JP2003329145A - Magnetic fluid sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high performance magnetic fluid sealing device having a long life. <P>SOLUTION: The property variation by evaporation of a magnetic fluid 4 is reduced by coating the magnetic fluid 4 with a coating fluid 5, thereby, the life of the device is prolonged. Variation of the oil-repellent property of a surface modification film 6 is reduced by preventing the magnetic fluid 4 from directly contacting with the surface modification film 6, thereby, the life of the device is also prolonged. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relative magnetic fluid seal device, for example, a dust seal device for a precision machine, a vacuum seal device, a light-shielding seal device for a zoom lens of a camera, a drip-proof seal device, and the like. It is applied.

[0002]

2. Description of the Related Art Conventionally, an O-ring or packing made of an elastic material such as rubber or resin is usually used as a sealing device for sealing a gap between a shaft and a housing, which are two members that relatively move. It was being done.

However, in the sealing device using these elastic materials, since the solids of the sealing device and the shaft are in sliding contact with each other to exert a sealing function, friction loss increases and wear of the sliding portion occurs. Due to the deterioration of the sealing function due to, the problem that it cannot withstand long-term use, the problem that abrasion powder stains the inside of the device, the problem that the shape of elastic material deforms due to friction resistance and seal leakage occurs, the shaft can be scratched There was a problem such as seal leakage.

Therefore, a magnetic fluid sealing device may be used as a sealing device for solving such a problem.

A conventional magnetic fluid seal device uses a magnetic fluid having a characteristic capable of being adsorbed and held in a strong magnetic field portion as shown in FIGS. The sealing between the two regions is performed by bringing the magnetic fluid magnetically held by the magnetic flux of the magnetic circuit formed by the annular magnet provided inside the housing into contact with the shaft.

The construction of the magnetic fluid sealing device shown in FIGS. 15 and 16 includes a shaft 2 made of a magnetic material, a pair of annular pole pieces 8 fixed to a housing 1 surrounding the shaft 2, and a pair of annular members. An annular magnet 3 sandwiched between pole pieces 8 and having different poles (NS poles) magnetized in the axial direction, and a magnetic fluid 4 are provided.

The shaft 2, the pair of pole pieces 8 and the ring-shaped magnet 3 form a magnetic circuit that makes one round, and the magnetic fluid 4 is held between the shaft 2 and each ring-shaped pole piece 8. Exerts a sealing function.

In the magnetic fluid sealing device shown in FIGS. 15 and 16, the shaft 2 and the magnetic fluid 4 are in contact with each other.
Since there is no sliding part between solids, friction loss is small, and since there is no wear, dust is not generated and it can withstand long-term use.

This magnetic fluid seal device is put to practical use as a seal device for a rotary shaft that performs a rotary motion capable of completely sealing with low friction, and is a dust seal device used in magnetic disks for computers, semiconductor manufacturing equipment, etc., and a sealing area. It is applied in various fields such as vacuum sealing devices used in vacuum devices where there is a pressure difference on both sides.

Further, as shown in FIG. 17, the surface of the shaft 2 or the housing 1 in contact with the magnetic fluid 4 is surface-modified with a surface-modifying film 6 so that the magnetic fluid 4 does not get wet. The device can now also be used as a reciprocating seal device.

[0011]

However, in the case of the above-mentioned prior art, the following problems have occurred.

The magnetic fluid seal device of the prior art has a problem that the service life thereof is determined by a characteristic change such as gelation due to evaporation of the base oil of the magnetic fluid or the activator.

When used as a reciprocating seal device, when the magnetic fluid is in contact with the surface modification film on the shaft surface for a long time, the oil repellency of the surface modification film gradually changes. Since the contact time at the position in the stopped state is the longest, there is a problem that the change in oil repellency at the position in the stopped state determines the life.

Furthermore, it takes time and effort to bond the housing and the fixed portion, and it has been desired to facilitate the mounting.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a high-performance magnetic fluid seal device having a long life.

[0016]

In order to achieve the above object, the present invention provides a magnetic fluid seal device for sealing between two members assembled so as to be movable relative to each other.
By a magnetic circuit forming means that is arranged between two members and forms a magnetic circuit that allows a magnetic flux to pass through a gap between at least one of the two members, and a magnetic flux that passes through the gap of the magnetic circuit formed by the magnetic circuit forming means. A magnetic fluid that is magnetically held and contacts at least one of the surfaces of the two members to seal the gap, and that the compatibility with the magnetic fluid is low and the surface tension is smaller than the surface tension of the magnetic fluid. And a coating fluid that coats the surface of the magnetic fluid.

Here, the coating amount of the coating fluid is sufficient if a monomolecular layer is formed, but it is determined from the operating environment, the evaporation rate of the coating fluid, and the required life in consideration of the decrease due to the evaporation of the coating fluid itself. To do.

According to this structure, by coating the magnetic fluid with the coating fluid, it is possible to reduce characteristic changes due to evaporation of the magnetic fluid, and it is possible to prolong the life of the apparatus.

It is preferable that after the magnetic fluid is filled, the coating fluid is dropped on the surface of the magnetic fluid to coat the surface of the magnetic fluid with the coating fluid.

According to this, the magnetic fluid can be satisfactorily coated with the coating fluid.

The magnetic fluid and the coating fluid are mixed and filled in an emulsion state, and only the magnetic fluid is attracted by the magnetic flux of the magnetic circuit forming means to coat the surface of the magnetic fluid with the coating fluid. Is preferred.

According to this, the magnetic fluid can be satisfactorily coated with the coating fluid.

While the magnetic fluid is hydrocarbon-based, it is preferable to use silicone oil or fluorine-based oil as the coating fluid.

