JP7224182B2 - Fluid dynamic bearings and spindle motors - Google Patents

Description

The present invention relates to fluid dynamic bearings and spindle motors.

A hard disk drive uses a spindle motor to rotate the hard disk. A spindle motor has, for example, a base plate, a shaft (shaft member) supported by the base plate, a stator fixed to the base plate, and a rotor rotatably supported by the shaft. Among fluid dynamic pressure bearings in such a spindle motor, for example, there is a shaft in which a cone (conical bearing member) is press-fitted and fixed (see, for example, Patent Document 1).

JP-A-2006-38073

A gas such as helium, which has a lower density than air, is enclosed in the internal space of the housing. In a hard disk drive, the number of stacked hard disks is increased to increase the storage capacity. Along with this, in hard disk drives, it is required to increase the fastening strength between the shaft (shaft member) and the cone (conical bearing member) to improve durability against external impact. However, if the joint strength is increased only by press-fitting the shaft and cone, there is a risk that the hard disk will vibrate during driving due to the deformation of the cone's dynamic pressure surface (the outer surface of the cone) when the cone is press-fitted. be.

An object of the present invention is to provide a technique capable of suppressing deformation of the conical outer surface of the conical bearing member when the conical bearing member is press-fitted while securing the fastening strength between the shaft member and the conical bearing member. be.

A fluid dynamic bearing according to an aspect of the present invention includes a shaft member, a first conical bearing member and a second conical bearing member fixed to an end portion of the shaft member, and the first conical bearing member and the second conical bearing member. a rotor member rotatably supported by the shaft member via a bearing member, wherein the second conical bearing member contacts the first conical bearing member and the conical portion of the second conical bearing member A tapered seal portion that retains lubricating oil is formed between the surface and the rotor member, and dynamic pressure is generated by the lubricating oil between the conical bearing surface of the first conical bearing member and the rotor member. A bearing is provided.

According to the fluid dynamic bearing according to the present invention, it is possible to suppress deformation of the conical outer surface of the conical bearing member when the conical bearing member is press-fitted while securing the fastening strength between the shaft member and the conical bearing member. .

1 is a perspective view showing a schematic configuration of a hard disk drive according to a first embodiment of the invention; FIG. 3 is a cross-sectional view schematically showing the configuration of a fluid dynamic pressure bearing in the spindle motor of the hard disk drive according to the first embodiment of the present invention; FIG. FIG. 3 is a partially enlarged cross-sectional view schematically showing the configuration of a portion near an upper conical bearing member of the fluid dynamic pressure bearing shown in FIG. 2; FIG. 4 is a plan view schematically showing the configuration of an upper lower conical bearing member of the upper conical bearing member shown in FIG. 3; FIG. 5 is a cross-sectional view taken along line AA schematically showing the configuration of the upper and lower conical bearing member shown in FIG. 4; FIG. 5 is a BB cross-sectional view schematically showing the configuration of the upper and lower conical bearing member shown in FIG. 4; FIG. 4 is a cross-sectional view schematically showing the configuration of an upper upper conical bearing member of the upper conical bearing member shown in FIG. 3; FIG. 3 is a partially enlarged cross-sectional view schematically showing the configuration of a portion near a lower conical bearing member of the fluid dynamic pressure bearing shown in FIG. 2; FIG. 6 is a partially enlarged cross-sectional view schematically showing the configuration of the portion near the upper conical bearing member of the fluid dynamic pressure bearing according to the second embodiment of the present invention; FIG. 9 is a cross-sectional view schematically showing the configuration of an upper upper conical bearing member of the upper conical bearing member shown in FIG. 8; FIG. 6 is a partially enlarged cross-sectional view schematically showing the configuration of the portion near the lower conical bearing member of the fluid dynamic pressure bearing according to the second embodiment of the present invention; FIG. 11 is a partially enlarged cross-sectional view schematically showing the configuration of a portion near an upper conical bearing member of a fluid dynamic pressure bearing according to a third embodiment of the present invention; FIG. 13 is a partially enlarged cross-sectional view schematically showing a configuration of a portion near an oil reservoir portion of the upper conical bearing member shown in FIG. 12; FIG. 11 is a partial enlarged cross-sectional view schematically showing the configuration of a portion near an upper conical bearing member of a fluid dynamic pressure bearing according to a fourth embodiment of the present invention; FIG. 11 is a partially enlarged cross-sectional view schematically showing the configuration of a portion near an upper conical bearing member of a fluid dynamic pressure bearing according to a fifth embodiment of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing a schematic configuration of a hard disk drive device 200 to which a spindle motor 1 according to the first embodiment of the invention is applied. In the hard disk drive device 200, the spindle motor 1 is fixed or formed on the bottom portion 201a of the housing 201 and supports the hard disk 202 rotatably. A cover (not shown) and housing 201 form a housing for hard disk drive 200 . An internal space S formed by a cover (not shown) and the housing 201 is filled with a gas having a density lower than that of air (for example, helium, nitrogen, or a mixed gas of helium and nitrogen).

The hard disk drive device 200 has a head portion 205 at the tip of a swing arm 204 that is swingably supported by a bearing device 203 . The head portion 205 is provided with a magnetic head at its tip. In the hard disk drive 200, the head unit 205 moves over the rotating hard disk 202. FIG. Thus, information can be recorded on the hard disk 202 and information recorded on the hard disk 202 can be read.

FIG. 2 is a cross-sectional view schematically showing the configuration of the fluid dynamic pressure bearing 20 in the spindle motor 1 shown in FIG. Hereinafter, for convenience of explanation, one side (direction of arrow a) in the direction of axis Y1 of spindle motor 1 in FIG. . In FIG. 2, in the radial direction extending perpendicular to the axis Y1 of the spindle motor 1, the one side (the direction of arrow c) approaching the axis Y1 is defined as the radially inner side, and the other side (the direction of the arrow c) moving away from the axis Y1 is defined as the radially inner side. d direction) is defined as radially outward. In the following description, when the positional relationship and direction of each member are used, the positional relationship and direction in the drawings are shown, and the positional relationship and direction when incorporated into an actual device are not shown.

The fluid dynamic pressure bearing 20 in the spindle motor 1 according to the first embodiment of the present invention includes a shaft member 21 and an upper and lower conical bearing member 40 as a first conical bearing member fixed to the end of the shaft member 21. and an upper upper conical bearing member 50 as a second conical bearing member, and a rotor member 31 rotatably supported by the shaft member 21 via the upper lower conical bearing member 40 and the upper upper conical bearing member ing. The upper upper conical bearing member 50 abuts on the upper lower conical bearing member 40, and a tapered seal portion T is formed between the conical surface 50d of the upper upper conical bearing member 50 and the rotor member 31 to hold the lubricating oil G, A dynamic pressure bearing portion DB is provided in which dynamic pressure is generated by the lubricating oil G between the lower conical outer surface 40 b as the conical bearing surface of the upper lower conical bearing member 40 and the rotor member 31 .

Specifically, the fluid dynamic pressure bearing 20 includes a shaft member 21 fixed to the base plate 11 and a rotor member 31 having a through hole 31a through which the shaft member 21 is inserted. The through hole 31a has a conical inner surface 31du whose inner diameter increases upward and a conical inner surface 31db whose inner diameter increases downward. The spindle motor 1 has a lower conical outer surface 40b as a conical outer surface facing the conical inner surface 31d, an upper conical outer surface 60u and an upper conical bearing member 22 as a conical bearing member fixed to the shaft member 21. and a side conical bearing member 23 .

The spindle motor 1 also includes dynamic pressure grooves D formed in the conical inner surfaces 31du and 31db. The dynamic pressure groove D is formed on at least one of the conical inner surface 31du and the lower conical outer surface 40b, and may be formed on at least one of the conical inner surface 31db and the upper conical outer surface 60u.

