CN105202198B - Flexible pole shoe device for sealing magnetic fluid - Google Patents

Abstract

A flexible pole piece magnetic fluid sealing device belongs to the field of mechanical engineering sealing. It mainly includes casing (1), end cover (3), permanent magnet (5), flexible pole piece (6), soft iron (7), front plate (8), back plate (9), shaft sleeve (11) and Parts such as coating (12). When the flexible pole piece magnetic fluid seal device works, the magnetic induction line starts from the permanent magnet, passes through soft iron, flexible pole piece, coating and shaft sleeve to form a magnetic circuit. The magnetic fluid is gathered and adsorbed around the flexible pole piece between the baffle plate and the surface of the rotating shaft and in the gap, which plays the role of bearing the axial pressure of the sealing medium and blocking the leakage channel of the medium, thereby realizing the sealing function.

Description

Flexible Pole Piece Magnetic Fluid Sealing Device

technical field

The invention belongs to the field of mechanical engineering sealing, in particular to a magnetic fluid sealing device.

technical background

When solving the problem of large-diameter spindle seals in some large-scale petrochemical equipment and marine machinery, the seal of the rotating shaft directly affects the stability of the overall operation of the mechanism. It can be said that the sealing technology is usually the key factor that determines whether a certain major technology can be fundamentally realized. . The traditional sealing form has advantages and disadvantages: the packing seal structure is simple, but the sealing ability is insufficient, the service life cycle is short, and the packing needs to be replaced regularly, causing a series of related complex problems such as assembly; the mechanical seal has good sealing performance, and the seal is pressure-bearing. The capacity is high, but under the condition of large diameter, the structure of the sealing device is huge, the assembly relationship is relatively complicated, and the assembly accuracy is difficult to guarantee. The magnetic fluid seal has the advantages of zero leakage, simple sealing structure, low sealing power consumption, and can be applied at a higher speed.

In the magnetic fluid sealing structure, the gap between the pole teeth and the rotating shaft is a sealing gap, which is filled with magnetic fluid. Since the pole shoe structure can gather and enhance the magnetic field, the magnetic fluid is adsorbed there, forming an O-ring in the sealing gap. The liquid sealing ring plays the role of bearing the axial pressure of the sealing medium and blocking the leakage channel of the medium. The existence of the sealing gap is the advantage of the magnetic fluid sealing structure, and it is also the key point for leakage and sealing.

In general, in order to ensure the pressure resistance and reliability of the ferrofluid seal, the sealing gap should be selected as small as possible in the design of the sealing device. However, in practical applications, the small sealing gap will bring many problems: first , the sealing gap is constrained by the radial runout of the rotating shaft. If the sealing gap is too small, it is easy to cause bumps between the rotating shaft and the pole teeth, and even the phenomenon of "shaft holding" of the pole teeth occurs. This not only affects the performance of the magnetic fluid seal, but also causes The failure and destruction of the seal, at the same time, the small sealing gap also brings great difficulty to processing and assembly; secondly, in the dynamic seal, the smaller sealing gap will bring greater shear rate, so the magnetic fluid The frictional heat generated is also greater, especially in the case of large diameters, and the friction caused by circular runout will also lead to an increase in local temperature, and the stability and service life of the magnetic fluid will also be reduced.

The existing brush-type ferrofluid sealing device is as described in the patent application with the publication number of CN 103925372A. While solving the problems and defects of the original ferrofluid sealing device, this device also has its own shortcomings: it is very difficult to manufacture and assemble the seal composed of bristles of different lengths; Magnetic flux leakage will weaken the magnetic field strength around the brush filaments and reduce the sealing performance; the long bristle bundles directly contact the surface of the rotating shaft, and long-term operation will cause wear to the rotating shaft, and the premise of sealing is to form a magnetic circuit, that is, the rotating shaft must be a guide Magnetic materials, which further limit the application of the seal.