According to this, the coating of the coating fluid can be favorably maintained.

At least one of the surfaces of the two members that come into contact with the magnetic fluid is subjected to an oil repellent treatment by a surface modification film, and the coating fluid has a surface tension larger than the surface tension of the surface modification film. It is preferable that the surface modified film does not change the oil repellency.

According to this, direct contact between the magnetic fluid and the surface modification film can be prevented, change in oil repellency of the surface modification film can be reduced, and the life of the device can be extended.

While the magnetic fluid is hydrocarbon-based and the surface modification film is a fluorine-based surface modification film, it is preferable to use silicone oil or fluorine-based oil as the coating fluid.

According to this, the coating of the coating fluid can be favorably maintained.

It is preferable to dispose a porous body impregnated with the coating fluid at a position in contact with the magnetic fluid and the coating fluid.

According to this, the coating fluid for coating the magnetic fluid can be replenished from the porous body, and the life can be further extended.

The magnetic circuit forming means is fixed to the other of the two members, and it is preferable that the magnetic flux be passed through the gap between the one of the two members.

According to this, the magnetic fluid is held in the gap between the magnetic circuit forming means and one of the two members, and the gap is sealed.

It is preferable to interpose an elastic body between the magnetic circuit forming means and the other of the two members.

According to this, the adhesion at the time of attaching the magnetic circuit forming means is not required, which does not require any trouble and facilitates the attachment.

It is preferable that the magnetic circuit forming means is provided so as to be relatively movable in the radial direction and the axial direction between the two members, and is floated and supported by the magnetic fluid.

According to this, the position of the magnetic circuit means can be moved while maintaining the sealing property by the magnetic fluid at the time of eccentricity, and the followability at the time of eccentricity is improved.

It is preferable to include a sleeve that encloses the magnetic circuit forming means and is fixed to the other of the two members so that the magnetic circuit forming means can be relatively moved between the two members in the radial direction and the axial direction. Is.

According to this, the movable area of the magnetic circuit forming means can be defined by the sleeve.

It is preferable to interpose an elastic body between the sleeve and the other of the two members.

According to this, the attachment at the time of attaching the sleeve is not required, which does not require any labor and facilitates the attachment.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions of the components described in this embodiment,
Unless otherwise specified, the material, the shape, the relative arrangement, and the like are not intended to limit the scope of the present invention thereto. Further, the materials, shapes, and the like of the members once described in the following description are the same as those in the first description unless otherwise specified.

In the present embodiment, the magnetic fluid sealing device is applied as a dust sealing device for a precision machine, a vacuum sealing device, a light-shielding sealing device for a zoom lens portion or a focus lens portion of a compact camera, a drip-proof sealing device, or the like. .

(First Embodiment) The structure of the magnetic fluid seal device according to the first embodiment will be described with reference to FIG. FIG. 1 is a half sectional view showing a magnetic fluid sealing device according to a first embodiment.

The magnetic fluid seal device shown in FIG. 1 has a cylindrical housing 1 as two members that can rotate and reciprocate.
And the shaft 2 inserted into the housing 1 are provided. Relative rotary motion and relative reciprocating motion are performed between the housing 1 and the shaft 2, and in this embodiment, only the shaft 2 rotates and reciprocates. The housing 1 and the shaft 2 are made of a non-magnetic material.

The magnetic fluid seal device includes a pair of ring-shaped magnets 3 attached to the housing 1 and bonded with the same poles magnetized in the axial direction, and a magnetic fluid 4 held inside the pair of ring-shaped magnets 3. A coating fluid 5 for coating the magnetic fluid 4, and a surface modification film 6 on the surface of the shaft 2 as an oil repellent treatment.
And

Here, the pair of annular magnets 3 serve as a magnetic circuit forming means. The magnetic fluid 4 is magnetically held by the magnetic flux passing through the gap between the shaft 2 and the ring magnet 3 of the magnetic circuit formed by the pair of ring magnets 3. In the present embodiment, the pair of annular magnets 3 are in a state where the same poles that are magnetized in the axial direction are adhered, and a method of increasing the magnetic flux density at the central portion in the axial direction is adopted. Further, the method of adhering the pair of annular magnets 3 is not limited to the method of adhering the same poles magnetized in the axial direction.

As the annular magnet 3, a permanent magnet made of a monopolar or multipolar magnetized metal or an organic material filled with magnet powder can be used. In this embodiment, a ring-shaped plastic magnet is used as an example. To use. Besides, a rubber magnet or the like can also be used.

A hydrocarbon-based fluid is used as the magnetic fluid 4.

As the surface modification film 6, a fluorine-based surface modification film is used.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4. Further, the coating fluid 5 has a surface tension higher than that of the surface modification film 6 and does not change the oil repellency of the surface modification film 6.

Here, the coating amount of the coating fluid 5 is sufficient if a monomolecular layer is formed, but in consideration of the decrease due to evaporation of the coating fluid 5 itself, the use environment, the evaporation rate of the coating fluid, and the required life. To decide from.

As the coating fluid 5, fluorine oil can be used in addition to silicone oil.

The coating fluid 5 is dropped onto the surface of the magnetic fluid 4 after filling the holding position of the magnetic fluid 4 to coat the surface of the magnetic fluid 4. As a result, the magnetic fluid 4 can be coated well.

In addition to the above method of dropping the coating fluid 5 on the surface of the magnetic fluid 4, the magnetic fluid 4 and the coating fluid 5
It is also possible to adopt a method in which the coating fluid 5 coats the surface of the magnetic fluid 4 by mixing and filling in an emulsion state and filling, and attracting only the magnetic fluid 4 by the magnetic flux of the annular magnet 3.

In the magnetic fluid sealing device having the above-described structure, the magnetic fluid 4 is coated with the coating fluid 5 so that the magnetic fluid 4 is covered.
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

Further, direct contact between the magnetic fluid 4 and the surface reforming film 6 can be prevented, and the change in oil repellency of the surface reforming film 6 can be reduced, which also makes it possible to prolong the life of the device. .

(Second Embodiment) FIG. 2 shows a magnetic fluid seal device according to a second embodiment. In the second embodiment, the sleeve 7 is fixed to the housing 1, and the sleeve 7 includes a pair of annular magnets 3 so as to be relatively movable in the radial direction and the axial direction. The other structure is the same as that of the first embodiment.

In this embodiment, the sleeve 7 fixed to the housing 1 is provided. The sleeve 7 is made of polyphenylene oxide, which is a cylindrical non-magnetic material, and is formed with a recessed central portion so that the projecting portions project in the inner diameter direction at both axial end portions.

Then, a pair of annular magnets 3 are placed in the recess.
Are arranged with a gap. Therefore, the pair of annular magnets 3 can be relatively moved in the radial direction and the axial direction only in the gap portion of the recess.

The sleeve 7 has an elastic deformation characteristic that allows the pair of annular magnets 3 to be inserted into the concave portion of the sleeve 7, and the pair of annular magnets 3 can be smoothly mounted.

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

As the magnetic fluid 4, a hydrocarbon-based one is used.

As the surface modification film 6, a fluorine-based surface modification film is used.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4. Further, the coating fluid 5 has a surface tension higher than that of the surface modification film 6 and does not change the oil repellency of the surface modification film 6.

In the magnetic fluid sealing device having the above-described structure, the magnetic fluid 4 is coated with the coating fluid 5 to cover the magnetic fluid 4.
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

Further, direct contact between the magnetic fluid 4 and the surface modification film 6 can be prevented, and the change in oil repellency of the surface modification film 6 can be reduced, which also makes it possible to prolong the life of the device. .

Further, in such a magnetic fluid seal device, the magnetic fluid 4 held by the pair of annular magnets 3 is floated and supported, and the pair of annular magnets 3 are radially and axially arranged in the concave portion of the sleeve 7. Since they can be moved relative to each other, the position of the pair of annular magnets 3 can be moved while the sealing property of the magnetic fluid 4 remains the same at the time of eccentricity, and the followability at the time of eccentricity of the device is improved.

(Third Embodiment) FIG. 3 shows a magnetic fluid seal device according to a third embodiment. In the third embodiment, a magnetic fluid seal device using the coating fluid 5 is applied to a rotary dust seal device.

The magnetic fluid sealing device shown in FIG. 3 is provided between a cylindrical housing 1 as two rotatable members and a shaft 2 inserted in the housing 1.
A relative rotational movement is performed between the housing 1 and the shaft 2, and only the shaft 2 rotates in this embodiment. The housing 1 is made of a non-magnetic material, and the shaft is made of a magnetic material.

The magnetic fluid seal device includes a pair of pole pieces 8 attached to the housing 1, an axially magnetized annular magnet 3 sandwiched between the pair of pole pieces 8, and a pair of pole pieces 8. The magnetic fluid 4 held at the tip of the inner periphery of the magnetic recording medium and the coating fluid 5 coating the magnetic fluid 4 are provided.

The pole piece 8 has a gap for holding the magnetic fluid 4 with the shaft 2 and is fitted to the inner circumference of the housing 1.

Here, a magnetic circuit is formed around the annular magnet 3, the pole piece 8, the shaft 2, and the pole piece 8, and these are magnetic circuit forming means. The magnetic fluid 4 is magnetically held by the magnetic flux passing through the gap between the pole piece 8 and the shaft 2 of the magnetic circuit.

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

A hydrocarbon-based fluid is used as the magnetic fluid 4.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4.

A bearing 9 is arranged next to the magnetic fluid seal device.

In the magnetic fluid sealing device having the above-described structure, the magnetic fluid 4 is coated with the coating fluid 5 to form the magnetic fluid 4.
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

(Fourth Embodiment) FIG. 4 shows a magnetic fluid seal device according to a fourth embodiment. In the fourth embodiment, a magnetic fluid seal device using the coating fluid 5 is applied to a rotary vacuum seal device.

The magnetic fluid sealing device shown in FIG. 4 is provided between a cylindrical housing 1 as two rotatable members and a shaft 2 inserted in the housing 1.
A relative rotational movement is performed between the housing 1 and the shaft 2, and only the shaft 2 rotates in this embodiment. The housing 1 is made of a non-magnetic material, and the shaft 2 is made of a magnetic material.

The magnetic fluid seal device includes a pair of pole pieces 8 attached to the housing 1, an axially magnetized annular magnet 3 sandwiched between the pair of pole pieces 8, and a pair of pole pieces 8. The magnetic fluid 4 held at the tip of the inner periphery of the magnetic recording medium and the coating fluid 5 coating the magnetic fluid 4 are provided.

In the present embodiment, on the surface of the shaft 2,
A plurality of protrusions 2 a are formed so as to face the pole piece 8.

The pole piece 8 has a gap for holding the magnetic fluid 4 between itself and the shaft 2, and is fitted to the inner circumference of the housing 1. Between the pole piece 8 and the housing 1,
An O-ring 10 inserted in an O-ring groove formed on the outer circumference of the pole piece 8 is interposed.

Here, a magnetic circuit is formed around the annular magnet 3, the pole piece 8, the shaft 2, and the pole piece 8, and these are magnetic circuit forming means. The magnetic fluid 4 is magnetically held by the magnetic flux passing through the gap between the pole piece 8 of the magnetic circuit and the protrusion 2a of the shaft 2.

