JP2020139608A - Hydrodynamic pressure bearing device and motor including the same - Google Patents

Abstract

To provide a hydrodynamic pressure bearing device that can secure an adhesive strength to a housing without changing density of a sintered metal, and to provide a motor including the same.SOLUTION: A hydrodynamic pressure bearing device includes a bearing sleeve made of a porous sintered material into which volatile liquid can be impregnated. The bearing sleeve is fixed to an inner peripheral surface of a housing while being impregnated with the liquid via an adhesive agent formed in a radial clearance between an outer peripheral surface of the bearing sleeve and the inner peripheral surface of the housing.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fluid dynamic bearing device and a motor including the same.

The fluid dynamic bearing device has features such as high speed rotation, high rotation accuracy, and low noise. Therefore, the hydrodynamic bearing device can be used for various motors mounted on various electric devices, for example, for spindle motors incorporated in disk drive devices such as HDDs, fan motors incorporated in PCs, or laser beam printers. It is suitably used as a bearing device for a built-in polygon scanner motor.

For example, in Patent Documents 1 to 3 below, a housing, a bearing sleeve made of a porous sintered material (sintered metal) fixed to the inner circumference of the housing, and a fluid formed on the inner peripheral surface of the bearing sleeve. The radial bearing gap (for example, lubricating oil) and the shaft (shaft member inserted into the inner circumference of the bearing sleeve) to be supported by the dynamic pressure generated in the fluid in the radial bearing gap can be rotated relative to each other in the radial direction. Various forms of hydrodynamic bearing devices are disclosed that include a radial bearing portion that non-contactly supports the bearing.

Japanese Unexamined Patent Publication No. 2004-116667 JP-A-2010-96202 JP-A-2010-255777

By the way, the usage environment of hard disk drives and fan motors is becoming more severe, and there is a high demand for vibration characteristics. In a fluid bearing of the type in which the outer peripheral surface of a sintered bearing (bearing sleeve) and the inner peripheral surface of the housing are adhered and fixed, low adhesive strength causes vibration, so the adhesive strength between the sintered bearing and the housing is an important parameter. It becomes. Since there are innumerable pores on the surface of the sintered metal, the adhesive is sucked into the pores during bonding, which causes a decrease in adhesive strength. Further, when the adhesive is sucked into the pores, a space where air is trapped is generated inside the bearing, which causes poor lubrication during assembly, leakage of lubricating oil, and deterioration of rotation accuracy.

Therefore, it is possible to propose a method of reducing the amount of pores by increasing the density of the sintered metal and preventing the suction of the adhesive. However, if the density is too high, the strength of the sintered metal becomes high, which causes a decrease in workability and an increase in cost due to an increase in material cost.

Therefore, in view of the above problems, the present invention provides a fluid dynamic bearing device capable of ensuring adhesive strength with a housing without changing the density of the sintered metal, and a motor provided with the hydrodynamic bearing device. is there.

In the fluid dynamic bearing device of the present invention, a bearing sleeve, a shaft member forming a bearing gap between the bearing sleeves, a housing for accommodating the bearing sleeve, and a dynamic pressure action of fluid generated in the bearing gap. In a fluid dynamic bearing device that non-contactly supports the shaft member and the bearing sleeve so as to be relatively rotatable in the radial direction, the bearing sleeve is made of a porous sintered material capable of impregnating a volatile liquid, and the liquid is used. Is impregnated with the bearing sleeve and fixed to the inner circumference of the housing via an adhesive layer formed in a radial gap between the outer peripheral surface of the bearing sleeve and the inner peripheral surface of the housing.

According to the fluid dynamic bearing device of the present invention, the adhesive is applied to the outer peripheral surface of the sintered metal or the inner peripheral surface of the housing in a state where the inside of the sintered metal is impregnated with the liquid. In this way, if the inside of the sintered metal is impregnated with a liquid in advance, the pores are filled with the liquid, so that the liquid becomes a lid and the adhesive is less likely to be sucked into the inside of the pores.

