JP2001200936A - Reciprocating seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reciprocating seal capable of reducing sliding resistance and saving space while maintaining sealability with a small amount of magnetic fluid. SOLUTION: This reciprocating seal is provided with a magnetic pole member 3 and a magnetic pole member 5 having a L shape cross-sectional shape (the cross-sectional shape cut to pass through a shaft center), and a tip end surface of the other end side of the magnetic pole member 3 is provided so as to oppose to that of the magnetic pole member 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reciprocating seal for sealing an annular gap between two members reciprocating relative to each other.

[0002]

2. Description of the Related Art Conventionally, various seals have been known as this type of reciprocating seal in order to realize low sliding resistance.

[0003] Conventionally known constructions include, for example, a seal made of oil-containing silicone rubber, a seal made by coating silicone rubber with PTFE (polytetrafluoroethylene resin), a seal made by baking oil-containing silicone rubber on a metal fitting, or And PTFE-coated silicone rubber baked on metal fittings.

As an example of a reciprocating seal according to the prior art, a seal obtained by baking a silicone rubber coated with PTFE on a metal fitting will be described with reference to FIGS. 6 and 7. FIG.

FIG. 6 is a schematic sectional view showing a state in which a reciprocating seal according to the prior art is mounted, and FIG. 7 is a schematic sectional view showing a state in which the shaft is eccentric.

[0006] The reciprocating seal 100 is for sealing an annular gap between the inner cylinder and the outer cylinder, for example, as shown in the figure, which reciprocates relatively to each other.

Then, as shown in FIG.
Reference numeral 00 generally comprises a seal lip portion 101 made of a silicone rubber ring coated with PTFE and a reinforcing portion 102 made of a metal ring as a metal fitting. The part 102 is adhered.

Here, the inner diameter end of the seal lip portion 101 is provided with a slightly smaller diameter than the outer diameter of the inner cylinder 200. When the inner lip 200 is used, the inner cylinder 200 is inserted into the inner diameter of the seal. The seal lip portion 101 is deformed into an L-shape and adheres to the surface of the inner cylinder 200 by its restoring force, thereby providing a sealing property against dust and the like.

As described above, in the conventional reciprocating seal, the sliding resistance is reduced by impregnating the seal lip with oil or coating PTFE.

[0010]

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

[0011] In recent years, various devices using a reciprocating seal have been reduced in size and realized multiple functions. On the other hand, since the amount of power from the power source of the device main body is limited, power saving is achieved for each unit.

Under such circumstances, in the conventional reciprocating seal, no matter how the oil is impregnated or the PTFE is coated to reduce the sliding resistance, the sliding effect is caused by the contact between the solids. Had limitations.

As described above, since the sliding resistance of the seal is large, a relatively large amount of electric power is consumed when the reciprocating member (tube) is reciprocated.

On the other hand, when the cylinder reciprocates, the seal installation space changes depending on the amount of eccentricity of the cylinder. If the amount of eccentricity is large, for example, even if the entire reciprocating seal is made of rubber, the seal installation space may be used. Where the space is narrow, it is crushed, and where the space is wide, a gap is created, which causes leakage.

For this reason, conventionally, even when the size of the device is reduced, it is necessary to provide a space S on the outer diameter side of the reciprocating seal at least equal to the eccentricity as shown in FIG. By providing the space S, the eccentricity is absorbed by the space S at the time of eccentricity, so that the function of the seal is not impaired.

As described above, in the case of the prior art, there is a limit in reducing the sliding resistance and a limit in saving space.

By the way, the present applicant has proposed a technique for solving the above-mentioned problem in Japanese Patent Application No. 11-150559 filed by the present applicant.

This technique is a seal using a magnetic fluid. By sealing with a magnetic fluid, the sliding resistance is drastically reduced as compared with the prior art in which the solids are in sliding contact with each other. Therefore, the power consumption when the reciprocating member is reciprocated can be reduced, and even when the seal installation space changes due to the eccentricity of the two members, the magnetic fluid follows the magnetic field distribution and moves between the two members. By properly filling the gap, the followability of eccentricity is improved, so that a space corresponding to the amount of eccentricity as in the related art is not required, and the space can be saved.

However, in the case of the technique proposed in Japanese Patent Application No. 11-150559, a hollow disk-shaped magnetic pole is used.
In order to hold the magnetic fluid held between the pair of magnetic poles properly, the magnetic fluid held between the pair of magnetic poles can be properly held because the distal end surface of the outer periphery is arranged to face the member to which the magnetic fluid slides. Has a problem that a relatively large amount of magnetic fluid is required.

