Magnetic fluid float dynamic seal device

Abstract

The application discloses a magnetic fluid floating dynamic sealing device and relates to the technical field of sealing, which comprises a thrust disc, a static sealing connector, a dynamic sealing piece and a control piece. The dynamic sealing piece is used for dynamic sealing between the thrust disc and a dynamic sealing shell. The dynamic sealing piece comprises a pole shoe and a magnetic fluid. The pole shoe is fixedly installed on the sealing shell. The pole shoe is provided with pole teeth. The magnetic fluid is located between the pole teeth and the thrust disc. The control piece is used for adjusting and controlling the distance between the first end of the pole teeth of the dynamic sealing piece and the first side surface of the thrust disc. The distance between the first end of the pole teeth of the dynamic sealing piece and the first side surface of the thrust disc is adjusted and controlled through the control piece. On the one hand, the thrust disc can always keep parallel with the end surface of the pole teeth, so that the gap between the thrust disc and the end surface of the pole teeth can always be kept at 0.1 mm or even smaller, thereby guaranteeing the stability of the magnetic fluid liquid film sealing. On the other hand, the gap size between the first end of the pole teeth and the first side surface of the thrust disc can be adjusted and controlled according to the rotating speed of the rotating shaft.

Description

Technical Field

[0001] This invention relates to the field of sealing technology, and in particular to a magnetic fluid floating dynamic sealing device. Background Technology

[0002] Magnetohydrodynamic sealing devices use a magnetic field to confine the magnetohydrodynamic fluid within the gap between relatively moving mating surfaces, thereby preventing leakage of the sealing medium. They are widely used in semiconductor, aerospace, defense, chemical, petroleum, instrumentation and metering and other fields.

[0003] To ensure the relative stability of the magnetohydrodynamic fluid within the sealing gap, the magnetic field strength within the gap must be sufficiently high. Therefore, the gap between the relatively moving mating surfaces must be very small. Currently, high-precision rolling bearings are generally used in shafts with low surface linear velocity and stable operation to ensure a small gap between the shaft and the sealing housing. However, in high-speed, heavy-load rotating machinery, the shaft exhibits radial runout under asymmetric and unstable loads. To avoid rubbing between the shaft and the housing's sealing interface, the sealing gap needs to be increased to be greater than the radial runout of the shaft. Under high-speed and large-gap conditions, the stability of the magnetohydrodynamic fluid is significantly reduced, making it difficult to guarantee pressure resistance. Furthermore, commonly used multi-stage magnetohydrodynamic sealing devices rely on the gradual pressure reduction or increase of each stage of the magnetohydrodynamic fluid film to improve the overall sealing capacity, with each stage bearing only a small pressure. The process of balanced load sharing among the various stages of the magnetohydrodynamic fluid relies on the continuous rupture and self-repair of the various stages of the magnetohydrodynamic fluid film, and the appropriate leakage of the sealing medium from the high-pressure end to the low-pressure end. Under high-speed and large-gap conditions, due to the reduced stability of the magnetic fluid, a large amount of magnetic fluid is transferred from the high-pressure side to the low-pressure side under the influence of the sealing medium during the rupture of the magnetic fluid film. This results in a significant reduction in the amount of magnetic fluid filling the sealing gap, the magnetic fluid film cannot achieve self-repair, the sealing capacity is significantly reduced, and it cannot meet the requirements for long-life operation. Summary of the Invention

[0004] The purpose of this invention is to design a magnetic fluid floating dynamic sealing device to solve the above-mentioned problems.

[0005] The present invention achieves the above objectives through the following technical solutions: A magnetic fluid floating dynamic seal device, used for dynamic sealing between a rotating shaft and a dynamic seal housing, includes: Thrust plate; Static sealing connector; the static sealing connector is used for static sealing and fixed connection between the thrust disc and the rotating shaft; At least one set of dynamic seals; the dynamic seals are used for dynamic sealing between the thrust disc and the dynamic sealing housing, and the dynamic seals are installed on the first side of the thrust disc; each set of dynamic seals includes an annular pole shoe and a magnetorheological fluid, the first end of the pole shoe is fixedly installed on the sealing housing, the second end of the pole shoe is provided with multiple annular pole teeth, the magnetorheological fluid is located between the first end of the pole teeth and the first side of the thrust disc, and the pole shoe has magnetic force; Control element; The control element is used to adjust the distance between the first end of the pole tooth of the dynamic seal and the first side of the thrust disc.