It is preferable that the liquid is a hydrocarbon-based cleaning liquid. Here, the hydrocarbon-based cleaning liquid is a compound consisting only of carbon and hydrogen. Hydrocarbon-based cleaning agents are classified into four types according to their chemical structure: normal paraffin-based, isoparaffin-based, naphthenic-based, and aromatic-based. Its features include low corrosiveness to metals, recyclability by distillation regeneration, relatively low cost and economy, and high degreasing power.

When the sintered metal is manufactured, it is cleaned and dried, and a hydrocarbon-based cleaning solution can be used as the cleaning solution for this cleaning, and this hydrocarbon-based cleaning solution is added to the liquid to be impregnated in advance in the sintered metal. If used, the drying step after cleaning the sintered metal can be simplified. That is, if only the cleaning liquid on the surface layer is dried at a level that does not cause a problem during transportation, the drying temperature can be lowered and the drying time can be shortened.

Lubricating oil is impregnated inside the bearing (including the inside of the sintered metal) after the assembly of the bearing is completed. ..

The motor of the present invention has the fluid dynamic bearing device, a rotor magnet, and a stay coil.

In the present invention, since the adhesive is not sucked into the pores of the sintered metal (bearing sleeve), the gap between the outer peripheral surface of the bearing sleeve and the inner peripheral surface of the housing is filled with the adhesive and adheres uniformly over the entire surface. It is fixed and sufficient adhesive strength can be secured. In addition, since there is no gap that traps air, there is no need to worry about leakage of lubricating oil or deterioration of rotation accuracy due to air mixing inside the bearing.

It is a vertical sectional view of the motor (spindle motor) which concerns on this invention. It is sectional drawing of the fluid dynamic bearing apparatus which concerns on this invention. It is a vertical sectional view of a bearing sleeve. It is a bottom view of the bearing sleeve. It is an enlarged sectional view of the main part of a bearing sleeve.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 shows a configuration example of a spindle motor for information equipment incorporating the fluid dynamic bearing device 1 according to the present embodiment. This spindle motor is used for a disk drive device such as an HDD, and includes a fluid dynamic bearing device 1 that rotatably and non-contactly supports the shaft member 2, a disc hub 3 mounted on the shaft member 2, and, for example, a radius. It includes a stator coil 4 and a rotor magnet 5 that are opposed to each other via a directional gap. The stator coil 4 is attached to the casing 6, and the rotor magnet 5 is attached to the disk hub 3. The outer peripheral surface of the housing 7 of the fluid dynamic bearing device 1 is mounted on the inner circumference of the casing 6. A predetermined number of disks D such as magnetic disks are held in the disk hub 3. When the stator coil 4 is energized, the rotor 5 is rotated by an electromagnetic force acting between the stator coil 4 and the rotor magnet 5, whereby the disc hub 3 and the shaft member 2 are integrally rotated.

As shown in FIG. 2, the hydrodynamic bearing device 1 is provided in the shaft member 2, the housing 7, the bearing sleeve 8 held on the inner circumference of the housing 7, and the opening at one end in the axial direction of the housing 7. It has a sealing portion 9 and a lid portion 10 that closes the other end of the housing 7 in the axial direction. In the following description, for convenience, the closed side of the housing 7 is referred to as the lower side and the opening side of the housing 7 is referred to as the upper side in the axial direction, but this does not mean that the usage mode of the fluid dynamic bearing device 1 is limited.

The shaft member 2 includes a shaft portion 2a and a flange portion 2b provided at the lower end of the shaft portion 2a. The shaft member 2 is made of a metal material such as stainless steel, and in the present embodiment, the entire shaft member 2 including the shaft portion 2a and the flange portion 2b is integrally formed. The shaft portion 2a and the flange portion 2b can be formed separately.

