CN107906207B - Series-parallel magnetic fluid sealing device - Google Patents

Abstract

The invention discloses a hybrid magnetic fluid sealing device, which comprises a hollow casing, a rotating shaft arranged in the inner cavity of the casing, and at least one axial filling device is arranged in the radial direction between the outer surface of the rotating shaft and the inner wall of the casing. Magnetic first permanent magnets, pole shoes are respectively arranged on both sides of each first permanent magnet, at least one second groove is opened on the inner surface of each pole shoe in the upper direction, and each second groove is provided with The second permanent magnet; the second permanent magnet is a radially magnetized permanent magnet ring; the inner circular surface of the second permanent magnet stretches out from the second groove, and the inner circular surface of the second permanent magnet and the outer surface of the rotating shaft There is a second gap between them, and the second gap is filled with magnetic fluid. The invention increases the magnetic field intensity in the gap through structural improvement, and improves the pressure resistance and sealing performance of the magnetic fluid seal.

Description

A hybrid magnetic fluid sealing device

technical field

The invention belongs to sealing technology, in particular to a hybrid magnetic fluid sealing device.

Background technique

The magnetic fluid seal has the advantages of no solid friction between the seals, long service life of the seals, and zero leakage.

The existing magnetic fluid sealing structure generally includes a housing with a hollow cavity, a rotating shaft, a permanent magnet and a pole shoe are arranged between the rotating shaft and the housing for magnetic fluid sealing, and the inner ring of the pole shoe is provided with pole teeth.

This structure mainly has the following defects:

1. On the outer surface of the rotating shaft, the area where the magnetic fluid is sealed is the optical axis section. Once the magnetic fluid leaks, it will cause complete leakage and the seal will fail.

2. If a single-stage seal is used, the magnetic supply capacity is weak, the magnetic sealing performance is poor, and it is difficult to meet the requirements of vacuum sealing; if a multi-stage seal is used, the sealing performance can be improved, but the effect is not obvious, and it cannot reach high speed, etc. Occasionally, the scope of application is narrow. Moreover, the use of multi-stage sealing will make the equipment size large and occupy space.

Contents of the invention

In view of the above problems, the present invention aims to provide a hybrid magnetic fluid sealing device with high sealing performance and high pressure resistance performance.

The technical solution for solving the problem of the present invention is: a hybrid magnetic fluid sealing device, including a hollow housing, a rotating shaft arranged in the inner cavity of the housing, and a radial direction between the outer surface of the rotating shaft and the inner wall of the housing. At least one axially magnetized first permanent magnet, pole shoes are provided on both sides of each first permanent magnet, and at least one second groove is circumferentially opened on the inner surface of each pole shoe, and each second A second permanent magnet is arranged in the groove; the second permanent magnet is a radially magnetized permanent magnet ring;

The inner circular surface of the second permanent magnet protrudes from the second groove, and there is a second gap between the inner circular surface of the second permanent magnet and the outer surface of the rotating shaft, and the second gap is filled with magnetic fluid.

In the above solution, the second permanent magnet not only serves as the pole tooth of the pole shoe, but also reduces the length of the magnetic circuit of the first permanent magnet, enhances the magnetic field, and improves the magnetic sealing performance and pressure resistance performance.

Preferably, there are at least two second grooves, and the polarities of the magnetic poles of two adjacent second permanent magnets are opposite.

Further, in the radial direction of the rotating shaft, a disc-shaped shaft is provided at the position facing each of the first permanent magnets, the diameter of the disc-shaped shaft is larger than the diameter of the rotating shaft, and the disc-shaped shaft is located on both sides of the corresponding first permanent magnet between the pole shoes;

At least one third groove is circumferentially opened on the end surface of each pole piece facing the disk-shaped shaft, and a third permanent magnet is arranged in each third groove;

At least one fourth groove is circumferentially opened on the end surface of the disk-shaped shaft, and a fourth permanent magnet is arranged in each fourth groove;

The third permanent magnet and the fourth permanent magnet are axially magnetized permanent magnet rings, and the polarities of the two are opposite;

The outer end surface of the third permanent magnet stretches out the third groove, and there is a third gap between the outer end surface of the third permanent magnet and the end surface of the disk-shaped shaft; the outer end surface of the fourth permanent magnet stretches out the fourth groove, and the fourth permanent magnet There is a fourth gap between the outer end surface of the magnet and the end surface of the pole shoe;

The third permanent magnet and the fourth permanent magnet are distributed alternately and staggered along the radial direction;

The third and fourth gaps are filled with magnetic fluid.

In the above further improved solution, the third permanent magnet acts as the pole tooth of the pole shoe, and adopts a staggered arrangement, which can well block the magnetic fluid once the magnetic fluid leaks, greatly reducing the loss of the magnetic fluid. Moreover, compared with the prior art, the number of magnetic circuits is increased, the magnetic field strength is increased, the magnetic sealing performance and pressure resistance performance are improved, and the loss of magnetic fluid can be reduced when the sealing fails.

The design of the disk shaft, due to the blocking of the shoulder, will not cause all the magnetic fluid to leak once it fails, which further reduces the loss of the magnetic fluid when the seal fails.

In a specific solution, two third grooves are provided, one fourth groove is provided, the fourth permanent magnet is located between the two third permanent magnets, and the two fourth permanent magnets closest to the first permanent magnet The poles of the three permanent magnets are opposite to the polarity of the first permanent magnet.

The direction of the magnetic poles is specified in order to make the magnetic field direction of the added permanent magnet the same as the direction of the magnetic circuit where it is located, so as to enhance the magnetic field.

Preferably, the sizes of the second gap, the third gap and the fourth gap are each 0.05-3 mm.

Preferably, the second permanent magnet is a split permanent magnet.

The outer circular surface of the pole shoe and the inner wall of the casing are sealed by a sealing ring.

Magnetic isolation rings are provided on the outer surfaces of the two outermost pole pieces.

The rotating shaft is a stepped shaft, and the rotating shaft and the housing are assembled and connected by bearings, and the bearings include a first bearing and a second bearing that abut against the shoulder of the rotating shaft; a step is provided at one end of the inner cavity of the housing, and the first bearing One end surface is in contact with the step, and the second bearing is pressed and sealed in the inner cavity of the housing through the end cover; the first bearing and the second bearing are respectively arranged outside the two outermost pole pieces.

The invention expands the safe working range through structural improvement, and can meet the requirements of high-speed and other occasions, and its specific and remarkable effects are as follows:

1. Adopting the parallel arrangement, once the magnetic fluid leaks, it can well block the magnetic fluid, reduce the loss of the magnetic fluid, and increase the number of magnetic circuits compared with the existing technology; at the same time, it reduces the magnetic flux of the first permanent magnet. The length of the loop increases the magnetic field strength within the gap. The above improved structure realizes the function of magnetic fluid sealing in both radial and axial directions, thereby improving the pressure resistance and sealing performance of the magnetic fluid seal and reducing the loss of magnetic fluid when the seal fails.

2. The design of the disk shaft, due to the blocking of the shoulder, will not cause all the magnetic fluid to leak once it fails, which further reduces the loss of the magnetic fluid when the seal fails.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing.

Fig. 1 is a sectional view of the sealing device of the present invention.

In the figure: 1-rotating shaft, 2-housing, 3-first bearing, 4-magnetic isolation ring, 5-pole shoe, 6-first permanent magnet, 8-disc shaft, 9-second permanent magnet, 10 -sealing ring, 11-the third permanent magnet, 12-the second bearing, 13-step, 14-end cover, 15-the fourth permanent magnet.

Detailed ways

As shown in Figure 1, a hybrid magnetic fluid seal device includes a hollow housing 2, a rotating shaft 1 arranged in the inner cavity of the housing 2, and a radial direction between the outer surface of the rotating shaft 1 and the inner wall of the housing 2 At least one axially magnetized first permanent magnet 6 is arranged on the top, and pole pieces 5 are respectively arranged on both sides of each first permanent magnet 6 .

At least two second grooves are provided on the inner surface of each pole piece 5 in the circumferential direction, and a second permanent magnet 9 is arranged in each second groove. The second permanent magnet 9 is a radially magnetized split permanent magnet ring. The polarities of the magnetic poles of two adjacent second permanent magnets 9 are opposite.

The inner circular surface of the second permanent magnet 9 protrudes from the second groove, and there is a second gap between the inner circular surface of the second permanent magnet 9 and the outer surface of the rotating shaft 1, and the second gap is filled with magnetic fluid.

In the radial direction of the rotating shaft 1, a disc-shaped shaft 8 is provided at the position facing each of the first permanent magnets 6. The diameter of the disc-shaped shaft 8 is larger than that of the rotating shaft 1, and the disc-shaped shaft 8 is located at the corresponding first permanent magnet. between the pole pieces 5 on both sides of the magnet 6 .

Two third grooves are circumferentially formed on the end surface of each pole piece 5 facing the disk shaft 8 , and a third permanent magnet 11 is arranged in each third groove.

A fourth groove is circumferentially opened on the end surface of the disk shaft 8 , and a fourth permanent magnet 15 is arranged in the fourth groove.

The third permanent magnet 11 and the fourth permanent magnet 15 are axially magnetized permanent magnet rings with opposite polarities.

The outer end surface of the third permanent magnet 11 extends out of the third groove, and there is a third gap between the outer end surface of the third permanent magnet 11 and the end surface of the disk-shaped shaft 8 .

The outer end surface of the fourth permanent magnet 15 extends out of the fourth groove, and there is a fourth gap between the outer end surface of the fourth permanent magnet 15 and the end surface of the pole piece 5 .

The third permanent magnets 11 and the fourth permanent magnets 15 are distributed alternately and staggered along the radial direction. The fourth permanent magnet 15 is located between the two third permanent magnets 11 . The polarities of the two third permanent magnets 11 closest to the first permanent magnet 6 are opposite to those of the first permanent magnet 6 .

The third and fourth gaps are filled with magnetic fluid.

The sizes of the second gap, the third gap and the fourth gap are each 0.05-3mm.

The sealing ring 10 is used to seal between the outer surface of the pole shoe 5 and the inner wall of the housing 2 .

Magnetic isolation rings 4 are provided on the outer surfaces of the two outermost pole pieces 5 .

The rotating shaft 1 is a stepped shaft, and the rotating shaft 1 and the housing 2 are assembled and connected by bearings, and the bearings include a first bearing 3 and a second bearing 12 that abut against the shoulder of the rotating shaft 1; one end of the inner cavity of the housing 2 There is a step 13, the other end surface of the first bearing 3 abuts against the step 13, and the second bearing 12 is compressed and sealed in the inner cavity of the housing 2 through the end cover 14; the first bearing 3 and the second bearing 12 are respectively set On the outside of the two outermost pole shoes 5.

Claims (8)

1. The utility model provides a series-parallel connection formula magnetic fluid sealing device, includes hollow casing (2), sets up in pivot (1) of casing (2) inner chamber, is equipped with at least one axial first permanent magnet (6) that magnetizes on the radial direction between pivot (1) surface and casing (2) inner wall, and every first permanent magnet (6) both sides are equipped with pole shoe (5) respectively, its characterized in that: at least one second groove is circumferentially formed in the inner circular surface of each pole shoe (5), and a second permanent magnet (9) is arranged in each second groove; the second permanent magnet (9) is a radial magnetizing permanent magnet ring;

the inner circular surface of the second permanent magnet (9) extends out of the second groove, a second gap is formed between the inner circular surface of the second permanent magnet (9) and the outer surface of the rotating shaft (1), and magnetic fluid is injected into the second gap; a disc-shaped shaft (8) is arranged at the position, which is opposite to each first permanent magnet (6), in the radial direction of the rotating shaft (1), the diameter of the disc-shaped shaft (8) is larger than that of the rotating shaft (1), and the disc-shaped shaft (8) is positioned between pole shoes (5) at two sides of the corresponding first permanent magnet (6);

at least one third groove is circumferentially formed in the end face of each pole shoe (5) facing the disc-shaped shaft (8), and a third permanent magnet (11) is arranged in each third groove;

at least one fourth groove is circumferentially formed in the end face of the disc-shaped shaft (8), and a fourth permanent magnet (15) is arranged in each fourth groove;

the third permanent magnet (11) and the fourth permanent magnet (15) are axial magnetizing permanent magnet rings, and the polarities of the third permanent magnet and the fourth permanent magnet are opposite;

the outer end surface of the third permanent magnet (11) extends out of the third groove, and a third gap exists between the outer end surface of the third permanent magnet (11) and the end surface of the disc-shaped shaft (8); the outer end surface of the fourth permanent magnet (15) extends out of the fourth groove, and a fourth gap exists between the outer end surface of the fourth permanent magnet (15) and the end surface of the pole shoe (5);

the third permanent magnets (11) and the fourth permanent magnets (15) are alternately staggered and distributed along the radial direction;

magnetic fluid is injected into the third and fourth gaps.

2. A series-parallel magnetic fluid sealing device according to claim 1, wherein: at least two second grooves are arranged, and the polarities of the magnetic poles of two adjacent second permanent magnets (9) are opposite.

3. A series-parallel magnetic fluid sealing device according to claim 1, wherein: the number of the third grooves is two, one fourth groove is arranged, the fourth permanent magnet (15) is positioned between the two third permanent magnets (11), and the polarities of the two third permanent magnets (11) closest to the first permanent magnet (6) are opposite to those of the magnetic poles of the first permanent magnet (6).

4. A series-parallel magnetic fluid sealing device according to claim 1, wherein: the second gap, the third gap and the fourth gap are respectively 0.05-3 mm in size.

5. A series-parallel magnetic fluid sealing device according to claim 1, wherein: the second permanent magnet (9) is a split permanent magnet.

6. A series-parallel magnetic fluid sealing device according to claim 1, wherein: the outer circular surface of the pole shoe (5) is sealed with the inner wall of the shell (2) through a sealing ring (10).

7. A series-parallel magnetic fluid sealing device according to claim 1, wherein: the outer side surfaces of the two pole shoes (5) at the outermost side are respectively provided with a magnetism isolating ring (4).

8. A series-parallel magnetic fluid sealing device according to claim 1, wherein: the rotating shaft (1) is a stepped shaft, the rotating shaft (1) is connected with the shell (2) through bearing assembly, and the bearing comprises a first bearing (3) and a second bearing (12) which are abutted with a shoulder of the rotating shaft (1); one end of the inner cavity of the shell (2) is provided with a step (13), the other end face of the first bearing (3) is abutted against the step (13), and the second bearing (12) is tightly sealed in the inner cavity of the shell (2) through an end cover (14); the first bearing (3) and the second bearing (12) are respectively arranged outside the two pole shoes (5) at the outermost side.

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