JP2006077927A - Dynamic pressure fluid bearing apparatus, electric motor having dynamic pressure fluid bearing apparatus, and method for manufacturing dynamic pressure fluid bearing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dynamic pressure fluid bearing apparatus which does not cause noises and vibrations and is highly reliable, and further to provide an electric motor having the dynamic pressure fluid bearing apparatus and a method for manufacturing the dynamic pressure fluid bearing apparatus. <P>SOLUTION: In the dynamic pressure fluid bearing apparatus, a sleeve 3, which is penetrated by a shaft 1 and can rotate relative to the shaft, has a first annular wall 3A and a second annular wall 3B, which are formed around the rotation axis of the shaft and have different diameters respectively. A cover plate 4 is arranged so as to face to a flange fixed to one end of the shaft and is fixed by the first annular wall 3A. The connecting portion of the cover plate and the sleeve is fixed by an epoxy adhesive agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a bearing device used in a spindle motor or the like that rotationally drives a disk-shaped recording medium, and includes a hydrodynamic fluid bearing device that uses fluid dynamic pressure, a motor that uses the hydrodynamic bearing device, and The present invention relates to a method for manufacturing a hydrodynamic bearing device.

2. Description of the Related Art In recent years, a recording apparatus that rotationally drives a disk-shaped recording medium such as a magnetic disk, an optical disk, or a magneto-optical disk has an increased memory capacity and an increased data transfer speed. Accordingly, since the bearing device used in this type of recording apparatus is required to hold a shaft that rotates at high speed with high accuracy, a hydrodynamic bearing device is used as a bearing device that satisfies this requirement. .
In the hydrodynamic bearing device, one having a one-side sealed cantilever type bearing structure in which one side of the rotating shaft is open to the atmosphere and the other side is sealed is mainly used. In the hydrodynamic bearing device having such a bearing structure, a fixing method such as caulking, adhesive, welding or the like is used to seal one of the rotating shafts.

Hereinafter, a conventional one-side sealed type cantilever type hydrodynamic bearing device will be described with reference to FIG.
FIG. 4 is a cross-sectional view showing a spindle motor using the conventional hydrodynamic bearing device disclosed in Patent Document 1. As shown in FIG. In the conventional spindle motor shown in FIG. 4, the rotor portion 100 is rotatably supported with respect to the stator portion 200 by a radial direction dynamic pressure bearing 50 and a thrust direction dynamic pressure bearing 60.
The stator unit 200 includes a motor base 201, a sleeve 202 press-fitted and fixed to the motor base 201, and a core 204 around which a coil 203 is wound. The rotor unit 100 includes a shaft 101 that is rotatably inserted into the sleeve 202, a rotor hub 102 that is press-fitted and fixed to the shaft 101, and a magnet 104 that is disposed to face the core 204 and is fixed to the yoke 103. have.

A herringbone-shaped (fishbone-shaped) dynamic pressure groove is formed at a predetermined position on either the outer surface of the shaft 101 or the inner surface of the shaft hole 202a of the sleeve 202. A radial direction dynamic pressure bearing 50 is configured by holding a lubricant in a gap between the opposed surfaces of the shaft 101 and the sleeve 202 where the dynamic pressure grooves are formed. An annular flange 105 is press-fitted and fixed to the lower end portion of the shaft 101.
A circumferential portion of the lower end surface of the sleeve 202 is formed in a step shape, and the lower end surface of the sleeve 202 has an opening. A disc-shaped cover plate 205 is press-fitted and fixed to the opening. An adhesive 207 is applied to seal the fixing portion between the cover plate 205 and the sleeve 202. Lubricant is held in a gap where the flange 105 fixed to the shaft 101 and the cover plate 205 fixed to the sleeve 202 face each other. Dynamic pressure grooves are formed on the upper and lower surfaces of the flange 105. The flange 105, the cover plate 205, the sleeve 202, and the lubricant constitute a thrust direction dynamic pressure bearing 60.

In the conventional spindle motor shown in FIG. 4, a cylindrical wall 201 </ b> A surrounding the sleeve 202 is formed in the central portion of the motor base 201. A concave portion 206 is formed on the inner peripheral surface of the cylindrical wall 201A. The sleeve 202 is held and fixed at both upper and lower portions of the recess 206.
JP 2003-289646 A (page 3-5, FIG. 1)

  As described above, the one-side sealed type cantilever type bearing mechanism has an opening in which one side of the rotary shaft in the lubricant held in the radial direction dynamic pressure bearing and the thrust direction dynamic pressure bearing is open to the atmosphere, The side is sealed. In the hydrodynamic bearing device shown in FIG. 4, the cover plate 205 is press-fitted into one end of a sleeve 202 that rotatably holds the shaft 101, and is fixed by an adhesive, and is of a one-side sealed type cantilever type. It has a bearing structure.

  In manufacturing the conventional spindle motor having the above-described configuration, stress is generated when the sleeve 202 having the cover plate 205 press-fitted and fixed is press-fitted into the motor base 201. The stress generated at this time is applied to each portion of the outer peripheral portion of the cover plate 205 via the sleeve 202. If the stress generated when the sleeve 202 is press-fitted into the motor base 201 is applied to the outer peripheral portion of the cover plate 205 via the sleeve 202 and the cover plate 205 is deformed, the flatness of the cover plate 205 is lowered. This may cause a serious problem that the dynamic pressure in the thrust direction is reduced or unbalanced. Further, when the cover plate 205 is deformed, the lubricating oil leaks and causes other components to become dirty, or the lubricant is insufficient. Further, when a stress generated when the sleeve 202 to which the cover plate 205 is fixed is press-fitted and fixed to the motor base 201 is indirectly applied to the radial direction dynamic pressure bearing or the thrust direction dynamic pressure bearing, the radial direction dynamic pressure bearing. Further, the shape of the thrust direction dynamic pressure bearing may be deformed, and the dynamic pressure balance may be lost. If such an imbalance occurs, there is a problem that the rotation accuracy of the spindle motor deteriorates and noise and vibration are generated.

  In the conventional spindle motor, a recess 206 is formed on the inner peripheral surface of the cylindrical wall 201A, and the motor base 201 and the sleeve 202 are fixed in contact with each other only at the upper and lower sides of the recess 206. Due to such a structure, the stress generated when the sleeve 202 is press-fitted into the motor base 201 is somewhat absorbed in the recess 206, and all of the stress is applied to the outer peripheral portion of the cover plate 205 and the radial dynamic pressure bearing 50. This is a configuration that cannot be added. However, in the configuration of the conventional spindle motor shown in FIG. 4, the shape of the recess 206 is important, and high-precision machining is required. For example, in order to reliably prevent the deformation of the cover plate 205, the depth of the concave portion 206 is set to 5 times or more of the press-fit interference between the sleeve 202 and the motor base 201, and the depth is 10 μm or more when the press-fit interference is 2 μm. Is set. When the depth of the concave portion 206 is less than twice the above-mentioned press-fit interference, deformation occurs and inconvenience occurs. As described above, in the configuration of the conventional spindle motor shown in FIG. 4, the concave portion 206 is formed on the inner peripheral surface of the cylindrical wall 201a to suppress the transmission of stress when the sleeve 202 is press-fitted into the motor base 201. It was a structure. However, since a part of the stress is transmitted to the outer peripheral portion of the cover plate 205 and each portion of the radial direction dynamic pressure bearing 50 through the sleeve 202, the above-mentioned problem cannot be solved completely. .

  In order to solve the above problem, a method of fixing the sleeve 202 to the motor base 201 not by press-fitting but by bonding using only an adhesive has been studied. However, fixing with an adhesive causes curing shrinkage, so that there is a problem that high-precision assembly cannot be performed.

  Further, when the conventional spindle motor configured as described above is used in a relatively high temperature environment, each member in the stator portion 200 such as the motor base 201, the sleeve 202, and the cover plate 205 has a difference in thermal expansion coefficient. As a result, there is a risk that the entire spindle motor may be deformed, which is problematic in terms of reliability as a spindle motor. The acrylic adhesive generally used as an adhesive does not have the strength to withstand deformation due to thermal expansion of each member in the relatively high temperature use environment as described above. There was no effect of suppressing deformation of the member. In particular, the acrylic adhesive has a feature that the lubricant used in the bearing portion is likely to swell, and there is also a problem that the lubricant oozes out from the adhesive portion.

  The present invention solves the problems in the above-described conventional configuration, and can provide a highly reliable hydrodynamic fluid bearing device that can assemble a bearing mechanism with high accuracy and does not generate noise and vibration, and the hydrodynamic fluid bearing device thereof. It is an object of the present invention to provide a method of manufacturing a hydrodynamic bearing device that can easily manufacture a highly reliable hydrodynamic bearing device.

A hydrodynamic bearing device according to the present invention includes a shaft, as described in claim 1.
An annular first annular wall having a small diameter and an annular second annular wall having a large diameter, which are penetrated by the shaft and are rotatable relative to the shaft. And a sleeve formed on an end face near one end of the shaft,
A flange fixed to one end of the shaft and having a surface perpendicular to the rotation axis of the shaft;
A disc-shaped cover plate disposed opposite to the flange and pressed and fixed to a first annular wall formed on the sleeve;
An epoxy-based adhesive that secures a joint portion between the cover plate and the sleeve and is held in a recess formed by the first annular wall and the second annular wall;
Radial direction dynamic pressure generating means formed on at least one of the opposing surfaces of the shaft and the sleeve;
A thrust direction dynamic pressure generating means formed on at least one surface of the sleeve and the flange facing each other, and a lubricant held in a minute gap between the radial direction dynamic pressure generating means and the thrust direction dynamic pressure generating means, It comprises.
The hydrodynamic bearing device of the present invention configured as described above is a highly reliable bearing device in which the bearing mechanism is assembled with high accuracy and no noise or vibration is generated.

  The hydrodynamic bearing device according to the present invention, as described in claim 2, is such that the height of the first annular wall in claim 1 is smaller than the thickness of the cover plate. The height of the two annular walls is larger than the thickness of the cover plate. In the hydrodynamic bearing device of the present invention formed as described above, the adhesive is reliably held between the recess formed inside the second annular wall and the circumferential portion of the cover plate.

As described in claim 3, the motor according to the present invention includes a shaft,
An annular first annular wall having a small diameter and an annular second annular wall having a large diameter, which are penetrated by the shaft and are rotatable relative to the shaft. And a sleeve formed on an end face near one end of the shaft,
A flange fixed to one end of the shaft and having a surface perpendicular to the rotation axis of the shaft;
A disc-shaped cover plate disposed opposite to the flange and pressed and fixed to a first annular wall formed on the sleeve;
An epoxy-based adhesive that secures a joint portion between the cover plate and the sleeve and is held in a recess formed by the first annular wall and the second annular wall;
Radial direction dynamic pressure generating means formed on at least one of the opposing surfaces of the shaft and the sleeve;
Thrust direction dynamic pressure generating means formed on at least one of the facing surfaces of the sleeve and the flange;
A lubricant held in a minute gap between the radial direction dynamic pressure generating means and the thrust direction dynamic pressure generating means;
A motor rotor portion substantially fixed to the shaft; and a motor stator portion arranged at a position facing the motor rotor portion and substantially fixed to the sleeve.
The motor of the present invention configured as described above has a bearing mechanism assembled with high precision, uses a hydrodynamic bearing device that does not leak lubricating oil, and does not generate noise or vibration. And a long-life driving device.

  According to a fourth aspect of the present invention, in the motor according to the fourth aspect, the height of the first annular wall in the third aspect is smaller than the thickness of the cover plate. The height is longer than the thickness of the cover plate. In the motor of the present invention formed as described above, the adhesive is reliably held between the recess formed inside the second annular wall and the circumferential portion of the cover plate.