The spindle motor 1 also includes a lubricating oil G filled in the gap between the conical inner surface 31du and the lower conical outer surface 40b and the gap between the conical inner surface 31db and the upper conical outer surface 60u. As shown in FIG. 3, the upper conical bearing member 22 consists of an upper lower conical bearing member 40 as a first conical bearing member fixed to the shaft member 21 facing the conical inner surface 31d, and an upper lower conical bearing member 40. Also on the upper side, it has an upper upper conical bearing member 50 as a second conical bearing member fixed to the shaft member 21 in contact with the upper lower conical bearing member 40 .

The lower conical bearing member 23 includes, as shown in FIG. A lower lower conical bearing member 70 as a second conical bearing member fixed to the shaft member 21 in contact with the lower upper conical bearing member 60 is provided below the member 60 . The configuration of the spindle motor 1 will be specifically described below.

The spindle motor 1 has a stator 10, a fluid dynamic pressure bearing 20, and a rotor 30, as shown in FIG. The stator 10 has a base plate 11 and a stator core 12 fixed to the base plate 11 . The base plate 11 is formed with a through hole 11a through which the lower portion of the shaft member 21 is inserted and fixed, and a circumferential wall portion 11b concentric with the through hole 11a. A stator core 12 is fixed to the outer peripheral surface of the circumferential wall portion 11b, and a coil 13 is wound around the stator core 12. As shown in FIG.

The fluid dynamic pressure bearing 20 has a shaft member 21 and an upper conical bearing member 22 and a lower conical bearing member 23 inserted through the shaft member 21 . The upper conical bearing member 22 and the lower conical bearing member 23 are fixed to the shaft member 21 spaced apart in the direction of the axis Y1. The fluid dynamic pressure bearing 20 is, for example, a conical dynamic pressure bearing. The shaft member 21 is coaxial with the axis Y1 and has a substantially cylindrical shape. The shaft member 21 is made of SUS420J2, which is martensitic stainless steel, for example. Inside the shaft member 21, a shaft hole 21a extending in the direction of the axis Y1 is formed from the upper surface and the lower surface of the shaft member 21. As shown in FIG.

The shaft member 21 is coaxial with the axis Y<b>1 and is inserted through a through hole 31 a formed in the rotor member 31 of the rotor 30 . A lower portion of the shaft member 21 is inserted into a through hole 11a formed in the base plate 11 and fixed by press fitting or press fitting and adhesion. The upper conical bearing member 22 and the lower conical bearing member 23 are provided so as to surround the shaft member 21, and are made of SUS303, which is austenitic stainless steel, for example. Specific configurations of the upper conical bearing member 22 and the lower conical bearing member 23 will be described later.

The rotor 30 has a rotor member 31 , a yoke 32 , a rotor magnet 33 and an end cap 34 . The rotor member 31 is formed in a substantially cylindrical shape. Further, the rotor member 31 is formed with a through hole 31a for inserting the shaft member 21, two dynamic pressure groove portions 31b, and a yoke mounting portion 31c. A rotor magnet 33 is fixed via the yoke 32 to the yoke mounting portion 31c. The rotor magnet 33 is made of a permanent magnet and arranged to face the stator core 12 .

The dynamic pressure groove portion 31 b is formed radially outside the through hole 31 a and at a position facing the upper conical bearing member 22 and the lower conical bearing member 23 . A dynamic pressure groove D for generating dynamic pressure is formed in the dynamic pressure groove portion 31b. The dynamic pressure grooves D can be formed, for example, by electrochemically machining conical inner surfaces 31du and 31db provided on the upper and lower sides of the through hole 31a in the rotor member 31 .

In addition, the conical inner surface 31du and the lower conical outer surface 40b, which is the lower surface of the upper lower conical bearing member 40 (FIG. 3) of the upper conical bearing member 22, face each other with a minute gap (not shown). ing. In addition, the conical inner surface 31db and the upper conical outer surface 60u, which is the upper surface of the lower upper conical bearing member 60 (FIG. 8) of the lower conical bearing member 23, face each other with a minute gap (not shown). ing. The dynamic pressure groove D may be formed on the lower conical outer surface 40b of the upper conical bearing member 22 and the upper conical outer surface 60u of the lower conical bearing member 23 instead of the conical inner surfaces 31du and 31db. It is sufficient if it is formed.

A conical inner surface 31du facing the lower conical outer surface 40b of the upper conical bearing member 22 has an inner diameter that increases toward the upper side of the through hole 31a of the rotor member 31 . A conical inner surface 31db facing the upper conical outer surface 60u of the lower conical bearing member 23 has an inner diameter that expands toward the lower side of the through hole 31a of the rotor member 31 . The minute gap between the conical inner surface 31du and the lower conical outer surface 40b of the upper conical bearing member 22 and the minute gap between the conical inner surface 31db and the upper conical outer surface 60u of the lower conical bearing member 23 contain lubricating oil. G is filled.

The end cap 34 is a member fixed to the rotor member 31 . A minute gap is formed between the end cap 34 and the shaft member 21 so that the rotation of the rotor member 31 is not hindered by the end cap 34 . The end cap 34 is secured to the rotor member 31 by gluing or gluing and press fitting.

The rotor magnet 33 fixed to the rotor 30 and the stator core 12 fixed to the stator 10 face each other across a minute gap. When drive currents having different phases are passed through the plurality of coils 13 of the stator core 12, a rotating magnetic field is generated, and a rotating force is generated in the rotor magnet 33 by this rotating magnetic field. This causes rotor 30 to rotate relative to stator 10 and fluid dynamic bearing 20 .

Further, when the rotor 30 rotates with respect to the fluid dynamic pressure bearing 20, the conical inner surfaces 31du and 31db of the rotor 30 and the upper conical bearing member of the fluid dynamic pressure bearing 20 are moved by the dynamic pressure groove D provided in the dynamic pressure groove portion 31b. 22 and the upper conical outer surface 60u of the lower conical bearing member 23 are separated from each other. Thereby, the conical inner surfaces 31du, 31db, the lower conical outer surface 40b, and the upper conical outer surface 60u are supported in a non-contact state. Since the conical inner surfaces 31du and 31db are supported in a non-contact state with the lower conical outer surface 40b and the upper conical outer surface 60u, the rotor 30 can be freely moved relative to the stator 10 to which the fluid dynamic pressure bearing 20 is fixed. Rotate.

3 is a partially enlarged cross-sectional view schematically showing the configuration of a portion near the upper conical bearing member 22 of the fluid dynamic pressure bearing 20 in the spindle motor 1 shown in FIG. 2, and FIG. 4 is a plan view schematically showing the structure of an upper and lower conical bearing member 40 of the bearing member 22; FIG. 5 is a cross-sectional view taken along line AA schematically showing the configuration of the upper and lower conical bearing member 40 shown in FIG. 4, and FIG. 6 schematically shows the configuration of the upper and lower conical bearing member 40 shown in FIG. It is a BB sectional view. FIG. 7 is a cross-sectional view schematically showing the configuration of the upper upper conical bearing member 50 of the upper conical bearing member 22 shown in FIG.

In the spindle motor 1, the upper conical bearing member 22 includes an upper lower conical bearing member 40 as a first conical bearing member fixed to the shaft member 21 facing the conical inner surface 31du, and an upper lower conical bearing member 40 above the upper and lower conical bearing member 40. , an upper upper conical bearing member 50 as a second conical bearing member fixed to the shaft member 21 in contact with the upper lower conical bearing member 40 .

