JPH0366983A - Sealing device - Google Patents

Abstract

PURPOSE:To improve the measuring accuracy and compact the device by providing a ring-formed magnet member for blocking a first through hole and a magnetic fluid injected into a gap formed between a shaft piercing a second through hole and the inner peripheral surface of the second through hole. CONSTITUTION:A sealing device 20 is integrally formed into ring shape by machining a magnet 21 made of manganese steel, and provided with a groove part 21b at its inner peripheral surface. The first flank 21C and second flank 21D of the sealing device 20 are respectively magnetized to the S pole and N pole by magnetizing the magnet 21, thus forming a magnetic field in the direction indicated by an arrow (a). When the device 20 is mounted at the fixed shaft 10 of a motor, the motor side is sealed from outside by a fluid injected and held between the fixed shaft 10 and the groove part 21B of the magnet 21. The fluid 6 held by magnetic force is not scattered even if a rotary hub 9 is rotated at this time, and a sealing characteristic can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a sealing device, and is suitable for application to, for example, a sealing device designed to seal a drive section of a hard disk drive.

B Summary of the Invention According to the present invention, a sealing device is integrally formed using a machinable magnet, so that the sealing device can be configured to be simpler and thinner.

C. Prior Art Conventionally, for example, in a hard disk drive, a magnetic head for reading and reproducing information is placed on a magnetic disk as a recording medium. By suspending the magnetic disk with a gap of several [μ■] and rotating the magnetic disk at high speed, information can be recorded or reproduced on the magnetic disk at high speed.

Therefore, even if extremely fine dust adheres to the magnetic disk, there is a risk that the dust will collide with the magnetic head, making it impossible to read or write information accurately.

The motor that rotates the magnetic disk is of a fixed iron core type, and as shown in FIG.
The rotary hub 9 is rotatably engaged through the rotary hub 9, and a magnetic disk is fixed to the upper surface 9A of the rotary hub 9.

Therefore, by rotationally driving the rotating hub 9, the magnetic disk is rotated.

Further, a sealing device 1 that seals magnetic fluid is provided in the fixed shaft penetration hole 9B of the rotating hub 9, and this sealing device generates from bearing grease etc. injected into the bearing 8. The hole 9 allows dust to pass through the fixed shaft.
This prevents dust from diffusing from B to the outside, thereby preventing dust from adhering to the magnetic disk.

As shown in FIG. 5, this sealing device 1 consists of two upper surfaces 2B and a lower surface 2B of an annular magnet 2 made of sintered material such as ferrite.
Metallic discs 3 and 4 are attached to the.

The disks 3 and 4 are provided with through holes 3A and 4A having a diameter larger than the diameter of the fixed shaft 10 at the center thereof, and by passing the fixed shaft 10 through the through holes 3A and 4A without contact, an annular magnet is formed. A magnetic fluid 6 (FIG. 4) is injected into a portion surrounded by the inner circumferential surface 2C of the disk 2 and the disks 3 and 4.

This magnetic fluid 6 is made by mixing magnetic powder into the fluid, and is designed to be held within a magnetic field.

Therefore, the sealing device l
The ring-shaped A magnetic fluid 6 is held between the inner peripheral surface of the magnet 2 and the fixed shaft 10 by the magnetic force of the annular magnet 2, thereby sealing the motor side from the outside.

D Problems to be Solved by the Invention Here, the sealing device 1 has the magnetic fluid 6 by pasting the disks 3 and 4 on the upper side 2A and lower side 2B of the annular magnet 2.
The structure of the entire valve to which the discs 3 and 4 are attached becomes complicated and the assembly process becomes complicated. The thickness of magnet 2 is extremely thin (and the magnetic force decreases,
There was a problem in that the magnetic fluid could not be held sufficiently for practical purposes.

Furthermore, it is difficult to perform mechanical processing such as grinding and polishing on the sintered annular magnet 2, and there is a problem in that it is difficult to perform finishing processing with high precision to improve dimensional accuracy.

The present invention has been made in consideration of the above points, and aims to propose a sealing device that has a simple configuration, further improves dimensional accuracy, and can be made thinner.

E Means for Solving the Problem In order to solve the problem, in the first invention, the inner circumferential surface of the first through hole 9B provided in the outer casing member 9 and the first through hole 9B are In the sealing device E20 that seals between the shafts 10 that are penetrated and rotated relative to the outer casing member 9, a second through hole 21A having a diameter larger than the diameter of the shaft 10 is formed. , an annular magnet member 21 that can be machined and fixed to the outer housing member 9 so as to close the first through hole 9B, and a second through hole 2.
1A through the ring 10, the axis lO and the second
The magnetic fluid 6 is injected into the gap formed between the inner peripheral surfaces of the through hole 21A and held by the magnetic field a formed by the magnet member 21.

In the second aspect of the invention, the magnet member 21 is provided with a groove 21B on the inner circumferential surface of the second through hole 21A that communicates with the second through hole 21A and stores the magnetic fluid 6.

Further, in the third invention, the magnet member 21 is made of manganese steel or a plastic magnet.

2-action 81 By configuring the sealing device 20 using the magnet 21 that can be machined, the sealing device 20 can be integrally formed with the magnet, which makes the sealing device 20 even more precise and It can be made into a simple configuration.