On the outer peripheral surface of the shaft portion 2a, an annular recess 2a2 provided between two cylindrical surfaces 2a1 formed at two locations separated in the axial direction and an annular recess 2a2 having a diameter smaller than that of the cylindrical surface 2a1 is provided. Be done. The cylindrical surface 2a1 functions as a bearing facing surface that faces the bearing surface 8a1 of the inner peripheral surface 8a of the bearing sleeve 8 in the radial direction.

The housing 7 is a member that holds the bearing sleeve 8, and is formed in a cylindrical shape such as brass. The outer peripheral surface 8d of the bearing sleeve 8 is fixed to the inner peripheral surface 7a of the housing 7 by adhesion. As the bonding, so-called gap bonding is adopted in which the outer peripheral surface 8d of the bearing sleeve 8 and the inner peripheral surface 7a of the housing 7 are bonded in a gap-fitted state. Gap adhesion is performed by crevice fitting the bearing sleeve 8 on the inner circumference of the housing 7 (see JIS B 0401-1) between the inner peripheral surface 7a of the housing 7 and the outer peripheral surface 8d of the bearing sleeve 8 facing each other. This is a method of forming a radial gap 15 (see FIG. 5) and curing the adhesive 17 interposed in the radial gap 15 to fix both of them. The outer peripheral surface 8d of the bearing sleeve 8 and the inside of the housing 7 are fixed. This is performed by injecting the adhesive 17 into the gap between both sides with the peripheral surface 7a fitted in the gap and pulling it into the gap by the capillary force. In addition, an adhesive may be applied to either the outer peripheral surface 8d of the bearing sleeve 8 or the inner peripheral surface 7a of the housing 7, and then the two may be fitted by gap fitting. As the adhesive 17, anaerobic adhesives that cure by blocking from air, heat-curable adhesives such as epoxy-based adhesives, and ultraviolet-curable adhesives that cure by irradiation with ultraviolet rays are known. .. In this embodiment, a known adhesive can be used arbitrarily.

Due to the gap adhesion, an adhesive layer 18 (see FIG. 5) made of the cured adhesive 17 is formed between the outer peripheral surface 8d of the bearing sleeve 8 and the inner peripheral surface 7a of the housing 7. The adhesive layer 18 is formed over the entire area of the gap between the outer peripheral surface 8d of the bearing sleeve 8 and the inner peripheral surface 7a of the housing 7, and is also formed in a part of the gap (a part of the axial direction or the circumferential direction). It may be formed only in a part of the region, etc.).

The bearing sleeve 8 is a sintered bearing formed in a cylindrical shape by a porous sintered body. As the sintered body, for example, a sintered metal containing 20% by mass or more of copper is used. As long as it contains 20% by mass or more of copper, other contained elements are arbitrary, and in addition to a copper-based sintered metal containing only copper as a main component, a copper-iron-based sintered metal containing copper and iron as main components, or It is also possible to use a stainless-based sintered metal or the like whose main components are copper and stainless steel.

As shown in FIG. 3, radial bearing surfaces 8a1 are formed on the inner peripheral surface 8a of the bearing sleeve 8 at two positions separated in the axial direction. Dynamic pressure generating grooves G1 and G2 arranged in a herringbone shape are provided on each radial bearing surface 8a1 as dynamic pressure generating portions. The area indicated by cross-hatching in the figure indicates a hill portion that rises toward the inner diameter side (the same applies to FIG. 4). The upper dynamic pressure generating groove G1 has an axially asymmetrical shape, and the lower dynamic pressure generating groove G2 has an axially symmetrical shape. The axially asymmetrical shape of the upper dynamic pressure generating groove G1 pushes the lubricating fluid in the radial bearing gap downward in the axial direction, and the lubricating fluid is forcibly circulated inside the housing 7 (described later). A cylindrical surface 8a2 is provided in the axial region of the radial bearing surface 8a1. The cylindrical surface 8a2 is continuously provided on the same cylindrical surface as the bottom surfaces of the dynamic pressure generating grooves G1 and G2.

Both the upper and lower dynamic pressure generating grooves G1 and G2 may have an axially symmetrical shape. Further, the upper and lower dynamic pressure generating grooves G1 and G2 may be made continuous in the axial direction, or one or both of the upper and lower dynamic pressure generating grooves G1 and G2 may be omitted. Further, the inner peripheral surface 8a of the bearing sleeve 8 may be a cylindrical surface, and a dynamic pressure generating portion may be provided on the outer peripheral surface (bearing facing surface) of the shaft portion 2a. It is also possible to use a so-called perfect circular bearing in which both the bearing surface 8a1 of the bearing sleeve 8 and the bearing facing surface of the shaft portion 2a are cylindrical surfaces.

A thrust bearing surface is formed on the lower end surface 8b of the bearing sleeve 8. A pump-in type spiral-shaped dynamic pressure generating groove 8b1 as shown in FIG. 4 is formed on the thrust bearing surface as a dynamic pressure generating portion. As the shape of the dynamic pressure generating groove, a herringbone shape, a radial groove shape, or the like may be adopted. Further, the lower end surface 8b of the bearing sleeve 8 may be used as a flat surface, and a dynamic pressure generating groove may be formed in the upper end surface 2b1 of the flange portion 2b of the shaft member 2.

The seal portion 9 projects from the upper end of the housing 7 toward the inner diameter side. In the present embodiment, the seal portion 9 is formed integrally with the housing 7, but the seal portion 9 can be separated from the housing 7. The inner peripheral surface 9a of the seal portion 9 has a tapered shape whose diameter is gradually reduced downward. A seal space S whose radial width is gradually narrowed downward is formed between the inner peripheral surface 9a of the seal portion 9 and the outer peripheral surface of the shaft portion 2a. In addition, while the inner peripheral surface of the seal portion 9 is a cylindrical surface, a tapered surface whose diameter is gradually reduced upward is provided on the outer peripheral surface of the shaft portion 2a, and a seal space S may be formed between them. Good. The upper end surface 8c of the bearing sleeve 8 is in contact with the lower end surface 9b of the seal portion 9.

The lid portion 10 is formed of a metal or resin such as brass, and is fixed to the lower end portion of the inner peripheral surface 7a of the housing 7 by an appropriate means such as press fitting or adhesion. As a result, the space inside the housing 7 becomes a closed space open to the atmosphere only in the seal space S. The lid portion 10 can also be formed integrally with the housing 7.

A thrust bearing surface is formed on the end surface 10a of the lid portion 10. For example, a pump-in type spiral-shaped dynamic pressure generating groove is formed on the thrust bearing surface (not shown). As the shape of the dynamic pressure generating groove, a herringbone shape, a radial groove shape, or the like may be adopted. Further, the end surface 10a of the lid portion 10 may be used as a flat surface, and a dynamic pressure generating groove may be formed in the lower end surface 2b2 of the flange portion 2b of the shaft member 2.

Inside the housing 7, an axial oil passage 11 extending in the axial direction and a radial oil passage 12 extending in the radial direction are formed. In the embodiment shown in FIG. 2, the axial oil passage 11 is formed between the outer peripheral surface of the bearing sleeve 8 and the inner peripheral surface 7a of the housing 7, and the radial oil passage 12 is above the bearing sleeve 8. It is formed between the end surface 8c and the lower end surface 9b of the seal portion 9. The lower end of the axial oil passage 11 opens in a space below the lower end surface 8b of the bearing sleeve 8, and the upper end communicates with the outer diameter end of the radial oil passage 12. The inner diameter end of the radial oil passage 12 opens in the seal space S.

In the embodiment of FIG. 2, an axial groove 8d1 extending in the axial direction is provided on the outer peripheral surface 8d of the bearing sleeve 8, and the bearing sleeve 8 is provided by a gap defined by the axial groove 8d1 and the inner peripheral surface 7a of the housing 7. An axial oil passage 11 is formed along the outer peripheral surface 8d of the above. The upper end surface 8c of the bearing sleeve 8 is provided with an annular groove 8c1 and a plurality of radial grooves 8c2 located on the inner diameter side of the annular groove 8c1, the annular groove 8c1 and the radial groove 8c2, and the lower side of the seal portion 9. A radial oil passage 12 along the upper end surface 8c of the bearing sleeve 8 is formed by the gap formed by the end surface 9a. Further, the outer diameter side region of the lower end surface of the seal portion 9 is located at a position separated from the upper end surface 8c of the bearing sleeve 8, and is formed between this outer diameter side region and the upper end surface 8c of the bearing sleeve 8. The upper end of the axial oil passage 11 and the outer diameter end of the radial oil passage 12 are opened in the annular gap 13, respectively. The annular gap 13 constitutes a part of the axial oil passage 11 or the radial oil passage 12. From this configuration, the space below the lower end surface 8b of the bearing sleeve 8 is in a state of communicating with the seal space S and the radial bearing gap via the axial oil passage 11 and the radial oil passage 12. ..

The axial oil passage 11 and the radial oil passage 12 may adopt any form as long as the space below the lower end surface 8b of the bearing sleeve 8 and the seal space S are communicated with each other. However, it is not limited to the form shown in FIGS. 2 and 3. For example, the axial groove 8d1 may be formed on the inner peripheral surface 7a of the housing 7. Further, the annular groove 8c1 and the radial groove 8c2 may be formed on the lower end surface 9a of the seal portion 9.

Lubricating oil as a lubricating fluid is supplied to the inside of the hydrodynamic bearing device 1 by means such as vacuum impregnation, and all the spaces inside the housing 7, for example, the inner peripheral surface 8a and the shaft portion 2a of the bearing sleeve 8. A gap between the outer peripheral surface, a gap between the lower end surface 8b of the bearing sleeve 8 and the upper end surface 2b1 of the flange portion 2b, and a gap between the lower end surface 2b2 of the flange portion 2b and the end surface 10a of the lid portion 10. , The axial oil passage 11, and the radial oil passage 12 are all filled with lubricating oil including the internal pores of the bearing sleeve 8. At this time, the oil level is formed in the seal space S.

When the shaft member 2 rotates, a radial bearing gap is formed between the radial bearing surface 8a1 on the inner peripheral surface 8a of the bearing sleeve 8 and the cylindrical surface 2a1 on the shaft portion 2a. Then, the pressure of the oil film formed in the radial bearing gap is increased by the dynamic pressure generating grooves G1 and G2, whereby the first radial bearing portion R1 and the second radial bearing portion R2 that non-contactly support the shaft member 2 in the radial direction. Is configured. At the same time, between the lower end surface 8b (thrust bearing surface) of the bearing sleeve 8 and the upper end surface 2b1 of the flange portion 2b, and the end surface 10a (thrust bearing surface) of the lid portion 10 and the lower end surface of the flange portion 2b. Thrust bearing gaps are formed between the two and 2b2. Then, the pressure of the oil film formed in each thrust bearing gap is increased by the dynamic pressure generating groove 8b1 on the lower end surface 8b of the bearing sleeve 8 and the dynamic pressure generating groove on the end surface 10a of the lid portion 10, whereby the shaft member is formed. A first thrust bearing portion T1 and a second thrust bearing portion T2 that support non-contact in both thrust directions are configured.

Further, during the rotation of the shaft member 2, due to the asymmetry of the dynamic pressure generating grooves G1 and G2 of the first radial bearing portion R1 and the second radial bearing portion R2, the inner peripheral surface 8a of the bearing sleeve 8 and the like. A flow in a certain direction (for example, downward) occurs in the lubricating oil that fills the gap between the shaft portion 2a and the outer peripheral surface. Therefore, the lubricating oil flowing out from the radial bearing gap of the second radial bearing portion R2 reaches the seal space S through the thrust bearing gap, the axial oil passage 11, and the radial oil passage 12, and further reaches the seal space S, and further, the first radial bearing. It returns to the radial bearing gap of the second radial bearing portion through the radial bearing gap of the portion R1.

