JPH075325Y2 - Sealing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a sealing device using magnetic fluid, which is used for bearings of equipment and devices used in a high cleanliness atmosphere or vacuum.

<Prior Art> A conventional sealing device using magnetic fluid will be described with reference to FIG.

In the figure, 1 is a housing having a hollow hole, 2 is a shaft which is coaxially inserted through and supported by the housing 1, and 3 is an annular magnet whose outer diameter side is fixed to the housing 1 and which is opposed to the shaft 2 through a minute gap. Fluid holding members 4 are magnetic fluids held in a minute gap between the inner diameter side of the magnetic fluid holding member 3 and the shaft 2.

Specifically, the magnetic fluid holding member 3 is composed of an annular magnet 5 and magnetic material control annular plates (hereinafter referred to as pole pieces) 6 and 7 fixed to both sides in the axial direction thereof. A magnetic circuit G as shown by a broken line in the figure is formed between the magnetic fluid holding member 3 and the shaft 2. Since the inner diameters of the pole pieces 6 and 7 are set to be smaller than the inner diameter of the ring magnet 5, two magnetic fields are formed between the inner peripheral surface of the pole pieces 6 and 7 and the outer peripheral surface of the shaft 2. The magnetic fluid 4 is held at these two locations.

By the way, for example, when the shaft 2 is a non-magnetic material or a magnetic material that is hard to be magnetized, the magnetic fluid 4 cannot be held in the gap between the pole pieces 6 and 7 and the shaft 2.

Therefore, in such a case, as shown in FIG. 4, a magnetic ring 8 made of a ferromagnetic material is attached at a position facing the pole pieces 6 and 7 on the outer peripheral surface of the shaft 2.

To position the magnetic ring 8 at a fixed position on the shaft 2, for example, an adhesive is used, a positioning member is used, or press fitting is performed. Further, since the magnetic ring 8 and the shaft 2 are fitted together by hard members, in order to prevent the internal lubricant or gas such as air from leaking from the fitted surface, the shaft 2 on the fitted surface is prevented. The O-ring 9 is attached to.

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

That is, when the member (the shaft 2 in the above example) facing the magnetic fluid holding member 3 that forms the holding gap for the magnetic fluid 4 is a non-magnetic material, the magnetic ring 8 as described above is used. A member for positioning is required, and a member for preventing leakage of a lubricant or gas such as air on the fitting surface is required, resulting in high manufacturing cost. Further, when the magnetic ring 8 is positioned by press-fitting, if the mating member to be mounted is a relatively soft material or a thin material, it may be distorted and the rotation accuracy may be deteriorated. If the material is a hard material, the magnetic ring 8 itself is distorted, which makes it difficult to control the accuracy of the magnetic fluid holding gap.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a sealing device which requires a small number of parts and an assembling process, and which can facilitate accuracy control of a magnetic fluid holding gap.

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

In the sealing device according to the present invention, the magnetic fluid holding member is attached to the fixed side member of the inner and outer two members arranged coaxially, and a minute gap is provided in the radial direction with respect to the magnetic fluid holding member. The magnetic rings that are opposed to each other and form a part of the magnetic circuit are fitted to a member on the rotating side made of a non-magnetic material or a magnetic material that is hard to be magnetized via a cushioning material, and the magnetic fluid is retained in the minute gap. It is characterized by being present.

<Operation> The operation of this configuration is as follows.

That is, since the cushioning material is interposed between the magnetic ring and the mating member to which it is attached, if the magnetic ring is press-fitted, the cushioning material deforms and the tightening margin at the mating surface becomes small, resulting in a close contact. Will increase. Since the tightening margin is small, the magnetic ring is positioned in the axial direction, and the cushioning material absorbs the external force when the magnetic ring is fitted, so that the distortion of the magnetic ring is eliminated. Moreover, since the degree of adhesion of the fitting surfaces is increased, the leakage of the lubricant (or gas such as air) is suppressed.

That is, since the cushioning material serves both as a conventional positioning member and a lubricant leakage prevention member, the number of parts and the number of assembling steps can be reduced. Moreover, since the outer diameter accuracy of the magnetic ring after attachment is maintained at the accuracy of the manufacturing stage, it is easy to control the accuracy of the magnetic fluid holding gap formed between the magnetic ring and the magnetic fluid holding member.

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings. Here, an example in which such a sealing device is built in a ball bearing will be given.

FIG. 1 shows a first embodiment of the present invention.

The ball bearing 10 in the illustrated example includes an outer ring 11 that is non-rotatably fixed, an inner ring 12 that is used for rotation and is made of a non-magnetic material or a magnetic material that is hard to be magnetized, and a plurality of balls interposed therebetween.
It is composed of 13 and a cage 14 that rotatably retains these balls 13. Lubricants such as grease are filled in the raceways inside the bearing.

Further, in this embodiment, a non-contact type seal ring 15 is provided at one opening end in the axial direction between the inner peripheral surface of the outer ring 11 and the outer peripheral surface of the inner ring 12, and the other opening end has a sealing described in detail below. Each device 20 is attached.

The sealing device 20 includes a magnetic fluid holding member 21, a magnetic fluid 22, and a holder.
It consists of 23 and. The magnetic fluid holding member 21 includes, for example, an annular magnet 24 magnetized in the axial direction and pole pieces 25, 26 made of soft magnetic material attached to both axial side surfaces thereof. Both ends of the annular magnet 24 on the inner diameter side in the axial direction are chamfered in a tapered shape. Also, the holder 23
Is a thin ring-shaped core metal 27 having a substantially “L” -shaped cross section,
A non-magnetic rubber 28 is attached.

