JPH0671969U - Magnetic fluid sealing device - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the sealing performance. A rotating body 9 fixed to an inner member 3 of the two members 2 and 3 and rotating together with the inner member 3 is provided on both outer sides of a pair of magnetic pole pieces 5, and an outer diameter of the rotating body 9 is provided. The side is provided with a labyrinth seal portion 10.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetic fluid seal device used for sealing a bearing part or the like in which an object to be sealed is splashed.

[0002]

[Prior art]

 As a conventional magnetic fluid seal device of this type, there is one as shown in FIG. 7, for example. That is, the magnetic fluid seal device 100 seals the gap between the shaft 101 made of a non-magnetic material and the housing 102 made of a magnetic material as two members which are concentrically assembled with each other in relative rotation.

The magnetic fluid seal device 100 includes an annular magnetic force source 103 magnetized in the axial direction and a pair of annular magnetic pole pieces 104 arranged on both sides of the annular magnetic force source 103. Since the housing 102 is made of a magnetic material, the magnetic fluid 106 is retained by the magnetic attraction force in the minute gap 105 provided between the tip of the piece 104 and the housing 102 to be sealed, thereby sealing.

[0004]

[Problems to be solved by the device]

 However, in the case of the above-mentioned conventional technique, since the magnetic fluid 106 is used for sealing, only slight dust or gas can be sealed, and oil or water cannot be sealed.

Further, although there is an oil seal as a seal for oil, water, etc., it has a drawback of high torque.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a magnetic fluid seal device capable of improving the sealability and reducing the torque. To provide.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention seals a gap between two members which are concentrically and rotatably assembled with each other. An axially magnetized magnetic force source and both sides of the magnetic force source are provided. A pair of magnetic pole pieces arranged to hold the magnetic fluid in a minute gap between the pair of magnetic pole pieces and one of the two parts to be sealed by magnetic attraction. In the magnetic fluid sealing device, a rotating body fixed to a radially inner member of the two members and rotating together with the inner member is provided outside both of the pair of magnetic pole pieces in the axial direction. It is characterized in that it has a labyrinth seal portion on the outer diameter side.

[0008]

[Action]

 In the magnetic fluid seal device having the above-described configuration, the labyrinth seal portion is provided on the outer diameter side of the rotating body which is provided outside the pair of magnetic pole pieces and rotates together with the radially inner member of the two members. By doing so, the effect of shaking off oil, water, etc. when the inner member is rotated can be achieved, and intrusion of oil, water, etc. can be prevented.

Further, since the labyrinth seal portion is provided outside both of the pair of magnetic pole pieces in the axial direction, the suction force at the labyrinth seal portion becomes unrelated. Therefore, the magnetic fluid in the labyrinth seal part is stably held, and the sealing performance can be improved.

Further, since the labyrinth seal portion is provided, the non-contact state is achieved, and hence the torque can be reduced.

[0011]

【Example】

 The present invention will be described below based on the illustrated embodiment. In FIG. 1, which shows a magnetic fluid sealing device according to an embodiment of the present invention, reference numeral 1 denotes the entire magnetic fluid sealing device. The magnetic fluid sealing device 1 is assembled concentrically with each other and is rotatable relative to each other. The gap between the housing 2 made of a non-magnetic material and the shaft 3 made of a non-magnetic material inserted into the housing 2 is sealed.

The magnetic fluid seal device 1 is roughly configured as follows: a permanent magnet 4 as a magnetic force source magnetized in the axial direction, a yoke 5 as a pair of magnetic pole pieces arranged on both sides of the permanent magnet 4, and a yoke. 5A and a magnetic fluid 8 held by a magnetic attraction force in a minute gap 7 between the housing 2 to be sealed via a sleeve 6 fixed to the inner circumference of the housing 2, and a magnetic fluid seal member 1A. And a labyrinth seal portion 10 provided on the outer diameter side of the rotor 9, which is fixed to the shaft 3 and rotates together with the shaft 3, and a labyrinth seal constituting portion 1B. It is a combined type magnetic fluid sealing device.

The magnetic fluid seal portion 1A is composed of the permanent magnet 4, the pair of yokes 5, and the magnetic fluid 8 as described above.

The permanent magnet 4 is an annular member having a rectangular cross section, and a pair of yokes 5 is attracted to both end surfaces thereof. The yoke 5, which is an annular member, is fitted and fixed to the shaft 3 together with the permanent magnet 4, and the tip end portion thereof projects outward in the radial direction from the permanent magnet 3. The tip portion of the protruding yoke 5 has a tapered surface 51 whose outer end surface is reduced in diameter toward the tip so that the magnetic flux can be concentrated so that the tip has an acute angle.

The sleeves 6 are arranged opposite to each other with a minute gap 7 and the tips of the pair of yokes 5. The sleeve 6 is made of a magnetic material and has a T-shaped cross section. The cylindrical portion 61 is fitted and fixed to the inner peripheral surface of the housing 2, and the inner periphery of the cylindrical portion 61 is connected to the tips of the pair of yokes 5. The inward flange portion 62 extends inward in the radial direction and has surfaces facing each other with a minute gap 7 therebetween. Then, the magnetic fluid 8 is injected into the minute gap 7 between the tips of the pair of yokes 5 and the inner peripheral surface of the inward flange portion 62 of the sleeve 6, and the magnetic fluid 8 is held by the magnetic attraction force.

The gap between the shaft 3 and the housing 2 is sealed via the sleeve 6 by the magnetic fluid seal portion 1A configured as described above.

Then, labyrinth seal components 1B are provided on both sides of the magnetic fluid seal 1A.

The labyrinth seal-constituting portion 1B is composed of the rotating body 9 and the labyrinth seal portion 10 provided on the outer diameter side of the rotating body 9 as described above.

The rotating body 9 is fixed to the outer peripheral surface of the shaft 3 and rotates together with the shaft 3. The rotating body 9 is provided outside of both the pair of yokes 5 in the axial direction to form a pair. The shape of the rotating body 9 is an annular member having a U-shaped cross-section that is open to the outside in the axial direction.

The inner ends of the rotating members 9 are in contact with the outer ends of the yokes 5 (in this embodiment, they are in contact with each other, but they may be separated from the outer ends of the yoke 5). The inner peripheral surface of the inner peripheral side cylindrical portion 91 on the inner peripheral side is fitted and fixed to the outer peripheral surface of the shaft 3, and the outer peripheral surface of the outer peripheral side cylindrical portion 92 is larger than the outer diameter of the yoke 5. The inner peripheral surface of the housing 2 and the inner peripheral surface of the cylindrical portion 61 of the sleeve 6, which are fitted and fixed to each other, are disposed so as not to contact each other and face each other.

A labyrinth gap 11 is formed between the outer peripheral surface of the outer peripheral side cylindrical portion 92 of the rotating body 9 and the inner peripheral surface of the cylindrical portion 61 of the sleeve 6 in the non-contact state. A labyrinth seal portion 10 facing the labyrinth gap 11 is formed on the outer peripheral surface of the cylindrical portion 92. This labyrinth seal portion 10 has a concavo-convex cross section that is continuous in the axial direction.

Further, since the outer peripheral surface of the outer peripheral side cylindrical portion 92 has a larger diameter than the outer diameter of the yoke 5, the seal diameter of the magnetic fluid seal portion 1A (the portion where the magnetic fluid 8 is held) is larger than that of the magnetic fluid seal portion 1A. The labyrinth seal portion 10 has a large seal diameter.

In the magnetic fluid seal device having the above-mentioned configuration, the labyrinth seal portion 10 formed by the labyrinth seal constituting portion 1B is provided on the outer diameter side on both outer sides of the magnetic fluid seal portion 1A, and therefore is shown in FIG. Even if some dust OL such as oil or water comes toward the sealing target side, the rotating body 9 having the labyrinth seal portion 10 rotates together with the rotation of the shaft 3, so that the rotation of the shaft 3 is prevented. By the action of the centrifugal force at the time, the dust OL such as oil and water is shaken off, and the dust OL such as oil and water can be prevented from entering the magnetic fluid seal portion 1A.

Further, if the labyrinth seal portion 10 is only one side, the magnetic fluid 8 is pulled toward the labyrinth seal portion 10 side by negative pressure and is not stable. Are provided outside both of the pair of yokes 5, the suction force in the labyrinth seal portion 10 is not biased, and the magnetic fluid 8 in the magnetic fluid seal portion 1A inside the labyrinth seal portion 10 is stably held. Will be done. Therefore, good sealing performance can be maintained in the magnetic fluid seal portion 1A.

From the above, it is possible to improve the sealing property, and it is possible to seal the oil mist and grease from the sealing target side O and the oil and water from the outside A.

Further, the labyrinth seal portion 10 has good sealing performance at high speed rotation, but has a drawback that sealing performance is poor at low speed. However, since it is combined with the magnetic fluid seal portion 1A, the air flow is eliminated by the portion of the magnetic fluid 8 which is the seal portion of the magnetic fluid seal portion 1A, and the sealing performance at low speed is also improved. That is, a wide range of sealing is possible from low speed to high speed.

Further, since a contact type oil seal was conventionally used to seal dust OL such as oil and water, the torque was high, but the use of the labyrinth seal portion 10 causes a non-contact state. As a result, it is possible to significantly reduce the torque (equivalent to the torque in the magnetic fluid seal portion 1A) compared to the conventional case.

FIG. 3 shows a second embodiment of the present invention. In the above-described embodiment, the sealing portion formed by the magnetic fluid 8 is on the housing 2 side and the outer peripheral side is sealed. However, in this embodiment, the sleeve 6 fitted and fixed to the inner peripheral surface of the housing 2 is eliminated, and the inner peripheral surface of the housing 2 is eliminated. A magnetic fluid seal portion 1A is attached to the surface, the shaft 3 is made of a magnetic material, and the seal portion made of the magnetic fluid 8 is made to be the shaft 3 side to form an inner peripheral side seal. Since other configurations and operations are the same as those of the first embodiment, the same components are designated by the same reference numerals and the description thereof is omitted.

Here, referring to FIG. 4, the labyrinth seal portion 10 shown in the first embodiment is based on the magnetic fluid seal device 1 ′ in which the magnetic fluid seal device 1 A in the second embodiment is an inner peripheral side seal. It will be described that the sealability is improved by the relationship between the seal diameter and the seal diameter in which the magnetic fluid 8 which is the seal portion of the magnetic fluid seal portion 1A is interposed. FIG. 4 (a) shows a magnetic fluid seal device 1'in the second embodiment, in which the labyrinth seal portion 10 is on the outer diameter side. That is, "the seal diameter of the magnetic fluid seal portion 1A <the seal diameter of the labyrinth seal portion 10". On the other hand, FIG. 4 (b) shows a magnetic fluid seal device 1 ″ in which the labyrinth seal portion 10 is on the inner diameter side. That is, “the seal diameter of the magnetic fluid seal portion 1A ≧ the seal diameter of the labyrinth seal portion 10”. Is.

Therefore, as shown in FIG. 4, when some oil OIL comes to the shaft 3, in the case of “seal diameter of magnetic fluid seal portion 1A ≧ seal diameter of labyrinth seal portion 10” shown in FIG. 4 (b) The oil OIL is likely to enter the magnetic fluid seal portion 1A side directly from the shaft 3 and reduce the sealing function.

On the other hand, in the case of “the seal diameter of the magnetic fluid seal portion 1 A <the seal diameter of the labyrinth seal portion 10” shown in FIG. 4A, the shaft 3 is rotated by the centrifugal force when the shaft 3 rotates. The oil OIL adhering to 3 is splashed in the outer peripheral direction, and further, since the labyrinth seal portion 10 is provided on the outer diameter side, the oil OIL is less likely to enter the magnetic fluid seal portion 1A.

As described above, the dust OL such as oil and water is removed from the magnetic fluid seal portion 1A by the action of the centrifugal force, and the sealability is improved.

FIG. 5 shows a third embodiment of the present invention. This embodiment is a centrifugal pump type magnetic fluid seal device in which the tips of the pair of yokes 5 are flattened and the rotor 9 of the labyrinth seal constituting portion 1B has fin portions 12 in the second embodiment. is there. The fin portion 12 has an impeller shape as shown in FIG. As another aspect, a radial pattern as shown in FIG. 5C may be used. The fin portion 12 prevents the dust such as oil and water from entering due to the pumping action. In this case, when the fin portion 12 has an impeller shape, the pump action is large, but only one rotation. On the other hand, when the fin portion 12 is radial, the pump action is small but both rotations are possible. Since other configurations and operations are the same as those in the second embodiment, the same reference numerals are given to the same components and the description thereof will be omitted.

FIG. 6 shows a fourth embodiment of the present invention. This embodiment is a magnetic fluid seal device of a mixed flow pump type in which the fin portion 12 is inclined outward as shown in FIG. 6 in the third embodiment. Since other configurations and operations are the same as those of the third embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted.

[0035]

[Effect of device]

 The present invention has the above-described configuration and operation, and the labyrinth seal portion is provided on the outer diameter side of the rotating body that is provided outside the pair of magnetic pole pieces and rotates together with the inner member of the two members. Therefore, when rotating the inner member, the effect of wiping off oil, water, etc. can be achieved, and intrusion of oil, water, etc. can be prevented.

Further, since the labyrinth seal portion is provided on both outer sides of the pair of magnetic pole pieces, the suction force at the labyrinth seal portion becomes unrelated. As a result, the magnetic fluid inside the labyrinth seal can be held stably and the sealing performance can be improved.

Further, since the labyrinth seal portion is provided, the non-contact state is achieved, and hence the torque can be reduced.

[Brief description of drawings]

FIG. 1 is a longitudinal cross-sectional view of a main part of a magnetic fluid seal device according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a state in which a small amount of oil, water, or the like is coming toward the sealing target side in the magnetic fluid sealing device of FIG.

FIG. 3 is a vertical cross-sectional view of a magnetic fluid seal device according to a second embodiment of the present invention.

FIG. 4 is a fragmentary front view showing the relationship between the seal diameter of the labyrinth seal portion and the seal diameter of the magnetic fluid seal portion, and FIG. 4 (a) is a view showing that the seal diameter of the labyrinth seal portion is the magnetic fluid seal. The seal diameter of the labyrinth seal portion is the same as or smaller than the seal diameter of the magnetic fluid seal portion.

5 (a) is a fragmentary front view of a magnetic fluid seal device according to a third embodiment of the present invention, and FIG. 5 (b) is a sectional view taken along line XX of FIG. 5 (a). FIG. 6C is a cross-sectional view of the fin portion of another aspect.

FIG. 6 is a fragmentary front view of a magnetic fluid seal device according to a fourth embodiment of the present invention.

FIG. 7 is a vertical cross-sectional view of a main part of a conventional magnetic fluid sealing device.

[Explanation of symbols]

 1, 1 ', 1 "Magnetic fluid seal device 1A Magnetic fluid seal part 1B Labyrinth seal component part 2 Housing 3 Shaft 4 Permanent magnet (magnetic force source) 5 Yoke (pole piece) 51 Tapered surface 6 Sleeve 61 Cylindrical part 62 Inward flange Part 7 Micro gap 8 Magnetic fluid 9 Rotating body 91 Inner peripheral side cylindrical part 92 Outer peripheral side cylindrical part 10 Labyrinth seal part 11 Labyrinth gap 12 Fin part

Claims (1)

[Scope of utility model registration request] 1. A seal for sealing a gap between two members which are concentrically and rotatably assembled with each other, and comprises a magnetic force source magnetized in an axial direction and a pair of magnetic pole pieces arranged on both sides thereof. A magnetic fluid sealing device that holds a magnetic fluid by a magnetic attraction force in a minute gap between the pair of magnetic pole pieces and one of the two members to be sealed, wherein: A rotating body that is fixed to a radially inner member and rotates together with the inner member is provided outside both of the pair of magnetic pole pieces in the axial direction, and a labyrinth seal portion is provided on the outer diameter side of the rotating body. Magnetic fluid sealing device characterized by: