JPS63125825A - Sealing device - Google Patents

Abstract

PURPOSE:To enable magnetic fluid to be held powerfully by disposing an annular magnet on an annular shoulder of one of two members rotated relatively. CONSTITUTION:A bearing 10 is constituted from an inner ring 11 is first member, an outer ring 12 as second member, rollers 13 and a holder 14. Sealing devices 20 for sealing with magnetic fluid are respectively provided on opening ends of an annular gap between inner and outer rings. In an internal space 15 is enclosed lubricant such as lubricant grease. The the sealing device 20 is provided with a seal ring body 30, an annular magnet 40, non-magnetic body 50 and magnetic fluid 60. Here, in the N pole side of annular magnet 40, a portion of the inner diameter side cylindrical portion opposite thereto, the S pole side of annular magnet 40 and a portion of the inner diameter side of cylindrical portion opposite thereto are increased the densities of magnetic fluxes respectively so that the magnetic fluid 60 is concentrated and held powerfully.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a sealing device used for, for example, a bearing placed in a highly clean atmosphere or a vacuum.

<Prior art> For example, bearings used in equipment and equipment used in a highly clean atmosphere or in a vacuum are sealed with magnetic fluid to prevent the lubricant sealed inside from leaking to the outside. A sealing device is used.

A conventional sealing device for this type of bearing will be explained with reference to FIGS. 8 and 9.

In the illustrated bearing, numeral 1 is an inner ring, numeral 2 is an outer ring, numeral 3 is a spherical rolling element, numeral 4 is a retainer, numerals 5 and 5 are sealing devices for sealing with magnetic fluid, and the inner ring 1. An internal space A formed by the outer ring 2 and the sealing devices 5, 5 is filled with a lubricant such as grease. Inner circle 1. The outer ring 2 and the rolling elements 3 are made of a ferromagnetic material such as bearing steel.

The sealed bag W5 will be specifically explained.

This sealing device 5 includes a seal ring body 6, an annular magnet 7a,
It includes a non-magnetic ring 7b and a magnetic fluid 8.

The seal ring 6 has a core metal 5a made of a ferromagnetic material.

It is integrally formed with an elastic body 6b made of a non-magnetic material such as rubber, and the outer peripheral edge of the elastic body 6b is fitted into the fitting groove 2a at the end of the inner peripheral surface of the outer ring 2. . The inner peripheral edge of the core bar 6a of the seal ring body 6 is provided with an inner diameter side cylindrical portion 6C bent approximately parallel to the axial direction. This inner diameter side cylindrical portion 6C has rI in the annular step portion 1a at the end of the outer peripheral surface of the inner ring 1.
'I'm doing B. Note that the outer diameter side cylindrical portion 6d of the core metal 6a does not contact the outer ring 2 due to the elastic body 6b.

As shown in FIG. 9, the annular magnet 7a has a substantially L-shaped cross section, and is magnetized in the radial direction, with the outer circumferential surface 7C side being a north pole and the inner circumferential surface 7d side being a south pole. There is.

The annular magnet 7a is fitted onto the annular stepped portion 1a of the inner ring 1, and the outer peripheral surface 7C of the annular magnet 7a faces the inner cylindrical portion 6C of the seal ring 6 without contacting it. A flange 7e extending in the axial direction of the annular magnet 7a is in close contact with a side surface 1b extending in the radial direction of the annular step portion 1a. Annular magnet 7a
A reservoir IC having a rectangular cross section for storing the magnetic fluid 8 is formed in the circumferential direction by an inner surface 7f along the radial direction of the annular step portion 1a and a side surface 1b along the radial direction of the annular step portion 1a.

The non-magnetic ring 7b has an annular magnet 7 at the annular step portion 1a.
It is arranged on the outside in the axial direction so as to be adjacent to a.

As shown by the dashed line in FIG. 9, the magnetic force lines of the annular magnet 7a pass from the N pole of the annular magnet 7a to the inner cylindrical portion 6C1 of the seal ring 6 and then through the inner ring 1 to the annular magnet 7a.
A magnetic circuit is formed leading to the south pole of the

Furthermore, no magnetic circuit is formed outside the annular magnet 7a in the axial direction due to the presence of the nonmagnetic ring 7b.

Therefore, the outer peripheral surface 7C of the annular magnet 7a and the seal ring body 6
A magnetic field is generated between the inner cylindrical portion 6C and within the reservoir IC, and based on this, the magnetic fluid 8 is held.

<Problems to be Solved by the Invention> However, the conventional example having such a configuration has the following problems.

First, the annular magnet 7a has a flange 7e along its axial direction.
Therefore, the magnetic flux generated from the N pole of the annular magnet 7a is easily concentrated on the flange 7e and guided to the S pole of the annular magnet 7a. The magnetic flux passing through the side surface 1b along the radial direction of the stepped portion 1a decreases.For this reason, the inner diameter side cylindrical portion 6C
The magnetic flux density between the annular step portion 1a and the side surface 1b along the radial direction tends to decrease.

In addition, a side surface 1b along the radial direction of the annular stepped portion 1a and a side surface 6d along the radial direction of the inner diameter side cylindrical portion 6C of the seal ring body 6.
A gap B between the inner space A of the bearing and the annular reservoir 1c
and are connected linearly in the radial direction.

From the above, with the relative rotation between inner ring 1 and outer ring 2,
The lubricant in the internal space A flows into the magnetic fluid 8 in the reservoir IC, or conversely, the magnetic fluid 8 in the reservoir IC flows into the internal space A of the bearing.
As a result, there is a shortage of magnetic fluid 8 between the seal ring body 6 and the annular magnet 7a, and therefore, sufficient sealing between the internal space A of the bearing and the outside cannot be ensured.

The present invention was devised in view of the above circumstances, and an object of the present invention is to provide a sealing device that can retain a magnetic fluid well and ensure high sealing performance.

Means for Solving the Problems> In order to achieve the above object, the present invention has the following configuration.

That is, the sealing device of the present invention includes a first and a second member that rotate relative to each other, an annular magnet provided in an annular stepped portion formed in the first member made of a magnetic material, and an annular magnet provided in a radial direction of the annular magnet. A sealing device comprising: an annular magnetic body provided on the second member to face each other; and a magnetic fluid held between the annular magnetic body and the annular magnet, the sealing device having a radius of the annular stepped portion. A non-magnetic material is interposed between a side surface along the direction and one side surface of the annular magnet along the radial direction, and both magnetic poles of the annular magnet are arranged in the first direction. The second member is oriented in a direction along the axis of rotation of the second member.

<Effect> The effects of the configuration of the present invention are as follows.

The non-magnetic material reduces the magnetic flux generated on the first member side of the annular magnet. Therefore, the magnetic flux emitted from the N pole of the annular magnet is converged, passes through the inside of the annular magnetic body radially opposed to the annular magnet, and reaches the S pole of the annular magnet.

Since the magnetic flux passing through the inside of the annular magnetic body is converged, the axial direction between the N pole of the annular magnet and the radially opposing annular magnetic body and between the S pole of the annular magnet and the annular magnetic body The magnetic flux density increases at two locations separated by .

Since the magnetic fluid is concentrated and strongly held at the two locations where the magnetic flux density is high, the magnetic fluid existing between them is held by the strongly held portions.

1st. The relative rotation of the second member causes the first. The magnetic fluid receives the centrifugal force in the radial direction of the second member, but either the annular magnet or the annular magnetic body facing in the radial direction receives the magnetic fluid in the radial direction, and therefore, the annular magnet and the annular The magnetic fluid becomes difficult to flow out from between the magnetic bodies.

<Example> Hereinafter, each example of the present invention will be described in detail based on the drawings.

A first embodiment of the present invention is shown in FIGS. 1 and 2. In this embodiment, a case where the sealing device is used in a bearing will be explained.

In these figures, reference numeral 10 indicates a bearing such as a ball bearing, and this bearing 10 has an inner ring 11° as a first member, an outer ring 12° as a second member, and 10° as a first member. It is composed of rolling elements 13 and a cage 14.

An annular gap extending along the rotational axis Q is formed between the outer circumferential surface of the inner ring 11 and the inner circumferential surface of the outer ring 12 opposing thereto, and both open ends of the annular gap are sealed with a magnetic fluid. A sealing device 20.20 is provided in each case.

And inner ring 11. Outer ring 12 and sealing device 20.20
A lubricant such as lubricating grease is sealed in the internal space 15 surrounded by. As this lubricant, a lubricant that is incompatible with the solvent of the magnetic fluid 60, which will be described later, is used.

The sealing device 20.20 in this embodiment prevents the lubricant sealed inside the bearing 10 from leaking outside, and
This ensures a tight seal of 0.

This sealing device 20 will be specifically explained.

The sealing device 20 includes a seal ring 30 as shown in FIG.
, an annular magnet 40 , a nonmagnetic material 50 , and a magnetic fluid 60 .

The seal ring body 30 includes a core bar 31 made of a ferromagnetic material and having a U-shaped cross section, and an elastic member 32 made of a non-magnetic material such as rubber. The core metal 31 includes a core metal main body 31a, an outer diameter side cylindrical part 31b, and an inner diameter side cylindrical part 3L as an annular magnetic body.
It is equipped with e.

The elastic member 32 covers the outer surface 31d of the core body 31a of the core 31 along the radial direction and the outer peripheral surface of the outer diameter side cylindrical portion 31b. The outer diameter side cylindrical portion 31 of this seal ring body 30
The elastic member 32 covering b
It is fitted into the l groove L2a.

The annular magnet 40 has its N pole and S pole oriented in a direction along the rotation axis Q of the bearing 10, and its outer peripheral surface 41
A circumferential groove 42 having a V-shaped cross section is formed at the center in the axial direction in which a magnetic fluid 60, which will be described later, is stored.

The annular magnet 40 is fitted into the annular stepped portion 11a of the inner ring 11, and one side surface 4 along the radial direction of the annular magnet 40
A disc-shaped non-magnetic material 50 is interposed between the annular step portion 11a and the radially extending side surface 11b of the annular step portion 11a.

In this state, the outer circumferential surface 41 of the annular magnet 40 is radially opposed to the inner circumferential surface 31e of the inner cylindrical portion 31c of the core bar 31 of the seal ring body 30.

Specifically, one side surface 43 along the radial direction of the annular magnet 40
The side surface 31 along the radial direction of the inner diameter side cylindrical portion 31C
f projects inward in the axial direction, and the outer surface 31d of the core body 31a in the radial direction projects outward in the axial direction with respect to the other side surface 44 of the annular magnet 40 in the radial direction. .

The magnetic fluid 60 is conventionally known, and is composed of solid ferromagnetic fine powder such as magnetite contained in a colloidal form in a non-magnetic oil medium.

This magnetic fluid 60 is filled between the outer circumferential surface 41 of the annular magnet 40 and the inner cylindrical portion 31c of the core bar 31 of the seal ring body 30.

In the above configuration, due to the presence of the non-magnetic material 50, the annular magnet 4 passes through the side surface 11b along the radial direction of the annular step portion 11a.
Since the magnetic flux at 0 is reduced, the magnetic flux emitted from the N pole of the annular magnet 40 is converged and passes through the inside of the inner cylindrical portion 31C of the annular magnetic body 30, as shown by the dashed line in FIG. It forms a magnetic circuit leading to the S pole side.

From this, the N pole side of the annular magnet 40 and the inner diameter side cylindrical portion 3
The magnetic flux density is increased in the portion facing the magnet 1c and in the portion facing the S pole side of the annular magnet 40 and the inner diameter side cylindrical portion 31C. In other words, the portions with high magnetic flux density are the outer circumferential surface 41 of the annular magnet 40 and the inner circumferential surface 3 of the inner diameter side cylindrical portion 31c.
1e and at two separate locations along the rotational axis Q (see FIG. 1), between which the magnetic fluid 60
is concentrated and strongly held, thereby holding the magnetic fluid 60 present between the two locations.

In this way, the magnetic fluid 60 is strongly applied in the gap between the inner circumferential surface 31e of the inner diameter side cylindrical portion 31c and the outer circumferential surface 41 of the annular magnet 40, which face each other in the radial direction, and along the rotation axis Q of the bearing 10. Therefore, when the inner ring 11 and the outer ring 12 rotate relative to each other, the lubricant in the internal space 15 of the bearing 10 is transferred to the magnetic fluid 60 present in the gap, or the magnetic fluid 60 is transferred to the internal space 15 of the bearing IO. It becomes difficult for both sides to flow into each other. Therefore, the sealing performance between the outside and the internal space 15 of the bearing 10 can be ensured.

Note that the annular magnet 40 in this embodiment has its circumferential groove 42
This not only makes it possible to hold a large amount of magnetic fluid 60, but also separates the magnetic poles of the annular magnet 40 in the axial direction by the circumferential groove 42, thereby separating the locations where the magnetic flux density is increased in the axial direction. You can do it like this. Of course, the present invention also includes annular magnets that are not provided with this circumferential groove 42.

Figure 3 shows a second embodiment of the present invention. The same figure is the second
In the figure corresponding to the figure, only the configuration different from the first embodiment will be explained. In FIG. 3, the same reference numerals as those shown in FIG. 2 refer to the same or corresponding parts.

The second embodiment is different from the first embodiment in that the non-magnetic body 50a is composed of a small diameter disc part 51a and a large diameter disc part 52a, and the large diameter disc part 52a is arranged in the radial direction of the annular step part 11a. An annular projecting piece 33 is formed by elongating the elastic member 32 radially inward, which covers the outer surface 31d of the core body 31a of the seal ring body 30 along the radial direction. This is what we are doing.

The large-diameter disk portion 52a of the non-magnetic material 50a is connected to the seal ring 30.
A slight annular gap is formed between the inner cylindrical portion 31c and the inner surface 31f along the radial direction, and this annular gap provides a labyrinth between the internal space 15 of the bearing 10 and the gap in which the magnetic fluid 60 is held. forming a seal.

The annular projecting piece 33 forms a slight annular gap with the other side surface 44 along the radial direction on the S pole side of the annular magnet 40, and this annular gap holds the outside of the bearing 10 and the magnetic fluid 60. It forms a labyrinth seal for the gaps between the two.

Due to the labyrinth effect of the labyrinth seal between the large-diameter disk portion 52a and the inner-diameter cylindrical portion 31d, the lubricant in the internal space 15 of the bearing 10 reaches the area where the magnetic fluid 60 is present.
Further, the effect of preventing the magnetic fluid 60 from flowing out into the internal space 15 is even stronger than in the first embodiment.

Further, due to the labyrinth effect of the labyrinth seal between the annular projection piece 33 and the annular magnet 40, the effect of preventing the magnetic fluid 60 from flowing out to the outside is even stronger than in the first embodiment. Note that conventionally, the magnetic fluid 8
However, since the gap between the inner cylindrical portion 6C and the non-magnetic material 7b is parallel to the axis of rotation of the bearing, that is, it communicates linearly with the outside, the magnetic fluid is prevented from leaking to the outside. 8 was leaking to the outside due to capillary action. This leakage can be prevented in this embodiment as described above.

In this embodiment, the small diameter disc part 51a and the large diameter disc part 52a of the nonmagnetic material 50a are described as being integral, but of course the small diameter disc part 51a and the large diameter disc part 52a
It does not matter if it is divided into

FIG. 4 shows a third embodiment of the present invention. The figure is the third
FIG. In this embodiment, only the differences from the second embodiment will be explained. In FIG. 4, the same reference numerals as those shown in FIG. 3 refer to the same or corresponding parts.

The third embodiment differs from the second embodiment in that the inner surface 31f along the radial direction of the inner cylindrical portion 31C of the seal ring body 30 and the outer circumferential surface 31g of the inner cylindrical portion 31C are made of an elastic material such as rubber. It is covered with a covering member 70 made of.

