JPS63163029A - Sealing device - Google Patents

Abstract

PURPOSE:To provide a compact sealing device at a low cost with improved wear resisting performance, by providing an annular magnetic plate having the inner diameter approximately equal to that of a second magnetic pole in the side of a first magnetic pole saving the inner diameter larger than the diameter of the annular magnetic plate to form a high magnetic flux density portion between said plate and a second member. CONSTITUTION:A 2-piece type seal ring 21 consisting of an annular magnetic pole 23 and an annular magnetic plate 24 made of magnetic material is supported through a non-magnetic annular rubber ring 30 in a peripheral groove 12a of an outer ring 12 of a ball bearing 10. Also, the inner diameter of a S pole 23b of annular magnetic pole 23 is formed to be approximately equal to the diameter of annular magnetic plate 24 and smaller than that of a N pole 23a. The S pole 23b is opposed to a shoulder 11a of an inner ring 11 through a predetermined gap to ensure two high magnetic flux density portions between a second member, said plate 24 and a second magnetic pole. Further, a labyrinth seal is formed on the inner peripheral surface of a flange of said ring 30 and the side surface of the shoulder 11a, so that the pressure resisting performance can be improved with the compact device at a low cost.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is a sealing device for shielding a highly clean place from a part using elements that contaminate the atmosphere, and is particularly suitable for use in magnetic fluids. Regarding the sealing device used.

<Prior Art> A conventional sealing device of this type will be explained with reference to FIG.

In the figure, reference numeral 1 denotes a shaft, and this shaft l is supported by a cylindrical housing 3 via a ball bearing 2.
Both are designed to rotate relative to each other.

Reference numeral 4 denotes a sealing device, and this sealing device 4 includes a three-piece type seal ring 5 and a magnetic fluid 6.

The seal ring 5 has an annular magnet 7. It consists of annular magnetic plates 8 and 9 made of magnetic material. The annular magnet 7 is sandwiched between annular magnetic plates 8 and 9, and the annular magnetic plate 8 is joined to the magnetic pole surface 7c of the N pole 7a of the annular magnet 7, and the annular magnetic plate 9 is joined to the magnetic pole surface of the S pole 7b. 7d.

With the N pole 7a and the S pole 7b oriented along the axis of the shaft 1 and the housing 30, the outer peripheral surfaces of the N pole 7a and the S pole 7b of the annular magnet 7 are aligned with the outer periphery of the annular magnetic plate 8.9. It is fixed to the inner circumferential surface of the housing 3 together with the surface.

There is a gap between the inner circumferential surface of each of the N pole 7a and S pole 7b of the annular magnet 7 and the outer circumferential surface of the shaft l.

are formed, and gaps ht, h, which are smaller than the above-mentioned gaps, are formed between the inner circumferential surface of the annular magnetic plate 8.9 and the outer circumferential surface of the shaft 1. The gap ht and the gap are configured to have substantially the same dimensional relationship.

In such a sealing device 4, the annular magnetic plate 8.9, which is magnetized by the annular magnet 7, magnetizes the shaft l facing the annular magnetic plate 8.9, so that the annular magnetic plate 8.9 on the NiTa side of the annular magnet 7 A magnetic circuit G (indicated by a dashed line in the figure) is installed between the magnetic plate 8 and the annular magnetic plate 9 on the S pole 7b side.
is configured.

In this magnetic circuit G, the magnetic lines of force coming out of the Ni7a of the annular magnet 7 gather inside the annular magnetic plate 8
from the inner circumferential edge of the annular magnetic plate 9 through the inside of the shaft 1, and return to the S pole 7b. The gap between the shaft 1 and the outer circumferential surface of the shaft 1, .h, 02, is a high magnetic flux density portion.

The magnetic fluid 6 is concentrated and held in these two high magnetic flux density parts. That is, the three-piece type sealing device 4 constitutes one magnetic circuit G, and forms high magnetic flux density portions at two locations separated by a predetermined distance in the axial direction.

As shown in FIG. 7, there is also a sealing device 4a in which the above-mentioned gap h1 and gaps h are made almost the same and the magnetic fluid 6 is held in all of the gaps h1 to h3. In this case, since a large amount of expensive magnetic fluid 6 is required, it is disadvantageous in terms of cost compared to the sealing device 4 shown in FIG.