[0006] The beneficial effects of the present invention are as follows: by adjusting the distance between the first end of the pole tooth of the control dynamic seal and the first side of the thrust plate by the control component, on the one hand, the thrust plate can always be kept parallel to the end face of the pole tooth, so the gap between the thrust plate and the end face of the pole tooth can always be kept at 0.1mm or even smaller, ensuring the stability of the magnetofluid liquid film seal; on the other hand, the size of the gap between the first end of the control pole tooth and the first side of the thrust plate can be adjusted according to the rotation speed of the shaft. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the structure of the magnetic fluid floating dynamic sealing device of the present invention; Figure 2 This is a schematic diagram of the dynamic sealing element in the magnetic fluid floating dynamic sealing device of the present invention; Figure 3 This is a schematic diagram of the pole teeth in the magnetic fluid floating dynamic sealing device of the present invention; Figure 4 This is a schematic diagram of the elastic disc in the magnetic fluid floating dynamic sealing device of the present invention; The corresponding figure labels are: 1-Thrust plate, 2-Elastic plate, 3-Rotating shaft, 4-Pole shoe, 5-Magnetic fluid, 6-Pole tooth, 7-Pressure relief hole, 8-Permanent magnet ring, 9-Electromagnet, 10-Distance sensor, 11-Coolant, 12-First pressure ring, 13-Second pressure ring, 14-First screw, 15-Second screw, 16-Anti-collision block, 17-Anti-collision groove, 18-Dynamic sealing housing. Detailed Implementation

[0008] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0009] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0010] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0011] In the description of this invention, it should be understood that the terms "upper," "lower," "inner," "outer," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0012] Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0013] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, terms such as "set" and "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0014] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0015] like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the magnetic fluid 5 floating dynamic seal device, used for dynamic sealing between the rotating shaft 3 and the dynamic seal housing 18, includes: Thrust plate 1; Static sealing connector; the static sealing connector is used for static sealing and fixed connection between the thrust disc 1 and the rotating shaft 3; At least one set of dynamic seals; the dynamic seals are used for dynamic sealing between the thrust disk 1 and the dynamic sealing housing 18, and the dynamic seals are installed on the first side of the thrust disk 1; each set of dynamic seals includes an annular pole shoe 4 and a magnetorheological fluid 5, the first end of the pole shoe 4 is fixedly installed on the sealing housing, the second end of the pole shoe 4 is provided with a plurality of annular pole teeth 6, the magnetorheological fluid 5 is located between the first end of the pole teeth 6 and the first side of the thrust disk 1, and the pole shoe 4 has magnetic force; Control component; The control component is used to adjust the distance between the first end of the pole tooth 6 of the dynamic seal and the first side of the thrust disk 1. The dynamic seal housing 18 is made of non-magnetic material and is fixedly installed on the cavity structure that needs to be sealed by static sealing measures.

[0016] Each of the second ends of the pole teeth 6 is provided with a pressure relief hole 7.

[0017] A permanent magnet ring 8 is fixed on the pole shoe 4, and the pole shoe 4 is made of magnetically conductive material.

[0018] The control components include an electromagnet 9 and a thrust disk 1 made of a magnetically conductive material.

[0019] The control unit also includes a distance sensor 10, a microprocessor, and a driver. The distance sensor 10 is used to collect the distance between the thrust disk 1 and the distance sensor 10. The data signal output terminal of the distance sensor 10 is connected to the data signal input terminal of the microprocessor. The control signal output terminal of the microprocessor is connected to the control signal input terminal of the driver. The output terminal of the driver is connected to the control signal input terminal of the electromagnet 9.

[0020] The static sealing connector includes an elastic disc 2, a first pressure ring 12, a second pressure ring 13, a set of first screws 14 and a set of second screws 15. A connecting ring is provided on the outer wall of the rotating shaft 3. A set of first threaded connecting holes is provided on the inner side of the connecting ring, the first pressure ring 12 and the elastic disc 2. A first screw 14 is threadedly connected to a first threaded connecting hole of the first pressure ring 12, the elastic disc 2 and the connecting ring respectively. A set of second threaded connecting holes is provided on the outer side of the thrust disc 1, the second pressure ring 13 and the elastic disc 2. A second screw 15 is threadedly connected to a second threaded connecting hole of the second pressure ring 13, the elastic disc 2 and the thrust disc 1 respectively.

[0021] The magnetic fluid 5 floating sealing device also includes at least three anti-collision blocks 16. The inner side of the anti-collision block 16 is provided with an anti-collision groove 17. The outer side wall of the thrust plate 1 is provided with an anti-collision ring. The anti-collision ring is located in the anti-collision groove 17. Multiple anti-collision blocks 16 are arranged in a ring array around the central axis of the rotating shaft 3. The distance between the anti-collision block 16 and the anti-collision ring is greater than zero. The anti-collision groove 17 is coated with a self-lubricating layer, such as polytetrafluoroethylene.