This magnetic fluid holding member 21 is fitted and fixed to a peripheral groove 11a formed in the inner diameter shoulder portion of the outer ring 11 via a holder 23, and its inner peripheral surface is opposed to the outer peripheral surface of the inner ring 12 in a non-contact state. ing. A circumferential step portion 12a is formed at a position of the inner ring 12 facing the magnetic fluid holding member 21, and a magnetic ring 30 having an inner diameter portion integrally formed with a cushioning material 31 such as rubber is formed in the circumferential step portion 12a. It is fitted. An annular minute gap is formed in the portion where the outer peripheral surface of the magnetic ring 30 and the inner peripheral surface of the pole pieces 25 and 26 of the magnetic fluid holding member 21 face each other. Since a strong magnetic field is formed at this gap, that is, at two locations where the pole pieces 25, 26 and the magnetic ring 30 are opposed to each other, the magnetic fluid 22 is concentrated and held by the magnetic force around the gap. Has become. The magnetic fluid 22 is made of, for example, an oil medium containing solid ferromagnetic fine powder such as magnetite in a colloidal form.

In the sealing device 20 of the present embodiment as described above, the magnetic fluid 22 is held at two separate positions in the axial direction to enhance the sealing performance. A slinger portion 32 extending outward in the radial direction is connected to a cushioning material 31 integrally formed with the magnetic ring 30. The slinger portion 32 is for preventing the internal lubricant from being mixed into the magnetic fluid 22, and is effective in preventing the concentration of the magnetic fluid 22 from decreasing due to the mixing of the lubricant and avoiding the decrease in pressure resistance.

FIG. 2 shows a second embodiment of the present invention. In the figure, the same reference numerals as those given in FIG. 1 indicate the same parts or the facing parts.

The second embodiment shows a mounting structure of the sealing device 20 in a form in which the ball bearing 10 is rotated on the outer ring. The structure of this embodiment different from that of the first embodiment is a magnetic fluid holding member.
21 is attached to the inner ring 12, and the magnetic ring 30 and the cushioning material 31 are fitted to the outer ring 11.
The shape has not been changed.

As shown in FIGS. 1 and 2, the mounting form of the magnetic fluid holding member 21 is changed according to the rotating form of the ball bearing 10 in order to suppress the scattering of the magnetic fluid 22 as much as possible.

As described above, since the cushioning material 31 is interposed between the magnetic ring 30 and the mating member (inner ring 12 or outer ring 11) to which it is attached, if the magnetic ring 30 is press-fitted,
As the cushioning material 31 is deformed, the tightening margin of the mating surface becomes smaller and the degree of adhesion increases. Therefore, not only the magnetic ring 30 is positioned in the axial direction but also the sealing effect is enhanced, so that the leakage of the internal lubricant is prevented. Moreover, since the external force due to the press-fitting is absorbed by the elastic deformation of the cushioning material 31, the magnetic ring
No distortion is generated in 30 or the mating member (inner ring 12 or outer ring 11). Therefore, the accuracy of the outer diameter surface of the magnetic ring 30 mounted on the inner ring 12 can be maintained at the accuracy at the time of manufacture, and the magnetic fluid holding gap can be easily and highly accurately managed.

By the way, in each of the above embodiments, the magnetic ring 30 and the cushioning material 31 are described as being integrally molded, but the present invention is not limited to this, and may be configured separately. In addition, although the example in which the sealing device 20 is built in the rolling bearing such as the ball bearing 10 is given, the present invention is not limited to this, and is also used for an apparatus or device including two members inside and outside coaxially arranged. It goes without saying that you can do it.

<Effects of the Invention> According to the present invention, the following effects are exhibited.

Since the magnetic ring that faces the magnetic fluid holding member and forms the magnetic fluid holding gap is attached to the rotation side member via the cushioning material, the cushioning material can be simply fitted to the rotation side member. As a result of deformation, the tightening margin on the mating surface becomes smaller and the degree of adhesion increases. Therefore, axial positioning can be performed without causing distortion between the magnetic ring and the mating member, and the sealing effect at the mating surfaces is enhanced, so that leakage of gas such as internal lubricant or air can be eliminated.

Therefore, since the cushioning material serves both as a member for positioning and a member for preventing leakage of a gas such as a lubricant or air in the conventional example, the number of parts and the number of assembling steps can be reduced. Further, since the magnetic ring can be attached to the mating member while maintaining the outer diameter accuracy with high accuracy, the accuracy of the magnetic fluid holding gap can be easily controlled.

As described above, it is possible to provide a sealing device that is low in cost and excellent in sealing performance.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the device of the present invention, and FIG. 2 is a sectional view showing a second embodiment of the device of the present invention. 3 and 4 are sectional views showing a conventional example. 11 ... Outer ring 12 ... Inner ring 20 ... Sealing device 21 ... Magnetic fluid holding member 22 ... Magnetic fluid 30 ... Magnetic ring 31 ... Buffer material.

Claims (1)

[Scope of utility model registration request] 1. A magnetic fluid holding member is attached to a fixed member of two members inside and outside coaxially arranged, and is opposed to the magnetic fluid holding member with a minute gap provided in the radial direction. The magnetic ring forming a part of the magnetic circuit is fitted to a member on the rotation side made of a non-magnetic material or a magnetic material that is hard to be magnetized via a cushioning material, and the magnetic fluid is retained in the minute gap. Characteristic sealing device.