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

The three-piece type sealing device 4 shown in FIG.
Since two high magnetic flux density parts are formed between the two parts, the pressure resistance is superior to a one-piece type sealing device (not shown) that does not use the annular magnetic plate 8.9.

On the other hand, since the three-piece type sealed bag N4 uses an annular magnetic plate 8.9 made of magnetic material, the cost is higher than that of the one-piece type, and the annular magnetic plate 8.
, 9, the overall width dimension becomes larger.

The present invention was devised in view of these circumstances, and aims to achieve pressure resistance comparable to that of the three-piece type, while reducing cost and width.

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

That is, the sealing device according to the present invention has two first parts arranged coaxially and relatively rotating. a second member; a first member; Both second magnetic poles are connected to the first magnetic pole. An annular magnet oriented along the axial direction of the second member and a first m of the annular magnet
a two-piece type seal ring made of an annular magnetic plate made of a magnetic material bonded to the magnetic pole surface side of the pole, and the seal ring forms a predetermined gap with the second member. In the sealing device that is supported by one member and holds a magnetic fluid in the gap, the circumferential surface of the second magnetic pole on the gap side protrudes from the circumference of the first magnetic pole and the annular magnetic plate on the gap side, and the circumference of the second magnetic pole peripheral surface and second
The gap between the first magnetic pole and the second member is smaller than the gap between the circumferential surface of the first magnetic pole and the second member, and is substantially the same as the gap between the circumferential surface of the annular magnetic plate and the second member. , A magnetic circuit is configured between the annular magnetic plate and the second magnetic pole via the second member, and the axial direction between the annular magnetic plate and the second member and between the second magnetic pole and the second member is High magnetic flux density portions are formed at two separate locations.

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

Since the annular magnetic plate is only provided on the magnetic pole surface side of the first magnetic pole of the annular magnet, and no annular magnetic plate is provided on the magnetic pole surface side of the second M1 pole, the number of parts is smaller than that of the 3-piece type. Become.

Furthermore, if the annular magnetic plate on the second magnetic pole side is simply eliminated, lines of magnetic force will no longer be concentrated between the second magnetic pole and the second member, resulting in inferior pressure resistance compared to a three-piece type sealing device.

In order to equalize the pressure resistance performance, the circumference on the gap side of the second magnetic pole is made to protrude more than the first magnetic pole, so that the gap between the circumferential surface of the second magnetic pole and the second member is reduced to the circumferential surface of the first magnetic pole. and the second member, and the peripheral surface of the annular magnetic plate and the second member.
By making the gap approximately the same as that between the second
In the magnetic circuit formed between the annular magnetic plate and the second magnetic pole via a member, a magnetic circuit is formed between the second magnetic pole and the second member as well as between the peripheral edge of the annular magnetic plate and the second member. A high magnetic flux density area equivalent to the high magnetic flux density area is secured.

Moreover, since the annular magnetic plate and the second magnetic pole are arranged on both sides of the first magnetic pole, the high magnetic flux density part between the annular magnetic plate and the second member and the second magnetic pole and the second member The high magnetic flux density portion in between is separated in the axial direction by the first magnetic pole.

In other words, two high magnetic flux density parts can be secured, and the two shoulder magnetic flux density parts are separated in the axial direction.
It provides pressure resistance performance comparable to that of piece-type sealing devices.

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

FIG. 1 shows a first embodiment of the invention. Here, an example in which the sealing device is provided inside the bearing will be described.

In the same figure, reference numeral lO is a ball bearing, and this ball bearing 10 has an inner ring 11. Outer ring 12. Ball 13. A retainer 14 is provided, and an inner ring 11. The outer ring 12 and balls 13 are made of bearing steel.

Reference numeral 20 denotes a sealing device, which is composed of a seal ring 21 and a magnetic fluid 22.

The seal ring 21 has an annular magnet 23. It is a two-piece type consisting of an annular magnetic plate 24 made of magnetic material and having a roughly L-shaped cross section. The annular magnet 23 is made of, for example, a plastic magnet, and the magnetic pole surface 23C of the N pole 23a is connected to the annular magnetic plate 24.
is joined to one side of the N8i of this annular magnet 23
The outer diameters of 123a and Sff123b are formed to have the same size, but the inner diameter of 5i23b is formed smaller than that of the north pole 23a. Furthermore, the inner diameter of the S pole 23b is approximately the same as the inner diameter of the annular magnetic plate 24.

