JPH0341693A - Enclosed type magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent breakage of a magnetic seal by providing a duct linking a space in an air-tight enclosed package and an enclosed space in the inside of a hub of a spindle motor on a shaft and providing a pressure adjusting member on the duct. CONSTITUTION:A duct 15 is provided on a shaft 9 of a spindle motor 2, which links an enclosed space A in the inside of a hub 12 and a space B in an enclosed package 1. Then an air filter 16 or a pressure adjustment member 17 expanded or contracted depending on the pressure difference between both the spaces is provided on the duct. Thus, the pressure in the enclosed space in the inside of the hub 12 of the spindle motor 2 and the space in the enclosed package 1 is always kept in equilibrium, then a pressure over its breakdown pressure is not exerted on the magnetic seal. Thus, breakage of the magnetic seal is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sealed magnetic disk device that includes a magnetic seal on the bearing end side of a spindle motor that rotates a magnetic disk at high speed.

[Prior Art] FIG. 4 is a sectional view showing a conventional sealed magnetic disk device disclosed in Japanese Patent Application Laid-Open No. 117378/1983.

In the figure, (1) is an airtight container, and (2) is this airtight container (
1) a spindle motor housed and fixed in the spindle motor (3), a magnetic disc that is detachably attached to this spindle motor (2) and rotated by it, and (4) a magnetic disc that is rotated by this magnetic disc (3).
), (5) is an actuator that positions this magnetic head at a target position on the magnetic disc (3), (6) is for adjusting the pressure inside the sealed container (1). The pump for (7) is this pump (6
) and an air filter interposed in the communication path between the outside air and the outside air, (8)
is an air pump consisting of this air filter (7) and the pump (6).

FIG. 5 is a sectional view showing the internal structure of a spindle motor (2) in a sealed magnetic disk device that has recently become mainstream, as disclosed in Japanese Patent Application Laid-Open No. 61-34771. Shaft fixed to the container, (
10a) is the lower bearing inserted and fixed to this shaft (9), (lob) is the upper bearing, (11) is the coil core attached to the shaft (9), and (12) is the magnetic disk. A hub (13) is a magnet polymerized and bonded to the inner circumferential wall of the hub (12).
(14) is a magnetic seal for preventing scattering of grease oil mist from each of the bearings (10a) (lob), and is provided on the bearing end side of the shaft (9).

Next, the operation will be explained. That is, in the one shown in FIG. 4, the air pump (8) serves to automatically adjust the pressure inside the closed container (1) in accordance with fluctuations in the outside air pressure.

Therefore, this closed container (1) must have sufficient airtightness. On the other hand, inside the spindle motor (2), as shown in Figure 5, the sealed space (A) inside the hub (12) is separated from the space CB inside the closed container (1) by a magnetic seal (14). It is an independent space. However, this state occurs when the difference between the pressure in the space (B) inside the sealed container (1) and the pressure in the sealed space (A) inside the hub (12) is less than the withstand pressure of each magnetic seal (14) described above. If the pressure exceeds the withstand pressure, the magnetic seal (14) will break, and the internal sealed space (A) of the hub (12) will become the same air pressure space as the internal space (B) of the sealed container (1). .

[Problems to be Solved by the Invention] Since the conventional sealed magnetic disk device is configured as described above, the pressure between the space inside the sealed container (B) and the sealed space inside the hub of the spindle motor (A) is reduced. If the difference exceeds the withstand pressure of the magnetic seal, the magnetic seal will break and grease oil mist from the bearing will scatter inside the sealed container, causing problems such as a head crash.

This invention was made to solve the above-mentioned problems, and it is possible to prevent the magnetic seal from breaking by constantly balancing the pressure between the space inside the sealed container and the sealed space inside the hub of the spindle motor. With the goal.

[Means for Solving the Problem] In the sealed magnetic disk device according to the present invention, the shaft (9) of the spindle motor (2) has a sealed space (A) inside the hub (12) and a space inside the sealed container (1). A ventilation path (15) connecting the (B) is provided, and an air filter (15) is provided in this ventilation path.
16) Alternatively, a pressure regulating member (17) is attached that expands and contracts in response to the pressure difference between the two spaces.