The bearing sleeve 8 forms a green compact by compression-molding a raw material powder containing a metal powder in a metal, and a sintered body is formed by sintering the green compact under predetermined conditions. After sizing (recompressing), cleaning, etc., the body is impregnated with a lubricant (lubricating oil). That is, the inside of the bearing is impregnated with lubricating oil. Normally, when the fluid dynamic bearing device in which the inside of the bearing is sealed is impregnated with the lubricating oil, the inside of the bearing is depressurized once and the inside of the bearing is lubricated by the pressure difference. Is impregnated.

By the way, in this fluid dynamic bearing device, the bearing sleeve 8 is impregnated with a volatile liquid in the assembled state before the lubricant (lubricating oil) is impregnated. The volatilizing liquid is preferably a hydrocarbon-based cleaning liquid. Here, the hydrocarbon-based cleaning liquid is a compound consisting only of carbon and hydrogen. Hydrocarbon-based cleaning agents are classified into four types according to their chemical structure: normal paraffin-based, isoparaffin-based, naphthenic-based, and aromatic-based. Its features include low corrosiveness to metals, recyclability by distillation regeneration, relatively low cost and economy, and high degreasing power.

Therefore, when the pressure is reduced, the pre-impregnated liquid (here, the hydrocarbon cleaning liquid) volatilizes, so that the pre-impregnated liquid does not remain inside the sintered metal during oiling. As an example of the above decompression conditions, the temperature can be set to 60 ° C. or higher, the decompression level is 13 Pa or less, and the decompression holding time is 10 min or more.

Further, as the cleaning liquid used in the cleaning step, a hydrocarbon-based cleaning liquid which is a liquid impregnated in advance can be used. If this hydrocarbon-based cleaning liquid is used as the liquid to be impregnated in the sintered metal in advance, the drying step after cleaning the sintered metal can be simplified. That is, if only the cleaning liquid on the surface layer is dried at a level that does not cause a problem during transportation, the drying temperature can be lowered and the drying time can be shortened.

In the hydrodynamic bearing device of the present invention, the adhesive 17 is applied to the outer peripheral surface 8d of the bearing sleeve 8 or the inner peripheral surface 7a of the housing 7 in a state where the inside of the sintered metal (bearing sleeve 8) is impregnated with liquid. .. If the inside of the sintered metal is impregnated with a liquid in advance, the pores are filled with the liquid, so that the liquid serves as a lid and the adhesive 17 is less likely to be sucked into the inside of the pores. Lubricating oil is impregnated inside the bearing (including the inside of the sintered metal) after the assembly of the bearing is completed. However, if the above-mentioned pre-impregnated liquid can be removed before oiling, the lubricating oil can be appropriately lubricated. ..

Therefore, since the adhesive 17 is not sucked into the pores of the sintered metal (bearing sleeve 8), the gap between the outer peripheral surface 8d of the bearing sleeve 8 and the inner peripheral surface 7a of the housing 7 is filled with the adhesive, and the entire surface is filled with the adhesive. It is uniformly adhered and fixed over the bearing, and sufficient adhesive strength can be ensured. In addition, since there is no gap that traps air, there is no need to worry about leakage of lubricating oil or deterioration of rotation accuracy due to air mixing inside the bearing.

Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and various modifications can be made, and the volatile liquid and the depressurizing condition before oiling are those of the embodiment. It is not limited to this, and it is sufficient that no residue remains on the bearing sleeve when the lubricating oil is impregnated inside the bearing. Further, in the above-described embodiment, the liquid to be impregnated in advance is exhibited in the decompression step before oiling, but a decompression step (step of volatilizing the liquid) may be added individually after adhesion fixing.

Further, the bearing sleeve 8 can also be applied when a material formed of a non-porous material such as a soft metal such as brass or a resin material is used.

Further, the present invention includes not only a fluid dynamic bearing device in which the shaft member 2 is on the rotating side and the bearing sleeve 8 is on the stationary side, but also a fluid dynamic bearing device in which the shaft member 2 is on the stationary side and the bearing sleeve 8 is on the rotating side. It can also be preferably applied to.