As described in claim 5, the manufacturing method of the hydrodynamic bearing device according to the present invention,
Forming an annular first annular wall having a small diameter and an annular second annular wall having a large diameter on the end surface of the sleeve in the vicinity of one end of the shaft, with the rotational axis of the shaft as a substantial central axis;
Forming a radial dynamic pressure generating portion on at least one of the opposing surfaces of the shaft and the sleeve;
Forming a thrust direction dynamic pressure generating portion on at least one surface of the flange and the sleeve facing each other;
Fixing the flange to one end of the shaft;
Inserting the shaft into the sleeve;
A cover plate is disposed to face the flange, a fixing jig is inserted into a recess between the first annular wall and the second annular wall formed in the sleeve, and the first annular wall is placed on the cover plate. And a step of applying an epoxy-based adhesive to the entire circumference of the joint portion between the sleeve and the cover plate including the inside of the recess.
With the manufacturing method according to the present invention having such steps, the hydrodynamic bearing device can be easily manufactured with a simple jig, and the manufacturing cost can be greatly reduced.

  In the method for manufacturing a hydrodynamic bearing device according to the present invention, as described in claim 6, the height of the first annular wall in claim 5 is formed smaller than the thickness of the cover plate. The height of the second annular wall is greater than the thickness of the cover plate. In the motor of the present invention formed as described above, the adhesive is reliably held between the recess formed inside the second annular wall and the circumferential portion of the cover plate.

  Since the hydrodynamic bearing device according to the present invention is configured to apply an epoxy adhesive to the joint portion between the sleeve and the cover plate and seal the joint portion between the sleeve and the cover plate, the lubricating oil leaks. Therefore, it is a long-life device, and each component of the bearing portion can be incorporated with high accuracy, so that it becomes a highly reliable hydrodynamic bearing device that does not generate noise and vibration. Further, the hydrodynamic bearing device according to the present invention can be easily manufactured with a simple jig, and the manufacturing cost can be greatly reduced. Furthermore, since the motor according to the present invention uses the hydrodynamic bearing device having the above-described effects as a bearing mechanism, the motor has a long life and high reliability.

  Preferred embodiments of a hydrodynamic bearing device according to the present invention, a motor using the hydrodynamic bearing device, and a method of manufacturing the hydrodynamic bearing device will be described below with reference to the accompanying drawings.

<< First Embodiment >>
A hydrodynamic bearing device according to a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a cross-sectional view showing a spindle motor using the hydrodynamic bearing device of the first embodiment. FIG. 2 is an enlarged sectional view of a part of the spindle motor according to the first embodiment shown in FIG. The spindle motor shown in FIG. 1 is a hydrodynamic fluid bearing device of a one-side sealed type cantilever type, like the conventional spindle motor shown in FIG. 4, and includes a radial direction dynamic pressure bearing 50 and a thrust direction dynamic pressure bearing. The rotor part 100 is rotatably supported with respect to the stator part 200 by 60 and the lubricant held by them.

In the spindle motor according to the first embodiment, the stator unit 200 includes the motor base 11, the sleeve 3, the cover plate 4, the core 8, the coil 9, and the like. The sleeve 3 and the core 8 are directly fixed to the motor base 11. A cylindrical wall 11 </ b> A is formed in the central portion of the motor base 11. The sleeve 3 is press-fitted and fixed inside the cylindrical wall 11A. A cover plate 4 is fixed to the lower end surface of the sleeve 3. A core 8 is fixed to the outer peripheral surface of the cylindrical wall 11 </ b> A of the motor base 11, and a coil 9 is wound around the core 8.
A first annular wall 3 </ b> A and a second annular wall 3 </ b> B are formed at the lower end of the sleeve 3 so as to surround the cover plate 4 coaxially about the rotation axis of the shaft 1. The first annular wall 3A is formed inside the second annular wall 3B that forms the side surface of the lower end portion of the sleeve 3, and a recess 15 is formed between the first annular wall 3A and the second annular wall 3B. ing.