This covering member 70 covers the inner cylindrical portion 3 of the seal ring body 30.
This prevents the magnetic flux of the annular magnet 40 passing through 1c from leaking to the core body 31a side, and is similar to 2 described in the first embodiment.
This has the effect of further increasing the magnetic flux density at the location.

Furthermore, by providing the elastic member 70, in combination with the non-magnetic material 50a, there is an effect of reducing the magnetic flux generated inward of the bearing 10 and further increasing the magnetic flux density at the two locations. The magnetic fluid 60 between the outer circumferential surface 41 and the inner diameter side cylindrical portion 3IC of the seal ring body 30
It is possible to effectively prevent the inward swelling of the axial direction.

A fourth embodiment of the present invention is shown in FIG. 5. The figure shows the fourth
FIG. In this embodiment as well, only the differences from the third embodiment shown in FIG. 4 will be explained. In FIG. 5, the same reference numerals as those shown in FIG. 4 refer to the same or corresponding parts.

The fourth embodiment differs from the third embodiment in that the inner circumferential surface 31e of the inner cylindrical portion 31C of the seal ring body 30 is covered with a covering member 71 made of rubber or the like.

This covering member 71 can be easily formed by a single coating process together with the covering member 70 in the third embodiment. Moreover, the magnetic flux density between the inner cylindrical portion 31C and the annular magnet 40 is not reduced.

hair FIG. 6 shows a fifth embodiment of the present invention.

In this embodiment, a sealing device 90 corresponding to the sealing device 20 of each of the above embodiments is installed on a shaft 80 having an annular stepped portion 80a.
This is used to seal the space 82 between the housing 81 and the housing 81 fitted concentrically around the outer periphery of the shaft 80 from the outside.

The interior of the space 82 is filled with lubricant for the plurality of rolling elements 83 interposed between the stepped shaft 80 and the inner peripheral surface of the housing 81 .

In the case of the sealing device 90 of this embodiment, the magnetic flux generated from the N pole of the annular magnet 91 fitted to the annular stepped portion 80a of the shaft 80 is transmitted to the housing 81 as shown by the dashed line in the figure.
forming a magnetic circuit that passes through the inside of the annular magnetic body 92 fitted into the fitting groove 84 and enters the S pole of the annular magnet 91;
A magnetic fluid 93 is held between an annular magnet 91 and an annular magnetic body 92.

Then, the annular magnet 91 and the annular stepped portion 80a of the shaft 80
By means of a non-magnetic material 94 and a disc member 95 made of a non-magnetic material provided between the side surface 85 along the radial direction,
Since the magnetic flux generated from the annular magnet 91 is made difficult to pass through the inside of the shaft 80, the annular magnetic body 92 and the annular magnet 9
1 becomes stronger, and the magnetic fluid 93 is strongly held between them.

The elastic member 92a attached to the radially inner surface of the annular magnetic body 920 and the disk member 95 form a labyrinth seal, and the labyrinth effect of this labyrinth seal causes the magnetic fluid 93 to flow into the space 82. It is designed to prevent leakage.

Furthermore, the elastic member 92b attached to the radially outer surface of the annular magnetic body 920 and the radially outer surface of the annular magnet 91 form a labyrinth seal, and the labyrinth effect of this labyrinth seal causes magnetic fluid 93
is designed to prevent it from leaking outside.

According to the sealing device 90, which also seals the space 82 between the shaft 80 and the housing 81 from the outside, high sealing performance can be ensured.

Ee big tanenitis FIG. 7 shows a sixth embodiment of the present invention.

In this embodiment, when the sealed ball bearing 100 is interposed between the shirt 1-80 and the housing 81 in the fifth embodiment, the lubricant sealed in the sealed ball bearing 100 is exposed to the outside. This is an example of sealing with a sealing device 90 to prevent leakage. Since the sealing device 90 has the same configuration as that of the fifth embodiment, a description thereof will be omitted here.

Note that the present invention is not limited to the first to sixth embodiments described above, and can be used for sealing parts in various other devices.

Further, in the first to sixth embodiments described above, the annular magnet 4
It is also possible to install a plurality of 0.91 magnets along the rotational axis Q, and in this case, the number of regions with high magnetic flux density can be further increased.

<Effect of the invention> According to the present invention, the following effects are achieved.

The non-magnetic material reduces the magnetic flux of the annular magnet generated on the annular step side of the first member, converges the magnetic flux of the annular magnet, and causes it to pass through the annular magnetic body facing the annular magnet in the radial direction. It is possible to increase the magnetic flux density at two locations separated in the axial direction between the annular magnet and the annular magnetic body that face each other in the radial direction. Therefore, the magnetic fluid can be strongly held in these two locations, and the magnetic fluid that exists between them can also be strongly held by these locations.

In addition, the part that holds the magnetic fluid is located between the annular magnet and the annular magnetic body facing each other in the radial direction, and the first part holds the magnetic fluid. Since it is along the rotational axis of the second member, the first member. Even if the magnetic fluid receives a centrifugal force in the radial direction due to the relative rotation of the second member, the annular magnet or the annular magnetic body receives the magnetic fluid in the radial direction.

Therefore, when the sealing device of the present invention is used, for example, in a sealed portion of a sealed bearing, high sealing performance can be ensured between the inside and outside of the bearing.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a longitudinal sectional view showing a bearing using a sealing device, and FIG. 2 is an enlarged view of the sealing device in the circle in FIG. 1. It is a diagram. 3 to 7 show other embodiments of the present invention, with FIG. 3 being a vertical sectional view showing a sealing device as a second embodiment, and FIG. 4 showing a sealing device as a third embodiment. 5 is a longitudinal sectional view showing a sealing device as a fourth embodiment, FIG. 6 is a longitudinal sectional view showing a sealing device as a fifth embodiment, and FIG. 7 is a longitudinal sectional view showing a sealing device as a sixth embodiment. It is a longitudinal cross-sectional view showing a sealing device. Further, FIGS. 8 and 9 relate to a conventional example, where the eighth recess is a vertical sectional view showing a sealed bearing, and FIG. 9 is an enlarged view of the sealing device in the circle in FIG. 8. 11... Inner ring (first member) 11a... Annular stepped portion 11b... Side surface 12 along the radial direction of the annular stepped portion...
Outer ring (second member) 20, 90...Sealing device 31C...Inner diameter side cylindrical part (annular magnetic body) 40...Annular magnet 43...One side along the radial direction 50, 50a...Non Magnetic bodies 60, 94...Magnetic fluid Q...Rotation axis of bearing (first and second members).

Claims (5)

[Claims] (1) Of the first and second members that rotate relative to each other, an annular magnet provided in an annular stepped portion formed on the first member made of a magnetic material, and an annular magnet provided in an annular step formed in the first member, which is made of a magnetic material, and In a sealing device including an annular magnetic body provided in two members, and a magnetic fluid held between the annular magnetic body and the annular magnet, a side surface along the radial direction of the annular stepped portion and the annular magnet A non-magnetic material is interposed between the annular magnet and one side surface along the radial direction of the annular magnet, and both magnetic poles of the annular magnet are oriented in a direction along the rotation axis of the first and second members. Features a sealing device. (2) The sealing device according to claim (1), wherein the annular magnet has a circumferential groove for storing the magnetic fluid near the center in the axial direction on its outer peripheral surface. (3) All or one of the surfaces of the annular magnetic body facing the annular magnet, the surface along the radial direction, and the back surface of the surface facing the annular magnet, is coated with a non-magnetic material. Claims (1) or (2), in which a covering member is attached.
Sealing devices as described in Section. (4) Claim (1), wherein the non-magnetic body has a large-diameter disk portion that faces the radially extending side surface of the annular magnetic body with a slight gap therebetween. The sealing device according to any one of items 1 to 3. (5) The annular magnetic body has an annular protrusion made of a non-magnetic material that faces the other side surface along the radial direction of the annular magnet with a slight gap therebetween. The sealing device according to any one of items 1) to (4).