JP3652817B2 - Spindle motor and assembly method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spindle motor that drives a disk of a disk drive device such as a hard disk, and more particularly to a spindle motor that substantially completely prevents oil leakage from the inside of the motor.
[0002]
[Prior art]
A spindle motor for driving a disk of a disk drive device is well known to those skilled in the art, for example, as a hard disk drive device as shown in FIG. In FIG. 6 showing a sectional view of the spindle motor, the spindle motor 1 has a hub 2 supported by a rotor yoke 3 as a rotor for holding and driving a hard disk (not shown). The hub 2 and the yoke 3 are rotatably arranged by a pair of ball bearings 5 and 6 with respect to a fixed shaft 4. That is, the upper ball bearing 5 directly holds the upper portion of the rotor yoke 3, while the lower ball bearing 6 holds the lower portion of the rotor yoke 3 via the bush 7. A stator 8 is disposed between the pair of ball bearings 5 and 6, and the stator 8 is fixed to the shaft 4. Further, a rotor magnet 9 is fixed to the inner surface of the yoke 3 facing the stator 8. Thus, the hub 2 holding the hard disk is rotationally driven together with the yoke 3 and the bush 7 by the rotor magnet 9 that is excited and activated by the stator 8. A magnetic fluid seal is disposed on the upper part of the upper ball bearing 5, and a cap is fixed to the hub 2 with an adhesive on the outer periphery thereof.
[0003]
[Problems to be solved by the invention]
However, in such a known spindle motor 1, oil mist generated from the inside of the ball bearings 5, 6 at the time of rotational operation causes the space 10 inside the spindle motor 1, especially the yoke 3 or the shaft 4 of the rotor magnet 9. When the oil mist collected in the dew condensation state reaches a certain amount, a part of the oil mist enters the fitting surface 11 formed between the yoke 3 and the bush 7. The other part of the oil mist that passes through the gap portion of the fitting surface 11 and oozes out to the outside of the motor 1 as indicated by an arrow 12 and accumulates in the dew condensation state is the yoke 3 and the upper ball bearing. 5 entered into the fitting surface 13 formed between the outer ring 5 and the gap portion of the fitting surface 13 so as to exude to the outside of the motor 1 and ooze out from these fitting surfaces. Other oil There is a problem that contaminate the original.
[0004]
Usually, since the yoke 3 and the bush 7 or the yoke 3 and the bearing 5 are fixed by an adhesive, no gaps should be formed between the fitting surfaces 11 and 13. It is impossible to completely seal the fitting surfaces 11 and 13 by allowing the adhesive to penetrate the fitting surfaces 11 and 13 without any gaps due to uneven application of the adhesive or the degree of roughness of the member surface. Yes, this is a problem.
[0005]
As a spindle motor provided with means for preventing oil leakage caused by such a cause, there is a spindle motor 15 as shown in FIG. 7 (Japanese Utility Model Laid-Open No. 2-101365). The spindle motor 15 is configured such that adhesives 18 and 19 are applied from the outside of the motor to the lower periphery or upper periphery of the fitting surfaces 16 and 17 from which oil oozes out. However, with such means, the adhesives 18 and 19 must be applied again after the spindle motor is assembled, and there is a problem that the working efficiency is remarkably poor. Furthermore, in the case where the adhesives 18 and 19 are applied to the fitting surfaces 16 and 17 after the spindle motor is assembled in this manner, the applied adhesives 18 and 19 and the end openings of the fitting surfaces 16 and 17 are applied. There was a problem that air bubbles were easily formed between them and complete sealing could not be performed.