[0022] An annular cooling chamber is provided inside the dynamic sealing housing 18, and the cooling chamber is filled with coolant 11.

[0023] The working principle of the magnetic fluid 5 floating dynamic sealing device of the present invention is as follows: The pole shoe 4 connects the dynamic sealing housing 18 to the cavity structure that needs to be sealed to form a static sealing circuit.

[0024] Magnetorheological fluid 5 fills the gap between the end face pole teeth 6 of the pole shoe 4 and the thrust plate 1. Under the constraint of the magnetic field generated by the permanent magnet ring 8, the magnetorheological fluid 5 forms an end face rotational dynamic sealing circuit between the pole shoe 4 and the thrust plate 1.

[0025] The elastic disk 2 is a thin-walled structure made of elastic material, which has high circumferential stiffness and low axial stiffness. The rotating shaft 3 can drive the thrust disk 1 to rotate through the elastic disk 2, and the elastic disk 2 allows the thrust disk 1 to move freely within a small range in the axial direction relative to the rotating shaft 3 or the sealed cavity.

[0026] The permanent magnet ring 8 simultaneously generates an upward magnetic attraction force on the thrust plate 1 through the pole shoe 4, and the electromagnet 9 generates a downward magnetic attraction force on the thrust plate 1. The thrust plate 1 is in a magnetic levitation state under the action of its own gravity, the magnetic attraction force of the pole shoe 4, and the magnetic attraction force of the electromagnet 9.

[0027] The distance sensor 10 detects the axial position of the thrust disk 1 in real time. By adjusting the current supplied to the electromagnet 9, the magnetic attraction force of the electromagnet 9 can be adjusted, thereby changing the position of the thrust disk 1 in a balanced state and adjusting the sealing gap between the end face pole teeth 6 of the pole shoe 4 and the thrust disk 1.

[0028] The end face of the pole shoe 4 has a set of radial pressure relief holes 7. The diameter of the pressure relief holes 7 is designed to maintain the pressure difference on both sides of each stage of the pole teeth 6 while ensuring the leakage requirement. When the pressure on both sides of the pole teeth 6 is higher than the set bearing pressure of the magnetic fluid 5 liquid film, the sealing medium accelerates through the pressure relief holes 7, the high-pressure side pressure decreases rapidly, and the low-pressure side pressure increases rapidly until the pressure difference on both sides of the pole teeth 6 returns to or falls below the set pressure.

[0029] The flexible disc 2 connects the rotating shaft 3 and the thrust disc 1, which not only achieves static sealing between the rotating shaft 3 and the thrust disc 1, but also ensures the transmission of torque between the rotating shaft 3 and the thrust disc 1. The radial runout generated by the rotating shaft 3 driving the thrust disc 1 will not affect the sealing gap between the thrust disc 1 and the pole shoe 4.

[0030] The permanent magnet ring 8, in conjunction with the pole shoe 4, on the one hand, confines the magnetofluid 5 within the gap between the pole shoe 4 and the thrust disk 1 to form a dynamic seal, and on the other hand, in conjunction with the electromagnet 9 and the distance sensor 10, puts the thrust disk 1 in a magnetic levitation state.

[0031] Based on the data fed back by the distance sensor 10, adjusting the current supplied to the electromagnet 9 can regulate its magnetic attraction force. This ensures that the thrust plate 1 remains parallel to the end face of the pole teeth 6 of the pole shoe 4, thus maintaining a gap of 0.1mm or even smaller between them and guaranteeing the stability of the magnetofluid 5 liquid film seal. Furthermore, the magnetic attraction force of the electromagnet 9 can be adjusted according to the rotational speed of the shaft 3, thereby controlling the size of the sealing gap.

[0032] When the rotational speed of the shaft 3 is low, the stability of the magnetic fluid film 5 is relatively high, which can increase the current flowing through the electromagnet 9 and increase the magnetic attraction force of the electromagnet 9. Under the action of the magnetic attraction force, the thrust disk 1 moves away from the pole shoe 4, thus appropriately increasing the sealing gap. At this time, the magnetic field strength within the sealing gap decreases, and the viscosity of the magnetic fluid 5 decreases; at the same time, the shear rate inside the magnetic fluid 5 decreases, and the internal friction decreases. Therefore, when the shaft 3 is operating at low speed, the frictional torque and heat generation of the magnetic fluid 5 can be reduced while ensuring the sealing capacity, thereby reducing energy consumption.

[0033] When the rotational speed of the shaft 3 is high, the stability of the magnetic fluid 5 liquid film is relatively poor. This reduces the current flowing through the electromagnet 9, decreasing its magnetic attraction. Under the magnetic attraction of the permanent magnet ring 8, the thrust disk 1 moves closer to the pole shoe 4, reducing the sealing gap. At this time, the flow stability of the magnetic fluid 5 liquid film within the sealing gap is enhanced, and the magnetic field strength within the gap is also increased, leading to an increase in the viscosity of the magnetic fluid 5 and a significant increase in the sealing capacity of the magnetic fluid 5 liquid film. Therefore, sufficient sealing capacity can be guaranteed even when the shaft 3 is operating at high speed.

[0034] The end face of the pole shoe 4 has a set of radial pressure relief holes 7. When the pressure on both sides of the pole teeth 6 exceeds the set bearing pressure of the magnetic fluid 5 liquid film, the pressure on both sides of the pole teeth 6 is adjusted through the pressure relief holes 7 to prevent the magnetic fluid 5 liquid film from rupturing under excessive pressure difference. This prevents the magnetic fluid 5 from being blown away by the high-speed moving sealing medium when the liquid film ruptures, thus protecting the integrity of the magnetic fluid 5 liquid film and greatly improving the service life of the magnetic fluid 5 seal.

[0035] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A magnetic fluid dynamic seal device for a dynamic seal between a rotating shaft and a dynamic seal housing, characterized in that, include: Thrust plate; Static sealing connector; the static sealing connector is used for static sealing and fixed connection between the thrust disc and the rotating shaft; At least one set of dynamic seals; the dynamic seals are used for dynamic sealing between the thrust disc and the dynamic sealing housing, and the dynamic seals are installed on the first side of the thrust disc; each set of dynamic seals includes an annular pole shoe and a magnetorheological fluid, the first end of the pole shoe is fixedly installed on the sealing housing, the second end of the pole shoe is provided with multiple annular pole teeth, the magnetorheological fluid is located between the first end of the pole teeth and the first side of the thrust disc, and the pole shoe has magnetic force; a permanent magnet ring is fixed on the pole shoe, and the pole shoe is made of magnetically conductive material; The control component is used to adjust the distance between the first end of the pole tooth of the dynamic seal and the first side of the thrust disk. The control component includes an electromagnet, the thrust disk is made of a magnetic material, and the control component also includes a distance sensor, a microprocessor, and a driver. The distance sensor is used to collect the distance between the thrust disk and the distance sensor. The data signal output terminal of the distance sensor is connected to the data signal input terminal of the microprocessor. The control signal output terminal of the microprocessor is connected to the control signal input terminal of the driver. The output terminal of the driver is connected to the control signal input terminal of the electromagnet. The permanent magnet ring generates an upward magnetic attraction force on the thrust plate through the pole shoes, while the electromagnet generates a downward magnetic attraction force on the thrust plate.

2. The magnetic fluid dynamic float seal apparatus of claim 1, wherein, Each of the pole teeth has a pressure relief hole at its second end.

3. The magnetic fluid dynamic float seal apparatus of claim 1, wherein, The static sealing connector includes an elastic disc, a first pressure ring, a second pressure ring, a set of first screws, and a set of second screws. A connecting ring is provided on the outer wall of the rotating shaft. A set of first threaded connecting holes is provided on the inner side of the connecting ring, the first pressure ring, and the elastic disc. A first screw is threadedly connected to a first threaded connecting hole of the first pressure ring, the elastic disc, and the connecting ring, respectively. A set of second threaded connecting holes is provided on the outer side of the thrust disc, the second pressure ring, and the elastic disc. A second screw is threadedly connected to a second threaded connecting hole of the second pressure ring, the elastic disc, and the thrust disc, respectively.

4. The magnetic fluid dynamic float seal apparatus of claim 1, wherein, The magnetic fluid floating dynamic sealing device also includes at least three anti-collision blocks. The inner side of the anti-collision blocks is provided with anti-collision grooves, and the outer side wall of the thrust plate is provided with anti-collision rings. The anti-collision rings are located in the anti-collision grooves, and multiple anti-collision blocks are arranged in a ring array around the thrust plate with the central axis of the rotating shaft as the center.

5. The magnetic fluid dynamic float seal apparatus of claim 4, wherein, The anti-collision groove is coated with a self-lubricating layer.

6. The magnetic fluid dynamic float seal apparatus of claim 1, wherein, The dynamic seal housing has an annular cooling chamber filled with coolant.

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