The rotor portion 100 is opposed to the shaft 1 rotatably inserted into the sleeve 3, the rotor hub 2 press-fitted and fixed to the shaft 1, the yoke 7 provided on the rotor hub 2, and the core 8 of the stator portion 200. And a magnet 6 fixed to the yoke 7.
A herringbone (fishbone-shaped) radial dynamic pressure groove is formed at a predetermined position on either the outer peripheral surface of the shaft 1 or the sleeve inner surface 16 of the shaft hole 14 of the sleeve 3. In the first embodiment, a first radial direction dynamic pressure groove 12 and a second radial direction dynamic pressure groove 13 are formed at two locations on the shaft 1. A lubricant as a working fluid is held in a gap between the opposed surfaces of the shaft 1 and the sleeve 3 where the radial dynamic pressure grooves are formed. The radial dynamic pressure is maintained by the shaft 1, the sleeve 3, and the lubricant. A bearing 50 is configured.
An annular flange 5 is press-fitted and fixed to the lower end portion of the shaft 1. In the first embodiment, a herringbone-shaped thrust direction dynamic pressure groove is formed on the upper surface and the lower surface of the flange 5. A lubricant is held in a gap formed by the surface on which the thrust direction dynamic pressure groove is formed. The sleeve 3, the cover plate 4, the flange 5, and the lubricant constitute a thrust direction dynamic pressure bearing 60.

In the first embodiment, the rotor part 100 and the stator part 200 are constituted by a one-side sealed type cantilever type bearing mechanism. That is, the upper end portion of the shaft 1 and the rotor hub 2 is open to the atmosphere and the other side is sealed in the gap that holds the lubricant that is the working fluid of the radial dynamic pressure bearing 50.
In the first embodiment, an example in which thrust dynamic pressure grooves are formed on both upper and lower surfaces of the flange 5 will be described. However, the present invention is not limited to this configuration, and both surfaces facing the flange 5 or A thrust direction dynamic pressure groove may be formed on either surface.

  FIG. 2 is an enlarged cross-sectional view showing a fixed state of the sleeve 3 and the cover plate 4 in the spindle motor according to the first embodiment. As shown in FIG. 2, the first annular wall 3 </ b> A is tilted inward so as to press the cover plate 4, and the cover plate 4 is fixed to the sleeve 3. The adhesive 10 is applied to the entire circumference of the joint portion between the sleeve 3 and the cover plate 4 including the recess 15 formed between the first annular wall 3A and the second annular wall 3B, and the sleeve becomes a hardened state. 3 and the cover plate 4 are fixed. The adhesive 10 used in the spindle motor of the first embodiment is an epoxy adhesive that does not swell. In the spindle motor according to the first embodiment, since an epoxy adhesive is used as the adhesive 10, the adhesive 10 does not swell with the lubricant and prevents the lubricant from seeping out from the bonded portion. Has been.

As shown in FIG. 2, the height A from the lower surface P of the sleeve 3 to which the upper surface of the cover plate 4 abuts to the tip of the first annular wall 3A (the lower end in FIG. 2) is shorter than the thickness B of the cover plate 4 ( A <B). The height C from the lower surface P of the sleeve 3 to the tip of the second annular wall 3B (lower end in FIG. 2) is longer than the thickness B of the cover plate 4 (C> B). Therefore, the tip of the first annular wall 3A does not protrude from the lower surface of the cover plate 4 pressed by the first annular wall 3A. Further, since the second annular wall 3B is formed longer than the thickness B of the cover plate 4, the applied adhesive 10 is formed on the inner side of the second annular wall 3B and the circumferential portion of the cover plate 4 The adhesive is prevented from protruding from the lower surface of the spindle motor.
The outer peripheral surface of the second annular wall 3B is formed so as to be inclined inward. That is, the tip of the second annular wall 3B is formed so as to be inclined inward. This is because the outer peripheral surface of the second annular wall 3 </ b> B protrudes in the lateral direction due to the expansion of the adhesive 10, and unnecessary stress is not generated between the cylindrical wall 11 </ b> A of the motor base 11.