Therefore, in this embodiment, the magnetic fluid 4 is held between the pole piece 8 and each projection 2a of the shaft 2.

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

A hydrocarbon-based fluid is used as the magnetic fluid 4.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4.

Bearings 9 are arranged on both sides of the magnetic fluid seal device.

In the magnetic fluid sealing device having the above-described structure, the magnetic fluid 4 is coated with the coating fluid 5 to cover the magnetic fluid 4.
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

(Fifth Embodiment) FIG. 5 shows a magnetic fluid seal device according to a fifth embodiment. In the fifth embodiment, a magnetic fluid seal device using the coating fluid 5 is applied to a rotary dust seal device.

The magnetic fluid seal device shown in FIG. 5 is provided between a cylindrical housing 1 as two rotatable members and a shaft 2 inserted in the housing 1.
A relative rotational movement is performed between the housing 1 and the shaft 2, and only the shaft 2 rotates in this embodiment. The housing 1 and the shaft 2 are made of a non-magnetic material.

The magnetic fluid seal device includes a pair of annular magnets 3 to which the same poles that are magnetized in the axial direction are adhered, a magnetic fluid 4 held on the inner and outer circumferences of the pair of annular magnets 3, and a magnetic fluid 4. A coating fluid 5 for coating and a sleeve 7 fixed to the housing 1 are provided.

Here, the pair of annular magnets 3 serve as magnetic circuit forming means. The magnetic fluid 4 is magnetically held by the magnetic flux passing through the gap between the shaft 2 and the ring magnet 3 of the magnetic circuit formed by the pair of ring magnets 3. Further, the magnetic fluid 4 is magnetically held by the magnetic flux passing through the gap between the annular magnet 3 and the sleeve 7.

The sleeve 7 is made of polyphenylene oxide, which is a cylindrical non-magnetic material, and is formed with a recessed central portion so that the projecting portions project radially inward at both axial end portions.

Then, a pair of annular magnets 3 are placed in the recess.
Are arranged with a gap. Therefore, the pair of annular magnets 3 can be relatively moved in the radial direction and the axial direction only in the gap portion of the recess.

The sleeve 7 has an elastic deformation characteristic that allows the pair of annular magnets 3 to be inserted into the concave portion of the sleeve 7, so that the pair of annular magnets 3 can be smoothly mounted.

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

A hydrocarbon-based fluid is used as the magnetic fluid 4.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4.

A bearing 9 is arranged next to the magnetic fluid seal device.

In the magnetic fluid sealing device having the above-described structure, the magnetic fluid 4 is coated with the coating fluid 5, and thus the magnetic fluid 4 is coated.
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

Further, in such a magnetic fluid sealing device, the magnetic fluid 4 held by the pair of annular magnets 3 is floated and supported, and the pair of annular magnets 3 are radially and axially arranged in the concave portion of the sleeve 7. Since they can be moved relative to each other, the position of the pair of annular magnets 3 can be moved while the sealing property of the magnetic fluid 4 remains the same when the device is eccentric, and the followability when the device is eccentric or the like is improved.

(Sixth Embodiment) FIG. 6 shows a magnetic fluid seal device according to a sixth embodiment. In the sixth embodiment, the coated fluid impregnated sleeve 11 is made of a porous material.
It is equipped with.

The magnetic fluid seal device shown in FIG. 6 has a cylindrical housing 1 as two members which can rotate and reciprocate.
And the shaft 2 inserted into the housing 1 are provided. Relative rotary motion and relative reciprocating motion are performed between the housing 1 and the shaft 2, and in this embodiment, only the shaft 2 rotates and reciprocates. The housing 1 and the shaft 2 are made of a non-magnetic material.

The magnetic fluid seal device includes a pair of annular magnets 3 having the same poles magnetized in the axial direction adhered thereto, a magnetic fluid 4 held on the inner circumference of the pair of annular magnets 3, and a magnetic fluid 4. A coating fluid 5 for coating, a surface modification film 6 on the surface of the shaft 2 that is subjected to oil repellent treatment, and a coating fluid impregnated sleeve 11 that is fixed to the housing 1 so as to surround the pair of annular magnets 3.
And

Here, the pair of annular magnets 3 serve as magnetic circuit forming means. The magnetic fluid 4 is magnetically held by the magnetic flux passing through the gap between the shaft 2 and the ring magnet 3 of the magnetic circuit formed by the pair of ring magnets 3.

The coated fluid impregnated sleeve 11 is a cylindrical non-magnetic material, and has a recessed central portion so that the projecting portions project radially inward at both axial end portions. Then, a pair of annular magnets 3 is arranged in this recess.

The coated fluid-impregnated sleeve 11 has an elastic deformation characteristic that allows the pair of annular magnets 3 to be inserted into the recesses of the coated fluid-impregnated sleeve 11, so that the pair of annular magnets 3 can be smoothly mounted. .

The coated fluid impregnated sleeve 11 may have a structure which does not have elastic deformation characteristics and which allows a pair of annular magnets 3 to be mounted.

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

As the magnetic fluid 4, a hydrocarbon-based one is used.

As the surface modification film 6, a fluorine-based surface modification film is used.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4. Further, the coating fluid 5 has a surface tension higher than that of the surface modification film 6 and does not change the oil repellency of the surface modification film 6.

Here, the tip of the protruding portion of the coating fluid-impregnated sleeve 11 is configured to come into contact with both the magnetic fluid 4 and the coating fluid 5. Thereby, the coating fluid 5 can be replenished from the coating fluid impregnated sleeve 11.