This sealing device 20 includes an inner ring 11 and an outer ring 12 of a ball bearing 10.
It is arranged on one peripheral edge side between.

A circumferential groove 128 is formed at the periphery of the inner peripheral surface of the outer ring 12, and the seal ring 21 is supported in this circumferential groove 12a via an annular rubber ring 30 made of a non-magnetic material.

This annular rubber ring 30 is provided to prevent the annular magnet 23 from forming a magnetic circuit on the outer ring I2 side of the ball bearing 10 made of bearing steel. In this embodiment, when insert molding the annular rubber ring 30, the annular magnetic plate 24 of the seal ring 21 is used as the core metal of the annular rubber ring 30. This annular magnetic plate 24 is arranged inside the ball bearing 10, and together with the side surface of the stepped portion 11a of the inner ring 11 constitutes a part of a labyrinth seal, which will be described later. Concentrates the lines of magnetic force coming out of the In this way, in this embodiment, the annular magnetic plate 24 has three functions.

Now, the annular magnet 23 of the seal ring 21 has its N pole 2
3a, the south pole 23b is oriented along the axial direction of the inner ring 11 and the outer ring 12, and the north pole 23a of the annular magnet 23,
Each inner circumferential surface of the S pole 23b faces the outer circumferential surface of a stepped portion 11a formed at the periphery of the outer circumferential surface of the inner ring 11 with a predetermined gap therebetween.

In other words, the inner peripheral surface of the N pole 23a and the stepped portion 11a of the inner ring 11
There is a gap 11 between the outer circumferential surface of the S pole 23b, a gap i2 between the inner circumferential surface of the S pole 23b and the outer circumferential surface of the stepped portion 11a of the inner ring 11, and a gap i2 between the inner circumferential surface of the annular magnetic plate 24 and the inner circumferential surface of the inner ring 11. step part 11
There is a gap 1. are formed respectively. Gap 2I is gap J,,j! , and the gap 12 and the gap l have a substantially equal relationship.

Further, a labyrinth seal is formed from between the inner surface of the annular magnetic plate 24 and the side surface of the stepped portion 11a to between the inner circumferential surface of the flange 31 of the annular rubber ring 30 and the outer circumferential surface of the inner ring 11. This labyrinth seal is suitable for ball bearing l
There is a gap in the lubricant (grease) inside O! 1-1. This prevents the magnetic fluid from being mixed into the magnetic fluid 22 held within the magnetic fluid. To prevent the lubricant from getting mixed into the magnetic fluid 22,
While not reducing the concentration of the magnetic fluid 22 there,
Prevents deterioration of pressure resistance performance.

In the sealing device 20 configured as described above, the annular magnet 2
3 magnetizes the annular magnetic plate 24, and this annular magnetic plate 2
4 magnetizes the inner ring 11, a magnetic circuit G is formed between the annular magnetic plate 24 and the S pole 23b via the inner ring 11.

In this magnetic circuit G, the magnetic pole surface 23C of the N pole 23a
Since the annular magnetic plate 24 is joined to the annular magnetic plate 2
4 and the stepped portion 11a of the inner ring 11! .

The lines of magnetic force are concentrated at the gap j! between the S pole 23b and the stepped portion 11a of the inner ring 11, which has approximately the same dimensions as the gap l! , magnetic field lines are also concentrated. In other words, two locations separated in the axial direction each have high magnetic flux density, so
The magnetic fluid 22 is concentrated and held here.

Also in this embodiment, since the two cylinder magnetic flux density portions are separated in the axial direction by the width of the N pole 23a between the annular magnetic plate 24 and the S pole 23b, the two cylinder magnetic flux density portions are substantially separated. ing.

In this way, according to the sealing device 20 of the present embodiment, only one annular magnetic plate 24 is used (and high magnetic flux density portions can be formed at two locations separated in the axial direction). It is possible to obtain pressure resistance performance comparable to that of the three-piece type sealing device.Furthermore, since the number of annular magnetic plates 24 can be reduced by one, it is possible to reduce costs and width dimensions.

