2nd Embodiment of this invention. The spindle motor concerning the embodiment WHEREIN: The expanded sectional view which shows the bearing part vicinity in the spindle motor shown in FIG. The spindle motor concerning the embodiment WHEREIN: The expanded sectional view which shows the bearing part vicinity in the spindle motor of another example.

Explanation of symbols

2,64 Hub 2u Disk receiving part 4,62 Rotating shaft 4v Stepped part 4w, 62w End face 8,63 Bearing member 11,61 Bearing holding member 13,66 Rotating body 14 Armature 15 Chassis 16 Rotating magnet 17 Magnetic attraction plate 19, 65 Retaining member 22 Radial bearing 23 Thrust bearing 40 Thrust plate 50 Disk drive device 51 Housing 52 Spindle motor 53 Disk plate 54 Actuator 55 Arm 56 Head 57 Head moving mechanism 61a Outer peripheral upper end 61b Tapered surface 61c Notch 61w Closed end ( Occlusion)
63a upper end surface 64a annular ring member 64b inner peripheral part 64x plane part

Claims (13)

A rotation axis;
A rotating body comprising a hub having a disk receiving portion, the rotating shaft fixed to the central portion thereof, and a rotating magnet fixed to the hub concentrically with the rotating shaft;
A bearing member that pivotally supports the rotating shaft;
An armature that opposes the rotating magnet and generates a rotational force about the central axis of the rotating shaft with the rotating magnet;
A bearing holding member for holding the bearing member;
In a spindle motor including a chassis for fixing the armature and the bearing holding member,
A spindle having a configuration in which materials having different values of linear expansion coefficient of each material of the bearing member, the bearing holding member, and the chassis are respectively used with the value of the linear expansion coefficient of the bearing holding member as a center. motor. A thrust plate fixed to the lower part of the bearing member so as to close the lower part of the bearing member and to face one end surface of the rotating shaft;
The rotating shaft is provided with a dynamic pressure generating groove on at least one of the outer peripheral surface thereof and the inner peripheral surface of the bearing member opposed thereto,
A shape that applies pressure acting on the inner side in the radial direction to the oil when the rotating body rotates, on at least one of the thrust plate and the one end surface of the rotating shaft facing the thrust plate. The spindle motor according to claim 1, wherein a dynamic pressure generating groove is provided. A rotation axis;
A rotating body comprising a hub having a disk receiving portion, the rotating shaft fixed to the central portion thereof, and a rotating magnet fixed to the hub concentrically with the rotating shaft;
A bearing member that pivotally supports the rotating shaft;
An armature that opposes the rotating magnet and generates a rotational force about the central axis of the rotating shaft with the rotating magnet;
A bearing holding member for holding the bearing member;
In a spindle motor comprising a chassis for fixing the armature and the bearing holding member,
A spindle motor having a configuration in which materials having substantially the same linear expansion coefficient values of the bearing holding member and the bearing member are used. A thrust plate fixed to the lower part of the bearing member so as to close the lower part of the bearing member and to face one end surface of the rotating shaft;
The rotating shaft is provided with a dynamic pressure generating groove on at least one of the outer peripheral surface thereof and the inner peripheral surface of the bearing member opposed thereto,
A shape that applies pressure acting on the inner side in the radial direction to the oil when the rotating body rotates, on at least one of the thrust plate and the one end surface of the rotating shaft facing the thrust plate. The spindle motor according to claim 3, wherein a dynamic pressure generating groove is provided. A rotation axis;
A rotating body comprising a hub having a disk receiving portion, the rotating shaft fixed to the central portion thereof, a rotating magnet fixed concentrically with the rotating shaft, and a retaining member;
A bearing member that pivotally supports the rotating shaft;
An armature that opposes the rotating magnet and generates a rotational force about the central axis of the rotating shaft with the rotating magnet;
A bearing holding member for holding the bearing member, and having one opening shape having a closed end surface facing the end surface of the rotating shaft in the axial direction;
In a spindle motor comprising a chassis for fixing the armature and the bearing holding member,
A radial bearing in which a groove for generating dynamic pressure is provided on at least one of the outer peripheral surface of the rotating shaft and the inner peripheral surface of the bearing member facing the rotary shaft;
A movement of a shape that applies pressure acting on the inner side in the radial direction to the oil during rotation of the rotating body on at least one of the upper end surface of the bearing member and the plane of the hub facing the upper end surface. A spindle motor comprising a fluid dynamic pressure bearing comprising a thrust bearing provided with a pressure generating groove. An annular ring member is integrally formed on the hub, and an inner peripheral portion of the annular ring member and an outer peripheral portion of the bearing holding member face each other with a predetermined distance in the radial direction, and the bearing The outer peripheral portion of the holding member has a curved surface facing and spaced apart from the inner peripheral portion of the annular ring member by a predetermined distance, and has a tapered surface so that the outer diameter becomes smaller toward the closed end surface in the lower portion of the curved surface. The spindle motor according to claim 4, wherein the oil is filled up to a part of a portion where the annular ring member and the tapered surface face each other. Centering on the value of the coefficient of linear expansion of the bearing holding member, the bearing member, the bearing holding member and the material of the chassis each have a configuration using different materials of linear expansion coefficients. The spindle motor according to claim 5 or 6. The brass member is used as the material of the bearing member, the austenitic steel material is used as the material of the bearing holding member, and the martensite or ferritic steel material is used as the material of the chassis. The spindle motor according to claim 1, claim 2, or claim 7. A martensitic or ferritic steel material is used as the material of the bearing member, an austenitic steel material is used as the material of the bearing holding member, and an aluminum material is used as the material of the chassis. The spindle motor according to claim 1, claim 2, or claim 6. 4. A structure using a brass material as a material of the bearing member, a brass aluminum material as a material of the bearing holding member, and a martensitic or ferritic steel material as a material of the chassis, respectively. The spindle motor according to claim 6. The bearing member has a martensitic or ferritic steel material, the bearing holding member has a martensitic or ferritic steel material, and the chassis has an aluminum material. The spindle motor according to claim 3 or 4, wherein The spindle motor according to claim 9 or 11, wherein a magnetic attraction plate made of a martensitic steel material is provided at a position of the chassis facing the rotating magnet. In a disk drive device in which a disk-shaped recording medium capable of recording information is mounted,
A housing;
A spindle motor fixed inside the housing and rotating the disc-shaped recording medium;
A disk drive device having information access means for writing or reading information at a required position of the disk-shaped recording medium,
13. The disk drive device according to claim 1, wherein the spindle motor is a spindle motor according to any one of claims 1 to 12.

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