Contents of the invention

The technical problem to be solved by the present invention is the contradiction in the design of the sealing gap in the existing magnetic fluid sealing device. Too small sealing gap, while improving the pressure bearing capacity of the seal, is likely to cause bumps between the shaft and the pole teeth or even the phenomenon of "shaft holding", which reduces the safety and reliability of the seal, and brings great harm to the processing and assembly. Difficulty; and too large sealing gap can not provide enough sealing pressure capacity, which limits the application range of ferrofluid seals. Therefore, a flexible pole piece magnetic fluid sealing device is provided.

The technical solution adopted by the present invention to solve its technical problems is:

The flexible pole piece magnetic fluid sealing device is characterized in that it includes: a housing (1), a gasket (2), an end cover (3), a screw (4), a permanent magnet (5), a flexible pole piece (6), a soft Iron (7), front plate (8), back plate (9), sealing ring (10), bushing (11), coating (12), right sealing ring (13), left sealing ring (15) .

The connection relationship between the parts constituting the device: the sealing ring (10) is installed in the sealing groove on the inner surface of the shaft sleeve (11); the outer surface of the shaft sleeve (11) has a layer of coating (12), the shaft There is an annular permanent magnet (5) on the periphery of the cover (11), the annular permanent magnet (5) is coaxial with the axle sleeve (11), and there is a certain distance between the annular permanent magnet (5) and the axle sleeve (11). In the gap, a group of sealing elements are arranged on the left and right ends of the ring-shaped permanent magnet (5). plate (8), the sealing elements are fixedly connected by welding, gluing, etc. to form a whole, and the left and right ends of the permanent magnet (5) are in contact with the soft iron (7); inside the ring of the soft iron (7) is the back plate (9 ), the back plate (9) is not in contact with the shaft sleeve (11), and has a gap; the contact surface of the soft iron (7) and the back plate (9) is flush with the inner ring surface of the permanent magnet (5); in the soft iron ( 7) and the outer end surface of the back plate (9) are both flexible pole pieces (6), the flexible pole pieces (6) are made of magnetically permeable materials, and the flexible pole pieces (6) are rings composed of tightly and orderly arranged flexible filament bundles, The direction of the tow is along the radial direction of the ring. The flexible pole shoe (6) has a certain axial thickness. (12) Surface contact; the outer end surface of the flexible pole shoe (6) is the front plate (8), the outer end surfaces of the front plates (8) on the left and right sides are the shell (1) and the end cover (3) respectively, and the shell (1) ) and the end cover (3) are fixedly connected by screws and nuts, and the permanent magnet (5), flexible pole piece (6), soft iron (7), front plate (8), and back plate (9) are fastened to the shell (1 ), the housing (1) is fixed on the axle sleeve (11) by screws.

The right sealing ring (13) and the left sealing ring (15) are installed in the sealing grooves on the outer ring surfaces of the front plates (8) of the two sets of sealing elements.

The end cover (3) is installed on the right side of the housing (1), and the end cover (3) and the housing (1) are fixed by screws (4), so that the parts inside the housing (1) are positioned axially.

The gasket (2) is arranged at the junction between the end cover (3) and the casing (1).

The shaft sleeve (11) and the coating (12) are integrally formed by means of welding, gluing or spraying, and the coating (12) is made of a non-magnetic material.

The shaft sleeve (11) is fixed on the rotating shaft by a locking screw (14).

The shell (1) is processed with threaded holes for mounting screws (4).

The end cover (3) is processed with through holes for matching screws (4).

The inner circle of the shaft sleeve (11) is processed with an annular sealing groove for installing a sealing ring (10), and a threaded hole for installing a locking screw (14), and is made of a magnetically conductive material.

The front plate (8) is made of a non-magnetic material, and there is a certain gap between its inner ring surface and the surface of the coating (12), and its outer ring surface is processed with annular sealing grooves for installing left and right side sealing rings;

The back plate (9) is made of a non-magnetic material; there is a certain gap between its inner ring surface and the surface of the coating (12);

The soft iron (7) adopts a material with good magnetic permeability.