[0006]
[Means for Solving the Problems]
In order to solve such a problem, in the spindle motor of the present invention, a rotor for holding and rotating the disk, a rotor magnet that rotates together with the rotor, and an upper bearing in which an outer ring is fitted to the rotor, A rotor assembly, a shaft, a lower bearing in which an inner ring is fitted to the shaft, a stator fitted to the shaft on the upper side of the lower bearing, and an outer ring of the lower bearing A bush assembly fitted to the shaft, and an inner ring of the upper bearing is fitted to the shaft, and the bush is fitted to the rotor. In the spindle motor formed by coupling the shaft assembly, at least the upper outer peripheral edge portion of the bush has a chamfered portion, the rotor of the rotor assembly, the bush of the shaft assembly, When fixed by adhesive, it is formed on the outer peripheral surface of the bush and the volume of the bush fitting gap formed between the inner peripheral surface of the rotor, and its chamfered portion and the inner peripheral surface of the rotor An amount of adhesive that is approximately the total volume of the annular chamfered recess is applied to either the outer peripheral surface of the bush or the inner peripheral surface of the rotor before the rotor assembly and the shaft assembly are coupled. The applied adhesive is rubbed when the rotor assembly and the shaft assembly are joined, so that at least a part of the adhesive is chamfered between the bush and the inner peripheral surface of the rotor. It accumulates in the annular chamfering recess to be formed, and completely seals the motor internal space side of the fitting surface between the bush and the rotor assembly. Further, in the spindle motor assembling method of the present invention, the process of forming the rotor assembly and the shaft assembly, respectively, and a necessary amount of adhesive to be applied to the mating surface between the bush and the rotor at the time of coupling. More (that is, the volume of the bush fitting gap formed between the outer peripheral surface of the bush and the inner peripheral surface of the rotor, and the annular surface formed by the chamfered portion and the inner peripheral surface of the rotor And the step of applying to the volume of the recesses approximately in total) .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an assembled cross-sectional view of a motor similar to FIG. 6, showing an example of a spindle motor 20 according to the present invention. The spindle motor 20 generally has the same configuration as the known spindle motor 1 shown in FIG. That is, it has an outer protrusion 21 for holding and rotating a hard disk (not shown) at its lower end and prevents oil mist from flowing out of the spindle motor or dust from flowing into the spindle motor. Therefore, a hub 23 having an inner projecting portion 22 for supporting a seal 33 or a cap 34, which will be described later, is supported by a rotor yoke 24 on the inner surface thereof. A rotor to be configured is rotatably arranged by a pair of ball bearings 26 and 27 with respect to a fixed shaft 25.
[0008]
That is, the upper ball bearing 26 directly holds the upper portion of the rotor yoke 24, while the lower ball bearing 27 holds the lower portion of the rotor yoke 24 via the bush 28. Between the bush 28 and the inward projecting portion 22 of the hub 23, a motor internal space 29 is formed, which is an area that cannot be approached after the motor is assembled. Further, a space 30 is formed between the pair of ball bearings 26 and 27 in the internal space 29, and a stator 31 is disposed in the space 30. The stator 31 is fixed to the shaft 25. Further, a rotor magnet 32 is fixed to the inner surface of the yoke 24 facing the stator 31. In this way, the hub 23 holding a hard disk (not shown) is rotationally driven together with the yoke 24 and the bush 28 by the rotor magnet 32 activated by the stator 31. Further, a magnetic fluid seal 33 is disposed on the upper part of the upper ball bearing 26, and a cap 34 is fixed to the upper part of the ball bearing 26 with the adhesive 35 on the inner projecting part 22 of the hub 23. Yes.
[0009]
Therefore, in the present invention, compared to a known spindle motor fitting surface (for example, portions indicated by reference numerals 11 and 13 in FIG. 6), the fitting surface 36 between the rotor yoke 24 and the rotor bush 28, and the rotor yoke. The configuration of the fitting surface 37 between the outer ring 24 and the outer ring of the upper ball bearing 26 is different.
[0010]
In other words, in the present invention, the chamfered portion 38 is formed on the entire outer periphery of the upper outer peripheral portion of the bush 28 that defines the fitting surface 36 with the rotor yoke 24. Therefore, a chamfered recess 39 having a triangular cross section is formed between the inner peripheral surface of the rotor yoke 24 and the entire upper peripheral edge of the bush 28, and the chamfered recess 39 is filled with the adhesive 40. Therefore, the upper edge portion of the fitting surface 36 facing the motor internal space 29 is completely sealed with the adhesive 40.
