JPH0519741U - Sealing device - Google Patents

Abstract

(57) [Summary] [Purpose] To simplify the sealing device. [Structure] The main body 1 divides an atmosphere side A and a vacuum side B, and a shaft 6 penetrates the hole 1a. The shaft 6 has a threaded portion 7b formed on the atmosphere side and a ridge portion 7a formed on the vacuum side. The yokes 4a and 4b are annularly arranged at the portions of the shaft 6 corresponding to the ridges 7a and the threaded portions 7b. The magnet 3 is arranged between the yoke 4a and the yoke 4b.
The shaft 6, the yokes 4 a and 4 b, and the magnet 3 define the intermediate pressure chamber 2. The magnetic fluid 5 is retained by the action of magnetism between the ridges 7a and the threaded portions 7b of the shaft 6 and the yokes 4a and 4b, and the space between the atmosphere side A and the vacuum side B is sealed. The screw-shaped portion 7b discharges the air in the intermediate pressure chamber 2 by the rotation of the shaft 6 and reduces the pressure difference between the intermediate pressure chamber 2 and the vacuum side B.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a sealing device, and more particularly to a sealing device that seals between a high pressure side and a low pressure side using a magnetic fluid.

[0002]

[Prior art and its problems]

 Conventionally, as a sealing device which divides the atmosphere side and the vacuum side and seals between them, for example, one shown in FIG. 5 is known.

That is, the sealing device shown in FIG. 5 is a magnetic fluid sealing device in which the magnetic fluid 25 is used, and the first ridge 27 is formed in the main body 21 that divides the atmosphere side A and the vacuum side B. A portion of the main body 21 corresponding to the first ridge portion 27a and the second ridge portion 27b of the shaft 26 is pierced by a shaft 26 having a and a second ridge portion 27b. Further, yokes 24a and 24b are respectively arranged in a state of being slightly separated from the shaft 26, and a magnet 23 is arranged between the yokes 24a and 24b so that magnetic lines of force pass through the yokes 24a and 24b.

The magnetic fluid 25 is disposed between the yoke 24a and the first ridge portion 27b and between the yoke 24b and the second ridge portion 27b, respectively. By the action of magnetism from the magnetic fluid 23, the magnetic fluid 25 is retained in a film shape between the yokes 24a and 24b and the first and second ridges 27a and 27b. At 25, the space between the atmosphere side A and the vacuum side B is sealed.

In FIG. 5, A is the atmosphere side and B is the vacuum side, which is in a high vacuum state of, for example, 10 −8 Torr or more. The main body 21 divides the vacuum side B from the atmosphere side A.

A shaft 26 penetrates through the main body 21 from the atmosphere side A to the vacuum side B in a rotatable state. The shaft 26 has a first ridge portion 27a formed at a portion near the vacuum side B of a portion corresponding to the main body 21 and a second ridge portion 27b formed at a portion near the atmosphere side A. A plurality of ridges 28 projecting around the shaft 26 are formed on the first ridge 27a, and a plurality of ridges 30 projecting around the shaft 26 are formed on the second ridge 27b. It is stepped.

The yoke 24a is located at the portion of the body 21 corresponding to the first ridge 27a of the shaft 26, and the portion of the body 21 corresponding to the second ridge 27b is located at the portion of the body 21 corresponding to the second ridge 27b. Yokes 24b are provided respectively. The yokes 24a and 24b are annular and are fixed to the main body 21 with the inner peripheral surface thereof and the shaft 26 being slightly separated.

A magnet 23 is arranged between the yoke 24 a and the yoke 24 b and is fixed to the main body 21. At this time, the magnetic poles of the magnet 23 are arranged so as to contact the yokes 24a and 24b so that the magnetic lines of force of the magnet 23 pass through the yokes 24a and 24b.

A pressure chamber 22 is formed between the magnet 23 and the shaft 26 by surrounding a space with yokes 24 a and 24 b. The pressure chamber communicates with an external pump 32 via a communication hole 31 formed in the magnet 23 and the main body 21. Then, the air in the pressure chamber 22 can be discharged by the pump 32.

Reference numeral 25 is a magnetic fluid.

With this configuration, when the magnetic fluid 25 is arranged between the yokes 24 a and 24 b and the shaft 26, the sealing device has the yoke 24 a and the first convex strip due to the magnetism of the magnet 23. The magnetic fluid 25 is retained between the protrusions 28 of the portion 27a and between the yoke 24b and the protrusions 30 of the second protrusions 27b.