In this way, the sealing device 20 as a whole can be made even thinner.

G example An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, in which parts corresponding to those in FIG. It is fixed to the rotating hub 9 by being press-fitted into the fixed shaft penetration hole 9B of the rotating hub 9.

Therefore, when the rotary hub 9 is rotated about the fixed shaft 10, the sealing device 20 rotates together with the rotary hub 9.

As shown in FIG. 2, this sealing device 20 is integrally formed into an annular shape by processing a magnet 21 made of manganese steel that can be machined by grinding and/or polishing. , a groove portion 21B is provided on the inner peripheral surface.

Further, as shown in FIG. 3, the sealing device 20 magnetizes the first side surface 21C by magnetizing the magnet 21 made of manganese steel.
Since the second side surface 21D is magnetized to the S pole and the N pole, respectively, a magnetic field is generated in the direction indicated by the arrow a.

Therefore, when the magnetic fluid 6 is injected into the groove 21B, the magnetic fluid 6 receives a magnetic force from the magnetic field a, so that it is held within the groove 21B.

In the above configuration, the sealing device 20 is connected to the fixed shaft 1 of the motor.
0, the motor side is sealed from the outside by the magnetic fluid 6 injected and held between the fixed shaft 10 and the groove 21B provided on the inner peripheral surface of the magnet 21.

Even when the rotating hub 9 is rotated at this time, the magnetic fluid 6 held by the magnetic force does not scatter, and the sealing properties can be maintained.

Thus, according to the above configuration, the magnet 2 that can be machined
1 (manganese steel material) is integrally processed and formed into a sealing device 20.
By configuring this, the sealing device 20 can be further simplified in configuration, and the dimensional accuracy can be further improved.

Therefore, the assembly process can be further simplified.

Incidentally, the manganese steel material (21) that constitutes the sealing device 20 is
The sealing device 20, which generates a higher magnetic force than a conventional sintered magnet and is integrally formed from the manganese steel material (21), has disks 3 and 4 (
The magnet part can be made thicker than in the case where the sealing device 20 is made thinner as a whole than in the case where the magnetic fluid 6 is pasted (Fig. obtain.

Therefore, the sealing device 20 as a whole can be made even thinner.

In the above-mentioned embodiment, a case was described in which the sealing device 20 was formed by an annular magnet 21, but the present invention is not limited to this, and the present invention is not limited to this. Even if it is used, the same effect as in the above case can be obtained.

Further, in the above-described embodiment, a case was described in which the groove portion 21B continuous in the circumferential direction was provided on the inner circumferential surface of the annular magnet 21, but the present invention is not limited to this. A groove may be provided or the groove may be omitted.

Further, in the above-mentioned embodiment, a case was described in which manganese steel material was used as the magnet 21 constituting the sealing device 20, but the present invention is not limited to this. Other magnets, such as so-called plastic magnets, which can be machined by grinding and polishing, are widely applicable.

Furthermore, in the above-described embodiments, a case has been described in which the present invention is applied to a fixed core type (that is, a fixed ring type) motor. The same effect can be obtained as in the case of .

Further, in the embodiments described above, the present invention is applied to the shaft 10 of the motor.
Although the case has been described in which the present invention is applied to sealing between the outer casing members (rotating hub 9), the present invention can be widely applied to sealing the shafts of other drive devices.

Furthermore, in the above-described embodiments, a case has been described in which the present invention is applied to a hard disk drive, but the present invention is not limited to this and can be widely applied to other mechanisms having an output shaft.

Effects of the Invention As described above, according to the present invention, the sealing device is constructed by integrally forming a magnet that can be machined, thereby realizing a simple and thin sealing device. obtain.

[Brief explanation of drawings]

Fig. 1 is a partial cross-sectional view showing an embodiment of the sealing device according to the present invention, Fig. 2 is a perspective view showing the configuration of the sealing device, and Fig. 3 is a cross-sectional view taken along the line ■-■ in Fig. 2. Longitudinal cross-sectional view, No. 4
The figure is a partial sectional view showing a conventional sealing structure, and FIG. 5 is a perspective view showing the configuration of a conventional sealing device. 1.20... Sealing device, 2.21...
Magnet, 3.4...Disc, 6...Magnetic fluid, 9...Rotating hub, 10...Fixed shaft, 21B...・Groove.

Claims (3)

[Claims] (1) Sealing the inner circumferential surface of the first through hole provided in the outer casing member and the shaft that is penetrated by the first through hole and is configured to rotate relative to the outer casing member. In the sealing device, a second through hole having a diameter larger than the diameter of the shaft is formed, and the mechanical processing is performed so as to be fixed to the outer casing member so as to close the first through hole. an annular magnet member that can be injected into a gap formed between the inner circumferential surface of the shaft and the second through hole by passing the shaft through the second through hole; A sealing device comprising: a magnetic fluid held by a magnetic field formed by the magnetic fluid; (2) According to claim 1, the magnet member is provided with a groove on the inner circumferential surface of the second through hole that communicates with the second through hole and stores the magnetic fluid. The sealing device described. (3) The sealing device according to claim 1 or 2, wherein the magnet member is made of manganese steel or a plastic magnet.