[0011]
On the other hand, a chamfered portion 41 is formed on the entire inner periphery of the upper inner peripheral edge of the rotor yoke 24 that defines a fitting surface 37 between the upper ball bearing 26 and the outer ring. For this reason, a chamfered recess 42 having a triangular cross section is formed between the outer peripheral surface of the outer ring of the upper ball bearing 26 and the entire outer periphery of the upper outer peripheral edge of the rotor yoke 24, and the chamfered recess 42 is filled with the adhesive 43. ing. Therefore, the upper edge of the fitting surface 37 in the motor internal space 29 is completely sealed by the adhesive 43.
[0012]
FIG. 2 illustrates the process of assembling the spindle motor 20 according to the present invention. First, the hub 23, the yoke 24, and the rotor magnet 32 are integrally assembled by an adhesive and / or means such as press fitting, shrink fitting, and the upper ball bearing 26 is formed on the inner periphery of the yoke 24 by the adhesive. The rotor assembly 50 is formed by fixing. Subsequently, the lower ball bearing 27 in which the bush 28 is integrally assembled with the outer ring of the lower ball bearing 27 by an adhesive and / or press-fitting, and the stator 31 and the shaft 25 by the adhesive and / or press-fitting are integrally assembled. A shaft assembly 51 is formed.
[0013]
After that, the inner peripheral surface portion of the rotor yoke 24 constituting the rotor assembly 50, at least the entire periphery near the upper outer peripheral edge of the bush 28 where the bushing 28 is finally fitted and seated, and the shaft assembly 51 Adhesives 43 and 40 are applied, for example, to a known end of the free end portion of the shaft 25 constituting at least the entire circumference below the inner ring inner peripheral surface of the upper ball bearing 26 where the inner ring is finally fitted and seated. Granted by Spencer etc. At this time, it is necessary to apply a slightly larger amount of adhesive to the portion of the rotor assembly 50 to which the adhesive is to be applied than the amount necessary to perform the adhesive action on the mating surface. More specifically, the amount of the adhesive 40 applied in advance to the inner peripheral surface of the rotor yoke 24 of the rotor assembly 50 is the sum of the amount required to fill each fitting surface 36 and the volume of the recess 39. It is necessary to. Next, the shaft assembly 51 is moved in the direction indicated by the arrow 52 so that the shaft assembly 51 is fitted into the rotor assembly 50 and assembled. When the fitting is assembled, the adhesives 43 and 40 move to the free end portion of the upper shaft 25, the inner ring of the upper ball bearing 26, and the fitting surfaces 37 a and 36 of the bush 28 and the yoke 24. In particular, the adhesive 40 eventually accumulates in the recess 39. In addition, when the upper ball bearing 26 of the rotor assembly 50 is fixed to the yoke 24 with an adhesive, the rotor assembly 50 applies a somewhat larger amount of adhesive than is necessary in the same manner as described above. The adhesive accumulates.
[0014]
According to the present invention, since the chamfered recesses 39 and 42 are finally formed on the upper portions of the fitting surfaces 36 and 37, the fitting surfaces 36 and 37 are provided with a somewhat larger amount of adhesive in advance. The protruding adhesive is accumulated in the recesses 40 and 42, and the upper portions of the fitting surfaces 36 and 37, which are difficult to apply the adhesive after the assembly is completed, can be completely sealed without a gap. . On the other hand, for example, as shown in FIG. 6, when there is no chamfered recess in the upper part of the mating surface, the adhesive protruding from the mating surface does not accumulate, so it spreads unevenly on the surface of the bush facing the magnet, for example. As a result, it is impossible to provide a function of completely sealing the fitting surface without a gap.
[0015]
As the adhesive used in the state shown in FIG. 2 of the present invention, a naturally curable adhesive that is naturally cured at room temperature or a thermosetting adhesive that is forcibly cured at a high temperature is suitable.
