JPS6128178B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic storage device, particularly a magnetic storage medium,
The present invention relates to a bearing sealing mechanism in a magnetic storage device such as a magnetic disk device or a magnetic drum device in which a magnetic head or the like is enclosed in a clean atmosphere in a sealed chamber.

As the performance of magnetic storage devices such as magnetic disk devices improves, and as the floating amount of floating magnetic heads based on the principle of gas lubrication becomes smaller and smaller, the cleanliness of the atmosphere of magnetic storage media and magnetic heads has improved. There is a growing need to pay even more careful attention to For this reason, in recent years, chambers that house magnetic storage media, magnetic heads, etc. have been designed to be sealed from the outside environment to prevent the intrusion of dust, other foreign substances, harmful and unnecessary gases, vapors, etc.
Many devices are seen that use a labyrinth seal or similar sealing mechanism to prevent splashing particles of lubricating oil (lubricating oil or grease) from flying into the chamber from the bearing of the rotary drive shaft. It became. However, in recent high-performance devices, problems that cannot be prevented even with such measures, namely, the presence of liquid particles generated within the chamber, are becoming apparent. The main causes of liquid particle generation are said to be as follows. As the amount of levitation becomes minute, the point showing the highest pressure in the pressure distribution generated in the levitation gap moves to the vicinity of the trailing edge of the floating slider, and the pressure is distributed over a very short distance from that point to the trailing edge. The pressure suddenly drops to ambient pressure at
In that region, the adiabatic expansion phenomenon becomes dominant, and the temperature of the lubricating gas of the floating slider drops rapidly. The lubricating gas is usually air, and sometimes an inert gas such as nitrogen is used, but if the water vapor contains vapor of other substances, this may cause a rapid temperature drop or other changes in state quantities. Due to the sudden change, dew condenses and becomes liquid particles. When the partial pressure of each vapor reaches a certain ratio to its saturated vapor pressure, the amount of liquid particles generated exceeds the amount of evaporation, and they float in the lubricating gas as the magnetic storage medium rotates. It rotates inside the chamber. Part of it adheres to the surface of the magnetic storage medium and the floating slider, and part of it evaporates, increasing its viscosity. Therefore, such liquid particles or their deposits deteriorate the floating stability of the floating slider, and in extreme cases may cause a head crash accident. In addition, in a contact start/stop type magnetic head, when the magnetic storage medium is stopped and in contact with the floating slider, the two come into close contact, causing an abnormal increase in starting torque.
It is believed that water and oil are the main components of liquid particles that are undesirable for such a mechanical interface between a magnetic storage medium and a magnetic head. Moisture can be removed by sealing a moisture absorbent such as silica gel in the sealed chamber, and this technique is already in practical use as a known technique. Oils and fats are those that were originally mixed in the lubricating gas sealed inside the chamber, those that are based on the vapors of oils and fats adhering to the mechanical parts exposed inside the chamber, and those that are based on the vapors of lubricating oils and fats in the bearings. There are three possible types, but most of the former two can be suppressed or removed by removing oil and fat when assembling the sealed chamber or filling lubricating gas, and the applicant previously proposed Japanese Patent Application No. 50-115119 and Hope
50-115121, in which a particulate adsorbent such as activated carbon is enclosed in a closed chamber together with a moisture absorbent, the removal effect can be increased. However, if a completely different type of bearing, such as a gas bearing or a magnetic bearing, is used, the story is different, but when using a normal rolling bearing or plain bearing, the lubricating oil itself functions as a bearing. It is extremely difficult to suppress the evaporation of lubricating oil against the gas in the sealed chamber, since it is essential for this purpose and it is almost impossible to create a structure that keeps the bearing airtight from the sealed chamber. In other words, no matter how much lubricating oil vapor is captured by sealing particulate adsorbent inside the sealed chamber, the original lubricating oil will continue to evaporate, so the vapor pressure of the oil in the sealed chamber will be below a certain level. cannot be lowered.

In view of the above problems, the purpose of the present invention is to
It overcomes the drawbacks of the prior art methods and compensates for the disadvantages that have not been considered heretofore, particularly with respect to the mechanical interface between the magnetic storage medium surface and the floating slider. It is an object of the present invention to provide a bearing sealing mechanism for a magnetic storage device that can efficiently capture and remove steam or particulates generated from bearing lubricating oil.

According to the present invention, a bent slit section with a labyrinth packing or similar structure is provided between the bearing of the rotary drive shaft and the sealed chamber, and fine particles such as activated carbon are adsorbed so that the gas in this slit section passes through. By accommodating and arranging the agent, this purpose can be achieved.

That is, according to the present invention, the oil vapor or oil particles (hereinafter abbreviated as "oil vapor, etc.") generated from the bearing lubricating oil will pass through the labyrinth, that is, the bent narrow gap, before reaching the sealed chamber. However, since a particulate adsorbent is provided to maintain air permeability in this slit, there is a very high probability that oil vapor and the like will come into contact with this slit. The trapping and removal efficiency is significantly improved compared to the conventional method in which a particulate adsorbent is simply placed in a closed chamber. Of course, the dimensional structure of the slit can be made the same as in the conventional method, so the effect of the presence of the slit is the same as that of the conventional method, and in addition, the highly efficient trapping and removal effect described above can be achieved. They will overlap. Therefore, even though it is impossible to completely prevent the generation of oil vapor, etc. in the bearing,
According to the present invention, it is possible to suppress at least the generation of liquid particles to a practically negligible level, and the above-mentioned disadvantages can be extremely reduced, and the practical effects are truly remarkable. be.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a partial sectional view showing a first embodiment in which the present invention is applied to a fixed head magnetic disk device. In the figure, a magnetic disk 1 is fixed to a rotary drive shaft 2, and the rotary drive shaft 2 is rotatably attached to a base housing 4 via a bearing 3 and is driven by a drive motor (not shown). . 5 is a labyrinth rotating part, and 6 is a labyrinth fixing part, which are attached to the rotary drive shaft 2 and the base housing 4, respectively. Labyrinth rotating part 5
A rotary-side annular protrusion 51 is provided on a concentric circumference, and a stationary-side annular protrusion 61 is provided on the labyrinth fixed part 6, and these intertwine to form a labyrinth, that is, a bent slit. It constitutes section 7. This mechanism is already well known and is exactly the same as that of the so-called labyrinth packing, but in this embodiment, in addition to this, the A large number of ventilation holes 62 are bored in the pores, one of which opens into the slit 7 and the other into an annular groove in which a particulate adsorbent 64 is accommodated. In this embodiment, granular activated carbon is used as the particulate adsorbent 64, and a membrane filter 63 is attached to the bottom of the annular groove to prevent fine pieces of activated carbon from entering the slit 7. It is being In addition, retention of particulate adsorbent 6
4 and a presser plate 6 for ease of its replacement.
5 is attached to the labyrinth fixing part 6.
Reference numeral 8 denotes a cover housing of the device, and a sealed chamber 9 is constructed by airtightly fastening this to the base housing 4. In this example,
In order to ensure the airtightness of the sealed chamber 9, each fitting part of the sealed chamber 9 is sealed with an O-ring gasket, and the drive motor (not shown) is also designed to have a sealed structure. In addition, consideration has been taken such as applying a sealant to the attachment portion to the base housing 4 as well. Note that the magnetic head is not shown in this figure since it is not particularly necessary for explaining the effects of this embodiment.

Now, the effects of this embodiment having the above-described structure will be described. First, in the case of a normal structure in which there are no ventilation holes 62, particulate adsorbent 64, etc. in FIG. There is a possibility that the particles may enter the narrow gap 7 from the outer circumferential side of the labyrinth rotating portion 5 and enter the sealed chamber 9 via the. In the narrow gap 7, as in the general case, the gas pushing effect caused by the centrifugal force accompanying the rotation of the labyrinth rotating part 5 appears, but in the case of a magnetic disk device, etc., for example, in the case of a turbine or a compressor, etc. However, since the pressure difference between the inlet and the outlet of the narrow gap 7 is small, it can be said that almost no gas throttling effect based on this difference can be expected. Now, if we refer to both the indentation effect and the constriction effect as the slit effect, the content of the slit effect in this case is still dominated by the indentation effect, but the indentation effect is a secondary effect due to a slight increase in pressure. It is not so large as it shows the following aperture effect. Therefore, in the conventional method that relies only on the slit 7, the change in the state of the gas inside the slit 7 is considered to be significant, causing a phase change in the oil vapor, etc. contained therein, which is then captured and removed. It could not be expected that this would do much, and at most it could only remove the grease particles from the bearing 3. On the other hand, according to the method of this embodiment, the gas is somewhat squeezed due to the pushing effect in the middle of the bent narrow gap 7, and the movement of the gas in the radial direction of the labyrinth rotating part 5 and the labyrinth fixed part 6 is prevented. Even if the particles do not stagnate, the probability of contact with the particulate adsorbent 64 and therefore the capture and removal of oil vapor and the like increases. Of course, even in this case, the effect of removing grease splash particles also exists. As described above, the bearing sealing mechanism of this embodiment can efficiently capture and remove oil vapor and the like in the middle of the narrow gap 7, thereby achieving the object of the present invention.