At this time, the magnetic fluid 25 is retained in a film shape along the ridges 28 and 30 between the ridge 28 of the shaft 26 and the yoke 24a and between the ridge 30 and the yoke 24b. It has become. The magnetic fluid 25 blocks and seals between the atmosphere side A and the pressure chamber 22 and between the vacuum side B and the pressure chamber 22.

Here, the pump 32 is used to use a so-called intermediate drawing method, and by discharging the air in the pressure chamber 22 from the communication hole 31 with this pump 32, the inside of the pressure chamber 2 becomes the vacuum side. The pressure difference between the vacuum side B and the pressure chamber 22 is reduced by setting the vacuum state at a pressure slightly higher than B.

That is, when the pressure difference between the vacuum side B and the pressure chamber 22 is large, the pressure difference causes the film of the magnetic fluid 25 held between the ridge 28 and the yoke 24 a to be broken. Since the holes may be opened and the sealing performance may be deteriorated, the pressure difference between the vacuum side B and the pressure chamber 22 is reduced by the pump 32 to prevent the magnetic fluid 25 from being pierced. It was necessary to secure the sealing property.

Therefore, in such a sealing device, the size of the device is increased due to the need for a pump, and the cost is high, which is a problem.

An object of the present invention is to provide a sealing device which solves the above problems, has a simple structure, and can reduce the cost.

[0017]

[Means for solving problems]

 In order to solve the above problems, the present invention provides a shaft rotatably in a hole 1a of a main body in which a high pressure is applied from one side and a low pressure is applied from the other side. In a sealing device configured to hold a magnetic fluid by a magnetic action between the hole and to seal between the low pressure and the high pressure, a screw-shaped portion is provided on the shaft and the screw-shaped portion is provided. The magnetic fluid is retained between the top of the portion and the hole by the action of magnetism, and when the shaft rotates, an intermediate portion is formed between the high pressure side and the low pressure side in the hole via the groove portion of the threaded portion. A means for allowing a pressure chamber to be formed is adopted, and a means for forming a ridge projecting around the shaft at the end of the threaded portion provided on the shaft is adopted. , The threaded part of the shaft is It is obtained by employing means that are formed on the path shape.

[0018]

[Action]

 This device adopts the above-mentioned means, so that the magnetic fluid holds the magnetic fluid between the hole and the shaft of the main body, and the magnetic fluid seals between the high pressure side and the low pressure side. Is becoming

Then, the rotation of the shaft allows the pressure inside the hole of the main body to be discharged through the groove portion of the screw-like portion or the pressure to be introduced into the hole of the main body. An intermediate pressure chamber having an intermediate pressure between the high pressure side and the low pressure side is formed between the low pressure side and the low pressure side.

Therefore, so-called intermediate drawing can be performed with a simple structure, an intermediate pressure chamber is formed between the high pressure side and the low pressure side, and the pressure difference between the high pressure side and the low pressure side is formed by this intermediate pressure chamber. It can be made smaller.

At the same time, the magnetic fluid held between the screw-shaped portion of the shaft and the hole of the main body is such that the pressure discharged from the hole of the main body due to the action of the screw-shaped portion causes the pressure of the screw-shaped portion and the hole to be restored. It is necessary to prevent the pressure introduced into the intermediate pressure chamber through the gap between them or the pressure introduced into the hole of the main body from flowing out again through the gap between the threaded portion and the hole. It has become. As a result, the pressure in the intermediate pressure chamber can be maintained more appropriately.

[0022]

【Example】

 Embodiments of the present invention shown in the drawings will be described below.

FIG. 1 is a diagram showing an embodiment of the present invention.

That is, the sealing device shown in FIG. 1 is a magnetic fluid sealing device that seals the inside and the outside of the main body 1 with the magnetic fluid 5, and is a high pressure side atmosphere side A and a low pressure side vacuum side. A shaft 6 having a ridge 7a and a threaded portion 7b is rotatably passed through a hole 1a of the main body 1 which defines the side B, and the ridge 7a of the shaft 6 and the screw A yoke 4a and a yoke 4b are arranged at a position slightly separated from the shaft 6 at a portion of the main body 1 corresponding to the shape portion 7b, and a magnet 3 is arranged between the yoke 4a and the yoke 4b. Has been done.

By disposing the magnetic fluid 5 between the ridge 7a of the shaft 6 and the yoke 4a, and between the ridge 7b and the yoke 4b, the action of magnetism generated by the magnet 3 is obtained. At this point, the magnetic fluid 5 is retained in a film shape between the ridge 7a and the yoke 4a and between the threaded portion 7b and the yoke 4b. Thus, the air side A and the vacuum side B are sealed.

In FIG. 1, A is the atmospheric side and B is the vacuum side, and the main body 1 divides the atmospheric side A and the vacuum side B.

The shaft 6 extends from the atmosphere side A to the vacuum side B in the hole 1 a formed in the main body 1, and the shaft 6 is rotatably held. The shaft 6 is provided with a ridge 7a at a portion near the vacuum side B of a portion corresponding to the hole 1a of the main body 1, and a threaded portion 7b at a portion near the atmosphere side A.

The ridge 7a of the shaft 6 is formed by ridges 8 projecting around the shaft 6 in a plurality of steps, and the threaded portion 7b has an "left-hand thread" in the axial direction. And has a thread groove 9 and a thread 10, respectively.

A yoke 4a is provided at a portion of the main body 1 corresponding to the convex streak portion 7a of the shaft 6, and a yoke 4b is provided at a portion of the main body 1 corresponding to the threaded portion 7b. Each of the yokes 4a and 4b has an annular shape, and the yoke 4a and the yoke 4b are fixed to the main body 1 in a state where the inner peripheral surface thereof is slightly separated from the shaft 6.

At this time, the yoke 4a and the yoke 4b are arranged so as to be separated from each other at a required interval, and the magnet 3 is arranged between the two yokes 4a and 4b. The magnet 3 is fixed to the body 1 so that one magnetic pole of the magnet 3 is in contact with the end of the yoke 4a and the other magnetic pole is in contact with the end of the yoke 4b. Pass through the yokes 4a and 4b.

An annular intermediate pressure chamber 2 is formed in a space surrounded by the two yokes 4 a and 4 b, the magnet 3 and the shaft 6. When the magnetic fluid 5 is not installed in the sealing device, the intermediate pressure chamber 2 is in communication with the atmosphere side A and the vacuum side B, and the magnetic fluid 5 has a shaft 6 as shown in the drawing. When it is arranged between the ridge 7a and the yoke 4a and between the threaded portion 7b and the yoke 4b, the pressure chamber 2 and the vacuum side B are blocked by the magnetic fluid 5. Further, the intermediate pressure chamber 2 and the atmosphere side A are electrically connected via a screw groove 9.

Next, the operation of the above will be described.

By configuring the sealing device as described above, the space between the ridge 7a of the shaft 6 and the yoke 4a in the hole 1a of the main body 1, and between the screw-shaped portion 7b and the yoke 4b. When the magnetic fluid 5 is disposed between the ridges, the magnetic fluid 5 is retained by the magnetism of the magnet 3 between the ridge 7a and the yoke 4a and between the threaded portion 7b and the yoke 4b. The Rukoto.

At this time, the magnetic fluid 5 is provided between the ridge 8 of the ridge 7a of the shaft 6 and the yoke 4a, and between the thread 10 and the yoke 4b of the threaded portion 7b. Also, the shaft 6 and the yokes 4a and 4b are sealed with the magnetic fluid 5 because they are held in a film shape along the thread 10 and the atmosphere side A and the vacuum side B are sealed. It has become so.

Here, when the shaft 6 is rotated in the direction of arrow X, that is, to the left when viewed from the atmosphere side A toward the vacuum side B, the inside of the intermediate pressure chamber 2 becomes the atmosphere side A and the vacuum side B. The pressure difference between the intermediate pressure chamber 2 and the vacuum side B becomes smaller than the pressure difference between the atmosphere side A and the vacuum side B, due to the low vacuum state of the intermediate pressure between and. Therefore, the magnetic fluid 5 held in the form of a film between the ridge 7a of the shaft 6 and the yoke 4a is prevented from being perforated.

That is, since the threaded portion 7 b of the shaft 6 is formed in a “left-handed thread” shape, when the shaft 6 is rotated in the arrow X direction, the pressure difference between the atmosphere side A and the intermediate pressure chamber 2 is increased. Occurs, the air in the intermediate pressure chamber 2 is discharged from the screw groove 9 to the atmosphere side A, so that the intermediate pressure chamber 2 can be brought into a low vacuum state.

At this time, the magnetic fluid 5 arranged between the threaded portion 7 b of the shaft 6 and the yoke 4 b is held in a film shape along the thread 10 by the magnetic action of the magnet 3. Therefore, the air on the atmosphere side A is prevented from flowing into the intermediate pressure chamber 2 through the gap between the threaded portion 7b of the shaft 6 and the yoke 4b, and the inside of the intermediate pressure chamber 2 is efficiently It can maintain a low vacuum.

Next, FIG. 2 shows an example in which the sealing device shown in FIG. 1 is used for sealing a high-pressure liquid.

The sealing device shown in FIG. 2 is the same sealing device as the sealing device shown in FIG. 1, and parts having the same functions are designated by the same reference numerals as those in FIG.

A is the low-pressure side atmosphere side, and B is the high-pressure side high-pressure liquid enclosed side, both are partitioned by the main body 1, and a magnetic fluid 5 seals the two sides. Has been done.

In this case, the shaft 6 rotates in the direction of the arrow Y, that is, to the right when viewed from the atmosphere side A toward the high-pressure liquid side C, and the inside of the intermediate pressure chamber 2 is compared to the atmosphere side A. It is in an extremely high pressure state. As a result, the pressure difference between the intermediate pressure chamber 2 and the high-pressure liquid side C can be reduced, and the magnetic fluid 5 retained in a film shape between the ridge 7a of the shaft 6 and the yoke 4a. There is no hole in it.

That is, since the threaded portion 7 b of the shaft 6 is formed in a “left-handed thread” shape, when the shaft 6 is rotated in the arrow Y direction, the pressure difference between the atmosphere side A and the intermediate pressure chamber 2 is increased. Occurs, the air on the atmosphere side A is introduced into the intermediate pressure chamber 2 through the thread groove 9, and the intermediate pressure chamber 2 can be set to a relatively higher pressure than the atmosphere side A.

Therefore, the pressure difference between the high-pressure liquid side B and the pressure chamber 2 is smaller than the pressure difference between the high-pressure liquid side B and the atmosphere side A, so that the membranous magnetic fluid 5 The hole is not opened, and the sealing property is secured.

At this time, the magnetic fluid 5 arranged between the threaded portion 7 b of the shaft 6 and the yoke 4 b is held in a film shape along the thread 10 by the magnetic action of the magnet 3. Therefore, the magnetic fluid 5 prevents the air in the intermediate pressure chamber 2 from flowing out to the atmosphere side A from the gap between the threaded portion 7b of the shaft 6 and the yoke 4b. The inside can be maintained at a relatively high pressure.

Next, a modified example of the sealing device shown in FIG. 1 is shown in FIG.

That is, in the sealing device shown in FIG. 3, the ridge 11 is formed in a portion of the shaft 6 on the atmosphere side of the threaded portion 7 b.

The ridge 11 corresponds to the yoke 4 b, and the magnetic fluid 5 is held in a film shape along the ridge 11 by the action of magnetism of the magnet 3.

Normally, when the rotation speed of the shaft 6 is low, the magnetic fluid 5 held between the threaded portion 7 b and the yoke 4 b follows the rotation of the shaft 6 by the magnetic action of the magnet 3. Although the state of the membrane is maintained, when the rotation speed of the shaft 6 increases, the magnetic fluid 5 may flow out to the atmosphere side A due to the flow of air discharged from the intermediate pressure chamber 2.

Therefore, as shown in FIG. 3, a ridge 11 is formed on a portion of the screw-shaped portion 7b of the shaft 6 near the atmosphere side A, and the magnetic fluid 5 is held in a film shape at the portion of the ridge 11. By doing so, it is possible to prevent the magnetic fluid 5 held in the form of a film along the thread 10 of the threaded portion 7b from flowing out to the atmosphere side A, especially when the shaft 6 is rotating at a high speed. Is becoming

Therefore, even if the shaft 6 rotates at a high speed, the intermediate pressure chamber 2 can be maintained in a true air state, and the sealability as designed can be secured.

In FIG. 3, the sealing device has the same operation as that shown in FIG. 1 but is given the same reference numeral, and therefore the detailed description of the configuration is omitted.

Note that, in FIG. 3, when the high-pressure liquid is sealed and sealed on the B side, the ridge 11 may be formed at a portion of the ridge 7 b of the shaft 6 on the intermediate pressure chamber 2 side. Good. At this time, it goes without saying that the rotation direction of the shaft 6 is opposite to the arrow X direction.

Next, another modified example of the sealing device shown in FIG. 1 is shown in FIG.

That is, in the sealing device shown in FIG. 4, the screw diameter of the threaded portion 7b of the shaft 6 is gradually increased from the atmospheric side A toward the intermediate pressure chamber 2 side so that the threaded portion 7b is tapered. It was formed.