[0016]
In this embodiment, an example in which the rotor assembly 50 is configured by a rotor including a hub 23 and a yoke 24 and a rotary marnet 32 is described. However, the yoke 24 is not an essential element. 7, the rotor is constituted by only the hub 23, the rotor magnet 32 is directly fixed, the upper ball bearing 26 is fitted to the hub 23, and the lower bearing 27 of the shaft assembly 51 is further provided. Similarly, the present invention can also be applied to a spindle motor in which the bush 28 attached to the outer ring is directly fixed to the hub 23.
[0017]
FIG. 3 is a diagram showing the relationship between the bush 60 and the yoke 61 according to another embodiment of the present invention. In this embodiment, the recess 62 provided in the upper outer peripheral edge of the bush 60 has a quadrangular cross section. In this case, the upper sealing characteristic of the fitting surface 63 formed between the bush 60 and the yoke 61 is superior to that of the embodiment of FIG. This is because the amount of the adhesive 64 accumulated on the upper portion of the fitting surface 63 is large, and the volume of the adhesive contacting the upper portion of the fitting surface 63 is large. The gap 65 below the recess 62 is a known adhesion reservoir. As described above, also in this embodiment, the yoke 61 can be replaced by a hub.
[0018]
FIG. 4 is a view showing the relationship between the bush 70 and the yoke 71 according to still another embodiment of the present invention. In this embodiment, the recess 72 provided in the upper outer peripheral edge of the bush 70 has a square cross section as in the embodiment of FIG. The gap 76 is a known adhesion reservoir. Therefore, in this embodiment, the inner surface of the yoke 71 is also formed with a concave portion 73 having a substantially square cross section, and at least a part of these concave portions 72 and 73 are connected to each other. Therefore, the adhesive 74 accumulated in the recesses 72 and 73 is disposed so as to surely cross the fitting surface 75 formed between the bush 70 and the yoke 71. For this reason, sealing of the upper part of the fitting surface 75 can be achieved more reliably. In this embodiment, the yoke 71 can be replaced by a hub. Further, the recess 72 may have a triangular cross section as shown in FIG.
[0019]
FIG. 5 discloses yet another embodiment. In the embodiment shown in FIGS. 1 to 4, in order to prevent oil from leaking from the fitting surface formed between the bush and the yoke, a special shape is given to the upper outer peripheral edge of the bush, This embodiment shown in FIG. 5 discloses that the upper part of the fitting surface where oil leakage is caused by accumulating an adhesive is completely sealed so that oil does not enter the fitting surface. Then, the structure which prevents that oil reaches | attains the fitting surface in which an oil leak arises is provided. In other words, in this embodiment, the fitting surface 82 is arranged on the rotor magnet 83 so that the oil mist generated in the motor internal space 29 does not reach the fitting surface 82 defined between the bush 80 and the yoke 81. Then, the adhesive 85 is filled into the recess 84 formed by the yoke 81 and the bush 80. As a filling method, a rotor assembly and a shaft assembly are formed in advance in substantially the same manner as shown in FIG. 2, and at least at a position as shown in FIG. Apply a similar amount of adhesive as before and assemble both assemblies. By doing so, the adhesive 85 is properly positioned in the recess 84. In this case, recesses 40, 62, 72, 73 as in the embodiment of FIG. 1, FIG. 3, or FIG.
[0020]
Although the embodiment of the present invention has been described in detail above, the embodiment of the present invention is not limited to this, and various modifications can be made. For example, the adhesive applied in the above embodiment may be changed from the rotor assembly side to the opposite side as in the shaft assembly side. As a result, the adhesive is squeezed, and the same effect can be obtained.
[0021]
In the spindle motor of the present invention, a fitting portion between the yoke and the bush that may cause oil mist leakage from the inside of the spindle motor, which is difficult to seal due to application of an adhesive or the like for the convenience of assembly work. It can be easily and reliably sealed simultaneously with the assembly operation. As described above, this method can also be applied to the fitting surface 37 between the outer ring of the upper ball bearing 26 and the yoke 24 shown in FIG.
