JP2000078811A - Spindle motor for driving recording disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spindle motor for driving a recording disk capable of preventing the puncture of pressurization of a bearing at the time of temperature change when a bearing having ceramic rolling elements is used, and of maintaining the stable rotation of a rotor hub. SOLUTION: This spindle motor for driving a recording disk is provided with a rotor hub 4 supported in such a way as to be rotatable freely relatively to the base member of a driving device for the recording disk or a bracket 2 to be fixed to the base member, a pair of bearings 14, 16 for supporting the rotor hub 4, a rotor magnet 40, and a stator 42. The bearings 14, 16 are provided with inner races 18, 20 and outer races 22, 24 and ceramic rolling elements set between the races. An annular member 62 formed from a material having higher thermal expansion coefficient than a shaft member 12 is set between the outer races 22, 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor for rotating a recording disk such as a hard disk.

[0002]

2. Description of the Related Art A conventional spindle motor used for rotating a recording disk such as a hard disk is
A rotor hub rotatably supported by a base member of the recording disk drive or a bracket attached to the base member, a pair of bearings interposed between the base member or bracket and the rotor hub, and an inner periphery of the rotor hub A rotor magnet mounted on the surface, and a stator disposed opposite to the rotor magnet,
One or more recording disks are mounted on the rotor hub. And in the fixed shaft type spindle motor,
A shaft member is provided on the base member or the bracket, and the rotor hub is rotatably supported on the shaft member via a pair of bearings. In a rotary shaft type spindle motor, a shaft member is provided on a rotor hub, and the shaft member is rotatably supported on a base member or a bracket via a pair of bearings.

In such a spindle motor,
Generally, the shaft member is made of stainless steel (for example, SUS41).
6), and the rotor hub is made of stainless steel (for example, SUS430), aluminum (for example, A6061) or aluminum alloy. Further, a pair of bearings for rotatably supporting the rotor hub includes an inner ring and an outer ring,
A plurality of rolling elements interposed therebetween, wherein the inner ring, the outer ring and the plurality of rolling elements are made of bearing steel (for example, S
UJ2).

In recent years, as recording disk drives have been increasingly required to be reduced in size, increased in speed, and increased in capacity, in order to increase the recording capacity per unit area of the recording disk, magnetic characteristics have been reduced. An excellent thin film magnetic head and a magnetic head using an MR element whose internal resistance changes depending on the magnitude of a magnetic field have been adopted.

In the case of a recording disk drive employing a magnetic head using such an MR element, a constant voltage is applied to the magnetic head due to the characteristics of the MR element. As a result, a potential difference is generated between the recording disk and the magnetic head, and when the magnetic head flies above the recording disk, a discharge occurs between the recording disk and the magnetic head, and the information recorded on the recording disk may be destroyed. However, there is a disadvantage that the magnetic head is electrically corroded.

[0006] Also, with the spindle motor for rotating and driving the recording disk, with the increase in speed, in the bearing using the conventional steel ball, there is a problem of backlash and vibration due to the wear of the steel ball and the wear caused by this wear. New problems have arisen, such as contamination of the clean space in the recording disk drive due to the generated dust.

In order to prevent the above-mentioned discharge between the recording disk and the magnetic head, for example, Japanese Patent Application Laid-Open No. HEI 6-17647.
In Japanese Patent Application Publication No. 3 (1993) -1995, at least one of an inner ring, an outer ring and a rolling element of a bearing for rotatably supporting a rotor hub is formed of ceramic, and a base member of the recording disk drive and the rotor hub are electrically insulated. Means for doing so are disclosed. Above all, by configuring the ball as a rolling element interposed between the inner and outer rings with ceramic, electrical insulation between the base member and the rotor hub is ensured, and at the same time the use of a ceramic ball having high hardness, It is also possible to solve the problem of generation of rattling and vibration and dust generation due to wear of the ball.