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 reduce sliding resistance and save space while maintaining sealing properties with a small amount of magnetic fluid. It is to provide a reciprocating seal which is possible.

[0021]

According to the present invention, there is provided a reciprocating seal for sealing an annular gap between two members reciprocally assembled relative to each other. A magnetic field generating member that is provided on one of the members and generates a magnetic field such that an N pole is provided at one end in the reciprocating direction and an S pole is provided at the other end; A pair of magnetic pole members that are fixed to the pole side and whose other end surfaces are opposed to each other, and that are held between the opposed end surfaces of the pair of magnetic pole members and are in sliding contact with the surface of the other member. And a magnetic fluid.

Therefore, since the other end faces of the pair of magnetic pole members are opposed to each other, the magnetic flux therebetween is efficiently concentrated, so that even a small amount of magnetic fluid can be reliably held.
In addition, since the magnetic fluid is brought into sliding contact with the surface of the other member, sliding resistance is reduced, and excellent eccentricity followability due to eccentricity of the two members is achieved.

It is preferable that the cross-sectional shape of the other end of the magnetic pole member is rectangular.

Preferably, the cross-sectional shape of the other end of the magnetic pole member is an arc.

Thus, the magnetic flux can be more concentrated.

It is also preferable that the magnetic pole member has a tapered shape in which the tip on the other end side becomes thinner toward the tip.

Thus, the magnetic flux can be more concentrated.

It is preferable that the magnetic pole member is arranged such that the tip on the other end side is biased toward the other member side of the two members.

As a result, the magnetic flux is biased toward the other member,
The magnetic fluid can be sufficiently brought into sliding contact with the surface of the other member.

[0030]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The materials, shapes, relative arrangements, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

A reciprocating seal according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic sectional view showing a mounted state of a reciprocating seal according to an embodiment of the present invention.

The reciprocating seal 1 seals an annular gap between two members assembled so as to be able to reciprocate relative to each other. As an example, FIG. A reciprocating seal for sealing an annular gap between the outer cylinder 13 (one member) and the inner cylinder 14 (the other member) is shown.

The reciprocating seal 1 generally includes a magnet 2 as a magnetic field generating member, and a pair of magnetic pole members 3 and 5 fixed to both ends of the magnet 2 in the axial direction (reciprocating direction).
A magnetic fluid 4 held by a magnetic field formed by the pair of magnetic pole members 3 and 5.

Here, the magnet 2 has an annular shape, and is formed in an annular groove formed on the inner peripheral side of the outer cylinder 13 so that one end in the reciprocating direction has an N pole and the other end has an S pole. It is provided in. The magnet 2 may be made of, for example, a metal, an organic material filled with magnetic powder, or an electromagnet.

A magnetic pole member 3 and a magnetic pole member 5 are provided on the N pole side and the S pole side of the magnet 2, respectively. That is, one end of the magnetic pole member 3 is fixed to the N pole side of the magnet 2. One end side of the magnetic pole member 5 is fixed to the S pole side of the magnet 2, and is formed on the inner peripheral side of the outer cylinder 13 with the magnet 2 sandwiched between the pair of magnetic pole members 3 and 5. It is installed in the groove.

The magnetic pole members 3 and 5 may be made of, for example, an organic material filled with metal or magnetic metal powder.

The other end of each of the magnetic pole members 3 and 5 projects toward the inner cylinder 14 with respect to the inner peripheral surface of the outer cylinder 13. Even if eccentricity occurs between the inner cylinder 14 and the
Is set so as not to come into contact with the outer peripheral surface of.

The magnetic pole member 3 and the magnetic pole member 5 have an L-shaped cross-sectional shape (cross-sectional shape cut through the axis), and a tip end face on the other end side of the magnetic pole member 3 and a magnetic pole member 5
Is provided so as to be opposed to the tip end surface on the other end side.
In addition, as shown in the drawing, they are provided so as to face each other via a virtual plane substantially perpendicular to the axis (the reciprocating direction).

According to the magnetic field distribution formed by the magnet 2, the magnetic pole member 3 and the magnetic pole member 5, the magnetic fluid 4 is magnetically held between the opposed tip surfaces of the magnetic pole members 3 and the magnetic pole member 5. , The magnetic pole member 3, the magnetic fluid 4 and the magnetic pole member 5 form a magnetic circuit.

Then, an inner cylinder 1 is provided on the inner peripheral side of the reciprocating seal 1.
When the magnetic fluid 4 is mounted, since the magnetic fluid 4 is a fluid, the magnetic fluid 4 is deformed in accordance with the outer peripheral surface shape of the solid inner cylinder 14,
And the outer cylinder 13 is completely closed.

With the above configuration, when the inner cylinder 14 and the outer cylinder 13 relatively reciprocate, the magnetic fluid 4 and the outer peripheral surface of the inner cylinder 14 are in sliding contact with each other. , The sliding resistance can be drastically reduced.

Even when eccentricity occurs between the inner cylinder 14 and the outer cylinder 13, the magnetic fluid 4 appropriately follows the magnetic field distribution, so that the magnetic fluid 4 has excellent eccentricity followability and maintains the sealing performance. As a result, space can be saved without requiring a space for coping with eccentricity as in the related art.

Then, a tip end face on the other end side of the magnetic pole member 3,
By opposing the end face of the other end of the magnetic pole member 5, the magnetic flux between the opposing faces can be efficiently concentrated, and as a result, the amount of the magnetic fluid 4 necessary for maintaining the sealing performance is reduced. It becomes possible to reduce.

In the example shown in FIG. 1, the magnet 2 and the pair of magnetic pole members 3 and 3 are disposed on the side of the outer cylinder 13 as one of the two members reciprocally movable relative to each other.
5 and the magnetic fluid 4 is provided on the inner cylinder 14 side as the other member.
In contrast to this, the magnet 2 and the pair of magnetic pole members 3 and 5 are provided on the inner cylinder 14 side as one of the two members, as shown in FIG. Needless to say, a similar effect can be obtained even when the magnetic fluid 4 is slid in contact with the outer cylinder 13 as the other member.

Further, in the above-described example, the configuration in which the tip surfaces of the pair of magnetic pole members are opposed to each other by making the magnetic pole members have an L-shaped cross section has been described. However, the present invention is not limited to such a shape. For example, although not specifically shown, the end surfaces may be opposed to each other in a shape curved into an arm.

Further, in the above-described example, the cross-sectional shape of the leading end of the magnetic pole member to be opposed is rectangular.
It is not limited to such a shape. For example, although not particularly shown, if the cross-sectional shape is an arc shape, the magnetic flux between the opposed surfaces can be more concentrated, and necessary for maintaining the sealing performance. The amount of the magnetic fluid 4 can be further reduced.

Although not shown in the drawings, the opposed tip is tapered so as to become thinner toward the tip, and a member on the side with which the tip is slidably contacted (in the case of FIG. In the case of No. 3, the magnetic flux between the opposed surfaces can be more concentrated by arranging the magnetic flux so as to be biased toward the outer cylinder 13), and the magnetic flux can be biased near the sliding contact surface. The fluid 4 can maintain the sealing performance.

The results of an experimental comparison between a sample manufactured based on the above-described embodiment and a sample manufactured for comparison are shown below.

First, a comparative example will be briefly described with reference to FIG. FIG. 4 is a schematic sectional view showing a mounted state of a reciprocating seal according to a comparative example.

The reciprocating seal according to the comparative example has the same basic configuration as the reciprocating seal according to the above-described embodiment.
Only the shape of the magnetic pole member is different.

That is, also in the case of the reciprocating seal according to the comparative example, the magnetic pole members 6 and 7 are provided on the N pole side and the S pole side of the magnet 2, respectively. Is fixed to the N-pole side of the magnet 2, one end of the magnetic pole member 7 is fixed to the S-pole side of the magnet 2, and the pair of magnetic pole members 6, 7 sandwich the magnet 2 outside. It is installed in an annular groove formed on the inner peripheral side of the cylinder 13.

Here, in the comparative example, the magnetic pole members 6
Reference numeral 7 denotes a hollow disk shape. In the above-described embodiment, the magnetic pole member has an L-shaped cross-sectional shape (cross-sectional shape cut through the shaft core), whereas in the comparative example, The cross-sectional shape is an I-shape, and the front end surfaces of the magnetic pole members 6 and 7 (the front end surfaces opposite to the fixed side) are disposed on the outer peripheral surface of the inner cylinder 14 which is the sliding contact side member. Facing each other.

Then, according to the magnetic field distribution formed by the magnet 2, the magnetic pole member 6 and the magnetic pole member 7,
The magnetic fluid 8 is held in sliding contact with the outer peripheral surface of the inner cylinder 14, and the magnet 2, the magnetic pole member 6, the magnetic fluid 8 and the magnetic pole member 7 form a magnetic circuit.

The other basic configuration and the like are the same as in the above-described embodiment.

Next, a sample manufactured based on the embodiment and the comparative example will be described with reference to FIGS. FIG. 2 is a schematic diagram of a sample of a reciprocating seal manufactured based on the embodiment of the present invention, and FIG. 5 is a schematic diagram of a sample of a reciprocating seal manufactured based on a comparative example.