[0022]
【The invention's effect】
According to the configuration disclosed by the present invention, the following excellent effects can be expected.
According to the first, fourth, fifth, and seventh aspects, it is difficult to apply an adhesive after assembly of the motor, such as a portion located in the motor internal space of the fitting surface defined by the bush and the rotor. It can easily be completely sealed with an adhesive, and the flow of oil mist that may leak from the inside of the motor to the outside through these fitting surfaces can be almost completely prevented. Further, there is no problem that air bubbles are mixed into the adhesive as occurs when the adhesive is applied to the fitting surface after the motor is assembled.
[0023]
In particular, according to claim 2, a recess for accommodating an adhesive is formed in a portion of the fitting surface located in the motor internal space, and when the motor is assembled, Adhesive flows continuously into the recess, and a predetermined amount of adhesive accumulates in the recess, preventing oil from reaching the mating surface. It becomes possible to seal.
[0024]
Further, according to the sixth aspect of the present invention, the same applies to a portion where it is difficult to apply adhesive after assembling the motor at the location where the motor is located in the inner space of the fitting surface defined by the outer ring and the yoke of the upper ball bearing. The effect is obtained.
[0025]
According to the third aspect, the rotor assembly and the shaft assembly can be assembled and at the same time the fitting surfaces of both can be sealed with the adhesive, so that the adhesive is applied to the fitting surface after the motor is assembled. There is no need for a special post-process for the application, and the workability of the motor is good.
[Brief description of the drawings]
FIG. 1 is an assembled cross-sectional view of a spindle motor showing a first embodiment of the present invention.
FIG. 2 is a spindle motor assembly drawing disclosing a method for manufacturing a spindle motor of the present invention.
FIG. 3 is a diagram showing a second embodiment of the present invention.
FIG. 4 is a diagram showing a third embodiment of the present invention.
FIG. 5 is an assembled sectional view of a spindle motor similar to that of FIG. 1 showing a fourth embodiment of the present invention.
FIG. 6 is an assembled cross-sectional view of a known spindle motor.
FIG. 7 is an assembled sectional view of another known spindle motor.
[Explanation of symbols]
20 Spindle motor 22 Inner protrusion 23 Hub 24 Yoke 25 Shaft 26, 27 Ball bearing 28 Bush 29 Motor internal space 31 Stator 32 Rotor magnets 36, 37 Fitting surface 38 Chamfer 39 Recess 40 Adhesive 41 Chamfer 42 Recess 43 Adhesive 50 Rotor assembly 51 Shaft assembly

Claims (7)

A rotor assembly having a rotor for holding and rotating the disk, a rotor magnet that rotates together with the rotor, and an upper bearing in which an outer ring is fitted to the rotor;
A shaft, a lower bearing in which the inner ring is fitted to the shaft, a stator fitted to the shaft on the upper side of the lower bearing, and a bush fitted to the outer ring of the lower bearing. A shaft assembly, and
In a spindle motor in which an inner ring of the upper bearing is fitted to the shaft, and the bush is fitted to the rotor via an adhesive to couple the rotor assembly and the shaft assembly.
At least the upper outer peripheral edge of the bush has a chamfered portion,
The volume of the bush fitting gap formed between the outer peripheral surface of the bush and the inner peripheral surface of the rotor, and the volume of the annular chamfered concave portion formed by the chamfered portion and the inner peripheral surface of the rotor Before the coupling between the rotor assembly and the shaft assembly is applied to either the outer peripheral surface of the bush or the inner peripheral surface of the rotor. A part of the adhesive is collected in the chamfered recess by being squeezed to the other of the outer peripheral surface of the bush and the inner peripheral surface of the rotor when the solid body and the shaft assembly are coupled .