The present invention can also be preferably applied to a rotor having blades for blowing air or a fluid dynamic bearing device in which a polygon mirror is provided on the shaft member 2. That is, the present invention is a fluid incorporated not only in the spindle motor for the disk drive shown in FIG. 1, but also in other electric device motors such as a fan motor for a PC and a polygon scanner motor for a laser beam printer (LBP). It can also be preferably applied to a hydraulic bearing device.

In order to demonstrate the usefulness of the present invention, the confirmation test described below was carried out. That is, the difference in adhesive strength depending on the presence or absence of liquid impregnation inside the sintered metal (bearing sleeve 8) was confirmed. The evaluation conditions are as follows.
(A) The sintered metal material was copper iron, the housing material was brass, and the outer diameter of the sintered metal and the inner diameter of the housing were gap-bonded.
(B) Before bonding, the inside of the sintered metal was impregnated with a hydrocarbon cleaning solution (NS Clean 100: trade name of JX Nippon Oil & Energy Co., Ltd.).
(C) A thermosetting epoxy adhesive was used as the adhesive, and the coating amount was adjusted so as to have the same volume as the adhesive gap.
(D) After applying the adhesive, the material was fired at 120 ° C. for 1 hour, and the extraction force of the outer diameter of the sintered metal and the inner diameter of the housing was measured.

The measurement results are shown in Table 1. An axial load was applied to the bearing sleeve 8, and the evaluation was made based on the axial load (pulling force) when the adhesive layer 18 was broken (the bearing sleeve fell off from the housing). As a confirmation test, sample products of No, 1 to No, 15 were used. In this case, the sample products of No, 1 to No, 15 are completely dry (absolutely dry state and the bearing sleeve 8 is not impregnated with liquid) and NS Clean 100 impregnated with 2 The type was used. In Table 1, MAX shows the maximum extraction force of the absolutely dried product and the maximum extraction force of the product impregnated with NS Clean 100, and MIN is impregnated with the minimum extraction force of the absolutely dried product and NS Clean 100. The minimum withdrawal force of the thing is shown, and the average withdrawal power of the one impregnated with NS Clean 100 and the average withdrawal power of the one impregnated with NS Clean 100 are shown in Avg.

As a result of the measurement, the one impregnated with NS Clean 100 had a higher withdrawal force of about 2700 N on average than the one impregnated with absolute dryness. That is, in the case of the one impregnated with NS Clean 100, "the gap between the outer peripheral surface of the bearing sleeve and the inner peripheral surface of the housing is filled with an adhesive, and the entire surface is uniformly adhered and fixed to ensure sufficient adhesive strength. I can say. "

2 Shaft member 4 Stator coil 5 Rotor magnet 7 Housing 7a Inner peripheral surface 8 Bearing sleeve 8a Inner peripheral surface 15 Radial gap 18 Adhesive layer

Claims (4)

The shaft member forming a bearing gap between the bearing sleeve and the bearing sleeve, the housing for accommodating the bearing sleeve, and the dynamic pressure action of the fluid generated in the bearing gap causes the shaft member and the bearing sleeve to move in the radial direction. In a hydrodynamic bearing device that supports non-contact with relative rotation.
The bearing sleeve is made of a porous sintered material that can be impregnated with a volatile liquid, and in a state of being impregnated with this liquid, the radial direction between the outer peripheral surface of the bearing sleeve and the inner peripheral surface of the housing. A fluid dynamic bearing device characterized in that it is fixed to the inner circumference of the housing via an adhesive layer formed in a gap. The fluid dynamic bearing device according to claim 1, wherein the liquid is a hydrocarbon-based cleaning liquid. The fluid dynamic bearing device according to claim 1 or 2, wherein the liquid is drained from the bearing sleeve in a state where the lubricating oil is impregnated inside the motor. A motor comprising the fluid dynamic bearing device according to any one of claims 1 to 3, a rotor magnet, and a stay coil.

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