Compared with the prior art, the present invention has the following beneficial effects:

The flexible pole piece magnetic fluid sealing device uses flexible pole pieces made of magnetic materials to replace traditional pole teeth and magnetic poles. First, the fine and flexible pole pieces fill the sealing gap, forming a structure similar to brush-type sealing brush filaments, so that the fluid is produced The self-sealing effect improves the pressure bearing capacity of the seal to a certain extent; moreover, the finely and uniformly arranged flexible pole piece filaments will generate a stronger, more uniform and more stable magnetic field than the traditional hard pole piece, and the magnetic fluid is filled with The flexible pole piece wire gap further blocks the medium leakage channel. Therefore, the flexible pole piece ferrofluid seal has stronger pressure bearing capacity and stability than the traditional ferrofluid seal. Secondly, the use of flexible pole pieces makes it possible to achieve small gaps or even zero gaps that could not be achieved due to safety reasons in the past, and greatly improves the performance of the seal. The softness of flexible pole pieces can not only effectively solve the small gap, The problem of collision with the pole piece reduces the difficulty of processing and assembling the ferrofluid seal. At the same time, it can also keep the sealing ability unchanged under the condition of instantaneous interference between the start and stop of the equipment, which effectively increases the usability and safety of the ferrofluid seal. , to further expand the application range of magnetic fluid sealing technology.

Description of drawings

Fig. 1 Structural diagram of flexible pole piece magnetic fluid seal device.

In Figure 1: 1 shell, 2 gasket, 3 end cover, 4 screw, 5 permanent magnet, 6 flexible pole piece, 7 soft iron, 8 front plate, 9 back plate, 10 sealing ring, 11 shaft sleeve, 12 coating , 13 sealing ring on the right side, 14 locking screws, 15 sealing ring on the left side.

detailed description

The present invention will be further described by taking the accompanying drawings as specific implementation methods: obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

Example 1

Flexible pole shoe magnetic fluid sealing device, as shown in Figure 1, the device includes: shell 1, gasket 2, end cover 3, screw 4, permanent magnet 5, flexible pole shoe 6, soft iron 7, front plate 8, back plate 9 , sealing ring 10, shaft sleeve 11, coating 12, right sealing ring 13, locking screw 14 and left sealing ring 15;

Connections between the parts making up the device:

A group of sealing elements are respectively arranged at the left and right ends of the permanent magnet 5, and the sealing elements sequentially include soft iron 7, back plate 9, flexible pole shoe 6 and front plate 8, and the sealing elements are formed as a whole by welding, gluing, etc. The permanent magnet 5 is in contact with the soft iron 7 at the left and right ends;

The left and right sealing rings 15, 13 are installed in the sealing grooves of the outer circle of the front plate 8 of the two sets of sealing elements;

The end cover 3 is installed on the right side of the shell 1, and the end cover 3 and the shell 1 are fixed by screws 4, so that the parts inside the shell are axially positioned;

The gasket 2 is arranged between the end cover 3 and the shell 1;

The bushing 11 and the coating 12 are integrally formed by welding, gluing or spraying;

The sealing ring 10 is installed in the sealing groove of the inner circle of the shaft sleeve 11;

The shaft sleeve 11 is fixed on the rotating shaft by a locking screw 14;

The shell 1 is made of non-magnetic material, such as stainless steel, and is processed with threaded holes for mounting screws 4;

The end cap 3 is made of a non-magnetic material, such as stainless steel, and is processed with a through hole for the screw 4;

The flexible pole piece 6 is made of a material with excellent magnetic conductivity, such as permalloy. The flexible pole piece 6 is a flexible tow with a certain thickness arranged closely. Its length is such that its end is in contact with the surface of the coating 12;

The soft iron 7 is made of a material with good magnetic permeability, such as electrical pure iron;

The front plate 8 is made of non-magnetic material, such as stainless steel, there is a certain gap between its inner circle and the surface of the coating 12, and its outer circle is processed with annular sealing grooves for installing left and right side sealing rings 15, 13;

The back plate 9 is made of a non-magnetic material, such as stainless steel, and there is a certain gap between its inner circle and the surface of the coating 12;

The shaft sleeve 11 is made of a material with good magnetic conductivity, such as electrical pure iron, and its inner circle is processed with an annular sealing groove for installing the sealing ring 10, and is processed with a threaded hole for installing the locking screw 14;

The coating 12 is made of non-magnetic materials, such as copper and ceramics;

Described permanent magnet 5 selects RuFeB for use.

It solves the problems that the existing magnetic fluid sealing device has limited pressure bearing capacity, difficult processing and assembly, high precision requirements, easy collision between the pole teeth and the rotating shaft, and "shaft holding" phenomenon. When the flexible pole piece magnetic fluid seal device works, the magnetic induction line starts from the permanent magnet, passes through soft iron, flexible pole piece, coating and shaft sleeve to form a magnetic circuit. The magnetic fluid gathers and adsorbs around the flexible pole piece between the baffle plate and the surface of the rotating shaft and in the gap, and plays the role of bearing the axial pressure of the sealing medium and blocking the leakage channel of the medium, thereby realizing the sealing function.

Claims (5)

1. A magnetic fluid sealing device for flexible pole pieces, characterized in that it comprises: a housing (1), gaskets (2), end caps (3), screws (4), permanent magnets (5), flexible pole pieces ( 6), soft iron (7), front plate (8), back plate (9), seal ring (10), shaft sleeve (11), coating (12), right seal ring (13), left seal circle(15); The connection relationship between the parts constituting the device: the sealing ring (10) is installed in the sealing groove on the inner surface of the shaft sleeve (11); the outer surface of the shaft sleeve (11) has a layer of coating (12), the shaft There is an annular permanent magnet (5) on the periphery of the cover (11), the annular permanent magnet (5) is coaxial with the axle sleeve (11), and there is a certain distance between the annular permanent magnet (5) and the axle sleeve (11). In the gap, a group of sealing elements are arranged on the left and right ends of the ring-shaped permanent magnet (5). The plate (8) and the sealing element are fixedly connected to form a whole, and the left and right ends of the permanent magnet (5) are in contact with the soft iron (7); inside the ring of the soft iron (7) is the back plate (9), and the back plate (9) It is not in contact with the shaft sleeve (11), and has a gap; the contact surface of the soft iron (7) and the back plate (9) is flush with the inner ring surface of the permanent magnet (5); between the soft iron (7) and the back plate (9) ) are all flexible pole pieces (6), the flexible pole pieces (6) are made of magnetically permeable material, the flexible pole pieces (6) are rings composed of tightly and orderly arranged flexible tows, and the direction of the tows is along the direction of the ring Radially, the flexible pole piece (6) has a certain axial thickness, the tow is formed into a whole by clamping, gluing or welding, and the inner ring surface of the flexible pole piece (6) is in contact with the surface of the coating (12); the flexible pole piece The outer end surface of the boot (6) is the front plate (8), and the outer end surfaces of the front plates (8) on the left and right sides are the shell (1) and the end cover (3) respectively, and the shell (1) and the end cover (3) pass through The screws are fixedly connected, and the permanent magnet (5), flexible pole piece (6), soft iron (7), front plate (8), and back plate (9) are fastened in the cavity of the shell (1), and the shell (1) Be fixed on the shaft sleeve (11) by screws; The gasket (2) is arranged at the joint between the end cover (3) and the shell (1); the coating (12) is made of non-magnetic material; the front plate (8) is made of non-magnetic material; the back plate (9) The non-magnetic material is adopted, and the axle sleeve (11) adopts the magnetic material. 2. A flexible pole piece magnetic fluid sealing device according to claim 1, characterized in that the sealing elements are fixedly connected by welding or gluing to form a whole. 3. A flexible pole piece magnetic fluid sealing device according to claim 1, characterized in that the end cover (3) is installed on the right side of the casing (1), and the end cover (3) and The casing (1) is fixed so that the parts inside the casing (1) are positioned axially. 4. A magnetic fluid sealing device for flexible pole pieces according to claim 1, characterized in that, the bushing (11) and the coating (12) are integrally formed by welding or gluing or spraying. 5. A flexible pole piece magnetic fluid sealing device according to claim 1, characterized in that the shaft sleeve (11) is fixed on the rotating shaft by a locking screw (14).