[0008]

However, for example, when the balls of the members constituting the bearing are formed of ceramic and the inner and outer rings are formed of the same bearing steel as before, when the temperature in the recording disk drive rises, When the shaft member, the rotor hub, and the bearing thermally expand, the coefficient of thermal expansion between the ball formed of ceramic and other members is significantly different, so that a gap is generated between the inner and outer rings and the ball, and a pair of bearings is preloaded. Is not applied, the preload is released, and a rotational runout or the like occurs in the rotor hub, which causes a problem that the rotational characteristics are deteriorated.

The present invention has been made in consideration of such problems of the prior art, and an object of the present invention is to use a bearing having a ceramic rolling element when a temperature change occurs. It is an object of the present invention to provide a recording disk drive spindle motor capable of preventing a bearing from being released from preload and stably maintaining the rotation of a rotor hub.

[0010]

According to the present invention, there is provided a rotor hub rotatably supported by a base member of a recording disk drive or a bracket attached thereto and having at least one recording disk mounted thereon, A pair of bearings interposed at intervals in the axial direction between a base member or a bracket and the rotor hub, a rotor magnet mounted on an inner peripheral surface of the rotor hub, and disposed to face the rotor magnet. And a pair of bearings, each of which is provided with an inner ring and an outer ring that are arranged at a radial interval and a plurality of bearings interposed between the inner ring and the outer ring. Ceramic rolling elements, and between the outer rings of the pair of bearings, the coefficient of thermal expansion is greater than the member to which the inner ring is attached. An annular member formed of a threshold material is interposed, and at a high temperature, the annular member thermally expands and acts on the outer ring of the pair of bearings, whereby the preload of the pair of bearings is adjusted. .

According to the present invention, the rolling element of the bearing is formed of ceramic, and is formed between the outer rings of the pair of bearings supporting the rotor hub and formed of a material having a larger coefficient of thermal expansion than the member to which the inner ring is attached. Since the member is interposed,
When the temperature of the spindle motor rises, the thermal expansion of the annular member is larger than that of the member on which the inner ring is mounted, and therefore,
This annular member acts on the outer ring of the pair of bearings, and the amount of displacement of the outer ring toward both sides in the axial direction is greater than the amount of displacement between the inner rings, thus preventing a decrease in the preload applied to the pair of bearings. . Such a configuration can be applied to a shaft rotation type and a fixed shaft type motor.

Further, the present invention is characterized in that the annular member is constituted by a cylindrical sleeve member, and the cylindrical sleeve member is interposed between the outer rings of the pair of bearings.

According to the present invention, since the annular member is constituted by a cylindrical sleeve member, the preload at high temperatures can be reduced by a simple structure in which the cylindrical sleeve member is simply interposed between the outer rings of the pair of bearings. Can be prevented.

Further, according to the present invention, the annular member has an annular spacer portion, and a pair of annular support portions extending in the axial direction from both ends of the annular spacer portion. It is mounted on the inner peripheral surface of an annular support portion, and the annular spacer portion is interposed between the outer rings of the pair of bearings.

According to the present invention, since the annular member has the annular spacer portion and the pair of annular support portions, and the outer rings of the pair of bearings are mounted on the annular support portion, the annular member and the pair of bearings are configured as a unit. can do. Further, since the annular spacer portion is interposed between the outer rings, the annular spacer portion acts on the outer rings of the pair of bearings at a high temperature, thereby preventing a decrease in preload.

Further, according to the present invention, the annular member has an annular spacer portion and an annular support portion extending in an axial direction from one end of the annular spacer portion, and one outer ring of the pair of bearings is provided in the annular support portion. Mounted on the inner peripheral surface of the portion, the other outer ring of the pair of bearings is mounted on the inner peripheral surface of the rotor hub,
The annular spacer portion is interposed between the outer rings of the pair of bearings.

According to the present invention, since the annular spacer portion of the annular member is interposed between the outer rings of the pair of bearings, the annular spacer portion acts on the outer ring at a high temperature, thereby preventing a decrease in preload. it can.

Further, according to the present invention, the rotor hub has a hub body on which the recording disk is mounted, and the annular member is formed integrally with the hub body, and a pair of annular support members is provided on both sides of the annular member. Is disposed, and outer rings of the pair of bearings are mounted on inner peripheral surfaces of the pair of annular support members, and the annular member is interposed between the outer rings of the pair of bearings.

According to the present invention, since the annular member is formed integrally with the hub body, for example, by forming the annular member and the hub body from aluminum or aluminum alloy, the recording disk made of aluminum or aluminum alloy can be formed. The motor is suitable for the recording disk drive used. In addition, since annular support members are provided on both sides of the annular member, and the outer rings of the pair of bearings are mounted on the annular support member, by forming the annular support member from a material having substantially the same thermal expansion coefficient as the outer ring, An adverse effect on the bearing due to thermal expansion can be reduced. Furthermore, since the annular member is interposed between the outer rings of the pair of bearings, it is possible to prevent a decrease in preload at high temperatures.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a recording disk drive spindle motor according to the present invention will be described with reference to the accompanying drawings. First Embodiment FIG. 1 is a sectional view showing a first embodiment of a spindle motor according to the present invention. Referring to FIG. 1, the spindle motor includes a bracket 2 and a rotor hub 4 rotatable relative to the bracket 2, and the bracket 2 is a base of a recording disk drive such as a hard disk drive. It is attached to a member (not shown) as required. The bracket 2 includes a circular bracket main body 6, a peripheral side wall 8 extending upward is provided on an outer peripheral portion of the bracket main body 6, and a flange 10 extending radially outward is provided at an upper end of the peripheral side wall 8. Then, the flange 10 is attached to the base member.

One end (lower end) of the shaft member 12 is fixed to the center of the bracket body 6, and the other end (upper end) extends upward from the bracket body 6. In this embodiment, the shaft member 12 is attached to the bracket 2 and the bracket 2 is attached to the base member. However, the present invention is not limited to this, and the shaft member 12 may be directly attached to the base member. it can.

The shaft member 12 has a pair of ball bearings 1 spaced apart in the axial direction of the motor, that is, in the vertical direction in FIG.
The rotor hub 4 is rotatably supported via the bearings 14 and 16. Ball bearings 14,
Numeral 16 is substantially the same configuration, and as inner races 18, 20 and outer races 22, 24 arranged at intervals in the radial direction, and as rolling elements interposed between the inner races 18, 20 and outer races 22, 24. Of the inner ring 18,
20 is the shaft member 12 (in this embodiment, the shaft member 12 is
8 and 20).
2 and 24 are mounted on the rotor hub 4. In addition, a seal member 29 is attached to outer end portions of the outer rings 22 and 24,
The tip of the seal member 29 extends toward the inner rings 18 and 20. The bearings 14 and 16 and the configuration related thereto will be described later.

The illustrated rotor hub 4 has a cylindrical hub body 3.
An annular flange 32 is provided integrally at the lower end of the hub body 30 and protrudes outward in the radial direction. A recording disk (not shown) such as a hard disk is placed on the upper surface of the annular flange 32, and one or more recording disks (in the case of a plurality of recording disks, a spacer is interposed between adjacent recording disks) Is attached to the hub body 30.

A yoke member 34 is provided at the lower end of the hub body 30.
Is installed. The yoke member 34 has a peripheral side wall 36 and a mounting flange 38 extending radially inward from the upper end of the peripheral side wall 36.
Is attached to the lower end of the housing by, for example, caulking. An annular rotor magnet 40 is mounted on the inner peripheral surface of the peripheral side wall 36 of the yoke member 34, and a stator 42 is disposed radially inward facing the rotor magnet 40. The stator 42 includes a stator core 44 formed by stacking core plates, and a coil 46 wound around the stator core 44 as required.
The stator core 44 is mounted on an annular mounting wall 48 provided on the bracket body 6.

A magnetic fluid sealing means 50 is provided outside the one (upper) bearing 14, and the magnetic fluid sealing means 5 is provided.
Further, a cap member 52 for preventing scattering of the magnetic fluid is disposed outside the magnetic fluid seal 0, and the magnetic fluid sealing means 50 and the cap member 52 are mounted on the rotor hub 4 side. The air seal means 5 is provided outside the other (lower) bearing 16.
The air sealing means 54 is also provided with the rotor hub 4.
Mounted on the side.

In this spindle motor, a driving current is supplied to the coil 46 of the stator 42. When the driving current is supplied, the stator 42 is magnetized,
The rotor hub 4 and a recording disk (not shown) mounted thereon are rotated in a predetermined direction by a mutual magnetic action between the rotor hub 40 and the rotor hub 40.

Next, a description will be given of the pair of bearings 14 and 16 and a configuration related thereto. A pair of bearings 14,1
In No. 6, in order to provide sufficient wear resistance, it is important to form the plurality of balls 26 and 28 as rolling elements from a ceramic material, for example, silicon nitride (Si).
₃ N _4), it is formed from alumina _(Al 2 _{O 3).}
Further, the inner rings 18, 20 and the outer rings 22,
24 is formed of, for example, bearing steel (SUJ2 as an example). The shaft member 12 is formed of, for example, stainless steel (for example, SUS416), and the hub body 30 is formed of stainless steel (for example, SUS430).

In such bearings 14 and 16, when the plurality of balls 26 and 28 are formed of, for example, silicon nitride (or alumina), and the inner rings 16, 18 and the outer rings 20, 22 are formed of, for example, bearing steel, nitriding is performed. Silicon (or alumina) has a thermal expansion coefficient of 3.4 × 10 ⁻⁶ / ° C. (or 7.5 to 7.8 × 10 ⁻⁶ / ° C.), while the bearing steel has a thermal expansion coefficient of 12. Since the temperature is 5 × 10 ⁻⁶ / ° C., when the temperature of the recording disk drive rises and the spindle motor becomes hot, the inner rings 18 and 20 and the outer rings 2
Due to the difference in thermal expansion between the balls 2 and 24 and the plurality of balls 26 and 28, a gap is formed between them, and the preload of the bearings 14 and 16 tends to decrease. By configuring, this decrease in the preload is prevented.

More specifically, in the first embodiment, an annular member 62 is interposed between the outer rings 22 and 24 of the pair of bearings 14 and 16. The illustrated annular member 62 has a sleeve-like annular spacer portion 64 and annular support portions 66 and 68 extending from both ends of an outer peripheral portion of the annular spacer portion 64 to both sides in the axial direction (vertical direction in FIG. 1). ing. In this embodiment, as shown in FIG. 1, a part of the annular spacer 64 and a part of the annular support 66 are fixed to the inner peripheral surface of the hub body 30 by, for example, press fitting. The outer ring 22 of one bearing 14 is mounted on the inner peripheral surface of one annular support portion 66 of the annular member 62, and the outer ring 24 of the other bearing 16 is
The rotor hub 4 is mounted on a pair of bearings 14 and 16 via an annular member 62. Further, the annular spacer portion 64 protrudes radially inward from the pair of annular support portions 66, 68,
The annular spacer portion 64 is interposed between the outer rings 22 and 24 of the pair of bearings 14 and 16, and these outer rings 22 and 24
They are mounted so that their end faces (inner end faces) come into contact with the annular spacer portion 64.

The annular member 62 is a member to which the inner rings 18 and 20 of the bearings 14 and 16 are mounted, in this embodiment, the shaft member 1
It is important to form from a material having a larger coefficient of thermal expansion than 2. In the illustrated embodiment, since the shaft member 12 is formed of stainless steel (SUS416), the annular member 6 is formed.
2 is made of, for example, aluminum (for example, A6061), aluminum alloy, specific stainless steel (for example, SUS303, SUS304), copper alloy, engineering plastic, or the like having a larger thermal expansion coefficient.
For example, aluminum (or SUS303, SUS30
4) When formed from aluminum (or SUS30)
3, SUS304) has a coefficient of thermal expansion of 23.6 × 10 ^−6.
/ ° C (or 17.3 × 10 ⁻⁶ / ° C, 16.3 × 10
⁻⁶ / ° C.) and the coefficient of thermal expansion of the shaft member 12 (SUS4
16: 9.9 × 10 ⁻⁶ / ° C.). Therefore,
When the temperature of the recording disk drive rises and the temperature of the spindle motor rises, the annular member 62
Has a larger thermal expansion, and the annular spacer portion 64 of the annular member 62 acts on the outer rings 22 and 24 of the pair of bearings 14 and 16 to move them outward in the axial direction so that the dimensional displacement between the inner rings 18 and 20 is increased. Displacement greater than Therefore, when the temperature of the motor rises, the inner rings 18, 20 and the outer rings 22, 24
Due to the difference in thermal expansion between the inner ring 18 and the balls 26, 28
There is a tendency that a gap is formed between the outer ring 20 and the outer rings 22 and 24 and the balls 26 and 28 to reduce the preload. However, by interposing such an annular member 62 between the pair of bearings 14 and 16, The outer rings 22, 24 of the bearings 14, 16 are
The gap is eliminated so that the bearing is displaced in the direction of applying the preload, and thus the preload of the pair of bearings 14 and 16 can be adjusted to prevent the preload from lowering.

Further, by configuring the annular member 62 as described above, the outer races 22,
The reference numeral 24 is attached to the annular support portions 66, 68 of the annular member 62, so that the annular member 62 and the bearings 14, 16 can be configured as a unit, so that the motor can be easily assembled.

Further, in the first embodiment, as shown in FIG. 1, the annular spacer portion 64 is relatively freely thermally expanded by minimizing the fitting area between the annular member 62 and the hub body 30. And the above-mentioned effects are promoted. Further, since the thickness of the annular support portions 66, 68 is small, thermal deformation of these support portions 66, 68 in the radial direction is small, and therefore, even when the temperature rises, the support portions 66, 68 are reduced.
The outer rings 22, 24 of the bearings 14, 16 are not pulled radially outward by a large force due to the thermal deformation of the bearings 14, 16. Second Embodiment FIG. 2 is a half sectional view showing a second embodiment of the spindle motor according to the present invention. In the following embodiments, members that are substantially the same as those in the first embodiment are given the same numbers, and descriptions thereof are omitted.

Referring to FIG. 2, in the second embodiment, the annular member 72 is provided with a sleeve-like annular spacer portion 74.
And an annular support portion 76 extending outward from one end (lower end) of the outer peripheral portion of the annular spacer portion 74 in the axial direction (vertical direction in FIG. 2). , For example, by press fitting. The outer ring 22 of one bearing 14 is mounted on the inner peripheral surface of the hub body 30A, and the outer ring 24 of the other bearing 16 is
2 is mounted on the inner peripheral surface of the annular support portion 76, and the rotor hub 4
The upper end of A is directly supported by the bearing 14, and the lower end is supported by the other bearing 16 via the annular member 72.

As in the first embodiment, the annular spacer portion 74 projects radially inward from the annular support portion 76, and the annular spacer portion 74 serves as a pair of bearings 14 and 16.
Between the outer races 22, 24, and these outer races 22, 24
Are mounted such that their end faces (inner end faces) come into contact with the annular spacer portion 74. Other configurations of the second embodiment are substantially the same as those of the first embodiment.

The annular member 72 is formed of the shaft member 12 (SUS
416), a material having a higher coefficient of thermal expansion than, for example, aluminum, an aluminum alloy, a specific stainless steel (for example, SU
S303, SUS304), copper alloy, engineering plastic, and the like. By forming in this manner, thermal deformation of the annular member 72 becomes larger than that of the shaft member 12, and when the temperature of the spindle motor rises, the annular spacer 74 of the annular member 72 separates the pair of bearings 1 from each other.
Acts on the outer races 22, 24 of the bearings 4, 16, so that the preload of the bearings 14, 16 is adjusted in the same manner as in the first embodiment, and a decrease in the preload can be prevented.

In the second embodiment, the annular support portion 76 is provided in connection with the other (lower) bearing 16, but instead of this, the annular support portion 76 is provided in connection with the one (upper) bearing 14. Alternatively, an annular support may be provided. Third Embodiment FIG. 3 is a half sectional view showing bearings and their vicinity in a third embodiment of the spindle motor according to the present invention.

Referring to FIG. 3, in the third embodiment, the annular member 82 is formed of a cylindrical sleeve member 84, and the cylindrical sleeve member 84 is formed of a pair of bearings 14,1.
6 between the outer races 22 and 24 and a pair of bearings 14 and 1
6 is a cylindrical sleeve member 8 in which the inner end faces of the outer rings 22 and 24 are cylindrical sleeve members.
4 so as to abut. Also, a pair of bearings 1
The outer races 4 and 16 are mounted on the inner peripheral surface of the hub body 30, and the rotor body 30B of the rotor hub 4B is directly supported by the pair of bearings 14 and 16. Note that the seal members 29 are provided at both ends of the outer rings 22 and 24, and the tips thereof extend toward the inner rings 18 and 20. Other configurations of the third embodiment are substantially the same as those of the first embodiment.

Also in the third embodiment, the annular member 82,
That is, the cylindrical sleeve member 84 is made of a material having a larger coefficient of thermal expansion than the shaft member 12, for example, aluminum, an aluminum alloy,
Specific stainless steel (for example, SUS303, SUS30
4), formed from a copper alloy, engineering plastic, or the like, and formed in this manner, when the temperature of the spindle motor rises, the cylindrical sleeve member 84 acts on the outer rings 22, 24 of the pair of bearings 14, 16, Therefore, similarly to the first embodiment, a decrease in preload can be prevented. Further, since the annular member 82 is constituted by the cylindrical sleeve member 84, the bearings 14 and 14 have a relatively simple structure.
16 can be prevented from being reduced. Fourth Embodiment FIG. 4 is a half sectional view showing bearings and their vicinity in a fourth embodiment of the spindle motor according to the present invention. Referring to FIG. 4, the annular member 92 in the fourth embodiment has substantially the same configuration as the annular member 62 in the first embodiment, and has a sleeve-like annular spacer portion 94 and this annular spacer portion 94. Annular support portions 9 extending from both ends of the outer peripheral portion of the outer peripheral portion to both sides in the axial direction (vertical direction in FIG. 4).
The outer ring 22 of one bearing 14 is mounted on the annular support portion 96, the outer ring 24 of the other bearing 16 is mounted on the remaining annular support portion 98, and an annular ring is provided between the outer rings 22, 24. An annular spacer portion 94 of the member 92 is interposed. Then, substantially the entire outer peripheral surface of the annular member 92 is fitted to the inner peripheral surface of the hub main body 30C of the rotor hub 4C. Other configurations of the fourth embodiment are substantially the same as those of the first embodiment.

In the fourth embodiment, the annular member 9 is also provided.
2 is made of a material having a larger coefficient of thermal expansion than the shaft member 12, for example, aluminum, aluminum alloy, specific stainless steel (for example, SUS303, SUS304), copper alloy, engineering plastic, and the like. Since the configuration is the same as that of the first embodiment, substantially the same operation and effect as those of the first embodiment can be achieved, and a decrease in the preload of the bearings 14 and 16 can be prevented.

In addition, the hub body 30C of the rotor hub 4C
Has a smaller thermal expansion coefficient than the annular member 92, for example, a specific stainless steel (for example, SUS430: 10.4 × 10
^-6 / ° C.), the hub body 30C restrains the thermal expansion of the annular member 92 when the temperature of the spindle motor rises, and the outer rings 22 and 24 of the pair of bearings 14 and 16. Can be suppressed from moving outward in the radial direction. Fifth Embodiment FIG. 5 is a half sectional view showing bearings and their vicinity in a fifth embodiment of the spindle motor according to the present invention. Referring to FIG. 5, the annular member 102 in the fifth embodiment is formed integrally with the hub body 30D of the rotor hub 4D, and is formed on both sides of the annular member 102 and on the inner peripheral surface of the hub body 30D. Support members 104 and 106 are mounted. The annular support members 104 and 106 are provided corresponding to the pair of bearings 14 and 16, and the outer ring 22 of one bearing 14 is mounted on the inner peripheral surface of the annular support member 104, and the outer ring 24 of the other bearing 16 remains. Is mounted on the inner peripheral surface of the annular support member 106. Other configurations in the fifth embodiment are substantially the same as those in the first embodiment.

In the fifth embodiment, when a recording disk (not shown) to be employed is formed of aluminum or an aluminum alloy, the hub body 30 is integrally formed.
By forming D and the annular member 102 from aluminum or an aluminum alloy, the thermal expansion coefficients of the two become the same or almost equal, and a spindle motor suitable for using a recording disk made of aluminum or an aluminum alloy is obtained. Further, since the annular member 102 is interposed between the outer rings 22 and 24 of the pair of bearings 14 and 16, it is possible to prevent a decrease in the preload of the bearings 14 and 16, as in the first embodiment. Further, a material having a coefficient of thermal expansion smaller than that of the hub body 30D, for example, a specific stainless steel (for example, SUS43
0), the annular support members 104 and 106 form the bearing 1.
The deformation of the outer races 4 and 16 to the outside in the radial direction can be suppressed. Sixth Embodiment FIG. 6 is a half sectional view showing bearings and their vicinity in a sixth embodiment of the spindle motor according to the present invention. Referring to FIG. 6, in the sixth embodiment, annular member 112 is formed of cylindrical sleeve member 114, and most of the outer peripheral side of cylindrical sleeve member 114 is embedded in hub body 30E of rotor hub 4E. . The inner peripheral portion of the cylindrical sleeve member 114 protrudes inward in the radial direction from the inner peripheral surface of the hub body 30E.
4, 16 are interposed between the outer rings 22, 24. Also,
The outer ring 22 of one bearing 14 is attached to the upper end of the hub main body 30E (the part above the annular member 112), and the outer ring 24 of the other bearing 16 is the lower end of the hub main body 30E (the lower side than the annular member 112). Part). Other configurations of the sixth embodiment are substantially the same as those of the third embodiment.

Also in the sixth embodiment, the annular member 112, that is, the cylindrical sleeve member 114 is made of a material having a larger coefficient of thermal expansion than the shaft member 12, for example, aluminum, an aluminum alloy, or a specific stainless steel (for example, SUS303,
SUS304), a copper alloy, an engineering plastic, etc.
As in the third embodiment, a decrease in preload can be prevented. Further, a material having a coefficient of thermal expansion smaller than that of the annular member 112, for example, a specific stainless steel (for example, SUS43
By forming the hub main body 30E from 0), deformation of the bearings 14, 16 to the radially outer sides of the outer rings 22, 24 by the hub main body 30E can be suppressed.

Although various embodiments of the spindle motor according to the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and corrections can be made without departing from the scope of the present invention. It is.

For example, in the illustrated embodiment,
Although the shaft member is described as being applied to a fixed shaft type motor provided on a bracket, the present invention is not limited to such a motor, and is similarly applied to a shaft rotation type motor having a shaft member provided on a rotor hub. Can be applied. In addition,
In this shaft rotation type motor, a bracket is provided with a bearing support sleeve, outer rings of a pair of bearings provided at an interval in the axial direction are mounted on an inner peripheral surface of the bearing support sleeve, and an inner ring of the pair of bearings is provided. Is mounted on a shaft member provided on the rotor hub, and this shaft member is a member on which the inner ring is mounted.

[0045]

According to the recording disk drive spindle motor of the first aspect of the present invention, it is possible to prevent a decrease in the preload of the pair of bearings when the temperature rises.

According to the recording disk drive spindle motor of the second aspect of the present invention, it is possible to prevent a decrease in the preload of the bearing at a high temperature with a simple configuration.

According to the recording disk drive spindle motor of the third aspect of the present invention, the annular member and the pair of bearings can be formed as a unit, and the preload of the bearing at high temperatures can be prevented from lowering. Can be. Further, according to the recording disk drive spindle motor of the present invention, it is possible to prevent a decrease in the preload of the bearing at a high temperature.

Further, according to the recording disk driving spindle motor of the present invention, by forming the annular member and the hub body from aluminum or aluminum alloy, a recording disk using aluminum or aluminum alloy recording disk can be obtained. This is a suitable motor for the driving device. Further, by forming the annular support member from a material having a thermal expansion coefficient substantially equal to that of the outer ring, adverse effects on the bearing due to thermal expansion can be reduced. Further, it is possible to prevent a decrease in the preload of the bearing at a high temperature.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a recording disk drive spindle motor according to the present invention.

FIG. 2 is a half sectional view showing a second embodiment of a recording disk driving spindle motor according to the present invention.

FIG. 3 is a half sectional view showing bearings and their vicinity in a third embodiment of a recording disk drive spindle motor according to the present invention.

FIG. 4 is a half sectional view showing bearings and their vicinity in a fourth embodiment of a recording disk drive spindle motor according to the present invention.

FIG. 5 is a half sectional view showing bearings and their vicinity in a fifth embodiment of a recording disk driving spindle motor according to the present invention.

FIG. 6 is a half sectional view showing bearings and their vicinity in a sixth embodiment of a recording disk driving spindle motor according to the present invention.

[Explanation of symbols]

2 Bracket 4, 4A, 4B, 4C, 4D, 4E Rotor hub 6 Bracket body 12 Shaft member 14, 16 Bearing 18, 20 Inner ring 22, 24 Outer ring 26, 28 Ball (rolling element) 30, 30A, 30B, 30C, 30D, 30E Hub body 40 Rotor magnet 42 Stator 62, 72, 82, 92, 102, 112 Annular member 64, 74, 94 Annular spacer portion 66, 68, 76, 96, 98 Annular support portion 84, 114 Cylindrical sleeve member 104, 106 Annular support member

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takayuki Oe 248 Nakajuku, Aichigawa-cho, Aichi-gun, Shiga Prefecture Nidec Shiga Technology Development Center (72) Inventor Tomohiro Hasegawa 248 Nakajuku, Aichigawa-cho, Aichi-gun, Shiga Japan Japan F-term in the Shiga Technology Development Center (reference) 5H605 BB05 BB09 BB14 BB17 BB19 CC04 DD05 DD07 DD17 EA07 EB10 EB17 EB34 EB39 FF10 5H621 BB07 GA01 GA04 HH05 JK08 JK10 JK15 JK19

Claims (5)

[Claims] 1. A rotor hub rotatably supported by a base member of a recording disk drive or a bracket attached thereto and having at least one recording disk mounted thereon, and the base member or bracket and the rotor hub A recording disk comprising: a pair of bearings interposed at an axial distance therebetween; a rotor magnet mounted on the inner peripheral surface of the rotor hub; and a stator disposed to face the rotor magnet. In the driving spindle motor, the pair of bearings each include an inner ring and an outer ring that are arranged at a distance in a radial direction, and a plurality of ceramic rolling elements interposed between the inner ring and the outer ring. And between the outer rings of the pair of bearings, formed from a material having a larger coefficient of thermal expansion than the member to which the inner ring is attached. A spindle motor for driving a recording disk, wherein a ring-shaped member is interposed, and at a high temperature, the annular member thermally expands and acts on the outer rings of the pair of bearings, whereby the preload of the pair of bearings is adjusted. . 2. The recording disk drive spindle motor according to claim 1, wherein said annular member is formed of a cylindrical sleeve member, and said cylindrical sleeve member is interposed between said outer rings of said pair of bearings. . 3. The annular member has an annular spacer portion and a pair of annular support portions extending in the axial direction from both ends of the annular spacer portion, and the outer rings of the pair of bearings are formed of the pair of annular support portions. 2. The recording disk drive spindle motor according to claim 1, wherein the spindle motor is mounted on an inner peripheral surface, and the annular spacer portion is interposed between the outer rings of the pair of bearings. 4. The annular member has an annular spacer portion and an annular support portion extending from one end of the annular spacer portion in the axial direction, and one outer ring of the pair of bearings has an inner periphery of the annular support portion. The other outer ring of the pair of bearings is mounted on an inner peripheral surface of the rotor hub, and the annular spacer portion is interposed between the outer rings of the pair of bearings. A spindle motor for driving a recording disk according to the above. 5. The rotor hub has a hub body on which the recording disk is mounted, the annular member is formed integrally with the hub body, and a pair of annular support members is disposed on both sides of the annular member. An outer ring of the pair of bearings is mounted on an inner peripheral surface of the pair of annular support members, and the annular member is interposed between the outer rings of the pair of bearings. .