Next, a method of fixing the cover plate 4 in the spindle motor according to the first embodiment configured as described above will be described with reference to FIG. FIG. 3 is a process diagram showing a method of fixing the cover plate 4 in the spindle motor according to the first embodiment.
FIG. 3A shows a first step in the fixing step of the cover plate 4. In the previous stage of the first step, the sleeve 3 is press-fitted and fixed to the cylindrical wall 11 </ b> A of the motor base 11. Further, the shaft 1 to which the flange 5 is fixed is inserted into the shaft hole 14 of the sleeve 3. In this state, the cover plate 4 is disposed at a predetermined position, and the tip is formed at an acute angle by two planes in the recess 15 formed between the first annular wall 3A and the second annular wall 3B in the sleeve 3. The fixing jig 20 having the formed shape is inserted, and the first annular wall 3 </ b> A is tilted toward the cover plate 4.

  FIG. 3B shows a state in which the first annular wall 3A is tilted toward the cover plate 4 by the fixing jig 20, and the cover plate 4 is fixed by the first annular wall 3A. In this state, as shown in FIG. 3C, the epoxy adhesive is applied from the nozzle 30 of the adhesive injector over the entire circumference of the joint portion between the sleeve 3 including the concave portion 15 of the sleeve 3 and the cover plate 4. The After the application, it is placed for 1 hour at a temperature between 90 ° C. and 100 ° C. and dried to cure the applied epoxy adhesive. The cured adhesive 10 completely seals the joint portion between the sleeve 3 and the cover plate 4.

  In the spindle motor according to the first embodiment manufactured as described above, when the sleeve 3 is press-fitted and fixed to the motor base 11, the cover plate 4 is not fixed to the sleeve 3, and this occurs at this time. Stress is not applied to the cover plate 4. Further, in the hydrodynamic bearing device according to the first embodiment, since it is not a manufacturing method in which the cover plate 4 is press-fitted and fixed to the sleeve 3, stress during press-fitting is not applied to the cover plate 4. Furthermore, since the joint portion between the sleeve 3 and the cover plate 4 is completely sealed with an epoxy-based adhesive, the lubricant does not ooze out from the adhesive 10 and has a long life and high reliability as a bearing device. Become a product.

As described above, the hydrodynamic bearing device according to the present invention is epoxy-based around the entire circumference of the joint portion between the sleeve 3 and the cover plate 4 as will be apparent from the description of the preferred example in the embodiment. Since the adhesive 10 is applied and the joint portion between the sleeve 3 and the cover plate 4 is completely sealed, the lubricating oil does not leak, the device has a long life, and each component of the bearing portion is Since it can be incorporated with high precision, it becomes a highly reliable hydrodynamic bearing device that does not generate noise or vibration.
In the hydrodynamic bearing device according to the present invention, the fixing jig 20 is inserted into the recess 15 formed between the first annular wall 3A and the second annular wall 3B to press the first annular wall 3A. As a result, the sleeve 3 and the cover plate 4 can be easily joined to each other, so that it is possible to manufacture with high work efficiency and to greatly reduce the manufacturing cost.
Further, the motor which is a spindle motor using the hydrodynamic bearing device according to the present invention uses the hydrodynamic bearing device having the above-described effect as a bearing mechanism, and therefore has a long life and high reliability. .

  Since the present invention can provide a hydrodynamic bearing device having high reliability by a simple manufacturing method, it is highly versatile and useful as a bearing device for small equipment, and the hydrodynamic bearing device of the present invention is used. The motor used is useful as a drive mechanism for small equipment.

It is sectional drawing which shows the spindle motor using the dynamic pressure fluid bearing apparatus of 1st Embodiment which concerns on this invention. It is an expanded sectional view which shows the adhering state of the sleeve 3 and the cover plate 4 in the spindle motor of 1st Embodiment. It is process drawing which shows the adhering method of the cover plate 4 in the spindle motor of 1st Embodiment. It is sectional drawing which shows the spindle motor using the conventional hydrodynamic bearing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft 2 Rotor hub 3 Sleeve 3A 1st annular wall 3B 2nd annular wall 4 Cover plate 5 Flange 6 Magnet 7 Yoke 8 Core 9 Coil 10 Adhesive 11 Motor base 11A Cylindrical wall 12 1st radial direction dynamic pressure groove 13 2nd Radial direction dynamic pressure groove 14 Shaft hole 15 Recess 50 Radial direction dynamic pressure bearing 60 Thrust direction dynamic pressure bearing

Claims (6)

shaft,
An annular first annular wall having a small diameter and an annular second annular wall having a large diameter, which are penetrated by the shaft and are rotatable relative to the shaft. And a sleeve formed on an end face near one end of the shaft,
A flange fixed to one end of the shaft and having a surface perpendicular to the rotation axis of the shaft;
A disc-shaped cover plate disposed opposite to the flange and pressed and fixed to a first annular wall formed on the sleeve;
An epoxy-based adhesive that secures a joint portion between the cover plate and the sleeve and is held in a recess formed by the first annular wall and the second annular wall;
Radial direction dynamic pressure generating means formed on at least one of the opposing surfaces of the shaft and the sleeve;
A thrust direction dynamic pressure generating means formed on at least one surface of the sleeve and the flange facing each other, and a lubricant held in a minute gap between the radial direction dynamic pressure generating means and the thrust direction dynamic pressure generating means,
A hydrodynamic bearing device comprising:   The movement according to claim 1, wherein the height of the first annular wall is smaller than the thickness of the cover plate, and the height of the second annular wall is larger than the thickness of the cover plate. Hydrodynamic bearing device. shaft,
An annular first annular wall having a small diameter and an annular second annular wall having a large diameter, which are penetrated by the shaft and are rotatable relative to the shaft. And a sleeve formed on an end face near one end of the shaft,
A flange fixed to one end of the shaft and having a surface perpendicular to the rotation axis of the shaft;
A disc-shaped cover plate disposed opposite to the flange and pressed and fixed to a first annular wall formed on the sleeve;
An epoxy-based adhesive that secures a joint portion between the cover plate and the sleeve and is held in a recess formed by the first annular wall and the second annular wall;
Radial direction dynamic pressure generating means formed on at least one of the opposing surfaces of the shaft and the sleeve;
Thrust direction dynamic pressure generating means formed on at least one of the facing surfaces of the sleeve and the flange;
A lubricant held in a minute gap between the radial direction dynamic pressure generating means and the thrust direction dynamic pressure generating means;
A motor rotor portion substantially fixed to the shaft; and a motor stator portion disposed at a position facing the motor rotor portion and substantially fixed to the sleeve;
The motor characterized by comprising.   The motor according to claim 3, wherein the height of the first annular wall is smaller than the thickness of the cover plate, and the height of the second annular wall is larger than the thickness of the cover plate. . Forming an annular first annular wall having a small diameter and an annular second annular wall having a large diameter on the end surface of the sleeve in the vicinity of one end of the shaft, with the rotational axis of the shaft as a substantial central axis;
Forming a radial dynamic pressure generating portion on at least one of the opposing surfaces of the shaft and the sleeve;
Forming a thrust direction dynamic pressure generating portion on at least one surface of the flange and the sleeve facing each other;
Fixing the flange to one end of the shaft;
Inserting the shaft into the sleeve;
A cover plate is disposed to face the flange, a fixing jig is inserted into a recess between the first annular wall and the second annular wall formed in the sleeve, and the first annular wall is placed on the cover plate. And a step of applying an epoxy-based adhesive to the entire circumference of the joint portion between the sleeve and the cover plate including the inside of the recess,
The manufacturing method of the hydrodynamic bearing apparatus which has this.   The movement according to claim 5, wherein the height of the first annular wall is smaller than the thickness of the cover plate, and the height of the second annular wall is larger than the thickness of the cover plate. A method for manufacturing a hydrodynamic bearing device.

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