CN107893855B - Concave stepped shaft magnetic fluid sealing device - Google Patents

Abstract

The invention relates to a concave stepped shaft magnetic fluid sealing device which comprises a shell, a sealing component and an end cover; the sealing assembly comprises a shaft, the shaft is rotatably arranged in the shell through a bearing, the shaft comprises a concave step part, the concave step part comprises a plurality of steps which are sequentially arranged along the axial direction, and the outer walls of the adjacent steps are connected through chamfer-shaped transition surfaces; each transition surface is sleeved with a split type pole shoe matched with the transition surface, the split type pole shoe extends to a position corresponding to a corresponding step at the side part of the transition surface towards one side or two sides of the transition surface, gaps are reserved between the inner wall of the split type pole shoe and the corresponding transition surface and step, and pole teeth are arranged on the inner wall of the split type pole shoe; permanent magnets are arranged between the adjacent split pole shoes. The device has strong pressure resistance and convenient production and processing; when the sealing fails, the loss of the magnetic fluid is small, the secondary pressure bearing capacity and the self-repairing capacity are strong, and the pressure bearing capacity and the sealing reliability of the device under the condition of large gaps are effectively increased, so that the safe working range is enlarged.

Description

A concave stepped shaft magnetic fluid seal device

technical field

The invention relates to a magnetic fluid sealing device for a concave stepped shaft, which belongs to the field of mechanical engineering sealing.

Background technique

The magnetic fluid seal is to use the magnetic fluid seal ring formed by the magnetic fluid under the action of the magnetic field to seal the gas and liquid. Since the seal shaft is contacted and sealed by the magnetic fluid, the gap between the seal shaft and the seal is avoided. The direct friction reduces the additional load. It has incomparable advantages in other sealing methods in the rotary shaft seal, and has attracted the attention of scholars and engineers at home and abroad, and has important significance in the fields of industry and national defense. Compared with traditional mechanical seals or packing seals, magnetic fluid seals have unique advantages such as no leakage and low wear, but the pressure resistance of magnetic fluid seals is not too high, and the number of sealing stages of multi-stage seals cannot be too many. Therefore, how to reasonably design the structural parameters of the magnetic fluid seal, improve the utilization efficiency of the permanent magnet, and enhance the pressure resistance of the seal is also a meaningful research content of the current magnetic fluid seal technology.

One of the methods to improve the pressure resistance performance of magnetic fluid seals under large gaps is to increase the number of magnetic sources in the magnetic circuit of magnetic fluid seals and improve the shape of pole pieces, such as the seal described in reference 1 (the patent publication number is CN202332310U). Device and the sealing device described in reference 2 (publication number is the patent of CN206600473U). Although the sealing performance of the two sealing devices described in the above documents has been greatly improved compared with ordinary magnetic fluid, there is still room for further improvement in the sealing performance of the existing sealing structure.

The magnetic fluid seal is to use the permanent magnet to generate a magnetic field force in the sealing gap to firmly fix the magnetic fluid in the sealing gap and resist the pressure difference on both sides, so as to achieve the sealing effect.

Contents of the invention

The purpose of the present invention is to provide a magnetic fluid sealing device with a concave stepped shaft, thereby solving the problem of low pressure resistance existing in the existing single magnetic source magnetic fluid sealing device and multi-magnetic source magnetic fluid sealing device, and at the same time reducing stress concentration, This makes the sealing technology successfully applied in high-speed and heavy-duty fields.

In order to solve the above-mentioned technical problems, the technical solution of the present invention is as follows: a magnetic fluid sealing device for a concave stepped shaft, including a casing with two ends open, a sealing assembly and an end cover for pressing the sealing assembly in the casing; the sealing The assembly includes a shaft, the shaft is rotatably installed in the casing through a bearing, the shaft includes at least one concave step, and the concave step includes a plurality of steps arranged in sequence along the axial direction, and the outer walls of adjacent steps pass through The chamfered transition surface is connected; each transition surface jacket is provided with a split-type pole piece that matches the transition surface, and the split-type pole piece extends to one side or both sides of the transition surface to the corresponding side of the transition surface. At the position corresponding to the step, there is a gap between the inner wall of the split-type pole piece and the corresponding transition surface and the step, and the inner wall and/or axis of the split-type pole piece correspond to the inner wall of the split-type pole piece There are pole teeth in the parts; there are permanent magnets between adjacent split pole pieces.

Further, the included angle between the transition surface and the central axis of the shaft is 5-75 degrees, preferably 20-60 degrees. Correspondingly, the inclination angle of the portion of the inner wall of the split pole piece corresponding to the transition surface is the same as that of the corresponding transition surface.

Preferably, the number of transition surfaces is 2-10.

Further, the pole teeth include axial pole teeth and/or transition pole teeth, the axial pole teeth are arranged on the step and/or on the inner wall of the split pole shoe corresponding to the step, and the transition pole teeth are arranged on the transition surface and/or on the inner wall of the split pole piece corresponding to the transition surface.

Preferably, the pole teeth include axial pole teeth and transition pole teeth, the axial pole teeth are arranged on the inner wall of the split pole shoe corresponding to the step, and the transition pole teeth are arranged on the split pole pole corresponding to the transition surface on the inside of the boot.

Further, on the inner wall of a single split-type pole piece, the number of axial pole teeth and transition pole teeth are both 2-10.

As an embodiment of the present invention, the concave step part includes one first step, two second steps and two third steps, and the diameters of the first step, the second step and the third step increase successively. The two second steps and the two third steps are symmetrically distributed on both sides of the first step.

Further, the number of the split pole pieces is three, which are respectively the first split pole piece, the second split pole piece and the third split pole piece distributed along the axial direction in sequence, the The second split-type pole shoe is set outside the first step and extends to both sides of the first step to the corresponding position of the corresponding transition surface; the first split-type pole shoe and the third split-type pole shoe are respectively arranged on On the left and right sides of the second split pole shoe, the first split pole shoe is sleeved outside the second and third steps on the left side of the first step, and the third split pole shoe is sleeved Outside the second step and the third step on the right side of the first step; the inner walls of the first split pole piece, the second split pole piece and the third split pole piece are respectively connected to the corresponding steps and transition surfaces The shapes match.

Further, between the first split pole piece and the second split pole piece, between the second split pole piece and the third split pole piece, a first permanent magnet and a second For the permanent magnet, the magnetic poles on adjacent sides of the first permanent magnet and the second permanent magnet are the same.

Further, the size of the gap is 0.05-5mm.

Further, an annular groove is provided on the outer wall of the split-type pole piece, and a sealing ring is arranged in the annular groove.

Further, in the single concave step portion, a first magnetic isolation ring and a second magnetic isolation ring are respectively provided on the outer sides of the two outermost pole pieces.

Further, the number of the bearings is two, namely the first bearing and the second bearing, which are respectively arranged on both sides of the concave step.

Further, the end cover is detachably fixed to the right end of the housing.

The concave stepped shaft magnetic fluid sealing device of the present invention can solve the problem of insufficient pressure resistance of the sealing device under the condition of a large gap. By designing the shaft with the concave step part and the corresponding convex stepped pole piece structure (viewed from the longitudinal section of the split pole piece), the inner ring surface of the stepped pole piece and the inner wall corresponding to the transition surface are evenly distributed. According to the shape of the pole teeth, permanent magnets are embedded between the pole shoes, and magnetic fluid is injected into the radial and transitional surface sealing gaps formed by the pole shoes and the trapezoidal shaft, so as to realize a concave stepped shaft magnetic fluid seal. Based on the stepped magnetic fluid seal, the present invention improves the structure of the shaft by setting multi-level magnetic sources and improving the distribution of pole teeth on the pole shoe, thereby greatly enhancing the pressure resistance of the magnetic fluid seal; The stepped sealing structure can reduce the loss of magnetic fluid when the seal fails, reduce stress concentration, facilitate production and processing, and increase the secondary pressure bearing capacity and self-repairing ability of the sealing device; further improve the performance of the magnetic fluid seal under large gap conditions Pressure resistance and sealing reliability expand its safe working range.

In summary, the magnetic fluid sealing device of the present invention has strong pressure resistance and is convenient for production and processing; when the seal fails, the loss of the magnetic fluid is small, the secondary pressure bearing capacity and self-repairing ability are strong, and the pressure resistance of the device under the condition of a large gap is effectively increased Capability and sealing reliability, thereby extending the safe operating range.

Description of drawings

Fig. 1 is a schematic cross-sectional structure diagram of a magnetic fluid sealing device according to a first embodiment of the present invention.

Fig. 2 is a sectional view along line A-A in Fig. 1 .

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and examples. It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. For the convenience of description, if the words "up", "down", "left" and "right" appear in the following, it only means that the directions of up, down, left and right are consistent with the drawings themselves, and do not limit the structure.

As shown in FIG. 1 , a concave stepped shaft magnetic fluid sealing device includes a housing 2 open at both ends, a sealing assembly and an end cover 10 for pressing the sealing assembly into the housing 2; the sealing assembly includes a shaft 1 , the shaft 1 is rotatably installed in the housing 2 through bearings, the shaft 1 includes a concave step 101, and the concave step 101 includes 5 steps arranged in sequence along the axial direction, and the outer walls of adjacent steps Connected by a chamfered transition surface; each transition surface jacket is provided with a split-type pole shoe that matches the transition surface, and the split-type pole shoe extends to one or both sides of the transition surface to the side of the transition surface At the position corresponding to the corresponding step, there is a gap between the inner wall of the split pole shoe and the corresponding transition surface and the step, and pole teeth are provided on the inner wall of the split pole shoe; There are permanent magnets between them.

Wherein, the included angle between the transition surface and the central axis of the shaft is 45 degrees.

The pole teeth include axial pole teeth and transition pole teeth, the axial pole teeth are arranged on the inner wall of the split pole shoe corresponding to the step, and the transition pole teeth are arranged on the inner wall of the split pole shoe corresponding to the transition surface .

The concave step portion 101 includes one first step 1011, two second steps 1012 and two third steps 1013, the diameters of the first step 1011, the second step 1012 and the third step 1013 increase sequentially, The two second steps 1012 and the two third steps 1013 are sequentially and symmetrically distributed on both sides of the first step 1011 .

The number of split-type pole pieces is three, which are respectively the first split-type pole piece 19, the second split-type pole piece 17 and the third split-type pole piece 15 distributed along the axial direction in sequence. The second split pole shoe 17 is sleeved outside the first step 1011 and extends to the two sides of the first step to the corresponding position of the corresponding transition surface; the first split pole shoe 19 and the third split pole shoe 15 are respectively arranged on the left and right sides of the second split pole shoe 17, and the first split pole shoe 19 is sleeved outside the second step and the third step on the left side of the first step, and the third split pole shoe The petal-type pole piece 15 is set outside the second step and the third step on the right side of the first step; the first split-type pole piece 19, the second split-type pole piece 17 and the third split-type pole piece The inner wall of 15 matches the shape of the corresponding step and the transition surface respectively.

Between the first split pole piece 19 and the second split pole piece 17, between the second split pole piece 17 and the third split pole piece 15, the first permanent magnet 8 and the For the second permanent magnet 10, the magnetic poles of the adjacent sides of the first permanent magnet 8 and the second permanent magnet 10 are the same.

The first split pole piece 19 is respectively provided with the first pole piece axial pole teeth A5 and the first pole piece axial pole teeth B7 on the inner ring surface corresponding to the second step and the third step, and the first split pole piece The first pole piece transition pole tooth 6 is provided on the inner wall corresponding to the transition surface between the type pole piece 19 and the second step and the third step.

The second pole piece teeth 9 are arranged on the inner wall of the second split pole piece 17 corresponding to the first step and the corresponding transition surface. Correspondingly, third pole piece teeth 11 are provided on the third split pole piece 15 .

The size of the gap is 2.5mm.

An annular groove is provided on the outer wall of the split pole shoe, and a sealing ring is arranged in the annular groove. Correspondingly, a first sealing ring 20 is provided in the annular groove on the outer wall of the first split pole piece 19, and a second sealing ring 18 is arranged in the annular groove on the outer wall of the second split pole shoe 17. A third sealing ring 16 is provided in the annular groove on the outer wall of the three-split pole shoe 15 . Preferably, the split-type pole piece includes two sub-pole pieces, and the two sub-pole pieces can be combined with each other to form a split-type pole piece (see FIG. 2 ).

In the single concave step, the first split pole piece 19 and the third split pole piece 15 are respectively provided with a first magnetic isolation ring 4 and a second magnetic isolation ring 12 .

There are two bearings, which are the first bearing 3 and the second bearing 13 respectively, and are arranged on the outer sides of the first magnetic isolation ring 4 and the second magnetic isolation ring 12 respectively.

The end cap 14 is fixed to the right end of the housing 2 by threads.

During assembly, it mainly includes the following steps:

(1) Install the two sub-pole pieces of the first split pole piece 19 onto the shaft 1 from the upper and lower sides of the shaft 1; install the first sealing ring 20 on the outer surface of the first split pole piece 19 in the groove on the

Mount the first permanent magnet 8 on the shaft 1 from the right;

Install the two sub-pole pieces of the second split pole piece 17 onto the shaft 1 from the upper and lower sides of the shaft 1; in the tank;

Mount the second permanent magnet 10 on the shaft 1 from the right;

Install the two sub-pole pieces of the third split pole piece 15 onto the shaft 1 from the upper and lower sides of the shaft 1; in the tank;

(2) Inject the magnetic fluid into the sealing gap formed by the third split pole piece 15, the second split pole piece 17, the first split pole piece 19 and the shaft 1;

(3) Install the first magnetic isolation ring 4 and the first bearing 3 on the shaft 1 in sequence from the left side of the shaft;

Install the second magnetic isolation ring 12 and the second bearing 13 on the shaft 1 in order from the right side of the shaft to form a sealing assembly;

(4) Install the sealing assembly in the casing 2, and press the outer ring of the right bearing 13 through the threaded connection between the end cover 14 and the casing 2; realize a concave stepped shaft magnetic fluid seal.