As a result, the outer peripheral portion of the threaded portion 7b of the shaft 6 on the side of the intermediate pressure chamber 2 is closer to the yoke 4b than the outer peripheral portion of the threaded portion 7b on the atmosphere side A side. The holding force with respect to the magnetic fluid 5 due to the action of air gradually increases from the atmosphere side A of the threaded portion 7b toward the pressure chamber 2 side.

Therefore, the magnetic fluid 5 disposed between the threaded portion 7b of the shaft 6 and the yoke 4b is always subjected to the component force to the intermediate pressure chamber 2 side. It becomes possible to prevent the magnetic fluid 5 from flowing out to the atmosphere side A when the air in the pressure chamber 2 is discharged to the atmosphere side A.

In FIG. 4, the sealing device has the same operation as that shown in FIG. 1 but is given the same reference numeral, and therefore the detailed description of the configuration is omitted.

Further, in FIG. 4, when the high-pressure liquid is sealed and sealed on the B side, the screw-shaped portion 7 b of the shaft 6 is moved from the intermediate pressure chamber 2 to the atmosphere side A by the screw diameter. You may form in the taper shape which increases gradually toward. At this time, the rotation direction of the shaft 6 is, of course, opposite to the arrow X.

It should be noted that in the above-described embodiment, its modification, and other modifications, the threaded portion 7b of the shaft 6 may be formed in a "right-handed thread" shape. In this case, it goes without saying that the rotation direction of the shaft 6 is opposite to the arrow X.

[0060]

[Effect of the device]

 As described above, according to the present invention, by forming the threaded portion on the shaft, the pressure is introduced into the hole of the main body or the pressure is discharged from the hole of the main body when the shaft rotates. In this way, an intermediate pressure chamber that is in an intermediate pressure state between the high pressure side and the low pressure side is formed in the hole of the main body, so that the pump conventionally required for so-called intermediate pulling is unnecessary. Therefore, it is possible to increase or decrease the pressure in the intermediate pressure chamber and perform intermediate pulling with a simple structure.

Therefore, the device can be simplified and the cost can be reduced.

Further, at the same time, by holding the magnetic fluid between the threaded portion of the shaft and the yoke, the pressure introduced into the intermediate pressure chamber again flows between the threaded portion and the yoke and flows outward. Alternatively, it is possible to prevent the pressure discharged from the intermediate pressure chamber from flowing into the pressure chamber again through the space between the screw-shaped portion and the yoke, which makes it possible to more efficiently move the intermediate pressure chamber to the high pressure side. There is an effect that it is possible to maintain a predetermined pressure state at an intermediate position with respect to the low pressure side.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram illustrating another usage example of the sealing device shown in FIG.

FIG. 3 is a view showing a modified example of the sealing device shown in FIG.

FIG. 4 is a diagram showing another modification of the sealing device shown in FIG.

FIG. 5 is a diagram showing a conventional example.

[Explanation of symbols]

 1, 21 ...... Main body 2 ...... Intermediate pressure chamber 3,23 ...... Magnets 4a, 4b, 24a, 24b ...... Yoke 5, 25 ...... Magnetic fluid 6, 26 ...... Shaft 7a ...... Convex section 7b ...... Screw-shaped portion 8, 11, 28, 30 ... Convex strip 9 ... Screw groove 10 ... Screw thread 22 ... Pressure chamber 27a ... First convex strip portion 27b ... Second convex strip portion 31 ... Communication hole 32 ... Pump A ... Atmosphere side B ... Vacuum side C ... High pressure fluid

Claims (3)

[Scope of utility model registration request] 1. A shaft (6) is rotatably provided in a hole (1a) of a main body (1) in which a high pressure is applied from one side and a low pressure is applied from the other side. In a sealing device configured to hold a magnetic fluid (5) by a magnetic action between the hole (1a) and seal between the low pressure and the high pressure, a screw-like screw is provided on the shaft (6). The portion (7b) is provided, and the magnetic fluid (5) is retained between the top portion (10) of the screw-shaped portion (7b) and the hole (1a) by the action of magnetism, so that the shaft (6) When rotating, an intermediate pressure chamber (2) is formed between the high pressure side and the low pressure side in the hole (1a) via the groove portion (9) of the screw shaped portion (7b). And a sealing device. 2. The hermetic seal according to claim 1, wherein a ridge (11) protruding around the shaft (6) is formed at an end of a threaded portion (7b) provided on the shaft (6). apparatus. 3. A threaded portion (7b) of the shaft (6).
The sealing device according to claim 1, wherein the seal is formed in a tapered shape.