[Function] In the spindle motor of the sealed magnetic disk device according to the present invention, the pressure between the sealed space inside the hub of the spindle motor and the space inside the sealed container is controlled by the air filter or the pressure regulating member provided in the ventilation path of the shaft. Since the magnetic seal is always maintained in an equilibrium state, pressure exceeding its withstand pressure is not applied to the magnetic seal, and therefore the magnetic seal will not be broken.

[Example] An example of the present invention will be described below. That is, in Fig. 1, the same or corresponding parts as those in Figs. 4 and 5 are given the same reference numerals, and the redundant explanation thereof will be omitted. an air passage provided on the inner end side of the airtight container of the fixed shaft (9) of the spindle motor (2) housed in the hub (12) and connecting the airtight space CA) inside the hub (12) and the inner space of the airtight container (1);
(16> is an air filter attached to this ventilation passage, and the presence of this ventilation passage and air filter is a feature of the present invention. Therefore, in this invention, the airtight container (
1) The space (B) inside the hub (12) is the closed space (A) inside the hub (12).
), the air in the space (B) flows into the closed space (A) through the ventilation path (15), and the pressures in the rain spaces (A) and (B) are balanced.

On the other hand, if the pressure in the space CB inside the sealed container (1) becomes lower than that in the sealed space (A) inside the hub (12), for example, when the spindle motor (2) rotates and the coil core (11) generates heat, the hub ( 12) When the air in the internal closed space (A) expands and the pressure increases, the internal air in this closed space (A) passes through the ventilation path (15) and enters the space (B) inside the closed container (1). They flow out and their pressures balance out. At this time, the air discharged from the sealed space (A) inside the hub (12) contains grease oil mist from the bearings (10a) (10b), but this grease oil mist is removed by the air filter (16). Filtered air never enters the closed container (1) and only clean air always flows in.

In the above embodiment, the spindle motor (2) has a shaft (9) fixed to the closed container (1), and a bearing (10).
a) The outer ring side of (10b) is a fixed type with a rotating shaft, but as shown in another embodiment in Fig. 2, a bearing (10b) is used.
0a) It may be a shaft rotation type spindle motor in which the inner ring side of (10b) rotates together with the shaft (9). Further, in the above embodiment, the case where the air filter (16) is provided in the ventilation path (15) has been explained, but the third
As shown in the figure, instead of the air filter (16), there is a sealed space (A) inside the hub (12) at the end of the air passage (15).
A pressure regulating member (17) such as a bellows may be attached, which is provided to isolate the space (B) inside the airtight container (1) and expands and contracts in response to the pressure difference between the two spaces. , similar effects can be expected in this case as well.

[Effects of the Invention] As described above, the sealed magnetic disk device of the present invention provides air to the shaft of the spindle motor so that the pressure between the sealed space inside the hub of the spindle motor and the space inside the sealed container is always balanced. Since the ventilation passage is equipped with a filter or pressure regulating member, the magnetic seal will not break, and a highly reliable product with extremely low risk of head crash due to grease oil mist entering the sealed container can be obtained. effective.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a sealed magnetic disk device of the present invention, FIG. 2 is a similar sectional view showing another embodiment of the invention, and FIG. 3 is a sectional view of a spindle motor of the invention. FIG. 4 is a sectional view showing a conventional sealed magnetic disk drive, and FIG. 5 is a sectional view of the left half of a conventional spindle motor. In the figure, (1,) is a sealed container, (2) is a spindle motor, (3) is a magnetic disk, (9) is a shaft, (12)
is the hub, (14) is the magnetic seal, (15) is the ventilation path,
(16) is an air filter, (A) is a closed space, and (B) is a space. In other figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In a spindle motor that rotates a magnetic disk, in which a magnetic seal is provided on the bearing end side, ventilation connects the space inside the airtight container housing the spindle motor and the sealed space inside the hub of the spindle motor. A passage is provided on the shaft of the spindle motor, and an air filter or a pressure regulating member is attached to the air passage, which blocks the air passage and expands and contracts in response to the pressure difference between the two spaces. A sealed magnetic disk device.