As shown in FIG. 2, in the sample according to the present embodiment, the magnetic pole members 3 and 5 have outer diameters of 30 m.
m, the inner diameter is 27 mm, the width is 0.2 mm, the width of the magnet 2 in the axial direction (reciprocating direction) is 0.7 mm, and the inner cylinder 1
4 and the inner peripheral surfaces of the magnetic pole members 3 and 5 have a clearance of 0.
It was set to be 1 mm.

On the other hand, as shown in FIG. 5, in the sample based on the comparative example, the outer diameter of the magnetic pole members 6 and 7 is 30 m.
m, the inner diameter is 27 mm, the width is 0.2 mm, the width of the magnet 2 in the axial direction (reciprocating direction) is 0.7 mm, and the inner cylinder 1
The gap between the outer peripheral surface of the magnetic pole member 4 and the inner peripheral tip surfaces of the magnetic pole members 6 and 7 was set to be 0.1 mm.

When the sealability and the like were tested based on the above samples, the amount of the magnetic fluid required to maintain the sealability was as small as about 20 μl in the sample according to the present embodiment. On the other hand, in the case of the sample based on the comparative example, about 40 μl or more was required.

When the saturation magnetization of the magnetic fluid was 40 mT and the magnet was an Sm-based plastic magnet having a maximum energy product of 64 to 72 KJ / m ³ , the sealing pressure resistance was measured. About 5.05 × 10 ³ P
On the other hand, in the case of the sample according to the embodiment of the present invention, when the cross-section of the tip of the magnetic pole member is rectangular as shown in FIG. 2, about 9.09 × 10 ³ Pa In addition, although not particularly shown, in the case of a sample whose tip is tapered and whose tip is biased toward the member (inner cylinder 14) to be brought into sliding contact, about 1.01 × 10 ⁴ Pa, and it was confirmed that the pressure resistance was excellent.

[0060]

As described above, according to the present invention, the magnetic fluid is held at this position by efficiently concentrating the magnetic flux between the opposing surfaces by opposing the end surfaces of the pair of magnetic pole members. With this configuration, a small amount of magnetic fluid enables a seal having excellent pressure resistance, and the sliding with the magnetic fluid can reduce the sliding resistance and save space.

The magnetic flux can be more concentrated by making the cross-sectional shape of the tip on the other end side of the magnetic pole member arc-shaped or by making the tip on the other end side of the magnetic pole member taper toward the tip. The sealability can be maintained with a smaller amount of magnetic fluid.

Further, by arranging the magnetic pole member such that the tip on the other end side is biased toward the other member side of the two members, the magnetic flux can be biased toward the other member side, and a much smaller amount of magnetic fluid can be obtained. The sealability can be maintained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a mounted state of a reciprocating seal according to an embodiment of the present invention.

FIG. 2 is a schematic view of a sample of a reciprocating seal manufactured according to an embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing a mounted state of a reciprocating seal according to the embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view showing a mounted state of a reciprocating seal according to a comparative example.

FIG. 5 is a schematic view of a sample of a reciprocating seal manufactured based on a comparative example.

FIG. 6 is a schematic cross-sectional view showing a state when a reciprocating seal according to the related art is mounted.

FIG. 7 is a schematic cross-sectional view showing a state of a reciprocating seal according to the related art when the shaft is eccentric.

[Explanation of symbols]

 Reference Signs List 1 reciprocating seal 2 magnet 3, 5 magnetic pole member 4 magnetic fluid 13 outer cylinder 14 inner cylinder

Claims (5)

[Claims] 1. A reciprocating seal for sealing an annular gap between two members reciprocally assembled relative to each other, provided on one member side and having an N pole,
A magnetic field generating member that generates a magnetic field at the other end so as to be an S pole; one end of the magnetic field generating member is fixed to the N pole and S pole sides of the magnetic field generating member, and the other end faces are opposed to each other A reciprocating seal comprising: a pair of magnetic pole members that are engaged with each other; and a magnetic fluid held between opposed end surfaces of the pair of magnetic pole members and slidably in contact with the surface of the other member. 2. The reciprocating seal according to claim 1, wherein the cross-sectional shape of the other end of the magnetic pole member is rectangular. 3. The reciprocating seal according to claim 1, wherein the cross-sectional shape of the other end of the magnetic pole member is arc-shaped. 4. The reciprocating seal according to claim 1, wherein the tip of the other end of the magnetic pole member has a tapered shape that becomes thinner toward the tip. 5. The reciprocating seal according to claim 1, wherein the other end of the magnetic pole member is disposed so as to be deviated toward the other of the two members.