JPH0241393Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a magnetic fluid seal structure used as a non-contact shaft seal in the rotating shaft of vacuum equipment, rotating equipment that handles gas, and the like.

[Conventional technology]

The conventional magnetic fluid seal structure consists of a thick cylindrical pole piece that is placed in a housing around a magnetic shaft with a magnet in between to form a narrow gap and a magnetic circuit, and the magnetic fluid is inserted into this narrow gap. Based on the structure that magnetically captures the magnetic shaft, an annular protrusion is formed on the circumference of the magnetic shaft to form a wide and narrow gap (labyrinth), and a block ring with fine irregularities formed on the inner surface is used as a pole piece and alternately overlaps with the magnet. Some of the known types include those with cooling grooves cut into the circumferential surface of the blocking ring.

[Problem that the invention attempts to solve]

The above-mentioned known magnetic fluid seal structure is uneconomical in machining to form irregularities on the circumferential surface of the magnetic shaft and fine irregularities on the inner surface of the blocking ring with high precision, and is structurally disadvantageous in that the magnetic flux density is limited within a narrow gap in the axial direction. Not only is it not possible to form a large number of magnetic fluid traps, but it is also difficult to sufficiently cool the viscous heat generated by the viscosity of the magnetic fluid and the high speed rotation of the shaft, which adversely affects the sealing effect.

The present invention has focused on the above points, and aims to improve magnetic fluid capture and cooling performance with a simple configuration, and to provide a magnetic fluid seal structure with high pressure-resistant sealing effect.

[Means for solving problems]

In order to achieve the above object, the magnetic seal structure according to the present invention includes a non-magnetic housing arranged around a magnetic shaft, and an annular cooling chamber centered around the rotation axis of the magnetic shaft inside the non-magnetic housing. a first disk-shaped magnetic body having an inner diameter slightly larger than the outer diameter of the magnetic shaft and having a part of the circumferential outer peripheral edge cut out; and an inner diameter of the first disk-shaped magnetic body. and a second disk-shaped magnetic body having a larger inner diameter and the same diameter as the first disk-shaped magnetic body, with a part of the circumferential outer edge edge cut out, and the outer circumferential edge of each of the second disk-shaped magnetic bodies A disk pack is formed by facing into the cooling chamber and having an unnotched outer peripheral edge fitted into the inner wall of the cooling chamber so as to overlap and adhere to each other alternately, and a plurality of disk packs are fixed to the non-magnetic housing. to form pole pieces and sandwich a magnet between each pole piece.
Further, the gist is that the magnetic fluid is trapped in the gap between the first disc-shaped magnetic body and the magnetic shaft.

[Effect]

The magnetic seal structure constructed as above is
While the pole piece is cooled in the cooling chamber, the magnetic shaft and each The spacing between the disc-shaped magnetic bodies is always set uniformly. In addition, the pole piece is constructed by fixing a plurality of disc packs in which first and second disc-shaped magnetic bodies having different inner diameters are alternately superimposed and adhered, so that a magnetic shaft and a first disc adjacent to the magnetic shaft are fixed. A magnetic fluid seal structure is obtained in which the magnetic fluid is trapped between the disk-shaped magnetic body and the magnetic fluid is not trapped between the magnetic shaft and the second disk-shaped magnetic body.

〔Example〕

Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 shows a configuration diagram when the magnetic fluid seal structure according to the present invention is applied between the atmosphere side A and the vacuum side B, and FIG. 2 shows a cross-sectional view perpendicular to the axis of FIG. 1.

In the figure, reference numeral 1 denotes a non-magnetic housing consisting of a main body 1a integrally formed on the partition wall C between the atmosphere side A and the vacuum side B, and a cover 1b fixed to the main body 1a. A shaft hole 3 for the magnetic shaft 2 is provided through A and the vacuum side B. That is, the non-magnetic housing 1 is connected to the magnetic shaft 2.
are arranged around the. An annular cooling chamber 4 is formed in the non-magnetic housing 1 in a concentric circle with the shaft hole 3, that is, on a circumference centered on the rotation axis of the magnetic shaft 2. Cooling fluid is forced to be fed from a cooler (not shown) through an inlet passage 5 formed in the peripheral wall of the magnetic housing 1 . Also,
The non-magnetic housing 1 is provided with an outflow passage 6 for a cooling fluid in a peripheral wall facing the inflow passage 5. By connecting this outflow passage 6 to a cooler, the cooling fluid is cooled. It circulates between the container and the cooling chamber 4.

Reference numerals 7 and 8 are pole pieces fixed to the non-magnetic housing 1 around the magnetic shaft 2 with a permanent magnet 9 sandwiched therebetween, and each of the pole pieces 7 and 8 has a thickness of 1.0 mm or less and has a different inner diameter. First disc-shaped magnetic body 10 and second disc-shaped magnetic body 1
This is achieved by fixing a plurality of disk packs in which the disk packs 1 are alternately superimposed in close contact with each other. The first disk-shaped magnetic body 10 is made of a magnetic body having an inner diameter slightly larger than the outer diameter of the magnetic shaft 2 and an outer diameter equal to the diameter of the large-diameter inner wall 4a of the cooling chamber 4. By preparing a disk and cutting out the outer edge of this disk in four directions,
An uncut outer peripheral edge 10a is left at the four corners. Further, the second disc-shaped magnetic body 11
has a larger inner diameter than the first disc-shaped magnetic body 10, and has an outer peripheral shape that is exactly the same as that of the first disc-shaped magnetic body 10. That is, the first and second disk-shaped magnetic bodies are formed to differ only in their inner diameters. The first disc-shaped magnetic body 10 and the second disc-shaped magnetic body 11 are alternately polymerized and adhered using resin or silver solder. Further, as shown in FIG. 2, the second disc-shaped magnetic body 11 is superposed in a state rotated by 45 degrees with respect to the first disc-shaped magnetic body 10. By configuring the pole pieces 7 and 8 as described above, the uncut outer peripheral edges 10 of the first and second disk-shaped magnetic bodies 10 and 11
a, 11a are fitted into the inner wall 4a of the cooling chamber 4, so that they are set concentrically with the magnetic shaft 2 and with their outer peripheral edges facing into the cooling chamber 4. Incidentally, the permanent magnet 9 is also formed in an annular shape, and is also adhesively fixed to the pole pieces 7 and 8 using resin or silver solder. Further, the inner circumferential surfaces each constitute a part of the shaft hole 3. Further, the inner peripheral edge side of the first disc-shaped magnetic body 10 protrudes into the shaft hole 3 and forms a gap of 0.01 mm to 0.2 mm between it and the magnetic shaft 2. The inner peripheral edge is formed to be flush with the inner wall of the shaft hole 3.

The first disc-shaped magnetic body 10 and the second disc-shaped magnetic body 11 in the pole pieces 7 and 8
The difference in inner diameter between the magnetic shaft 2 and the magnetic shaft 2 alternately forms wide and narrow gaps, which increases the magnetic flux density and increases the flow resistance of the leak fluid. In addition, the first and second disk-shaped magnetic bodies 1
Since the magnetic disks 0 and 11 are polymerized while being rotated alternately by 45 degrees, the cooling fluid in the cooling chamber 4 effectively contacts each disc-shaped magnetic body, resulting in a good cooling effect.

The cover 1b of the non-magnetic housing 1 is fixed to the main body 1a so as to sandwich the ball pieces 7, 8 and the permanent magnet 9 fixed between the pole pieces 7, 8 between the cover 1b and the main body 1a. The chamber 4 is formed within the nonmagnetic housing 1 by coupling the main body 1a and the cover 1b.

A magnetic fluid 13 is captured by the magnetic force of the permanent magnet 9 in a gap formed between the inner diameter portion of the first disc-shaped magnetic body 10 and the circumferential surface of the magnetic shaft 2.

It should be noted that the present invention is of course not limited to the above-mentioned embodiments, and for example, although the pole pieces are shown in two stages in the embodiment, the pressure resistance can be further improved by using three or more stages. In addition, the number of first and second disk-shaped magnetic bodies that make up the pole piece can be set arbitrarily, and although it is desirable that the thickness of these is 1.0 mm or less, those with a thickness of 1.0 mm or more are excluded. It's not something you do. Furthermore, the shapes of the first and second disk-shaped magnetic bodies may be different from each other, for example, as shown in FIG. The first disc-shaped magnetic body 10' and the second disc-shaped magnetic body 11', which have three sides cut out, or the first disc-shaped magnetic body 10'' shown in FIG. and arms 10b, 11 having outer circumferential edges 10a'', 11a'' that abut against the inner wall 4a of the cooling chamber 4, like the second disk-shaped magnetic body 11''.
A portion of the outer peripheral edge of the disk may be cut out to form the portion b. Further, the outer peripheral shapes of the first and second disk-shaped magnetic bodies may be different.

Furthermore, the gap between the first disk-shaped magnetic body and the magnetic shaft is ideally 0.01 to 0.2 mm;
The present invention is not necessarily limited to this,
Depending on the improvement of the processing accuracy of the cooling chamber, it may be possible to make it even closer, or conversely, it may be made 0.2 mm or more.

[Effect of idea]

As is clear from the above explanation, according to the fluid seal structure of the present invention, since the pole piece is composed of the first disc-shaped magnetic body and the second disc-shaped magnetic body with different inner diameters, the difference in the inner diameter Then,
A large number of closely spaced strong magnetic fields can be formed in the inner diameter of the magnetic shaft in close proximity to the circumferential surface of the magnetic shaft with a simple configuration, thus increasing the capture of the magnetic fluid.

Furthermore, since the first and second disk-shaped magnetic bodies are set so that a part of their outer peripheral edges fit into the inner wall of the cooling chamber, it is easy to adjust the distance between each disk-shaped magnetic body and the magnetic shaft. The magnetic shaft and the first disk-shaped magnetic body can be set uniformly, so there are places where the magnetic shaft and the first disc-shaped magnetic body are too far apart to capture the magnetic fluid, or conversely, where they are too close to each other and end up in contact. This eliminates the appearance of sparse spots and makes it possible to obtain an ideal gap of 0.01 mm to 0.2 mm anywhere around the magnetic shaft.

Furthermore, since the cooling fluid passes through the notched portions of the outer peripheral edges of the first and second disc-shaped magnetic bodies and passes through the cooling chamber, each disc-shaped magnetic body is effectively cooled, and magnetic Reduced adsorption and trapping of fluids is eliminated.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing the main parts of the embodiment of the present invention, FIG. 2 is a cross-sectional view perpendicular to the axis of FIG. 1, and FIG. FIG. 4 is an axis-perpendicular sectional view illustrating still another modification. 1... Non-magnetic housing, 2... Magnetic shaft, 4... Cooling chamber, 7, 8... Pole piece, 9... Permanent magnet, 10, 10', 10''...
First disc-shaped magnetic body, 11, 11', 11''...
...Second disk-shaped magnetic body, 10a, 10a', 1
0a'', 11a, 11a'11a''...uncut outer peripheral edge, 13...magnetic fluid.

Claims (1)

[Claims for Utility Model Registration] A non-magnetic housing is provided around a magnetic shaft, an annular cooling chamber is provided within the non-magnetic housing and is centered around the rotational axis of the magnetic shaft, and the outside diameter of the magnetic shaft is a first disk-shaped magnetic body having an inner diameter slightly larger than the inner diameter of the first disk-shaped magnetic body and having a part of the circumferential outer peripheral edge cut out; A second disc-shaped magnetic body having the same diameter as the first disc-shaped magnetic body and having a part of its circumferential outer peripheral edge cut out, and the outer peripheral edge of each disc-shaped magnetic body facing into the cooling chamber and cut out. A disc pack is constructed by fitting the uncircumcised outer peripheral edge to the inner wall of the cooling chamber and overlapping and tightly contacting each other alternately. A plurality of disc packs are fixed to the non-magnetic housing to form a pole piece, and each A magnetic fluid seal structure characterized in that a magnet is sandwiched between pole pieces, and a magnetic fluid is trapped in a gap between the first disc-shaped magnetic body and a magnetic shaft.