FIG. 2 is a partial sectional view showing a second embodiment of the invention. In this embodiment, the present invention is applied to a movable head type magnetic disk device having a closed circulation air flow path system, but the entire structure of the magnetic head, its carriage, voice coil motor, etc. , illustration is omitted because it is not particularly necessary for the following explanation. Although the chamber that mainly accommodates the magnetic disk 1 and the above-mentioned members (not shown) forms a main part of the closed circulation air passage system, strictly speaking, there is a difference in structure from the first embodiment. However, in principle, they can be considered completely the same, so from now on, in such a case, the closed chamber 9
shall be treated as such. Now, referring to FIG. 2, in this embodiment, the labyrinth fixing part, which is an element constituting the labyrinth, that is, the bent narrow gap part 7, has two parts.
This embodiment differs from the first embodiment only in that it is divided into two parts, and the rest is almost the same. Accordingly, in FIG. 2, members having the same functions and structures as those in FIG. The labyrinth fixing part in this embodiment includes a first labyrinth fixing part 6' which forms part of the narrow part 7 and also serves as a holding plate for the bearing 3, and a first labyrinth fixed part 6' which forms the remaining part of the narrow part 7 and which attracts fine particles. The second labyrinth fixing part 6'' accommodates the adsorbent 64.The second labyrinth fixing part 6'' is designed so that replacement and maintenance of the particulate adsorbent 64 can be performed without removing the labyrinth rotating part 5. It is structurally particulate adsorbent 6
4 is disposed outside the outer periphery of the labyrinth rotating section 5, and a plurality of ventilation windows 68 are opened on the circumferential cylindrical surface facing the outer circumferential side of the labyrinth rotating section 5. A filter 63 is installed in a cylindrical shape inside the annular groove so as to cover them. The particulate adsorbent 64 is activated carbon particles as in the first embodiment, and a non-porous annular plate-shaped cover 66 is used to accommodate the particulate adsorbent, and the second labyrinth fixing part 6 is secured by an annular retaining ring 67. ″ is fixed to the main body.

The effects of this embodiment with such a structure are as follows:
Essentially, it is not much different from that of the first embodiment described earlier, but the air in the slit 7 containing oil vapor etc. is ejected in the outer circumferential direction by the centrifugal effect of the labyrinth rotating section 5. Since the particulate adsorbent 64 is located, there is an advantage that the removal effect of oil vapor, etc. is increased.

FIG. 3 is a partial cross-sectional view showing a third embodiment of the present invention, in which the structure is made of porous ceramic filter material, except for the parts related to screw fastening and the retaining plate 65. The advantage of this embodiment, when compared with the first embodiment of the present invention shown in FIG. 1, is that the structure is made of a filter material with structural strength. Therefore, the ventilation hole 62 and the filter 63 that comes into contact with one of the openings are unnecessary, and the mechanism is simple, except that machining is required to ensure the flatness of the surface that comes into contact with the presser plate 65. Since the sintered material after forming and pressing can be used almost as is, the processing cost can be reduced. However, since the precision is somewhat reduced in the parts that are not machined, the clearance in the narrow gap 7 is cannot be made minute, and some deterioration of the slit effect is unavoidable, and the structure of the labyrinth fixing part 6 is made of a breathable filter material.
There are two concerns: there is a possibility of gas leaking between the inner and outer circumferences of the narrow gap 7. However, if the air permeability of the filter material is selected appropriately, the deterioration of the slit effect is not so important because the pressure difference between the inlet and the outlet of the slit 7 is small as described above; As is clear from the structure, the advantage is that the gas passes through the bent slit 7 and has an increased chance of contacting the particulate adsorbent 64 through the filter material, thereby increasing the removal effect of oil vapor, etc. big.