Further, the sealing device 20 according to the present invention is not limited to the structure described in the first embodiment, but may also have a structure as shown in FIGS. 2 and 3, for example.

FIG. 2 shows a second embodiment of the invention. In this figure, the same reference numerals as those in FIG. 1 refer to the same parts or corresponding parts.

The configuration of this embodiment that differs from the first embodiment is the shape of the annular magnetic plate 24. The annular magnetic plate 24 here is the first
The magnetic pole face 23 of the Np123a of the annular magnet 23 has a shape without the outer flange 24a like the annular magnetic plate 24 shown in the figure.
It only covers c.

FIG. 3 shows a third embodiment of the invention. In this figure, the same reference numerals as those in FIG. 2 refer to the same parts or corresponding parts.

The difference between this embodiment and the second embodiment is that the annular rubber ring 30 is the first. Unlike that of the second embodiment, it is formed in a simple annular shape, and the first embodiment. A labyrinth seal unlike the second embodiment is not formed.

When a labyrinth seal is not formed as in this example, the lubricant (grease) inside the ball bearing lO
There is a possibility that it may get mixed into the magnetic fluid 22 held in the gap l located on the ball bearing IO side.

However, in this embodiment as well, since the magnetic fluid 22 is held at two locations and these two locations are separated in the axial direction, the lubricant inside the ball bearing 10 may temporarily enter the gap l. Even if the lubricant gets mixed into the held magnetic fluid 22, since the lubricant can be prevented from getting mixed in, a significant drop in pressure resistance performance is prevented.

In addition, the ball bearing 10 outer ring 1 in the above first to third embodiments
2 is made of a non-magnetic material such as ceramics, or if it is made of bearing steel but its surface is coated with a non-magnetic material, an annular magnet 23 and an annular magnetic plate are placed on the outer ring 12 side. 24 does not constitute a magnetic circuit, the annular magnetic plate 24 may be directly fixed to the outer ring 12 without using the annular rubber ring 30.

Further, although the first to third embodiments described above describe examples in which the sealing device 20 is provided inside the ball bearing 10, the sealing bag W20 according to the present invention is not limited to this, and FIG. Fifth
It is also possible to arrange it at a location as shown in the figure.

That is, FIG. 4 shows a fourth embodiment of the present invention. In this figure, the same reference numerals as those in FIG. 1 refer to the same parts or corresponding parts.

In the figure, reference numeral 40 is a shaft, and reference numeral 50 is a cylindrical housing, both of which rotate relative to each other. This shaft 40 is supported by a housing 50 via a ball bearing 60. A sealing device ff20 having the same configuration as the sealing device 20 shown in FIG. 1 is disposed on one side of this ball bearing 60.

The annular rubber ring 30 of this sealing device 20 is connected to the housing 5.
high magnetic flux density portions are formed at two locations spaced apart in the axial direction between the inner circumferential surface of the shirt 40 and the outer circumferential surface of the shirt 40. A magnetic fluid 22 is held in this high magnetic flux density portion. In addition, an annular rubber ring 30 and an annular magnetic plate 2
4, the inner ring 61, and the shaft 40 form a labyrinth seal.

FIG. 5 shows a fifth embodiment of the invention. In this figure, the same reference numerals as those in FIG. 1 refer to the same parts or corresponding parts.

This embodiment differs from the fourth embodiment in that a raceway surface 41 is formed on the shaft 40.
The second embodiment also serves as the inner ring 61 of the ball bearing 60, and the other components are the same as those of the fourth embodiment, so their explanation will be omitted.

This fourth. When the housing 50 in the fifth embodiment is made of a non-magnetic material such as ceramics, or when the surface is coated with a non-magnetic material, the annular magnet 23 and the annular magnetic plate 24 on the housing 50 side Since no magnetic circuit is formed, the annular rubber ring 30
The annular magnetic plate 24 may be directly fixed to the housing 50 without using the annular magnetic plate 24.

In addition, in each of the above embodiments, the N pole 23a and the S pole 23a
It is also possible to have b in the opposite relationship, in this case,
The magnetic pole surface 23d of the south pole 23b may be joined to the annular magnetic plate 24, and the inner diameter of the north pole 23a may be made smaller than the inner diameter of the south pole 23b.

Further, in each of the above embodiments, the annular magnetic plate 24 of the seal ring 21 is arranged inside the ball bearing 10, but the present invention is not limited thereto, and may be arranged outside.

Further, in each of the above embodiments, the sealing device 20 is provided only on one side of the ball bearing 10.60, but the sealing device 20 of the present invention is provided on both sides of the ball bearing 10.60. It is optional whether it is provided or only in favorable cases.

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

Since the annular magnetic plate is only provided on the first magnetic pole side of the annular magnet and no annular magnetic plate is provided on the second magnetic winding side, the seal ring is a two-piece type, so a three-piece type seal ring is provided. Compared to a sealing device, the cost can be reduced by halving the number of annular magnetic plates, and the width dimension can be reduced.

Moreover, in addition to simply eliminating the annular magnetic plate on the second magnetic pole side (the circumferential surface on the gap side of the second magnetic pole is made to protrude beyond the first magnetic pole, the circumferential surface of the second Mi pole of the annular magnet and the second The gap between the first magnetic pole and the second member is made smaller than the gap between the first magnetic pole and the second member, and is approximately the same as the gap between the annular magnetic plate and the second member. The annular magnetic plate and the 26th
In the magnetic circuit configured between the fl pole, in addition to the high magnetic flux density portion formed between the annular magnetic plate and the second member, there is also a portion between the second magnetic pole and the second member equivalent to the above. A high magnetic flux density area can be secured.

Moreover, since the annular magnetic plate and the second magnetic pole are separated in the axial direction by the first magnetic pole, the magnetic flux density portions of both cylinders can be substantially separated, and as a result, compared to a three-piece type sealing device, It is possible to obtain pressure resistance performance that is comparable to that of other materials.

As described above, according to the present invention, the pressure resistance is excellent, and
Moreover, a low-cost and compact sealing device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing a state in which a sealing device is disposed inside a bearing according to a first embodiment of the present invention. Figures 2 and 3 are part of the second aspect of the present invention. FIG. 7 is a longitudinal sectional view showing a state in which a sealing device is disposed inside a bearing according to a third embodiment. FIGS. 4 and 5 show the fourth embodiment of the present invention. FIG. 7 is a longitudinal sectional view showing a state in which a sealing device is disposed between a housing and a shaft according to a fifth embodiment. 6 and 7 are related to conventional examples, FIG. 6 is a vertical cross-sectional view showing a three-piece type sealing device, and FIG. 7 is a vertical cross-sectional view showing a three-piece type sealing device different from that in FIG. It is a front view. 11... Inner ring (first member or second member) 12...
Outer ring (second member or first member) 20... Sealing device 21... Seal ring 22... Magnetic fluid 23... Annular magnet 23a... N pole (first magnetic pole or second magnetic pole) 23b・
... S pole (second magnetic pole or first magnetic pole) 23C... N-pole magnetic pole surface 23d... S-pole magnetic pole surface 24... Annular magnetic plate.

Claims (2)

[Claims] (1) first and second members that are coaxially arranged and rotate relative to each other; an annular magnet in which both the first and second magnetic poles are oriented along the axial direction of the first and second members; and a two-piece type seal ring made of an annular magnetic plate made of a magnetic material bonded to the magnetic pole surface side of the first magnetic pole of the annular magnet, and this seal ring forms a predetermined gap with the second member. In the sealing device, the sealing device is supported by the first member in a state where the magnetic fluid is held in the gap, and the circumferential surface of the second magnetic pole on the gap side protrudes from the circumferential surfaces of the first magnetic pole and the annular magnetic plate on the gap side. The circumferential surface of the second magnetic pole and the second
The gap between the first magnetic pole and the second member is smaller than the gap between the circumferential surface of the first magnetic pole and the second member, and is substantially the same as the gap between the circumferential surface of the annular magnetic plate and the second member. , A magnetic circuit is configured between the annular magnetic plate and the second magnetic pole via the second member, and the axial direction between the annular magnetic plate and the second member and between the second magnetic pole and the second member is A sealing device characterized in that high magnetic flux density portions are formed at two separated locations. (2) The sealing device according to claim (1), wherein the annular magnetic plate of the seal ring is arranged inside the device to be sealed.