The spindle motor characterized in that the adhesive accumulated in the chamfered recess completely seals the motor internal space side of the bush fitting gap . A rotor assembly having a rotor for holding and rotating the disk, a rotor magnet that rotates together with the rotor, and an upper bearing in which an outer ring is fitted to the rotor;
A shaft, a lower bearing in which the inner ring is fitted to the shaft, a stator fitted to the shaft on the upper side of the lower bearing, and a bush fitted to the outer ring of the lower bearing. A shaft assembly, and
In a spindle motor in which an inner ring of the upper bearing is fitted to the shaft, and the bush is fitted to the rotor via an adhesive to couple the rotor assembly and the shaft assembly.
The volume of the bush fitting gap formed between the outer peripheral surface of the bush and the inner peripheral surface of the rotor, and a recess defined by the upper surface of the bush, the inner peripheral surface of the rotor, and the lower surface of the rotor magnet An amount of adhesive that is approximately the sum of the volume of the rotor is applied to either the outer peripheral surface of the bush or the inner peripheral surface of the rotor before the rotor assembly and the shaft assembly are joined. When the assembly and the shaft assembly are coupled, a part of the adhesive is collected in the recess by being squeezed to the other of the outer peripheral surface of the bush and the inner peripheral surface of the rotor .
A spindle motor characterized in that the adhesive accumulated in the recess completely seals the motor internal space side of the bush fitting gap . Forming a rotor assembly having a rotor for holding and rotating the disk, a rotor magnet that rotates together with the rotor, and an upper bearing in which an outer ring is fitted to the rotor;
A shaft, a lower bearing in which the inner ring is fitted to the shaft, a stator fitted to the shaft on the upper side of the lower bearing, and an outer ring of the lower bearing, and a chamfered portion on the upper outer peripheral edge forming a shaft assembly having an annular bushing, the having,
That the bushing is fitted to the rotor and fixed to couple with said rotor assembly and shaft assembly with fitting the inner ring of the upper bearing to the shaft,
The volume of the bush fitting gap formed between the outer peripheral surface of the bush and the inner peripheral surface of the rotor in the coupled state of the rotor assembly and the shaft assembly, the chamfered portion of the bush, and the rotor The volume of the annular chamfered recess formed by the inner peripheral surface of the rotor is approximately the total amount of adhesive on either the rotor inner peripheral surface of the rotor assembly or the bush outer peripheral surface of the shaft assembly. Applying,
The rotor assembly and the shaft assembly are joined together with an adhesive applied to either the rotor inner peripheral surface of the rotor assembly or the bush outer peripheral surface of the shaft assembly. Adhesive is squeezed by the other of the rotor inner peripheral surface of the rotor assembly and the bush outer peripheral surface of the shaft assembly and accumulated in the chamfered recess, and the adhesive accumulated in the chamfered recess is Completely sealing the motor internal space side of
A method for forming a spindle motor comprising the following steps.   4. An annular chamfered recess formed by a chamfered portion formed at an upper outer peripheral edge of the bush and an inner peripheral surface of the rotor has a substantially rectangular cross section. The spindle motor according to any one of the above and an assembling method thereof.  A concave portion for accommodating an adhesive is formed on the mating surface of the rotor fitted with the bush, and the concave portion communicates with a chamfered portion formed on the upper outer peripheral edge of the bush. 5. The spindle motor according to claim 1, and an assembly method thereof.  The rotor assembly includes a hub having a substantially cylindrical shape and having an inward protruding portion at one opening, and a substantially cylindrical yoke fitted inside the inward protruding portion of the hub; and An upper bearing fitted to the inner circumference of the yoke, and the upper inner peripheral edge of the yoke fitted to the outer ring of the upper bearing has a chamfered portion, and the yoke and the upper bearing are bonded to each other by an adhesive. At least a part of the adhesive accumulates in an annular chamfered recess formed by the outer peripheral surface of the outer ring and the chamfered portion, and the fitting surface formed by the yoke and the upper bearing is completely removed. 6. A spindle motor and an assembling method thereof according to claim 1, wherein the spindle motor is sealed.  The spindle motor according to any one of claims 1 to 6, and an assembling method thereof, wherein the adhesive is at least one of a natural curable adhesive and a thermosetting adhesive.

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