The above-mentioned embodiments should be understood that these embodiments are only used to illustrate the present invention more clearly, and are not intended to limit the scope of the present invention. After reading the present invention, those skilled in the art will understand the various equivalent forms of the present invention All modifications fall within the scope defined by the appended claims of this application.

Claims (8)

1. A magnetic fluid sealing device for a concave stepped shaft, comprising a casing (2) with openings at both ends, a sealing assembly and an end cover (14) for pressing the sealing assembly into the casing (2); the sealing assembly includes A shaft (1), the shaft (1) is rotatably installed in the housing (2) through a bearing, characterized in that the shaft (1) includes at least one concave step (101), and the concave step (101 ) includes a plurality of steps arranged in sequence along the axial direction, and the outer walls of adjacent steps are connected by a chamfered transition surface; each transition surface jacket is provided with a split-type pole piece matching the transition surface, and the split The pole shoe extends to one side or both sides of the transition surface to the position corresponding to the corresponding step on the side of the transition surface. There is a gap between the inner wall of the split pole shoe and the corresponding transition surface and steps. Pole teeth are provided on the inner wall of the split-type pole piece and/or on the shaft (1) corresponding to the inner wall of the split-type pole piece; permanent magnets are arranged between adjacent split-type pole pieces; The included angle between the transition surface and the central axis of the shaft is 5-75 degrees; The pole teeth include axial pole teeth and/or transition pole teeth, the axial pole teeth are arranged on the step and/or on the inner wall of the split pole shoe corresponding to the step, the transition pole teeth are arranged on the transition surface and/or Or on the inner wall of the split pole piece corresponding to the transition surface. 2. The concave stepped shaft magnetic fluid seal device according to claim 1, characterized in that, the concave stepped portion (101) includes one first step (1011), two second steps (1012) and two The third step (1013), the diameters of the first step (1011), the second step (1012) and the third step (1013) increase sequentially, the two second steps (1012) and the two third steps The steps (1013) are sequentially and symmetrically distributed on both sides of the first step (1011). 3. The concave stepped shaft magnetic fluid seal device according to claim 1, characterized in that, the number of split pole pieces is three, which are respectively the first split pole pieces ( 19), the second split pole shoe (17) and the third split pole shoe (15), the second split pole shoe (17) is sleeved outside the first step (1011) and The two sides of a step extend to the corresponding position of the corresponding transition surface; the first split pole shoe (19) and the third split pole shoe (15) are respectively arranged on the second split pole shoe (17) On the left and right sides, the first split-type pole shoe (19) is sleeved outside the second and third steps on the left side of the first step, and the third split-type pole shoe (15) is sleeved on the second step Outside the second and third steps on the right side of a step; the inner walls of the first split pole piece (19), the second split pole piece (17) and the third split pole piece (15) Match the shape of the corresponding step and transition surface respectively. 4. The concave stepped shaft magnetic fluid seal device according to claim 3, characterized in that, between the first split pole piece (19) and the second split pole piece (17), the second split A first permanent magnet (8) and a second permanent magnet (10) are arranged between the petal pole piece (17) and the third split pole piece (15), and the first permanent magnet (8) and the second The magnetic poles on the adjacent sides of the two permanent magnets (10) are the same. 5 . The magnetic fluid sealing device with concave stepped shaft according to claim 1 , wherein the size of the gap is 0.05-5 mm. 6 . The magnetic fluid sealing device with concave stepped shaft according to claim 1 , wherein an annular groove is provided on the outer wall of the split-type pole piece, and a sealing ring is arranged in the annular groove. 7 . 7. The concave stepped shaft magnetic fluid seal device according to claim 1, characterized in that, in a single concave stepped portion, the outermost two pole pieces are provided with a first magnetic isolation ring (4) and a second magnetic isolation ring (4) respectively. Magnetic isolation ring (12). 8. The concave stepped shaft magnetic fluid seal device according to claim 1, characterized in that, the number of the bearings is two, which are respectively the first bearing (3) and the second bearing (13), and are respectively arranged in Both sides of the concave step.

Images