Specifically, the upper and lower conical bearing member 40 is formed in a substantially annular shape as shown in FIG. 4, and is formed in a substantially inverted conical shape as shown in FIGS. A substantially cylindrical through hole 40a extending in the direction of the axis Y1 is formed substantially in the center of the upper and lower conical bearing member 40. As shown in FIG. The through hole 40a of the upper and lower conical bearing member 40 is coaxial with the shaft member 21, and the diameter of the through hole 40a is slightly larger than the diameter of the outer peripheral surface 21d, which is the radially outer surface of the shaft member 21. diameter. Therefore, the shaft member 21 can be inserted through the through-hole 40a, and the minute gap between the shaft member 21 and the outer peripheral surface 21d can be filled with the lubricating oil G. ing.

A lower conical outer surface 40 b facing the conical inner surface 31 du of the rotor member 31 is formed on the lower side of the upper lower conical bearing member 40 . The lower conical outer surface 40b is a tapered surface whose diameter increases upward from the lower edge of the through hole 40a. The lower conical outer surface 40b is arranged at a position facing the conical inner surface 31du provided on the upper side of the through hole 31a in the rotor member 31. As shown in FIG. The upper edge of the lower conical outer surface 40 b connects with the lower edge of the conical surface 40 d that is the radially outer surface of the upper lower conical bearing member 40 .

The conical surface 40d of the upper lower conical bearing member 40 is a tapered surface whose diameter decreases upward from the upper edge of the lower conical outer surface 40b. The upper edge of the conical surface 40 d connects with the radially outer edge of the conical facing surface 40 u that is the upper surface of the upper lower conical bearing member 40 . The conical facing surface 40u of the upper and lower conical bearing member 40 is a tapered surface whose diameter increases upward from the upper edge of the through hole 40a.

A pair of upper groove portions 41 radially extending from the radially inner side to the radially outer side are formed in the conical facing surface 40u of the upper lower conical bearing member 40 . Specifically, the pair of upper groove portions 41 are recessed downward from the conical facing surface 40u. The pair of upper groove portions 41 each extend upward as it goes radially outward from the axis Y1, and the axis Y1 is positioned between the radially inner edges of the pair of upper groove portions 41. there is

Each of the pair of upper groove portions 41 has a substantially rectangular shape when viewed from the radially outer side, and extends from the radially inner side to the radially outer side at a predetermined depth below the conical facing surface 40u. It has a bottom surface 41t which is an inclined surface extending upward as it faces radially outward. The bottom surface 41 t defines the lower boundary of the pair of upper groove portions 41 .

Also, the pair of upper groove portions 41 each have a pair of side surfaces 41p extending parallel to the axis Y1 direction from the conical facing surface 40u toward the bottom surface 41t. The pair of side surfaces 41p respectively define boundaries between the conical facing surface 40u and the bottom surface 41t. Therefore, lubricating oil G can be filled between the pair of upper groove portions 41 and the conical facing surface 50b (FIG. 3) of the upper upper conical bearing member 50. As shown in FIG. In addition, the shape of the pair of upper groove portions 41 is not limited to the substantially rectangular shape when viewed from the radially outer side, and the shape when viewed from the radially outer side is substantially V-shaped or substantially semicircular. It may be a semi-circular groove.

The upper end of the through hole 40a is provided with a partially cut annular flange 42 that protrudes radially inward from the through hole 40a. The flange portion 42 is coaxial with the shaft member 21 , and the radial inner diameter of the flange portion 42 is smaller than the diameter of the outer peripheral surface 21 d of the shaft member 21 . Therefore, when the shaft member 21 is inserted into the through hole 40a, the upper and lower conical bearing member 40 is fixed to the shaft member 21 by press-fitting the flange portion 42 into the shaft member 21 . The flange portion 42 is partially cut out by the pair of upper groove portions 41 . Note that the flange portion 42 is not limited to a partially notched annular shape, and it is sufficient that a portion of the flange portion 42 protrudes radially inward from the through hole 40 a and is press-fitted into the shaft member 21 .

FIG. 7 is a cross-sectional view schematically showing the configuration of the upper upper conical bearing member 50 of the upper conical bearing member 22 shown in FIG. The upper lower conical bearing member 40 and the upper upper conical bearing member 50 are press-fitted into the shaft member 21 , and the upper upper conical bearing member 50 has a greater press-fit allowance than the upper lower conical bearing member 40 . The press-fit allowance of the upper lower conical bearing member 40 is 5-20 μm, and the press-fit allowance of the upper upper conical bearing member 50 is 15-30 μm. The length of the press-fit margin of the upper upper conical bearing member 50 is longer than the length of the upper lower conical bearing member 40 . Specifically, the upper upper conical bearing member 50 is formed in a substantially cylindrical shape as shown in FIG. 50a is formed.

A through hole 50 a of the upper conical bearing member 50 is coaxial with the shaft member 21 and has a smaller diameter than the outer peripheral surface 21 d of the shaft member 21 . Furthermore, the diameter of the through-hole 50 a is smaller than the radially inner diameter of the flange portion 42 of the upper and lower conical bearing member 40 . Therefore, when the shaft member 21 is inserted into the through-hole 50a, the upper conical bearing member 50 is fixed to the shaft member 21 by press-fitting the through-hole 50a into the shaft member 21 . At this time, since the upper upper conical bearing member 50 is press-fitted more strongly than the upper lower conical bearing member 40, the fastening strength is made stronger than that of the upper lower conical bearing member 40 so that the fastening strength can be secured. It's becoming

The press-fit margin of the through hole 50a of the upper conical bearing member 50 is preferably in the range of 15-30 μm, more preferably in the range of 20-25 μm, and most preferably in the range of 22-23 μm. The press-fit margin of the flange portion 42 of the upper and lower conical bearing member 40 is preferably in the range of 5-20 μm, more preferably in the range of 10-15 μm, and most preferably in the range of 12-13 μm.

On the lower side of the upper upper conical bearing member 50, a conical facing surface 50b that abuts against the conical facing surface 40u of the upper lower conical bearing member 40 is formed. The conical facing surface 50b is a tapered surface whose diameter increases upward from the lower edge of the through hole 50a. The conical facing surface 50b is arranged at a position to contact the conical facing surface 40u of the upper and lower conical bearing member 40. As shown in FIG. The conical facing surface 50 b has the same inclination as the conical facing surface 40 u of the upper and lower conical bearing member 40 so that it can abut against the conical facing surface 40 u of the upper and lower conical bearing member 40 . The pair of upper groove portions 41 of the upper and lower conical bearing member 40 and the conical facing surface 50b of the upper and upper conical bearing member 50 define lubricating oil circulation holes through which the lubricating oil G is circulated. The upper edge of the conical facing surface 50 b connects with the lower edge of the conical surface 50 d which is the radially outer surface of the upper upper conical bearing member 50 .

The conical surface 50d of the upper upper conical bearing member 50 is a tapered surface whose diameter decreases upward from the upper edge of the conical facing surface 50b. The upper edge of the conical surface 50 d connects with the radially outer edge of the upper surface 50 u of the upper upper conical bearing member 50 . The conical surface 50d has the same inclination as the conical surface 40d of the upper and lower conical bearing member 40 so that it can be smoothly connected to the conical surface 40d of the upper and lower conical bearing member 40 . The upper surface 50u of the upper conical bearing member 50 is an annular flat surface extending radially outward from the upper edge of the through hole 50a.

As shown in FIG. 3, in the assembled state of the spindle motor 1, the upper and lower conical bearing member 40 has the through hole 40a inserted into the shaft member 21, and the flange portion 42 is press-fitted into the shaft member 21 so that the shaft member 21 is fixed. The lower conical outer surface 40b of the upper lower conical bearing member 40 is arranged at a position facing the conical inner surface 31du provided on the upper side of the through hole 31a in the rotor member 31 .