FIG. 4 is an enlarged sectional view of the vicinity of the slit, showing a fourth embodiment of the present invention. In this embodiment, the third
Although the object of the present invention can be fully achieved if the embodiment is implemented as in the first embodiment, the slit effect in the slit portion 7 is further promoted, and the first and second embodiments and the third embodiment are This can be applied when you want to have an intermediate character. That is, in this embodiment, although the structure is almost the same as that of the third embodiment, the narrow gap 7 is replaced with the first narrow gap 7' which has a small clearance and a high gap effect, and Although it is quite large, it is configured with a second slit 7'' to increase the possibility of contact between the particulate adsorbent 64 and the gas in the slit through the filter material of the labyrinth fixing part 6 in that part. The surface of the filter material of the labyrinth fixing part 6 constituting one side of the narrow gap 7' is made to have low air permeability.In other words, in this embodiment, the labyrinth fixing part 6
The structure is made of a sintered metal filter material, and the surface 69 that is in contact with the first slit 7' is machined using a cutting tool, a milling cutter, etc., and on the other hand, the accuracy for reducing the clearance is improved, On the other hand, the sintered metal particles are closed by machining, resulting in a decrease in air permeability. It should be noted that, as a matter of course, machining is also required for the portion 69' that contacts the presser plate 65, which inevitably reduces the air permeability, but as is clear from the figure, this example It does not have any negative effect on functionality. (4th
In the figure, the machined surface is indicated by a thick solid line. Although several embodiments of the present invention have been described in detail above, various modifications can be made without departing from the spirit of the present invention. For example, particulate adsorbent 6
The material 4 is not limited to granular activated carbon, but may be fibrous or solidified while maintaining porosity.In such a case, it can be easily attached to the labyrinth rotating part 5. In addition, in the fourth embodiment, a ceramic filter material as in the third embodiment is used instead of the sintered metal filter material for the structure material of the labyrinth fixing part 6, and 69 parts are provided for each part of the thick solid line in FIG. Instead of machining the parts, it is also possible to apply or impregnate them with an airtight paint to achieve a similar effect. Furthermore, although the above embodiments have mainly been applied to magnetic disk devices, it is clear that the present invention can be applied to all other airtight chamber type magnetic storage devices using rolling bearings or sliding bearings.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 respectively show the first embodiment of the present invention.
and a partial sectional view showing the second embodiment; FIG. 3 is a sectional view of the third embodiment near the slit;
The figure is also an enlarged cross-sectional view of the vicinity of the slit in the fourth embodiment. 1: Magnetic disk, 2: Rotation drive shaft, 3: Bearing, 4: Base housing, 5: Labyrinth rotating part, 51: Rotating side annular projection, 61: Fixed side annular projection, 62: Ventilation hole, 63 : Filter, 6
4: Particulate adsorbent, 65: Holding plate, 66: Cover, 67: Holding ring, 68: Ventilation window, 69,6
9': Machined surface, 6': First labyrinth fixing part, 6'': Second labyrinth fixing part, 6: Labyrinth fixing part by filter material, 7: Slit part,
7′: first slot, 7″: second slot, 8: cover housing, 9: sealed chamber.

Claims (1)

[Scope of Claims] 1. A magnetic storage device in which a magnetic storage medium, a magnetic head, and members associated therewith are inserted into a sealed chamber, comprising a bearing supporting a rotational drive shaft of the magnetic storage medium and the sealed chamber. a labyrinth rotating part having an annular protrusion on the rotary drive shaft between the two; and a labyrinth fixing part having an annular protrusion on the base housing that supports and fixes the bearing; Each of the parts is attached so as to form an intricately curved slit, and a particulate adsorbent is housed in at least one of the labyrinth rotating part and the labyrinth fixed part so that the gas in the slit passes through. Bearing sealing mechanism for magnetic storage devices. 2. A bearing seal for a magnetic storage device according to claim 1, characterized in that the structure of the labyrinth rotating part or the labyrinth fixing part that accommodates the particulate adsorbent is made of a filter material having structural strength. Stop mechanism. 3. Some of the slits in the bent slits are made more narrow, and the air permeability of the part of the labyrinth rotating part or labyrinth fixed part that accommodates the particulate adsorbent that is in contact with the narrow slits is reduced. A bearing sealing mechanism for a magnetic storage device according to claim 2, characterized in that: