JPH0239085Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention is designed to fill a minute gap between a rotating member and a stationary member by using magnetic fluid (Fe ₃ O _4, etc.) with fine particles of magnetic material such as oil, water, or organic The present invention relates to a magnetic fluid sealing device that prevents fluid such as gas from leaking from a high pressure side to a low pressure side through the micro gap.

(Prior Art) As a conventional magnetic fluid seal device of this type, there is one shown in FIG. 9, for example. That is, 100 is a housing, and this housing 10
A shaft 101 of a magnetic material serving as a rotating member is rotatably supported within the shaft 10 . A pair of magnetic poles 102 and 103 are provided on the inner periphery of the housing 100 to divide the inside of the housing 100 in the axial direction.
A minute gap 104 between the inner circumference of 103 and the shaft 101,
105 is formed. Also, each magnetic pole 102,1
A permanent magnet 106 is interposed on the outer peripheral side between 03,
A magnetic circuit 107 is formed by the combination of the permanent magnet 106, each magnetic pole 102, 103, and the shaft 101. The magnetic fluid F is magnetically attracted within the minute gaps 104 and 105 to seal the low pressure side and the high pressure side, thereby preventing leakage of the high pressure side fluid H to the low pressure side fluid L.

Magnetic fluid F into the minute gaps 104 and 105
The filling work was done as follows. First, as shown in FIG. 10, before inserting the shaft 101 into the housing 100, apply a magnetic fluid F to the magnetic poles 102, 10.
3, the permanent magnet 106 is magnetically attracted to the inner peripheral side. Next, the shaft 101 is inserted into the housing 100. Therefore, the tip of the shaft 101 is the housing 100.
Of the magnetic poles 102 and 103 arranged within the shaft 10
When it reaches the magnetic pole 103 on the far end side in the insertion direction of 1,
A magnetic circuit 107 is formed by the permanent magnet 106, each magnetic pole 102, 103, and the shaft 101, and the magnetic flux density passing through the minute gaps 104, 105 becomes high. As a result, the magnetic fluid F that was magnetically attracted to the permanent magnet 106 side is magnetically attracted within the minute gaps 104, 105 by the magnetic attraction force on the minute gaps 104, 105 side, and the magnetic fluid F is magnetically attracted within the minute gaps 104, 105. F is filled.

(Problem to be Solved by the Invention) However, in the case of such a conventional example, the tip of the shaft 101 is disposed within the housing 100 when the magnetic fluid F is filled into the minute gaps 104 and 105. Among the magnetic poles 102 and 103, the magnetic pole 103 on the far end side in the insertion direction of the shaft 101 is reached and the magnetic circuit 107
is formed, and at the same time the magnetic fluid F fills the minute gap 10
4,105 was magnetically adsorbed. However, the shaft 101 is assembled into the housing 100 by moving its tip further inward past the magnetic pole 103 on the rear end side in the shaft insertion direction. At that time, the magnetic fluid F filled in the minute gaps 104 and 105 is
The shaft 101 is moved while in contact with the 01 surface,
The magnetic fluid F closes the minute gap 10 due to the magnetic attraction force.
However, since the magnetic fluid F has high wettability, the adhesion force with the surface of the shaft 101 overcomes the magnetic attraction force in the minute gaps 104 and 105, and a part of the magnetic fluid F' is the magnetic pole 10 of the axis 101
2,103 and adheres to the circumferential surface of the magnetic pole passing region 101A. Therefore, the minute gap 104,
There was a problem in that the amount of magnetic fluid F filled into 105 decreased and sealing performance deteriorated. Therefore, in order to account for the loss of the magnetic fluid F' adhering to the magnetic pole passage area 101A of the shaft 101, it is better to increase the amount of magnetic fluid F that is attracted to the permanent magnet 106 in advance. The amount of minutes is not constant,
The amount of magnetic fluid F filled into the minute gaps 104 and 105 cannot be made uniform. In addition, magnetic fluid attached to the circumferential surface of the magnetic pole passage area 101A of the shaft 101
If F' is left as it is, the centrifugal force applied to the magnetic fluid F' adhering to the magnetic pole passage area 101A of the shaft 101 due to the rotation of the shaft 101 will overcome the adhesion force with the shaft 101 and cause the scattered magnetic fluid to scatter. When it adheres to the contact portion of each magnetic pole 102, 103 with the permanent magnet 106, the magnetic flux of the magnetic circuit 107 leaks due to the attached magnetic fluid, causing the small gap 104, 105 to leak.
The magnetic flux density passing through the micro gaps 104, 10 decreases.
The magnetic attraction force of the magnetic fluid F in 5 is weakened, and the sealing performance is deteriorated. Therefore, it is necessary to wipe off the magnetic fluid F' adhering to the magnetic pole passage area 101A of the shaft 101, resulting in a problem that the work process becomes complicated. Furthermore, a shaft 101 is provided within the housing 100.
Before inserting the magnetic fluid F, which is magnetically attracted to the permanent magnet 106 side between the magnetic poles 102 and 103, it is in contact with the low-pressure side and high-pressure side fluids L and H, which may cause contamination and deterioration of the magnetic fluid F. There was also the problem that sealing performance deteriorated.

The present invention was made to solve the problems of the prior art described above, and its purpose is to prevent a magnetic circuit from being formed during the insertion of the rotating member into the housing when the rotating member is inserted into the housing. The present invention also provides a magnetic fluid sealing device capable of sealing and holding a magnetic fluid between each magnetic pole, and filling a minute gap between the rotating member and each magnetic pole with the magnetic fluid after the rotating member is inserted. The object of the present invention is to equalize the amount of magnetic fluid filled in the gap, eliminate the need for wiping off the magnetic fluid, and prevent deterioration of the magnetic fluid due to contamination.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a minute gap is formed between the rotating member rotatably supported within the housing and the rotating member. a pair of magnetic poles that divide the inside of the housing in the axial direction; a magnetic force source that is interposed on the outer periphery between the magnetic poles and forms a magnetic circuit by the combination of the rotating member and the magnetic poles; In a magnetic fluid sealing device comprising a magnetic fluid that is magnetically attracted within a minute gap formed between the pair of magnetic poles, the cavity formed between the pair of magnetic poles and radially inward of the magnetic force source is called a large diameter chamber. and a small-diameter chamber, and a ring-shaped sealing member for sealingly holding the magnetic fluid toward the magnetic force source is arranged at the boundary between the large-diameter chamber and the small-diameter chamber, and a ring-shaped sealing member is arranged on one side in the radial direction of the sealing member. An endless shape memory alloy was attached to the chamber to urge the sealing member toward the large-diameter chamber when heated to form a communication path.

(Function) The minute gap between the rotating member and the shaft pole is filled with magnetic fluid by first forming the magnetic fluid radially inward of the magnetic source before inserting the rotating member into the housing at room temperature. The magnetic fluid is magnetically attracted to the inner circumferential side of the magnetic force source in the large-diameter chamber or the small-diameter chamber in the empty chamber.
The magnetic fluid magnetically attracted to the inner peripheral side of the magnetic force source is sealed and held by a sealing member. During the insertion of the rotating member into the housing, when the tip of the rotating member reaches the far end of the magnetic poles in the insertion direction among the magnetic poles arranged inside the housing, a magnetic circuit is formed due to the combination of the magnetic force source, each magnetic pole, and the rotating member. is formed, and the magnetic flux density in the microgap formed between each magnetic pole and the rotating member increases, and the magnetic fluid that was magnetically attracted to the inner circumference of the magnetic force source attempts to be attracted by the magnetic attraction force on the microgap side. is isolated from the small gap side by the sealing member, so it is sealed and held on the small diameter chamber or large diameter chamber side on the magnetic force source side. After the rotation member is inserted, the shape memory alloy is heated to urge the sealing member toward the large diameter chamber to form a communication path, and the magnetic fluid that was magnetically attracted to the inner circumference of the magnetic force source is released through the communication path. The rotating member moves to the side of the rotating member and is magnetically attracted into the minute gap, so that the minute gap is filled and held with magnetic fluid.

(Example) The present invention will be explained below based on the illustrated example. In FIGS. 1 to 4 showing a magnetic fluid sealing device according to a first embodiment of the present invention, 1 is a housing, and within this housing 1, a shaft 2 as a rotating member is rotatable concentrically with the housing 1. is supported by. A pair of ring-shaped magnetic poles 3 and 4 are provided on the inner periphery of the housing 1 to divide the inside of the housing 1 in the axial direction. The magnetic poles 3 and 4 are arranged parallel to each other and facing each other at a predetermined interval in the axial direction. The outer circumferences of the magnetic poles 3 and 4 are fitted into the inner circumference of the housing 1, and minute gaps 5 and 6 are formed between the inner circumferences of the magnetic poles 3 and 4 and the shaft 2. On the other hand, a ring-shaped permanent magnet 7 as a magnetic force source is interposed between the magnetic poles 3 and 4 on the outer peripheral side (that is, on the radially outer side), and both sides of the permanent magnet 7 are in close contact with each magnetic pole 3 and 4. . The magnetic force source is not limited to permanent magnets, but may also be electromagnets. Each magnetic pole 3,
4 and axis 2 is formed. Annular step portions 32 and 42 are formed on the opposing surfaces 31 and 41 of each of the magnetic poles 3 and 4, respectively,
The interval between the magnetic poles 3 and 4 is narrower on the outer circumferential side and wider on the inner circumferential side with the stepped portions 32 and 41 as boundaries, and the above-mentioned cavity A is separated from the small diameter chamber B on the outer circumferential side and the inner circumferential side with the stepped portions 32 and 42 as boundaries. It is divided into two chambers, a large diameter chamber C on the circumferential side. At the boundary between the small-diameter chamber B and the large-diameter chamber C, there is a sealing member that closely contacts the stepped portions 32 and 42 over the entire circumference and seals and holds the magnetic fluid F injected into the small-diameter chamber B on the magnet side. O made of rubber-like elastic material
A ring 9 is arranged. The diameter of the circular cross section of the O-ring 9 is at least larger than the width of the small diameter chamber B and smaller than the width of the large diameter chamber C. Also O ring 9
The outer diameter of the O-ring 9 is set so that the O-ring 9 is in close contact with the step portions 32 and 42 over the entire circumference. Of course, the sealing member is not limited to the above-mentioned O-ring 9, but may be any member that closely seals the small-diameter chamber B by the stepped portions 32, 42. For example, a molded packing such as a square ring or a V-ring may be used. good.

Further, in this embodiment, an injection hole 1 for injecting the magnetic fluid F into the small diameter chamber B in one of the magnetic poles 4 is used.
0 is provided. This injection hole 10 is a small diameter chamber B.
After the magnetic fluid F is injected into the opening, it is closed by a closing member (not shown).

On the other hand, on one side of the O-ring 9 in the radial direction, in this embodiment, on the radially outer side of the small-diameter chamber, an O-ring is placed at the time of heating.
An endless shape memory alloy 11 is attached that urges the ring 9 toward the large diameter chamber radially inward to connect the small diameter chamber B and the large diameter chamber C. shape memory alloy 1
1 is a regular polygon inscribed in the outer circumferential surface of the O-ring 9 at room temperature, as shown in FIG. Each side 11a, . . . is bent inward in the radial direction into a triangular shape to return to a shape having bent portions 11b, . During heating, the O-ring 9 is bent radially inward along each of the bent portions 11b, . . . , and as shown in FIG. A communication passage 12 that communicates the small-diameter chamber B and the large-diameter chamber C is formed by the gap between the two.

In the magnetic fluid sealing device having the above configuration, the minute gaps 5 and 6 are filled with the magnetic fluid F in the following manner. First, a predetermined amount of magnetic fluid F is injected into the small diameter chamber B from the injection hole 10 at room temperature, and the injection hole 10 is closed after injection. The injected magnetic fluid F is cut off from the outside and is magnetically attracted to the inside of the permanent magnet 7, which has a high magnetic flux density. Next, the shaft 2 is inserted between the magnetic poles 3 and 4. When the tip of the shaft 2 reaches the magnetic pole 4 on the far end side in the shaft insertion direction, a magnetic circuit 13 is formed between the permanent magnet 7, each magnetic pole 3, 4, and the shaft 2, and a magnetic circuit 13 is formed between the magnetic poles 3, 4 and the shaft 2. The magnetic flux density in the minute gaps 5 and 6 increases. As a result, the magnetic fluid F attempts to move toward the large-diameter chamber C due to the magnetic attraction force of the micro gaps 5 and 6, but its movement is restricted by the O-ring 9, and the magnetic fluid F is sealed inside the small-diameter chamber B. Retained. Next, after inserting the shaft 2 to a predetermined position and completing necessary processes such as alignment adjustment, when the shape memory alloy 11 is heated, the shape memory alloy 11 returns to its original state due to the shape memory effect, as shown in FIG. Return to shape. That is, each side 11a of the shape memory alloy 11 inscribed in the outer periphery of the O-ring 9 is bent radially inward, and the O-ring 9 is urged radially inward by the bent portion 11b. A communication passage 12 that communicates the small-diameter chamber B and the large-diameter chamber C is formed at the bent portions 91, . . . . The magnetic fluid F flows out from the small-diameter chamber B to the large-diameter chamber C through the communication path 12 due to the magnetic attraction force, and is filled and held in the micro-gaps 5 and 6 with high magnetic flux density.
6 is closed to prevent the high pressure side fluid H from leaking to the low pressure side fluid L side. In addition, in this example,
Although the injection hole 10 is provided in the magnetic pole 4, the injection hole 10
Instead, the O-ring 9 may be assembled after the magnetic fluid F is attracted to the inside of the permanent magnet 7 in advance.

Next, FIGS. 5 to 8 show a second embodiment of the magnetic fluid sealing device according to the present invention, and the same components as in the first embodiment will be described with the same reference numerals. In the second embodiment, the stepped portions 32, 42 provided on the opposing surfaces 31, 41 of the respective magnetic poles 3, 4 are narrower on the radially inner side than on the radially outer side, and the empty space A is formed on the stepped portion. Part 32, 4
2 as the boundary, the permanent magnet 7 side is in the large diameter chamber C', and the shaft 2
The side is divided into a small diameter chamber B'. The O-ring 9 is arranged in the large-diameter chamber C' on the side of the permanent magnet 7.
The large-diameter chamber C′ is sealed by

Furthermore, the shape memory alloy 14 is attached to the inner peripheral side of the O-ring 9 as shown in FIGS. 5 and 6, and its shape is the corner portion 14a,...
has a polygonal shape inscribed in the inner periphery of the O-ring 9, and as shown in FIG. 8 during heating, each corner 14a,
... returns to the straight line every other corner, and the other corners 14b,
... project radially outward to bias the O-ring 9 radially outward. That is, O
The ring 9 is partially bent radially outward to form a communication passage 12' that communicates the large diameter chamber C' and the small diameter chamber B' at the deflected portion 91, as shown in FIG. .

Furthermore, unlike the first embodiment, the magnetic poles 3 and 4 are not provided with an injection hole 10 for injecting the magnetic fluid F, and after the magnetic fluid F is attracted to the inside of the permanent magnet 7, it is magnetically It is designed to seal the fluid F. Of course, an injection hole may be provided as in the first embodiment. The other configurations and operations are the same as those in the first embodiment, so their explanations will be omitted.

(Effects of the invention) The present invention has the above-described structure and operation. During insertion of the rotating member into the housing, the magnetic fluid magnetically attracted to the inner periphery of the magnetic force source is sealed and held by the sealing member, and the rotating member is rotated. After the insertion of the member is completed, the shape memory alloy is heated to return to its original memorized shape, thereby energizing the sealing member and forming a communication path, through which the magnetic fluid is magnetically attracted within the minute gap. Therefore, even if a magnetic circuit is formed between the magnetic force source, each magnetic pole, and the rotating member during insertion of the rotating member into the housing, the magnetic fluid will not adhere to the rotating member as in the conventional case, and the rotating member Loss of the magnetic fluid due to adhesion of the magnetic fluid to the magnetic pole passage area is prevented, thereby making it possible to equalize the amount of magnetic fluid filled in the minute gap and improving sealing performance. Further, unlike the conventional method, it is not necessary to wipe off the magnetic fluid adhering to the magnetic pole passing region of the rotating member, and the work process can be shortened. Furthermore, the magnetic fluid magnetically attracted to the inner periphery of the magnetic force source is sealed and held by the sealing member, thereby shielding it from the outside.
Contamination and deterioration of the magnetic fluid can be prevented.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of the main part of the magnetic fluid sealing device according to the first embodiment of the present invention, showing the state before heating, FIG. 2 is a cross-sectional view taken along the line -- in FIG. 1, and FIG. Fig. 4 is a vertical cross-sectional view of main parts showing the state of the device after heating.
The figures are a cross-sectional view taken along the line - - in Fig. 3, Fig. 5 is a vertical cross-sectional view of main parts showing the state before heating of the magnetic fluid sealing device according to the second embodiment of the present invention, and Fig. 6 is a - line sectional view taken along the - line in Fig. 5.
7 is a longitudinal sectional view of the main part showing the state of the device after heating, and FIG. 8 is a line sectional view of FIG. 7.
9 is a longitudinal sectional view of the main part of a conventional magnetic fluid sealing device, FIG. 10 is a longitudinal sectional view of the main part showing the state of the magnetic fluid sealing device of FIG. 9 before the shaft is inserted, and FIG. 11 FIG. 2 is a vertical cross-sectional view of a main part of the sealing device after the shaft is inserted. Explanation of symbols, 1... Housing, 2... Shaft (rotating member), 3, 4... Magnetic pole, 32, 42... Step portion, 5, 6... Minute gap, 7... Permanent magnet (magnetic force source) , 9... O-ring (sealing member), 11, 14...
... Shape memory alloy, 91 ... Flexible part, 10 ... Inlet, 12, 12' ... Communication path, 13 ... Magnetic circuit,
A...vacant room, B, B'...small diameter room, C, C'...large diameter room.

Claims (1)

[Scope of utility model registration request] a rotating member rotatably supported within a housing; a pair of magnetic poles forming a minute gap between the rotating member and dividing the inside of the housing in the axial direction;
a magnetic force source that is interposed on the outer circumferential side between the magnetic poles and forms a magnetic circuit by the combination of the rotating member and the magnetic pole; and a magnetic force that is magnetically attracted within a minute gap formed between the rotating member and the magnetic pole. In a magnetic fluid sealing device comprising a fluid, a cavity formed between the pair of magnetic poles and radially inward of the magnetic force source is composed of two chambers, a large-diameter chamber and a small-diameter chamber, and the large-diameter A ring-shaped sealing member is disposed at the boundary between the chamber and the small-diameter chamber to seal and hold the magnetic fluid toward the magnetic force source, and a ring-shaped sealing member is arranged on one radial side of the sealing member to urge the sealing member toward the large-diameter chamber when heated. A magnetic fluid sealing device characterized in that an endless shape memory alloy is attached to form a communication path.