JP3845156B2 - Spindle motor for hard disk drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spindle motor for a hard disk drive, and more particularly to an improvement in a vibration isolator of the spindle motor. More specifically, the present invention relates to a spindle motor in which a vibration isolating portion of the spindle motor can appropriately cope with a surrounding temperature change, and can surely achieve a hard disk vibration preventing action accompanying this temperature change.
[0002]
[Prior art]
With recent technological advances, it has been required to rotate the spindle motor for hard disk drives at a higher speed. In order to satisfy this requirement, it is necessary to increase the steady rotation speed of the spindle motor. However, when the steady rotation speed of the spindle motor is increased, the value of the current flowing through the stator coil increases. As a result, vibration is generated in the coil itself. The vibration of the stator coil is transmitted to the shaft that supports the coil, and further, the vibration is transmitted to the housing and cover that supports the shaft, which generates large noise when the spindle motor rotates at high speed. I was letting.
[0003]
In order to improve such a problem, as shown in FIG. 6, a pair of rubber O-rings 4 having a damping action is provided between the stator 2 of the spindle motor 1 and the shaft 3 supporting the stator 2. There is known a structure in which they are arranged at a predetermined interval and elastically hold them (see, for example, Japanese Patent Laid-Open No. 6-52626). In the spindle motor having such a structure, the vibration excited by flowing a large current to the stator 2 is not directly transmitted to the shaft 3 as before, but is damped through the O-ring 4. It will be transmitted only in the state. As a result, the vibration transmitted from the shaft 3 to the housing, the cover, and the like is considerably damped, and thus the above-mentioned noise-related problems have been greatly improved.
[0004]
[Problems to be solved by the invention]
However, in such an improved spindle motor, the elastic force of rubber, which is a material constituting the O-ring, generally has a property of greatly fluctuating in the use environment, particularly in the ambient temperature during use. This is known, and this has a great influence on the attenuation characteristics. For example, even with the same spindle motor, the noise generation state of the spindle motor may differ between a relatively cool time zone or place and a relatively hot time zone or place. This is because normal rubber O-rings have a high elastic force at low temperatures and cannot absorb vibrations sufficiently, and at high temperatures, the elastic force is generally low and becomes too soft, resulting in noise absorption characteristics. There was a problem that the noise could not be sufficiently absorbed.
[0005]
The present invention has been made in consideration of the above-described problems, and the object of the present invention is to always stabilize the spindle motor against changes in ambient temperature when the spindle motor is rotated at a high speed. It is an object of the present invention to provide a spindle motor that can exhibit the noise attenuation characteristics.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, for example, an O-ring made of a material whose elastic characteristics are always stable with respect to a temperature change around the spindle motor is used, or a spindle motor is used. The spindle motor is surrounded by a constant temperature device or driven in a temperature controlled environment by the constant temperature device so that the surrounding temperature change does not affect the spindle motor. A means such as incorporating a temperature compensation element is conceivable.
[0007]
However, there is currently no material that has stable elastic characteristics over a wide range of temperature changes, can be used as an O-ring, and has a reasonable price for the use of the spindle motor. Also, the provision of a constant temperature device has the problem that the device becomes large and extremely expensive.
[0008]
On the other hand, the incorporation of the temperature compensation element into the spindle motor can be achieved, for example, by disposing a known synthetic resin annular member having a relatively large thermal expansion coefficient between the shaft and the rubber O-ring. Such a measure avoids a large burden in terms of cost.
[0009]
Based on such knowledge, in the present invention, in order to reduce the influence on the temperature change of the rubber O-ring that provides the damping action, the shaft and the stator are connected by at least two ring elements, A first ring-shaped member fitted in an annular groove provided on the shaft, and a second ring-shaped member disposed radially outward of the first ring-shaped member, and a second ring shape A radially inner portion of the member contacts only the first ring-shaped member without contacting the shaft, and a radially outer portion of the second ring-shaped member contacts and holds the stator. either the ring-shaped member and a second ring-shaped member 36 is a ring-shaped member having a damping property, configured so that the other is a ring-shaped member made of a relatively large synthetic resin thermal expansion coefficient It was. The above-mentioned problem can be solved by such means.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. In this figure, reference numeral 10 denotes a spindle motor according to the present invention showing only the main part of the constituent elements. The spindle motor 10 includes a stationary part, a rotating part, and a bearing part that connects the two parts. The stationary portion is formed of a shaft 12 fixed to a frame (not shown) and a stator 14 that is stationary with respect to the shaft 12. The rotating portion has a rotor magnet 16 disposed opposite to the outer side in the radial direction of the stator 14, a yoke 18 that holds the rotor magnet 16, a yoke 18 that holds the yoke 18, and And a hub 20 on which a hard disk (not shown) can be mounted. The stationary part and the rotating part are connected by bearings 22 and 24. That is, the yoke 18 is rotatably mounted on the shaft 12 through a bearing 22 disposed above the stator 14 and a bearing 24 disposed below the stator 14 via the bush 26. Further, a dustproof cap, a magnetic fluid seal, and the like are provided between the hub 20 and the shaft 12 as in the prior art. The lower bearing 24 is supported via a flange 28 fixed to a housing (not shown). The functions of these elements and their attachment means are substantially the same as those shown in FIG. 6 and are not described in detail because they are known per se.
[0011]
In the present invention, at least a pair of upper and lower annular grooves 30 having a predetermined interval are formed in the shaft 12. These grooves 30 are preferably formed somewhat deeper than the depth of the grooves receiving the conventional O-ring shown in FIG. In these grooves 30, ring elements 32 (see FIGS. 2 to 5) are respectively inserted. The stator 14 is held in a predetermined pressure state with respect to the shaft 12 via these ring elements 32.
[0012]
Here, the ring element 32 includes a ring-shaped member 34 in which an O-ring having damping characteristics against vibration and an annular member made of a synthetic resin having a relatively large thermal expansion coefficient are concentrically arranged in the same plane, 36. Accordingly, the ring-shaped members 34 and 36 are arranged as follows. That is, the inner diameter portion of the first ring-shaped member 34 is disposed in contact with the inner wall surface of the groove 30, and the inner diameter portion of the second ring-shaped member 36 is disposed in contact with the outer diameter portion of the first ring-shaped member 34. In addition, the inner wall surface of the stator 14 is disposed in contact with the outer diameter portion of the second ring-shaped member 36. As a result, the stator 14 serving as a vibration generating source includes a ring-shaped member having damping characteristics against the vibration with respect to the shaft 12, and a ring-shaped member made of a synthetic resin having a relatively large thermal expansion coefficient. , Are connected via a ring element 32. The configuration of the ring element 32 will be described in more detail by way of the embodiment shown in FIGS.
[0013]
FIG. 2 shows a first embodiment for the ring element 32. In this figure, the first ring-shaped member 34 of the ring element 32 inserted into the groove 30 of the shaft 12 is a ring-shaped member made of synthetic resin having a relatively large thermal expansion coefficient, while the second The ring-shaped member 36 is a ring-shaped member having a damping characteristic against vibration. Here, as the most preferable synthetic resin material constituting the ring-shaped member having a relatively large thermal expansion coefficient, for example, there is a polyurethane resin or a polyethylene resin. A most preferable material for forming a ring-shaped member having a damping characteristic against vibration is fluorine-based rubber (FR). It should be understood from the figure that the first ring-shaped member 34 is completely accommodated in the groove 30, while the second ring-shaped member 36 is in contact with the first ring-shaped member 34, but the groove 30. Or, it is not in contact with the shaft 12. In other words, in the present invention, of the members constituting the ring element 32 that supports the stator 14, the second ring-shaped member 36 that is in direct contact with the stator 14 is not in contact with the shaft 12. is there.
[0014]
The inner diameter of the groove 30 of the shaft 12, the thickness and diameter of the first and second ring-shaped members 34 and 35, and the inner diameter of the stator 14 are respectively set to appropriate initial settings for the second ring-shaped member 36 with respect to the stator 14 at room temperature. It is set so as to make contact with pressure, whereby the vibration from the stator 14 is appropriately absorbed by the second ring-shaped member 36, and the vibration generated by the stator 14 is attenuated.
[0015]
On the other hand, when the ambient temperature of the spindle motor 10 is relatively low, the second ring-shaped member 36 seems to be contracted and is somewhat hardened, and vibrations cannot be sufficiently absorbed with the initial set pressure for the stator 14. However, at this time, the outer diameter of the first ring-shaped member 34 is somewhat reduced due to heat shrinkage, the degree of freedom of the second ring-shaped member 36 is increased, and the deterioration of noise absorption characteristics is alleviated. The contact pressure of the two ring-shaped member 36 against the stator 14 is improved close to an appropriate value, and the vibration from the stator 14 is appropriately absorbed by the second ring-shaped member 36, and the vibration generated by the stator 14 is attenuated.
[0016]
Further, when the ambient temperature of the spindle motor 10 becomes relatively high, the second ring-shaped member 36 is somewhat softened and its elastic characteristics are lowered. As a result, the vibration absorption characteristics of the second ring-shaped member 36 deteriorate. On the other hand, at this time, the first ring-shaped member 34 expands due to thermal deformation due to high temperature. For this reason, the first ring-shaped member 34 pushes the second ring-shaped member 36 outward in the radial direction, and as a result, the second ring-shaped member 36 moves radially outward and contacts the stator 14. At this time, the pressure with which the second ring-shaped member 36 presses the stator 14 is set in advance so as to be approximately equal to the value at normal temperature. As a result, even when the ambient temperature of the spindle motor 10 becomes relatively high, the second ring-shaped member 36 contacts the stator 14 at the initial appropriate setting pressure, and the vibration from the stator 14 causes the second ring-shaped member to vibrate. The vibration generated by the stator 14 is attenuated in the same manner as at normal temperature.
[0017]
As described above, in order to prevent the function of the first ring-shaped member 34 from being blocked, the second ring-shaped member 36 has its radially inner portion only in contact with the first ring-shaped member 34, The radially outer portion contacts the stator 14 and must always be prevented from contacting the shaft 12 or groove 30 directly. For this reason, if necessary, the cross-sectional shape of the groove 30 can have a trapezoidal shape having an opening extending radially outward as shown in FIG. At this time, the first ring-shaped member 34 can have a trapezoidal cross-sectional shape so that the first ring-shaped member 34 can be substantially present in the groove 30, and the second ring-shaped member 36 has a substantially circular cross section. It is desirable that the cross-sectional diameter is smaller than the opening size of the groove 30 when pressed.
[0018]
Furthermore, in this case, the second ring-shaped member 36 made of, for example, FR has a sufficient elastic force, so that no major problem occurs during mounting, but the first ring-shaped member 34 made of, for example, polyurethane resin has a sufficient elastic force. Therefore, in order to properly install the first ring-shaped member 34 on the shaft 12, it is necessary to cut a part of the first ring-shaped member 34 in advance.
[0019]
FIG. 3 is a view similar to FIG. 2 showing another embodiment of the present invention. This embodiment differs from the embodiment of FIG. 2 in that the first ring-shaped member 34a is a ring-shaped member having an elastic force made of, for example, FR and having a vibration absorbing action, and the second ring-shaped member 36a is A ring-shaped member made of, for example, polyurethane resin or polyethylene resin and thermally expanding in response to a temperature change. That is, this is an example in which the arrangement of the ring-shaped members 34 and 36 in FIG. Also in this case, each ring-shaped member can provide the same function as in the case of FIG. 2 based on its own physical properties. Also in this case, the cross-sectional shapes of the groove 30a and the ring-shaped members 34a and 36a are appropriately formed so that the second ring-shaped member 36a does not directly contact the shaft 12a. In this case, for example, a part of the ring-shaped member 36a made of polyurethane resin may be cut at the time of mounting. This is because the mounting work is facilitated.
[0020]
FIG. 4 shows yet another embodiment. This embodiment is substantially similar to the embodiment of FIG. 2, but the shapes of the groove 30b and the first ring-shaped member 34b are different. That is, the groove 30b has a rectangular cross-sectional shape. For example, the first ring-shaped member 34b made of polyurethane resin and thermally expanding in response to a temperature change also has a rectangular cross-sectional shape so as to be adapted thereto. And a recess for receiving the second ring-shaped member 36b having a vibration absorbing function. This prevents the second ring-shaped member 36b from coming into contact with the shaft or groove. Also at this time, in order to facilitate the mounting of the first ring-shaped member 34b, it is preferable to cut a part thereof.
[0021]
FIG. 5 shows yet another embodiment. This embodiment is substantially similar to the embodiment of FIG. 3, but the shape of the groove 30c and the first ring-shaped member 34c having an elastic force made of, for example, FR, that is, a fluorine-based rubber and having a vibration absorbing function. Is different. That is, the groove 30c has a rectangular cross-sectional shape. The first ring-shaped member 34c also has a rectangular cross-sectional shape so as to be adapted thereto, and a second ring-shaped member 36c made of, for example, polyurethane resin and thermally expanding in response to a temperature change is formed on the outer portion thereof. The first ring-shaped member 34c is provided so as to be in contact with only the first ring-shaped member 34c. Also in this case, a part of the second ring-shaped member 36c can be cut for ease of mounting.
[0022]
In the illustrated example of the present invention, the stator 14 is attached to the shaft 12 by a pair of ring elements 32, 32, but preferably the pair of ring elements 32, 32 both have the same structure. . However, from the mounting procedure and other requirements, the combination of the first ring-shaped member and the second ring-shaped member is, for example, the upper ring element 32 as shown in FIG. 2 and the lower ring element 32 as shown in FIG. As such, each can have a different structure. Further, the first ring-shaped member can be simply fitted into the groove 30, but can be fixed thereto with an adhesive if necessary. Similarly, the second ring-shaped member can be simply disposed on the outer side in the radial direction of the first ring-shaped member, but can be fixed to the second ring-shaped member with an adhesive if necessary.
[0023]
【The invention's effect】
In the present invention, even if the operating environment temperature changes, regardless of the temperature change, by maintaining the holding pressure of the stator constant, the damping characteristic of the vibration generated by the stator is maintained in a stable state. I can do it. As a result, in the spindle motor of the present invention, the vibration noise of the spindle motor can always be maintained in a stable and low state regardless of the ambient temperature change.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of a first embodiment of a spindle motor according to the present invention.
FIG. 2 is a partially enlarged view showing a ring element of the spindle motor in FIG. 1;
FIG. 3 is a partially enlarged view showing a ring element of another embodiment of the spindle motor according to the present invention.
FIG. 4 is a partially enlarged view showing a ring element of still another embodiment of the spindle motor according to the present invention.
FIG. 5 is a partially enlarged view showing a ring element of another embodiment of the spindle motor in the present invention.
FIG. 6 is a cross-sectional view showing a main part of a known spindle motor.
[Explanation of symbols]
10 Spindle motor 12 Shaft 14 Stator 16 Rotor magnet 20 Hub 22, 24 Bearing 26 Bush 30, 30a, 30b, 30c Groove 32, 32a, 32b, 32c Ring elements 34, 34a, 34b, 34c First ring members 36, 36a , 36b, 36c Second ring-shaped member

Claims (9)

A stationary portion comprising a shaft 12 secured to the housing and a stator 14 in a fixed relationship with the shaft 12, and a rotor radially outward of the stator 14 and facing the stator 14 A rotating portion comprising a magnet 16 and a hub 20 that holds the rotor magnet 16 and can rotate together with the rotor magnet 16 and holds a hard disk; and a bearing 22 that rotatably supports the rotating portion on the shaft 12; 24, a spindle motor comprising:
The shaft 12 and the stator 14 are connected by at least two ring elements 32, 32, and the ring element is fitted in an annular groove 30 provided in the shaft 12; And a second ring-shaped member 36 disposed radially outward of the first ring-shaped member 34,
A radially inner portion of the second ring-shaped member 36 contacts only the first ring-shaped member 34 without contacting the shaft 12, and a radially outer portion of the second ring-shaped member 36 It contacts and holds the stator 14,
Either of said first ring-shaped member 34 and the second ring-shaped member 36 is a ring-shaped member having a damping property, the other is a ring-shaped member made of a relatively large synthetic resin thermal expansion coefficient A spindle motor for a hard disk drive. The first ring-shaped member 34 is a ring-shaped member made of a relatively large synthetic resin thermal expansion coefficient, claims, characterized in that the second ring-shaped member 36 is a ring-shaped member having a vibration damping property A spindle motor for a hard disk drive as described in 1. The first ring-shaped member is a ring-shaped member having vibration damping characteristics, and the second ring-shaped member is a synthetic resin ring-shaped member having a relatively large thermal expansion coefficient. Spindle motor for hard disk drive described in 1. The synthetic resin material constituting the ring-shaped member having a relatively large coefficient of thermal expansion is polyurethane resin or polyethylene resin, and the material constituting the ring-shaped member having damping characteristics against vibration is fluorine-based rubber (FR). The spindle motor for a hard disk drive according to claim 1, wherein the spindle motor is a hard disk drive spindle motor. 2. A spindle motor for a hard disk drive according to claim 1, wherein a part of the ring-shaped member made of synthetic resin is cut. 4. The spindle motor for a hard disk drive according to claim 1, wherein a cross-sectional shape of the groove 30 provided in the shaft 12 has a trapezoidal shape having an opening extending radially outward. . The spindle motor for a hard disk drive according to claim 6, wherein the first ring member (34) has a trapezoidal cross-sectional shape so that the first ring member (34) can substantially exist in the groove (30). The hard disk drive spindle motor according to any one of claims 1 to 7, wherein the first ring-shaped member 34 is fixed in the groove 30 with an adhesive. Hard disk drive spindle motor according to any one of the preceding claims 1-8 in which the second ring-shaped member 36, characterized in that it is secured by adhesive to the radially outside of the first ring-shaped member.

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