In the magnetic fluid sealing device having the above-described structure, the magnetic fluid 4 is covered with the coating fluid 5 to thereby cover the magnetic fluid 4.
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

Further, direct contact between the magnetic fluid 4 and the surface modification film 6 can be prevented, and the change in oil repellency of the surface modification film 6 can be reduced, which also makes it possible to prolong the life of the device. .

Further, the coating fluid 5 for coating the magnetic fluid 4
Can be replenished from the coated fluid-impregnated sleeve 11, and the life can be further extended.

(Seventh Embodiment) FIG. 7 shows a magnetic fluid seal device according to a seventh embodiment. In the seventh embodiment, the coated fluid impregnated sleeve 11 is used as a porous body.
And a coated fluid impregnated sleeve 11 and a pair of annular magnets 3
A gap is formed between the and.

The magnetic fluid seal device shown in FIG. 7 has a cylindrical housing 1 as two members that can rotate and reciprocate.
And the shaft 2 inserted into the housing 1 are provided. Relative rotary motion and relative reciprocating motion are performed between the housing 1 and the shaft 2, and in this embodiment, only the shaft 2 rotates and reciprocates. The housing 1 and the shaft 2 are made of a non-magnetic material.

The magnetic fluid seal device includes a pair of annular magnets 3 to which the same poles that are magnetized in the axial direction are adhered, a magnetic fluid 4 held inside the pair of annular magnets 3, and a magnetic fluid 4. A coating fluid 5 for coating, a surface-modified film 6 on the surface of the shaft 2 that has been subjected to an oil repellent treatment, a coating fluid impregnated sleeve 11 that surrounds the pair of annular magnets 3 with a gap and is fixed to the housing 1, Equipped with.

Here, the pair of annular magnets 3 are magnetic circuit forming means. The magnetic fluid 4 is magnetically held by the magnetic flux passing through the gap between the shaft 2 and the ring magnet 3 of the magnetic circuit formed by the pair of ring magnets 3.

The coated fluid impregnated sleeve 11 is a cylindrical non-magnetic material, and has a recessed central portion so that the projecting portions project in the inner diameter direction at both axial end portions. Then, a pair of annular magnets 3 are arranged in the recess with a gap. Therefore, the pair of annular magnets 3 can be relatively moved in the radial direction and the axial direction only in the gap portion of the recess.

The coated fluid-impregnated sleeve 11 has an elastic deformation characteristic that allows the pair of annular magnets 3 to be inserted into the recesses of the coated fluid-impregnated sleeve 11, so that the pair of annular magnets 3 can be smoothly mounted. .

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

As the magnetic fluid 4, a hydrocarbon-based one is used.

As the surface modified film 6, a fluorine-based surface modified film is used.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4. Further, the coating fluid 5 has a surface tension higher than that of the surface modification film 6 and does not change the oil repellency of the surface modification film 6.

Here, the tip of the protruding portion of the coating fluid-impregnated sleeve 11 is configured to come into contact with both the magnetic fluid 4 and the coating fluid 5. Thereby, the coating fluid 5 can be replenished from the coating fluid impregnated sleeve 11.

In the magnetic fluid sealing device having the above-described structure, the magnetic fluid 4 is coated with the coating fluid 5, and
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

Further, direct contact between the magnetic fluid 4 and the surface reforming film 6 can be prevented, and the change in oil repellency of the surface reforming film 6 can be reduced, which also prolongs the life of the device. .

Further, the coating fluid 5 for coating the magnetic fluid 4
Can be replenished from the coated fluid-impregnated sleeve 11, and the life can be further extended.

Further, in such a magnetic fluid seal device, the magnetic fluid 4 held by the pair of ring-shaped magnets 3 is floated and supported, and the pair of ring-shaped magnets 3 are radially supported in the recess of the coating fluid impregnated sleeve 11. In addition, since it is relatively movable in the axial direction, it is possible to move the positions of the pair of annular magnets 3 while maintaining the sealing property of the magnetic fluid 4 at the time of eccentricity and the like, thereby improving the followability at the time of eccentricity of the device.

(Eighth Embodiment) FIG. 8 shows a magnetic fluid seal device according to an eighth embodiment. In the eighth embodiment, the coated fluid-impregnated annular body 12 is provided as a porous body on both axial end faces of the pair of annular magnets 3.
The other configuration is the same as that of the second embodiment.

In this embodiment, the coated fluid-impregnated annular bodies 12 are provided on both axial end faces of the pair of annular magnets 3, respectively. The coated fluid-impregnated annular body 12 is bonded to the annular magnet 3.

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

As the magnetic fluid 4, a hydrocarbon-based one is used.

As the surface modification film 6, a fluorine-based surface modification film is used.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4. Further, the coating fluid 5 has a surface tension higher than that of the surface modification film 6 and does not change the oil repellency of the surface modification film 6.

Here, the tip of the inner circumference of the coated fluid-impregnated annular body 12 is configured to come into contact with both the magnetic fluid 4 and the coated fluid 5. Thereby, the coated fluid-impregnated annular body 1
It is possible to replenish the coating fluid 5 from 2.

In the magnetic fluid sealing device having the above-described structure, the magnetic fluid 4 is coated with the coating fluid 5, and
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

Further, the direct contact between the magnetic fluid 4 and the surface modification film 6 can be prevented, and the change in oil repellency of the surface modification film 6 can be reduced, which can also prolong the life of the device. .

Further, the coating fluid 5 for coating the magnetic fluid 4
Can be replenished from the coated fluid-impregnated annular body 12, and the life can be further extended.

Further, in such a magnetic fluid seal device, the magnetic fluid 4 held by the pair of annular magnets 3 is levitated and supported, and the pair of annular magnets 3 is attached to the sleeve 7.
Since it is relatively movable in the radial direction and the axial direction in the concave portion of the device, the position of the pair of annular magnets 3 can be moved while maintaining the sealing performance by the magnetic fluid 4 when the device is eccentric, and when the device is eccentric. Trackability is improved.