The upper conical bearing member 50 is fixed to the shaft member 21 by press-fitting the through hole 50 a into the shaft member 21 . The conical facing surface 50b of the upper upper conical bearing member 50 has the same inclination as the conical facing surface 40u of the upper lower conical bearing member 40, and is in contact with the conical facing surface 40u of the upper lower conical bearing member 40. . A lubricating oil circulation hole through which the lubricating oil G circulates is defined by the pair of upper groove portions 41 of the upper lower conical bearing member 40 and the conical facing surface 50b of the upper upper conical bearing member 50 . The conical surface 50d of the upper upper conical bearing member 50 has the same inclination as the conical surface 40d of the upper lower conical bearing member 40 and is smoothly connected with the conical surface 40d of the upper lower conical bearing member 40 .

The lubricating oil G penetrates into the minute gap between the through hole 40 a of the upper and lower conical bearing member 40 and the outer peripheral surface 21 d of the shaft member 21 and between the inner conical surface 31 du and the lower outer conical surface 40 b of the upper and lower conical bearing member 40 . It fills the tiny gaps between Also, the lubricating oil G flows through the lubricating oil circulation holes defined by the pair of upper grooves 41 of the upper and lower conical bearing member 40 and the cone-facing surfaces 50b of the upper and upper conical bearing member 50, and through the rotor member 31 and the upper and lower conical surfaces. It is filled between the conical surface 40 d of the bearing member 40 and the conical surface 50 d of the upper upper conical bearing member 50 . That is, a tapered seal portion T for retaining lubricating oil G is formed between the conical surface 50d of the upper upper conical bearing member 50 and the rotor member 31, and the lower conical outer surface as the conical bearing surface of the upper lower conical bearing member 40. Between 40b and rotor member 31, there is provided a dynamic pressure bearing portion DB in which dynamic pressure is generated by lubricating oil G. As shown in FIG.

FIG. 8 is a partially enlarged cross-sectional view schematically showing the structure of the vicinity of the lower conical bearing member 23 of the spindle motor 1 shown in FIG. In the spindle motor 1, the lower conical bearing member 23 includes a lower upper conical bearing member 60 as a first conical bearing member fixed to the shaft member 21 facing the conical inner surface 31db, and a lower upper conical bearing member 60. It has a lower lower conical bearing member 70 as a second conical bearing member fixed to the shaft member 21 in contact with the lower upper conical bearing member 60 on the lower side.

The lower lower conical bearing member 70 abuts on the lower upper conical bearing member 60, and a tapered seal portion T that retains lubricating oil G between the conical surface 70d of the lower lower conical bearing member 70 and the rotor member 31 is formed. A dynamic pressure bearing portion DB is provided in which dynamic pressure is generated by lubricating oil G between an upper conical outer surface 60u as a conical bearing surface of the lower upper conical bearing member 60 and the rotor member 31 . Specifically, the lower upper conical bearing member 60 is formed of the same material as the upper lower conical bearing member 40 shown in FIGS. That is, the lower upper conical bearing member 60 is formed in a substantially annular shape as shown in FIG. 4, and is formed in a substantially conical shape as shown in FIGS. As shown in FIG. 8, a substantially cylindrical through hole 60a extending in the direction of the axis Y1 is formed substantially in the center of the lower upper conical bearing member 60. As shown in FIG. A through hole 60 a of the lower upper conical bearing member 60 is coaxial with the shaft member 21 and has a diameter slightly larger than the diameter of the outer peripheral surface 21 d of the shaft member 21 . Therefore, the shaft member 21 can be inserted through the through-hole 60a, and the minute gap between the shaft member 21 and the outer peripheral surface 21d can be filled with the lubricating oil G. ing.

An upper conical outer surface 60 u facing the conical inner surface 31 db of the rotor member 31 is formed on the upper side of the lower upper conical bearing member 60 . The upper conical outer surface 60u is a tapered surface whose diameter increases downward from the upper edge of the through hole 60a. The upper conical outer surface 60u is arranged at a position facing the conical inner surface 31db provided on the lower side of the through hole 31a in the rotor member 31. As shown in FIG. The lower edge of the upper conical outer surface 60 u connects with the upper edge of the conical surface 60 d that is the radially outer surface of the lower upper conical bearing member 60 .

The conical surface 60d of the lower upper conical bearing member 60 is a tapered surface whose diameter decreases downward from the lower edge of the upper conical outer surface 60u. The lower edge of the conical surface 60d connects with the radially outer edge of the lower surface of the lower upper conical bearing member 60, the conical facing surface 60b. The conical facing surface 60b of the lower upper conical bearing member 60 is a tapered surface whose diameter increases downward from the lower edge of the through hole 60a.

A pair of lower groove portions 61 are formed on the conical facing surface 60b of the lower upper conical bearing member 60 as a pair of groove portions extending radially from the inner side to the outer side in the radial direction. Specifically, the pair of lower groove portions 61 are respectively recessed upward from the conical facing surface 60b. The pair of lower groove portions 61 each extend downward as it goes radially outward from the axis Y1, and the axis Y1 is positioned between the radially inner edges of the pair of lower groove portions 61. ing.

Each of the pair of lower groove portions 61 has a substantially rectangular shape when viewed from the radially outer side, and extends from the radially inner side to the radially outer side at a predetermined depth above the conical facing surface 60b. It has a bottom surface 61t which is an inclined surface extending downward as it faces radially outward. The bottom surface 61 t defines the lower boundary of the pair of lower grooves 61 .

Each of the pair of lower groove portions 61 has a pair of side surfaces 61p extending parallel to the axis Y1 direction from the conical facing surface 60b toward the bottom surface 61t. A pair of side surfaces 61p each define a boundary between the conical facing surface 60b and the bottom surface 61t. Therefore, the lubricating oil G can be filled between the pair of lower groove portions 61 and the conical facing surface 70u of the lower lower conical bearing member 70 . The shape of the pair of lower groove portions 61 when viewed from the outside in the radial direction is not limited to the substantially rectangular shape. It may be a groove or a semi-circular groove.

A partially cut annular flange portion 62 that protrudes radially inward from the through hole 60a is provided at the lower end of the through hole 60a. The flange portion 62 is coaxial with the shaft member 21 , and the radial inner diameter of the flange portion 62 is smaller than the diameter of the outer peripheral surface 21 d of the shaft member 21 . Therefore, the lower upper conical bearing member 60 is fixed to the shaft member 21 by pressing the flange portion 62 into the shaft member 21 when the shaft member 21 is inserted into the through hole 60a. The flange portion 62 is partially cut out by the pair of lower groove portions 61 . Note that the flange portion 62 is not limited to a partially notched annular shape, and it is sufficient that a portion of the flange portion 62 protrudes radially inward from the through hole 60 a and is press-fitted into the shaft member 21 .

The lower upper conical bearing member 60 and the lower lower conical bearing member 70 are press-fitted onto the shaft member 21 , and the lower lower conical bearing member 70 has a greater press-fit allowance than the lower upper conical bearing member 60 . The press-fit allowance of the lower upper conical bearing member 60 is 5-20 μm, and the press-fit allowance of the lower lower conical bearing member 70 is 15-30 μm. The press-fit margin of the lower lower conical bearing member 70 is longer than the length of the lower upper conical bearing member 60 . Specifically, the lower lower conical bearing member 70 is made of the same material as the upper upper conical bearing member 50 shown in FIG. That is, the lower lower conical bearing member 70 is formed in a substantially cylindrical shape as shown in FIG. 70a is formed.

A through hole 70 a of the lower lower conical bearing member 70 is coaxial with the shaft member 21 and has a diameter smaller than the diameter of the outer peripheral surface 21 d of the shaft member 21 . Furthermore, the diameter of the through-hole 70 a is smaller than the radially inner diameter of the flange portion 62 of the lower upper conical bearing member 60 . Therefore, the lower lower conical bearing member 70 is fixed to the shaft member 21 by press-fitting the through hole 70a into the shaft member 21 when the shaft member 21 is inserted into the through hole 70a. At this time, since the lower lower conical bearing member 70 is press-fitted more strongly than the lower upper conical bearing member 60, the fastening strength can be made stronger than that of the lower upper conical bearing member 60. .

The press-fit allowance of the through hole 70a of the lower lower conical bearing member 70 is preferably in the range of 15-30 μm, more preferably in the range of 20-25 μm, and most preferably in the range of 22-23 μm. Also, the press-fit allowance of the flange portion 62 of the lower upper conical bearing member 60 is preferably in the range of 5 to 20 μm, more preferably in the range of 10 to 15 μm, and most preferably in the range of 12 to 13 μm.

On the upper side of the lower lower conical bearing member 70 is formed a conical facing surface 70u that contacts the conical facing surface 60b of the lower upper conical bearing member 60 . The conical facing surface 70u is a tapered surface whose diameter increases downward from the upper edge of the through hole 70a. The conical facing surface 70u is arranged at a position to contact the conical facing surface 60b of the lower upper conical bearing member 60. As shown in FIG. The conical facing surface 70u has the same inclination as the conical facing surface 60b of the lower upper conical bearing member 60 so that it can abut against the conical facing surface 60b of the lower upper conical bearing member 60. . The pair of lower groove portions 61 of the lower upper conical bearing member 60 and the conical facing surface 70u of the lower lower conical bearing member 70 define a lubricating oil circulation hole through which the lubricating oil G is circulated. The lower edge of the conical facing surface 70u connects with the upper edge of the conical surface 70d, which is the radially outer surface of the lower lower conical bearing member 70. As shown in FIG.

The conical surface 70d of the lower lower conical bearing member 70 is a tapered surface whose diameter decreases downward from the lower edge of the conical facing surface 70u. The lower edge of the conical surface 70 d connects with the radially outer edge of the lower surface 70 b of the lower lower conical bearing member 70 . The conical surface 70d has the same inclination as the conical surface 60d of the lower upper conical bearing member 60, so that it can be smoothly connected to the conical surface 60d of the lower upper conical bearing member 60. The lower surface 70b of the lower lower conical bearing member 70 is an annular flat surface extending radially outward from the lower edge of the through hole 70a.

As shown in FIG. 8, in the assembled state of the spindle motor 1, the lower upper conical bearing member 60 has the through hole 60a inserted into the shaft member 21, and the flange portion 62 is press-fitted into the shaft member 21 so that the shaft It is fixed to member 21 . The upper conical outer surface 60u of the lower upper conical bearing member 60 is arranged at a position facing the conical inner surface 31db provided on the lower side of the through hole 31a in the rotor member 31. As shown in FIG.

The lower conical bearing member 70 is fixed to the shaft member 21 by press-fitting the through hole 70 a into the shaft member 21 . The conical facing surface 70u of the lower lower conical bearing member 70 has the same inclination as the conical facing surface 60b of the lower upper conical bearing member 60, and contacts the conical facing surface 60b of the lower upper conical bearing member 60. It is A lubricating oil circulation hole through which the lubricating oil G circulates is defined by the pair of lower groove portions 61 of the lower upper conical bearing member 60 and the cone-facing surface 70u of the lower lower conical bearing member 70 . The conical surface 70d of the lower lower conical bearing member 70 has the same inclination as the conical surface 60d of the lower upper conical bearing member 60, and is smoothly connected to the conical surface 60d of the lower upper conical bearing member 60. there is

The lubricating oil G is distributed between the small gap between the through hole 60a of the lower upper conical bearing member 60 and the outer peripheral surface 21d of the shaft member 21, the inner conical surface 31db and the upper conical outer surface 60u of the lower upper conical bearing member 60. It fills the tiny gaps between Also, the lubricating oil G flows through the lubricating oil circulation holes defined by the pair of lower groove portions 61 of the lower upper conical bearing member 60 and the conical facing surface 70u of the lower lower conical bearing member 70, and the rotor member 31 and the lower conical bearing member 70. The space between the conical surface 60d of the upper side conical bearing member 60 and the conical surface 70d of the lower lower conical bearing member 70 is filled. That is, a tapered seal portion T for retaining lubricating oil G is formed between the conical surface 70d of the lower conical bearing member 70 and the rotor member 31, and the upper conical surface serving as the conical bearing surface of the lower upper conical bearing member 60 is formed. A dynamic pressure bearing portion DB in which dynamic pressure is generated by the lubricating oil G between the outer surface 60u and the rotor member 31 is provided.

As described above, in the spindle motor 1 according to the first embodiment of the present invention, the upper conical bearing member 22 includes the upper lower conical bearing member 40 fixed to the shaft member 21 facing the conical inner surface 31du, and the upper and an upper upper conical bearing member 50 fixed to the shaft member 21 in contact with the lower conical bearing member 40 . Therefore, the upper and lower conical bearing members 40 are press-fitted more weakly than the upper and upper conical bearing members 50, suppressing deformation of the lower conical outer surface 40b of the upper and lower conical bearing members 40, thereby preventing the hard disk 202 from vibrating during driving. can be suppressed. In addition, the upper upper conical bearing member 50 is press-fitted more strongly than the upper lower conical bearing member 40, and the fastening strength is stronger than that of the upper and lower conical bearing member 40, so that the fastening strength can be secured. It is possible to improve the durability against

Further, in the spindle motor 1 according to the first embodiment of the present invention, the lower conical bearing member 23 includes a lower upper conical bearing member 60 fixed to the shaft member 21 facing the conical inner surface 31db, and a lower and a lower lower conical bearing member 70 as a second conical bearing member fixed to the shaft member 21 in contact with the upper side conical bearing member 60 . Therefore, the lower upper conical bearing member 60 is press-fitted more weakly than the lower lower conical bearing member 70, suppressing deformation of the upper conical outer surface 60u of the lower upper conical bearing member 60, and vibrating the hard disk 202 during driving. can be suppressed. In addition, the lower lower conical bearing member 70 can be press-fitted more strongly than the lower upper conical bearing member 60, and the fastening strength can be made stronger than the lower upper conical bearing member 60 to secure the fastening strength. It is possible to improve durability against impact from.

Further, in the spindle motor 1 according to the first embodiment of the present invention, the upper conical bearing member 22 is composed of two conical bearing members, the upper lower conical bearing member 40 and the upper upper conical bearing member 50. there is Therefore, the pair of upper groove portions 41 of the upper and lower conical bearing member 40 and the conical facing surface 50b of the upper and upper conical bearing member 50 can define a lubricating oil circulation hole. It can be formed by grooving instead of machining. Therefore, the processing time for machining the lubricating oil circulation holes of the upper conical bearing member 22 can be reduced, and the cost of manufacturing the upper conical bearing member 22 can be reduced.

Further, in the spindle motor 1 according to the first embodiment of the present invention, the lower conical bearing member 23 is formed by two conical bearing members, the lower upper conical bearing member 60 and the lower lower conical bearing member 70. It is configured. Therefore, the lubricating oil circulation hole can be defined by the pair of lower groove portions 61 of the lower upper conical bearing member 60 and the conical facing surface 70u of the lower lower conical bearing member 70, and the lubricating oil circulation hole can be formed by drilling. It can be formed by grooving instead of drilling. Therefore, the processing time for machining the lubricating oil circulation holes of the lower conical bearing member 23 can be reduced, and the cost of manufacturing the lower conical bearing member 23 can be reduced.

Next, the configuration of the fluid dynamic pressure bearing 80 according to the second embodiment of the invention will be described. FIG. 9 is a partially enlarged cross-sectional view schematically showing the configuration of the portion near the upper conical bearing member 90 of the fluid dynamic pressure bearing 80 according to the second embodiment of the present invention. FIG. 10 is a cross-sectional view schematically showing the configuration of an upper upper conical bearing member 91 of the upper conical bearing member 90 shown in FIG. FIG. 11 is a partially enlarged cross-sectional view schematically showing the configuration of a portion of the fluid dynamic pressure bearing 80 near the lower conical bearing member 100. As shown in FIG. Hereinafter, the same reference numerals will be given to the same or similar configurations as those of the spindle motor 1 according to the first embodiment described above, and the description thereof will be omitted, and only the different configurations will be described.

The fluid dynamic pressure bearing 80 according to the second embodiment of the present invention has an upper upper conical bearing member and a lower lower conical bearing member for the spindle motor 1 according to the first embodiment of the present invention. Different configurations. Specifically, in the fluid dynamic pressure bearing 80 , an upper upper conical bearing member 91 is provided in place of the upper upper conical bearing member 50 , and a lower lower conical bearing member 101 is provided in place of the lower lower conical bearing member 70 . is provided.

A pair of upper groove portions 41 are formed in the conical facing surface 40u of the upper and lower conical bearing member 40, and between the conical facing surface 91bc and the conical surface 50d of the upper upper conical bearing member 50, there are conical facing surfaces. An annular connecting surface 91bd is formed to face 40u while being spaced apart. An annular oil reservoir 92 communicating with the pair of upper grooves 41 is formed between the conical facing surface 40u and the connecting surface 91bd. That is, the upper upper conical bearing member 91 has a conical facing surface 91bc that contacts the conical facing surface 40u of the upper and lower conical bearing member 40, and a conical facing surface 40u of the upper and lower conical bearing member 40 radially outward of the conical facing surface 91bc. , and a connecting surface 91bd that is spaced apart is formed.

The conical facing surface 91bc is a tapered surface whose diameter increases upward from the lower edge of the through hole 50a. The conical facing surface 91bc is arranged at a position to contact the conical facing surface 40u of the upper and lower conical bearing member 40. As shown in FIG. The conical facing surface 91bc has the same inclination as the conical facing surface 40u of the upper and lower conical bearing member 40, so that it can come into contact with the conical facing surface 40u of the upper and lower conical bearing member 40. The upper edge of the conical facing surface 91bc is connected to the lower edge of the connecting surface 91bd.

The connecting surface 91bd is a tapered surface whose diameter increases upward from the upper edge of the conical facing surface 91bc. The connecting surface 91bd has a larger inclination angle with respect to the radial direction than the conical facing surface 91bc and the conical facing surface 40u of the upper and lower conical bearing member 40, and is separated from the conical facing surface 40u of the upper and lower conical bearing member 40. You can do it.

As shown in FIG. 9, in the assembled state of the fluid dynamic bearing 80, the upper conical bearing member 90 is positioned between the upper lower conical bearing member 40 and the upper upper conical bearing member 91 so that the upper upper conical bearing member 91 is radially It further has an oil reservoir portion 92 formed by notching from the inner side toward the outer side in the radial direction. Specifically, the oil reservoir 92 is an annular space formed between the conical facing surface 40u of the upper lower conical bearing member 40 and the connecting surface 91bd of the upper upper conical bearing member 91 . The oil reservoir 92 is separated from the conical facing surface 40u of the upper and lower conical bearing member 40, and its width in the direction of the axis Y1 increases from the radially inner side toward the radially outer side.

The lower lower conical bearing member 101 is made of the same material as the upper upper conical bearing member 91 shown in FIG. That is, the lower lower conical bearing member 101 has a conical facing surface 101uc that contacts the conical facing surface 60b (FIG. 11) of the lower upper conical bearing member 60, and a lower upper conical bearing surface 101uc radially outward of the conical facing surface 101uc. A conical facing surface 60b of the member 60 and a connecting surface 101ud are formed apart from each other.

The conical facing surface 101uc is a tapered surface whose diameter increases downward from the upper edge of the through hole 70a. The conical facing surface 101uc is arranged at a position to contact the conical facing surface 60b of the lower upper conical bearing member 60. As shown in FIG. The conical facing surface 101uc has the same inclination as the conical facing surface 60b of the lower upper conical bearing member 60 so that it can abut against the conical facing surface 60b of the lower upper conical bearing member 60. . The lower edge of the conical facing surface 101uc is connected to the upper edge of the connecting surface 101ud.

The connecting surface 101ud is a tapered surface whose diameter increases downward from the lower edge of the conical facing surface 101uc. The connecting surface 101ud has a larger inclination angle with respect to the radial direction than the conical facing surface 101uc and the conical facing surface 60b of the lower upper conical bearing member 60. and can be separated from each other.

As shown in FIG. 11 , in the assembled state of the fluid dynamic bearing 80 , the lower conical bearing member 100 is positioned between the lower upper conical bearing member 60 and the lower lower conical bearing member 101 . The member 101 further has an oil reservoir 102 formed by notching from the inner side in the radial direction toward the outer side in the radial direction. Specifically, the oil reservoir 102 is an annular space formed between the conical facing surface 60 b of the lower upper conical bearing member 60 and the connecting surface 101 ud of the lower lower conical bearing member 101 . The oil reservoir 102 is separated from the conical facing surface 60b of the lower upper conical bearing member 60, and its width in the direction of the axis Y1 increases from the radially inner side to the radially outer side.

Thus, in the fluid dynamic pressure bearing 80 according to the second embodiment of the present invention, the upper conical bearing member 90 is disposed between the upper lower conical bearing member 40 and the upper upper conical bearing member 91. The bearing member 91 has an oil reservoir portion 92 formed by notching from the radially inner side toward the radially outer side. Further, in the fluid dynamic pressure bearing 80, the lower conical bearing member 100 is arranged between the lower upper conical bearing member 60 and the lower lower conical bearing member 101, and the lower lower conical bearing member 101 is arranged radially inward from the radial direction. It further has an oil reservoir portion 102 formed by notching outward in the direction. Therefore, a large amount of the circulating oil G can be stored in the areas of the oil reservoirs 92 and 102, and failure of the fluid dynamic pressure bearing 80 due to depletion of the circulating oil G can be suppressed. 80 life can be improved.

Further, in the fluid dynamic pressure bearing 80 according to the second embodiment of the present invention, the upper conical bearing member 90 is composed of two conical bearing members, the upper lower conical bearing member 40 and the upper upper conical bearing member 91. It is Therefore, the oil reservoir portion 92 can be formed by cutting the upper upper conical bearing member 91 instead of grooving. Therefore, the processing time for processing the oil reservoir portion 92 can be reduced, and the cost for manufacturing the upper conical bearing member 90 can be reduced.

Further, in the fluid dynamic pressure bearing 80 according to the second embodiment of the present invention, the lower conical bearing member 100 consists of two conical bearings, the lower upper conical bearing member 60 and the lower lower conical bearing member 101. It is composed of members. Therefore, the oil reservoir portion 102 can be formed by cutting the lower lower conical bearing member 101 instead of grooving. Therefore, the processing time for processing the oil reservoir portion 102 can be reduced, and the cost of manufacturing the lower conical bearing member 100 can be reduced.

Next, the configuration of the fluid dynamic pressure bearing 110 according to the third embodiment of the invention will be described. FIG. 12 is a partially enlarged cross-sectional view schematically showing the configuration of a portion near upper conical bearing member 90 of fluid dynamic pressure bearing 110 according to the third embodiment of the present invention. FIG. 13 is a partially enlarged cross-sectional view schematically showing the structure of the upper conical bearing member 90 shown in FIG. 12 near the oil reservoir 111. As shown in FIG. Hereinafter, the same reference numerals will be given to the same or similar configurations as those of the fluid dynamic pressure bearing 80 according to the above-described second embodiment, and the description thereof will be omitted, and only the different configurations will be described.

A fluid dynamic pressure bearing 110 according to the third embodiment of the present invention differs in the configuration of an oil reservoir from the fluid dynamic pressure bearing 80 according to the above-described second embodiment of the present invention. Specifically, fluid dynamic pressure bearing 110 is provided with oil reservoir 111 instead of oil reservoir 92 .

The upper conical bearing member 91 according to the third embodiment of the present invention has a conical facing surface 91bc and a connecting surface 91bd that differ from the conical facing surface 91bc and the connecting surface 91bd according to the second embodiment of the present invention. It is constructed in the same manner as the upper upper conical bearing member 91 according to the second embodiment except for the above. That is, the radial width of the conical facing surface 91bc according to the third embodiment of the present invention is larger than the radial width of the conical facing surface 91bc according to the second embodiment of the present invention. . Further, the radial width of the connecting surface 91bd according to the third embodiment of the present invention is smaller than the radial width of the connecting surface 91bd according to the second embodiment of the present invention.

As shown in FIG. 12, in the assembled state of the fluid dynamic bearing 110, the upper conical bearing member 90 is positioned between the upper lower conical bearing member 40 and the upper upper conical bearing member 91 so that the upper upper conical bearing member 91 has a radial It has an oil reservoir portion 111 formed by notching from the inner side toward the outer side in the radial direction. Specifically, the oil reservoir 111 is an annular space formed between the conical facing surface 40u of the upper and lower conical bearing member 40 and the connecting surface 91bd of the upper and lower conical bearing member 91 . The oil reservoir portion 111 is separated from the conical facing surface 40u of the upper and lower conical bearing member 40, and its width in the direction of the axis Y1 increases from the radially inner side to the radially outer side.

As shown in FIG. 12 , the oil reservoir 111 is positioned above the bottom surfaces 41 t of the pair of upper grooves 41 of the upper and lower conical bearing member 40 . Specifically, the oil pool portion 111 has a contact portion P with the cone facing surface 40u of the upper and lower conical bearing member 40, which is the lower portion of the oil pool portion 92 in the direction of the axis Y1. 41t of the pair of upper groove portions 41 are arranged above the radially outer edge E1 of the bottom surface 41t in the direction of the axis Y1. Therefore, in the upper conical bearing member 90, it is possible to secure the circulating oil G for the area of the oil reservoir portion 111, thereby suppressing failure of the fluid dynamic pressure bearing 80 due to depletion of the circulating oil G, The life of the hydrodynamic bearing 80 can be further improved.

As shown in FIG. 13 , the radially outer width of oil pool portion 111 is smaller than the width between the upper edge of oil pool portion 111 and rotor member 31 . Specifically, the width (opening width) W1 at the radially outer edge of the oil pool portion 111 is the width of the rotor member 31 facing the upper edge E2 of the oil pool portion 111 and the conical surface 50d of the upper upper conical bearing member 50. It is smaller than the width W2 between the inner peripheral surface. Therefore, the upper conical bearing member 90 can prevent air bubbles from remaining in the oil reservoir 111 and discharge the air bubbles to the interface of the circulating oil G. As shown in FIG.

In fluid dynamic pressure bearing 110 , an oil reservoir having the same structure as oil reservoir 111 is provided in place of oil reservoir 102 of lower conical bearing member 100 .

Next, the configuration of the fluid dynamic pressure bearing 120 according to the fourth embodiment of the invention will be described. FIG. 14 is a partially enlarged cross-sectional view schematically showing the configuration of the portion near the upper conical bearing member 90 of the fluid dynamic pressure bearing 120 according to the fourth embodiment of the present invention. Hereinafter, the same reference numerals are given to the same or similar configurations as those of the fluid dynamic pressure bearing 110 according to the above-described third embodiment, and the description thereof will be omitted, and only the different configurations will be described.

The fluid dynamic pressure bearing 120 according to the fourth embodiment of the present invention has a pair of upper groove portions of the upper and lower conical bearing members in contrast to the fluid dynamic pressure bearing 110 according to the above-described third embodiment of the present invention. configuration is different. Specifically, in the fluid dynamic pressure bearing 120 , a pair of upper groove portions 122 of an upper lower conical bearing member 121 are provided in place of the pair of upper groove portions 41 of the upper and lower conical bearing member 40 .

The pair of upper groove portions 122 have a width (height) in the direction of the axis Y1 smaller than that of the pair of upper groove portions 41 according to the third embodiment of the present invention, except that the width (height) thereof is smaller than that of the pair of upper groove portions 122 according to the third embodiment of the present invention. It is constructed in the same manner as the pair of upper groove portions 41 according to the third embodiment. That is, in the pair of upper groove portions 122, the height of the pair of side surfaces 122p of the pair of upper groove portions 122 in the direction of the axis Y1 is smaller than the height of the pair of side surfaces 41p of the pair of upper groove portions 41. As shown in FIG. Therefore, the lubricating oil G accumulated in the lubricating oil circulation hole defined by the pair of upper groove portions 122 and the conical facing surface 91bc and the connecting surface 91bd of the upper upper conical bearing member 91 can be reduced. Therefore, failure of the fluid dynamic pressure bearing 80 due to depletion of the circulating oil G can be suppressed with a small amount of lubricating oil G, and the life of the fluid dynamic pressure bearing 80 can be further improved.

Further, in the fluid dynamic pressure bearing 120 according to the fourth embodiment of the present invention, the upper conical bearing member 90 is composed of two conical bearing members, an upper lower conical bearing member 121 and an upper upper conical bearing member 91. It is Therefore, the pair of upper groove portions 122 of the upper and lower conical bearing member 121 and the conical facing surface 91bc and the connecting surface 91bd of the upper and upper conical bearing member 91 can define a lubricating oil circulation hole. can be formed by grooving instead of drilling. Therefore, the width (height) of the pair of upper groove portions 122 in the direction of the axis Y1 of the lubricating oil circulation hole of the upper conical bearing member 22 can be reduced by simple processing.

In the fluid dynamic pressure bearing 120, instead of the pair of lower grooves 61 of the lower upper conical bearing member 60, a pair of lower grooves having the same structure as the pair of upper grooves 122 of the upper lower conical bearing member 121 are provided. department is provided.

Next, the configuration of the fluid dynamic pressure bearing 130 according to the fifth embodiment of the invention will be described. FIG. 15 is a partially enlarged cross-sectional view schematically showing the configuration of the portion near the upper conical bearing member 131 of the fluid dynamic pressure bearing 130 according to the fifth embodiment of the present invention. Hereinafter, the same reference numerals will be given to the same or similar configurations as those of the spindle motor 1 according to the first embodiment described above, and the description thereof will be omitted, and only the different configurations will be described.

A fluid dynamic pressure bearing 130 according to the fifth embodiment of the present invention differs from the above-described spindle motor 1 according to the first embodiment of the present invention in the configuration of the upper conical bearing member. Specifically, in the fluid dynamic pressure bearing 130, the upper lower conical bearing member 132 and the upper upper conical bearing member 132 of the upper conical bearing member 131 are replaced with the upper lower conical bearing member 40 and the upper upper conical bearing member 50 of the upper conical bearing member 22. A bearing member 133 is provided.

The upper lower conical bearing member 132 is made of a material having a higher hardness than the upper upper conical bearing member 133 . The upper upper conical bearing member 133 is made of, for example, plastic (resin). Since it is made of a material that costs less than 132, the cost of making the upper conical bearing member 131 can be reduced. For example, the upper lower conical bearing member 132 and the upper upper conical bearing member 133 can be made of various metals or resins.

The upper and lower conical bearing member 132 is made of brass, copper alloy, iron-based or copper-based sintered metal, aluminum, aluminum alloy, stainless steel, or the like, in order to suppress wear and deformation of the lower conical outer surface 40b. Metal is used. The upper and lower conical bearing members 132 may also be plated with electroless nickel to improve hardness.

Further, the lower conical outer surface 40b of the upper lower conical bearing member 132 may be subjected to surface treatment such as DLC (diamond-like carbon), plating, molybdenum disulfide, fluorine resin, or nitriding treatment. Through such surface treatment and nitriding treatment, it is possible to reduce contact resistance, reduce starting load torque, and improve high-speed durability. can be prevented from occurring, and smooth rotation can be enabled.

A thermoplastic resin, for example, is used for the upper upper conical bearing member 133 . Examples of thermoplastic resins include polyacetal, polyamide, polyamideimide (PAI), polyetheretherketone (PEEK), thermoplastic polyimide (TPI), polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), and polybutylene terephthalate. (PBT), polyetherimide (PEI) and the like can be used. A material in which two or more thermoplastic resins are mixed can also be used.

Also, the upper upper conical bearing member 133 does not necessarily have to be made of thermoplastic resin only, and may be a mixture of thermoplastic resin and thermosetting resin. As a thermosetting resin, it is possible to use, for example, a phenolic resin.

Further, as the upper conical bearing member 133, a liquid crystal polymer or the like can be widely used.

In the fluid dynamic pressure bearing 130 , instead of the lower upper conical bearing member 60 and the lower lower conical bearing member 70 of the lower conical bearing member 23 , the upper lower conical bearing member 132 and the upper upper conical bearing member 132 of the upper conical bearing member 131 are replaced. Lower upper and lower conical bearing members of the same material as conical bearing member 133 can be used. In addition, the materials of the upper lower conical bearing member 132 and the upper upper conical bearing member 133 of the upper conical bearing member 131 of the fluid dynamic pressure bearing 130 according to the fifth embodiment of the present invention are the same as those of the first to fourth aspects of the present invention. It can also be applied to the upper conical bearing member and the lower conical member of the spindle motor according to the embodiment.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and includes all aspects included in the concept of the present invention and the scope of claims. Moreover, each configuration may be selectively combined as appropriate so as to achieve at least part of the above-described problems and effects. For example, the shape, material, arrangement, size, etc. of each component in the above embodiment may be changed as appropriate according to the specific usage of the present invention.

For example, in the fluid dynamic pressure bearing 20 according to the first embodiment of the present invention, radial The embodiment of the present invention has been described by taking as an example the case where the pair of upper groove portions 41 are formed. However, the present invention is not limited to this, and the groove portion may be formed in the conical facing surface 50b of the upper upper conical bearing member 50 . That is, at least one of the conical facing surface 40u of the upper lower conical bearing member 40 facing the upper upper conical bearing member 50 and the conical facing surface 50b of the upper upper conical bearing member 50 facing the upper lower conical bearing member 40 has radial It suffices if a groove portion extending to .

In addition, in the fluid dynamic pressure bearing 20 according to the first embodiment of the present invention, the conical facing surface 60b of the lower upper conical bearing member 60 is radially outwardly facing from the radially inner side. The embodiment of the present invention has been described by taking as an example the case where the pair of lower groove portions 61 extending in the direction is formed. However, the present invention is not limited to this, and the groove portion may be formed in the conical facing surface 70u of the lower lower conical bearing member 70 . That is, at least one of the conical facing surface 60b of the lower upper conical bearing member 60 facing the lower conical bearing member 70 and the conical facing surface 70u of the lower lower conical bearing member 70 facing the lower upper conical bearing member 60 It suffices that a groove extending in the radial direction is formed.

DESCRIPTION OF SYMBOLS 1... Spindle motor 10... Stator 11... Base plate 11a... Through hole 11b... Circumferential wall part 12... Stator core 13... Coil 20, 80, 110, 120, 130... Fluid dynamic pressure bearing, 21... Shaft Members 21a... Shaft hole 21d... Peripheral surface 22, 90, 131... Upper conical bearing member 23, 100... Lower conical bearing member 30... Rotor 31... Rotor member 31a... Through hole 31b... Movement Pressure groove portion 31c Yoke mounting portion 31du, 31db Conical inner surface 32 Yoke 33 Rotor magnet 34 End cap 40, 121, 132 Upper and lower conical bearing member 40a Through hole 40b Bottom Side conical outer surface 40d Conical surface 40u Conical opposing surface 41, 122 Pair of upper groove portions 41p, 122p Pair of side surfaces 41t Bottom surface 42 Flange portion 50, 91, 133 Upper upper portion Conical bearing member 50a through hole 50b facing conical surface 50d conical surface 50u upper surface 60 lower upper conical bearing member 60a through hole 60b facing conical surface 60d conical surface 60u Upper conical outer surface 61 Pair of lower grooves 61p Pair of side surfaces 61t Bottom surface 62 Flanges 70, 101 Lower lower conical bearing member 70a Through hole 70b Lower surface 70d Conical surface 70u Conical opposing surface 91bc, 101uc Conical opposing surface 91bd, 101ud Connection surface 92, 102, 111 Oil reservoir 200 Hard disk drive 201 Housing 201a Bottom 202 Hard disk 203 Bearing device 204 Swing arm 205 Head portion D Dynamic pressure groove DB Dynamic pressure bearing portion E1, E2 Edge G Lubricating oil P Contact portion S Space , T... Taper seal portion, W1, W2... Width, Y1... Axis

Claims (7)

a shaft member;
a first conical bearing member and a second conical bearing member fixed to the shaft member;
a rotor member rotatably supported by the shaft member via the first conical bearing member and the second conical bearing member and having a through hole through which the shaft member is inserted ;
with
The second conical bearing member is positioned closer to the opening of the through hole than the first conical bearing member, and has a diameter that decreases toward the opening of the through hole,
The diameter of the first conical bearing member increases toward the opening of the through hole,
the first conical bearing member and the second conical bearing member are in contact with each other with their diameter-enlarged sides facing each other ;
A tapered seal portion for retaining lubricating oil is formed between the conical surface defining the reduced diameter of the second conical bearing member and the rotor member,
A dynamic pressure bearing portion is provided in which dynamic pressure is generated by the lubricating oil between the conical bearing surface of the first conical bearing member opposite to the second conical bearing member side and the rotor member. A fluid dynamic bearing characterized by: The first conical bearing member and the second conical bearing member are press-fitted into the shaft member,
2. The fluid dynamic bearing according to claim 1, wherein said second conical bearing member has a greater press-fit allowance than said first conical bearing member. At least one of the first facing surface of the first conical bearing member facing the second conical bearing member and the second facing surface of the second conical bearing member facing the first conical bearing member has a radial 3. A fluid dynamic pressure bearing according to claim 1, wherein an extending groove is formed. The groove is formed in the first facing surface of the first conical bearing member,
between the second facing surface and the conical surface of the second conical bearing member, an annular connecting surface facing the first facing surface with a gap therebetween is formed;
4. The fluid dynamic bearing according to claim 3, wherein an annular oil reservoir communicating with said groove is formed between said first opposing surface and said connecting surface. 5. The fluid dynamic bearing according to claim 1, wherein said first conical bearing member is made of a material having higher hardness than said second conical bearing member. 6. The fluid dynamic bearing according to claim 5, wherein said second conical bearing member is made of resin. A spindle motor comprising the fluid dynamic pressure bearing according to any one of claims 1 to 6.

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