(Ninth Embodiment) FIG. 9 shows a magnetic fluid seal device according to the ninth embodiment. In the ninth embodiment, the rubber 1 as an elastic body is provided on the outer circumference of the sleeve 7.
It is the one in which 3 was burned. The other structure is the same as that of the fifth embodiment.

In this embodiment, since the rubber 13 is interposed between the sleeve 7 and the housing 1, the sleeve 7
The rubber 13 is baked on the outer periphery of the housing 1 side.

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

A hydrocarbon-based fluid is used as the magnetic fluid 4.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4.

In the magnetic fluid sealing device having the above-described structure, the magnetic fluid 4 is coated with the coating fluid 5, and thus the magnetic fluid 4 is coated.
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

Further, in such a magnetic fluid seal device, the magnetic fluid 4 held by the pair of annular magnets 3 is floated and supported, and the pair of annular magnets 3 are radially and axially arranged in the concave portion of the sleeve 7. Since they can be moved relative to each other, the position of the pair of annular magnets 3 can be moved while the sealing property of the magnetic fluid 4 remains the same when the device is eccentric, and the followability when the device is eccentric or the like is improved.

Since the rubber 13 is baked on the outer periphery of the sleeve 7, no adhesion is required at the time of attaching the sleeve 7, no labor is required, and the attachment can be facilitated.

(Tenth Embodiment) FIG. 10 shows a magnetic fluid seal device according to the tenth embodiment. In the tenth embodiment, an O-ring groove is formed on the outer circumference of the sleeve 7, and the O-ring 14 as an elastic body is attached to the O-ring groove. The other structure is the same as that of the fifth embodiment.

In this embodiment, in order to interpose the O-ring 14 between the sleeve 7 and the housing 1, an O-ring groove is formed on the outer periphery of the sleeve 7 on the housing 1 side, and the O-ring groove is formed in the O-ring groove. 14 is attached.

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

A hydrocarbon-based fluid is used as the magnetic fluid 4.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4.

In the magnetic fluid sealing device having the above-described structure, the magnetic fluid 4 is coated with the coating fluid 5, and
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

Further, in such a magnetic fluid seal device, the magnetic fluid 4 held by the pair of annular magnets 3 is floated and supported, and the pair of annular magnets 3 are radially and axially arranged in the concave portion of the sleeve 7. Since they can be moved relative to each other, the position of the pair of annular magnets 3 can be moved while the sealing property of the magnetic fluid 4 remains the same when the device is eccentric, and the followability when the device is eccentric or the like is improved.

The O-ring 14 is attached to the outer circumference of the sleeve 7.
Since the mounting of the sleeve 7 is not necessary, the bonding at the time of mounting the sleeve 7 is not necessary, which does not require any labor and facilitates the mounting.

(Eleventh Embodiment) FIG. 11 shows a magnetic fluid seal device according to the eleventh embodiment. In the eleventh embodiment, rubber 15 as an elastic body is baked on the outer circumference of the pole piece 8. The other configuration is the same as that of the third embodiment.

In this embodiment, in order to interpose the rubber 15 between the pole piece 8 and the housing 1, the rubber 15 is baked on the outer periphery of the pole piece 8 on the housing 1 side.

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

A hydrocarbon-based fluid is used as the magnetic fluid 4.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4.

In the magnetic fluid sealing device having the above-described structure, the magnetic fluid 4 is coated with the coating fluid 5 to thereby remove the magnetic fluid 4.
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

Then, rubber 15 is attached to the outer periphery of the pole piece 8.
Since it is baked, there is no need for adhesion when the pole piece 8 is attached, which does not require any labor and facilitates the attachment.

(Twelfth Embodiment) FIG. 12 shows a magnetic fluid sealing device according to the twelfth embodiment. In the twelfth embodiment, a rubber square ring 16 as an elastic body is inserted into the space on the outer peripheral side of the annular magnet 3 sandwiched between the pair of pole pieces 8. The other configuration is the same as that of the third embodiment.

In the present embodiment, a pair of pole pieces 8 is used.
In order to interpose the rubber square ring 16 between the annular magnet 3 and the housing 1, the rubber square ring 16 is inserted in the space on the outer peripheral side of the annular magnet 3 sandwiched between the pair of pole pieces 8. .

The rubber square ring 16 has such a size that it projects toward the housing 1 side from the outer peripheral end of the pole piece 8 when inserted.

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

A hydrocarbon-based fluid is used as the magnetic fluid 4.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4.

In the magnetic fluid sealing device having the above-described structure, the magnetic fluid 4 is coated with the coating fluid 5, and thus the magnetic fluid 4 is coated.
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

Since the rubber square ring 16 is inserted in the space on the outer peripheral side of the annular magnet 3, the pair of pole pieces 8 and the annular magnet 3 need not be adhered to each other, which is troublesome. Therefore, the mounting can be facilitated.

(Thirteenth Embodiment) FIG. 13 shows a magnetic fluid sealing device according to the thirteenth embodiment. In the thirteenth embodiment, a magnetic fluid seal device using the coating fluid 5 is applied to a rotary dust seal device.

The magnetic fluid seal device shown in FIG. 13 is provided between a cylindrical housing 1 as two rotatable members and a shaft 2 inserted in the housing 1. A relative rotational movement is performed between the housing 1 and the shaft 2, and only the shaft 2 rotates in this embodiment. The housing 1 and the shaft 2 are made of a non-magnetic material.

The magnetic fluid seal device includes an annular magnet 3 which is magnetized in the axial direction and is arranged between the housing 1 and the shaft 2, and a magnetic fluid 4 which is held at the inner and outer peripheral ends of the annular magnet 3, respectively. A coating fluid 5 for coating the magnetic fluid 4, sleeves 7 and 18 fitted into the housing 1 and the shaft 2, respectively, and rubbers 17 and 19 as elastic bodies baked on the sleeves 7 and 18, respectively.

Here, the ring-shaped magnet 3 serves as a magnetic circuit forming means. Then, by the magnetic flux of the magnetic circuit formed by the annular magnet 3, the inner and outer peripheral ends of the annular magnet 3 and the sleeves 7, 1
The magnetic fluids 4 are magnetically held between the magnetic fluids 4 and 8.

The sleeves 7 and 18 are made of polyphenylene oxide, which is a cylindrical non-magnetic material, and the central portion is recessed so that the projecting portions project at both ends in the axial direction. The inner and outer peripheral ends of the ring-shaped magnet 3 are arranged in each of them with a gap. And the magnetic fluid 4
Is filled in the gap between the inner and outer peripheral ends of the annular magnet 3 and the recesses of the sleeves 7 and 18.

The sleeves 7 and 18 are
The ring magnet 3 has an elastic deformation characteristic that allows the ring magnet 3 to be inserted into the recessed portion 8, and the ring magnet 3 can be mounted smoothly.

In this embodiment, in order to interpose the rubbers 17 and 19 between the sleeve 7 and the housing 1 and between the sleeve 18 and the shaft 2, the rubber 17 is baked on the outer periphery of the sleeve 7 on the housing 1 side. The rubber 19 is baked on the inner circumference of the sleeve 18 on the shaft 2 side.

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

A hydrocarbon-based fluid is used as the magnetic fluid 4.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4.

A bearing 9 is arranged next to the magnetic fluid seal device.

In the magnetic fluid sealing device having the above-mentioned structure, the magnetic fluid 4 is coated with the coating fluid 5, and thus the magnetic fluid 4 is coated.
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

Further, in such a magnetic fluid sealing device, the magnetic fluid 4 held by the annular magnet 3 is levitated and supported, and the annular magnet 3 relatively moves in the recesses of the sleeves 7 and 18 in the radial and axial directions. Since it is possible, the position of the ring-shaped magnet 3 can be moved while maintaining the sealing property by the magnetic fluid 4 at the time of eccentricity, and the followability at the time of eccentricity of the device is improved.

Then, the rubbers 17, 1 are attached to the sleeves 7, 18, respectively.
Since 9 is baked, it is not necessary to attach the sleeves 7 and 18 when they are attached, which saves labor and facilitates attachment.

Furthermore, the annular magnet 3 and the sleeves 7, 1 are
Since the magnetic fluid 4 is preliminarily filled between the housing 8 and the housing 8, the housing 1 and the shaft 2 can be easily mounted by one-touch, so that the apparatus can be mounted in the assembled state in which the magnetic fluid 4 is preliminarily assembled. In addition to being easy to mount, the magnetic fluid filling amount can be easily controlled.

(Fourteenth Embodiment) FIG. 14 shows a magnetic fluid seal device according to a fourteenth embodiment. In the fourteenth embodiment, O-ring grooves are formed in the sleeves 7 and 18, and O-rings 20 and 2 as elastic bodies are formed in the O-ring grooves.
1 is attached. The other structure is the same as that of the thirteenth embodiment.

In this embodiment, in order to interpose the O-rings 20 and 21 between the sleeve 7 and the housing 1 and between the sleeve 18 and the shaft 2, an O-ring groove is formed on the outer periphery of the sleeve 7 on the housing 1 side. And the O-ring 20 is mounted in the O-ring groove, the O-ring groove is formed in the inner circumference of the sleeve 18 on the shaft 2 side, and the O-ring 21 is mounted in the O-ring groove.

Also in this embodiment, the surface of the magnetic fluid 4 is covered with the coating fluid 5.

As the magnetic fluid 4, a hydrocarbon-based one is used.

Silicone oil is used as the coating fluid 5. The coating fluid 5 has a low compatibility with the magnetic fluid 4 and a surface tension smaller than that of the magnetic fluid 4.

In the magnetic fluid sealing device having the above-mentioned structure, the magnetic fluid 4 is coated with the coating fluid 5 so that the magnetic fluid 4
It is possible to reduce the characteristic change due to the evaporation of water and prolong the life of the device.

Further, in such a magnetic fluid seal device, the magnetic fluid 4 held by the annular magnet 3 is floated and supported, and the annular magnet 3 is relatively moved in the recesses of the sleeves 7 and 18 in the radial and axial directions. Since it is possible, the position of the ring-shaped magnet 3 can be moved while maintaining the sealing property by the magnetic fluid 4 at the time of eccentricity, and the followability at the time of eccentricity of the device is improved.

The O-ring 2 is attached to the sleeves 7 and 18.
Since 0 and 21 are installed, sleeves 7 and 18
No need for adhesion when installing the
Installation can be facilitated.

Furthermore, the annular magnet 3 and the sleeves 7, 1 are
Since the magnetic fluid 4 is preliminarily filled between the housing 8 and the housing 8, the housing 1 and the shaft 2 can be easily mounted by one-touch, so that the apparatus can be mounted in the assembled state in which the magnetic fluid 4 is preliminarily assembled. In addition to being easy to mount, the magnetic fluid filling amount can be easily controlled.

[0199]

As described above, according to the present invention, by coating the magnetic fluid with the coating fluid, it is possible to reduce the characteristic change due to evaporation of the magnetic fluid, and it is possible to prolong the life of the device.

Further, direct contact between the magnetic fluid and the surface modification film can be prevented, the change in oil repellency of the surface modification film can be reduced, and the life of the device can be extended.

[Brief description of drawings]

FIG. 1 is a half cross-sectional view showing a magnetic fluid seal device according to a first embodiment.

FIG. 2 is a half sectional view showing a magnetic fluid seal device according to a second embodiment.

FIG. 3 is a half sectional view showing a magnetic fluid sealing device according to a third embodiment.

FIG. 4 is a half sectional view showing a magnetic fluid sealing device according to a fourth embodiment.

FIG. 5 is a half sectional view showing a magnetic fluid seal device according to a fifth embodiment.

FIG. 6 is a half sectional view showing a magnetic fluid seal device according to a sixth embodiment.

FIG. 7 is a half sectional view showing a magnetic fluid sealing device according to a seventh embodiment.

FIG. 8 is a half sectional view showing a magnetic fluid sealing device according to an eighth embodiment.

FIG. 9 is a half sectional view showing a magnetic fluid seal device according to a ninth embodiment.

FIG. 10 is a half sectional view showing a magnetic fluid sealing device according to a tenth embodiment.

FIG. 11 is a half sectional view showing a magnetic fluid sealing device according to an eleventh embodiment.

FIG. 12 is a half sectional view showing a magnetic fluid sealing device according to a twelfth embodiment.

FIG. 13 is a half sectional view showing a magnetic fluid sealing device according to a thirteenth embodiment.

FIG. 14 is a half sectional view showing a magnetic fluid sealing device according to a fourteenth embodiment.

FIG. 15 is a half cross-sectional view showing a magnetic fluid seal device of the related art.

FIG. 16 is a half cross-sectional view showing a magnetic fluid seal device of the related art.

FIG. 17 is a half cross-sectional view showing a magnetic fluid seal device of the related art.

[Explanation of symbols]

1 housing 2 shafts 2a protrusion 3 ring magnet 4 magnetic fluid 5 coating fluid 6 Surface modification film 7,18 sleeve 8 pole pieces 9 bearings 10 O-ring 11 Coated fluid impregnated sleeve 12 Coated fluid impregnated annular body 13 rubber 14 O-ring 15 rubber 16 rubber square ring 17,19 rubber 20,21 O-ring

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshimi Imamoto             4-3-1 Tsujido Shinmachi, Fujisawa City, Kanagawa Prefecture             NOK Co., Ltd. (72) Inventor Yoshiyuki Takeishi             4-3-1 Tsujido Shinmachi, Fujisawa City, Kanagawa Prefecture             NOK Co., Ltd. F-term (reference) 3J042 AA04 BA04 BA08 CA30 DA20                 4H017 AA22 AA31 AC10 AD06 AE05

Claims (12)

[Claims] 1. A magnetic fluid seal device for sealing between two members assembled so as to be movable relative to each other, the magnetic circuit being arranged between the two members and allowing a magnetic flux to pass through a gap between at least one of the two members. And a magnetic circuit forming means for forming a magnetic circuit, and the magnetic circuit formed by the magnetic circuit forming means magnetically held by a magnetic flux passing through the gap to contact at least one surface of the two members to seal the gap. A magnetic fluid seal, comprising: a magnetic fluid; and a coating fluid that has a low compatibility with the magnetic fluid and a surface tension smaller than the surface tension of the magnetic fluid to coat the surface of the magnetic fluid. apparatus. 2. The magnetic material according to claim 1, wherein after coating the magnetic fluid, the coating fluid is dropped on the surface of the magnetic fluid to coat the surface of the magnetic fluid with the coating fluid. Fluid sealing device. 3. The magnetic fluid and the coating fluid are mixed and filled in an emulsion state, and only the magnetic fluid is attracted by the magnetic flux of the magnetic circuit forming means so that the surface of the magnetic fluid is covered with the coating fluid. The magnetic fluid sealing device according to claim 1, which is coated. 4. The magnetic fluid sealing device according to claim 1, 2 or 3, wherein the magnetic fluid is hydrocarbon-based, and silicone oil or fluorine-based oil is used as the coating fluid. . 5. The oil repellent treatment by a surface modification film is applied to at least one surface of the two members that come into contact with the magnetic fluid, and the coating fluid has a surface tension higher than that of the surface modification film. The magnetic fluid sealing device according to claim 1, 2 or 3, wherein the oil repellency of the surface modified film is not changed. 6. The magnetic fluid is hydrocarbon-based and the surface modification film is a fluorine-based surface modification film, whereas silicone oil or fluorine-based oil is used as the coating fluid. The magnetic fluid sealing device according to claim 5. 7. The magnetic fluid seal according to any one of claims 1 to 6, wherein a porous body impregnated with the coating fluid is arranged at a position in contact with the magnetic fluid and the coating fluid. apparatus. 8. The magnetic circuit forming means is fixed to the other of the two members, and allows the magnetic flux to pass through a gap between the one of the two members.
The magnetic fluid sealing device according to the item. 9. The magnetic fluid seal device according to claim 8, wherein an elastic body is interposed between the magnetic circuit forming means and the other of the two members. 10. The magnetic circuit forming means is provided so as to be relatively movable between two members in a radial direction and an axial direction, and is floated and supported by the magnetic fluid. The magnetic fluid sealing device according to item 1. 11. A sleeve which includes the magnetic circuit forming means and is fixed to the other of the two members so that the magnetic circuit forming means can be relatively moved between the two members in a radial direction and an axial direction. The magnetic fluid sealing device according to claim 10, wherein 12. The magnetic fluid seal device according to claim 11, wherein an elastic body is interposed between the sleeve and the other of the two members.