Sealing device for generating magnetic liquid in situ to form micro gap

Abstract

The invention discloses a sealing device for generating magnetic liquid in situ to form a micro gap. The sealing device comprises a large shaft, a sealing shaft sleeve, a permanent magnet, a pole shoe and a magnetic phase change material. The sealing shaft sleeve is installed outside the large shaft and rotates along with the large shaft, the permanent magnet generates a magnetic field, the pole shoe forms different levels of permanent magnetic fields under the action of the magnetic field, and the magnetic phase-change material is filled between the sealing shaft sleeve and the pole shoe, becomes magnetic liquid after being heated to form a micro-gap and is sealed under the action of the magnetic field. By utilizing the characteristics of the magnetic phase change material and the principle of generating heat by friction, the function of generating magnetic liquid between the sealing shaft sleeve and the pole shoe of the magnetofluid sealing device is realized by controlling the rotation of the large shaft, the sealing reliability and stability are improved under the action of a magnetic field, and the problem that a magnetofluid sealing gap cannot be too large or too small is effectively solved; direct contact friction between the pole shoe and a rotating part is avoided, and abrasion damage is reduced.

Description

Technical Field

[0001] The present application relates to the field of sealing technology, and in particular to a sealing device for in-situ generating magnetic liquid to form a micro-gap. Background Art

[0002] Magnetic fluid sealing is a method of sealing by utilizing the magnetic and fluidity properties of magnetic liquids. It has very good adaptability to the sealing of rotating surfaces and is widely used in machinery, chemical industry, semiconductor manufacturing and other fields.

[0003] However, its sealing performance is affected by many factors, among which the size of the sealing gap is particularly critical. When the sealing gap is too large, the magnetic field strength that the magnetic fluid seal relies on will be weakened, resulting in poor sealing effect; when the sealing gap is too small, the pole shoe teeth of the magnetic fluid seal may contact and rub against the rotating shaft, and this collision and friction can easily cause wear and damage to the sealing device. Summary of the invention

[0004] In view of this, the present invention provides a sealing device for in-situ generating magnetic liquid to form a micro gap. Through the principle of frictional heat generation of magnetic phase change material, a micro gap is generated on the contact surface between the phase change material and the sleeve, solving the problem that the magnetic liquid sealing gap cannot be too large.

[0005] In order to solve the above problems, the technical solution of the present application is specifically a sealing device for in-situ generating magnetic liquid to form a micro-gap, comprising:

[0006] A sealing device for in-situ generating magnetic liquid to form a micro-gap, comprising:

[0007] The main shaft is the central axis of the sealing device;

[0008] A sealing sleeve is installed on the outer surface of the main shaft and rotates with the main shaft;

[0009] A permanent magnet is arranged outside the sealed magnetic sleeve and is used to generate a magnetic field;

[0010] a step shoe, in contact with the permanent magnet, and used to form permanent magnetic fields of different levels under the action of the magnetic field of the permanent magnet;

[0011] The magnetic phase change material is filled between the sealing sleeve and the pole shoe. After the contact surface is heated, the phase change becomes a magnetic liquid to form a tiny gap, and a seal is formed under the action of the permanent magnetic field of different levels.

[0012] According to a preferred embodiment, the sealing sleeve is installed on the outer surface of the main shaft in an interference fit manner.

[0013] According to a preferred embodiment, the pole shoe comprises a left pole shoe and a right pole shoe, and the permanent magnet contacts the left pole shoe and the right pole shoe through the action of a magnetic field and is located between the left and right pole shoes.

[0014] According to a preferred embodiment, the pole shoe and the sealing sleeve form a filling gap, and the magnetic phase change material is filled in the filling gap.

[0015] According to a preferred embodiment, a side of the filling gap close to the sealing sleeve is a flat contact surface, and a side of the filling gap close to the pole shoe is a non-flat contact surface.

[0016] Furthermore, the different levels of permanent magnetic fields include a primary permanent magnetic field, a secondary permanent magnetic field and a tertiary permanent magnetic field, the primary permanent magnetic field is on the outermost side, the tertiary permanent magnetic field is on the innermost side, and the secondary permanent magnetic field is located between the primary permanent magnetic field and the tertiary permanent magnetic field.

[0017] According to a preferred embodiment, the magnetic phase change material is a magnetic phase change paraffin material.

[0018] According to a preferred embodiment, the magnetic phase-change paraffin material is made of ferroferric oxide nanoparticles, a base liquid, a surfactant and paraffin.

[0019] According to a preferred embodiment, the temperature at which the prepared magnetic phase-change paraffin material changes into a magnetic liquid is 50°C to 70°C.

[0020] According to a preferred embodiment, when the friction between the magnetic phase-change wax material and the sealing sleeve generates a temperature of 50° C. to 70° C., the rotation speed of the main shaft is 10 to 40 r / s.

[0021] The present invention utilizes the characteristics of magnetic phase change materials and the principle of frictional heat generation, and realizes the function of generating magnetic liquid between the sealing sleeve and the pole shoe of the magnetic fluid sealing device by controlling the rotation of the large shaft, thereby improving the sealing reliability and stability under the action of the magnetic field, effectively solving the problem that the magnetic fluid sealing gap cannot be too large or too small, avoiding direct contact and friction between the pole shoe and the rotating parts, and reducing wear and damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a sealing device for in-situ generating magnetic liquid to form a micro gap disclosed by the present invention.

[0023] Explanation of the reference numerals: 1-main shaft, 21-left pole shoe, 22-right pole shoe, 3-permanent magnet, 4-magnetic phase change material, 41-magnetic liquid, 5-sealing sleeve, 61-primary permanent magnetic field, 62-secondary permanent magnetic field, 63-tertiary permanent magnetic field. DETAILED DESCRIPTION

[0024] Magnetic fluid sealing is a method of sealing by utilizing the magnetic and fluidity properties of magnetic liquids. It has very good adaptability to the sealing of rotating surfaces and is widely used in machinery, chemical industry, semiconductor manufacturing and other fields.

[0025] However, its sealing performance is affected by many factors, among which the size of the sealing gap is particularly critical. When the sealing gap is too large, the magnetic field strength that the magnetic fluid seal relies on will be weakened, resulting in poor sealing effect; when the sealing gap is too small, the pole shoe teeth of the magnetic fluid seal may contact and rub against the rotating shaft, and this collision and friction can easily cause wear and damage to the sealing device.

[0026] In view of this, the present invention provides a sealing device for in-situ generating magnetic liquid to form a micro gap. Through the principle of frictional heat generation of magnetic phase change material, a micro gap is generated on the contact surface between the phase change material and the sleeve, solving the problem that the magnetic liquid sealing gap cannot be too large.

[0027] To solve the above problems, the technical solution of this application is specifically as follows:

[0028] like Figure 1 As shown, a sealing device for in-situ generating a magnetic liquid 41 to form a micro gap comprises:

[0029] The main shaft 1, as the central shaft of the sealing device, is the rotating part of the entire device. The main shaft 1 is usually made of high-strength, corrosion-resistant materials, such as stainless steel, alloy steel, etc., to ensure its stability and durability under long-term high-speed rotation;

[0030] The sealing sleeve 5 is installed on the outer surface of the main shaft 1 and rotates with the main shaft 1. The inner wall of the sealing sleeve 5 is tightly fitted with the outer wall of the main shaft 1 to ensure the matching accuracy with the main shaft 1.

[0031] The permanent magnet 3 is arranged outside the sealing magnetic sleeve and is used to generate a magnetic field. The permanent magnet 3 is usually made of high-performance permanent magnetic materials, such as neodymium iron boron, samarium cobalt, etc., to ensure the strength and stability of the magnetic field. The magnetic field generated by the permanent magnet 3 can cover the entire sealing area and meet the requirements of sealing performance.

[0032] The step shoe is in contact with the permanent magnet 3 and is used to form different levels of permanent magnetic fields under the magnetic field of the permanent magnet 3. The step shoe is in contact with the permanent magnet 3 and is used to form different levels of permanent magnetic fields under the magnetic field of the permanent magnet 3. The step shoe is usually made of magnetic materials, such as iron, nickel-cobalt alloy, etc., to ensure that it can respond to the magnetic field of the permanent magnet 3 and generate the required permanent magnetic field. The design and arrangement of the step shoe need to ensure that it can form a stable and uniform magnetic field distribution;

[0033] The magnetic phase change material 4 is filled between the sealing sleeve 5 and the pole shoe. After the contact surface is heated, it changes into a magnetic liquid 41 to form a tiny gap, and forms a seal under the action of the permanent magnetic field of different levels.

[0034] The specific principle of the present invention is: when the main shaft 1 drives the sealing sleeve 5 to rotate, a relative motion is formed at the contact surface of the sealing sleeve 5 and the magnetic phase change material 4. Under the condition of a certain linear speed, heat is generated at the contact surface, and the magnetic phase change material 4 undergoes a phase change at the contact surface, changing from a flexible magnetic solid to a magnetic liquid 41, forming a tiny gap, and forming a seal under the action of a permanent magnetic field.

[0035] The present invention utilizes the characteristics of magnetic phase change materials and the principle of frictional heat generation. By controlling the rotation of the main shaft 1, the function of generating magnetic liquid 41 between the sealing sleeve 5 and the pole shoe of the magnetic fluid sealing device is realized, thereby improving the sealing reliability and stability under the action of the magnetic field, effectively solving the problem that the magnetic fluid sealing gap cannot be too large or too small, avoiding direct contact and friction between the pole shoe and the rotating parts, and reducing wear and damage.

[0036] Furthermore, the sealing sleeve 5 is installed on the outer surface of the main shaft 1 in an interference fit manner. Specifically, the inner diameter of the sealing sleeve 5 is slightly smaller than the outer diameter of the main shaft 1, so that the sleeve is elastically deformed after assembly, thereby holding the main shaft 1 tightly, achieving a tight connection between the two and being able to rotate synchronously with the main shaft 1. When the main shaft 1 rotates, the sealing sleeve 5 can stably and reliably follow the rotation, minimizing the possibility of relative displacement between the two.

[0037] Furthermore, the pole shoe includes a left pole shoe 21 and a right pole shoe 22 , and the permanent magnet 3 contacts the left pole shoe 21 and the right pole shoe 22 through the action of the magnetic field, and is located between the left pole shoe 21 and the right pole shoe 22 .

[0038] In some cases, the shape and size of the pole shoes can be adjusted to optimize the magnetic field distribution and improve the phase change efficiency of the magnetic phase change material 4, thereby achieving a better sealing effect. At the same time, the distance between the two pole shoes and the sealing sleeve 5 should be adjusted according to the phase change characteristics and sealing requirements of the magnetic phase change material 4. In general, the smaller the distance, the greater the magnetic field strength and the better the sealing effect, but it is also necessary to consider avoiding contact and friction between the sealing sleeve 5 and the pole shoes and reserving enough space for the magnetic phase change material 4.

[0039] Furthermore, the pole shoe and the sealing sleeve 5 form a filling gap, the magnetic phase change material 4 is filled in the filling gap, the side of the filling gap close to the sealing sleeve 5 is a flat contact surface, and the side of the filling gap close to the pole shoe is a non-flat contact surface.

[0040] During the design and manufacturing process, the dimensional accuracy of the pole shoe and the sealing sleeve 5 must be ensured to ensure the uniformity of the filling gap, and the magnetic phase change material 4 is filled in the filling gap. During the filling process, it is necessary to ensure that the magnetic phase change material 4 is evenly distributed to avoid defects such as voids and bubbles. Pressure filling, vacuum filling and other methods can be used to fully fill the magnetic phase change material 4 into the filling gap.

[0041] The side of the filling gap close to the sealing sleeve 5 is a flat contact surface. The design of this flat contact surface can ensure close contact between the sealing sleeve 5 and the magnetic phase change material 4, reduce heat loss, and improve phase change efficiency. The side of the filling gap close to the pole shoe is a non-flat contact surface. The design of the non-flat contact surface can increase the contact area between the pole shoe and the magnetic phase change material 4 and improve the effect of the magnetic field. The serrated shape as shown in the figure can be selected.

[0042] The filling gap provides space for the magnetic phase change material 4, so that it can undergo phase change and form a seal between the sealing sleeve 5 and the pole shoe. At the same time, the size and shape of the filling gap can affect the distribution and intensity of the magnetic field, thereby adjusting the sealing performance of the sealing device; the design of the flat contact surface and the non-flat contact surface can optimize the contact state between the magnetic phase change material 4 and the sealing sleeve 5 and the pole shoe, improve the phase change efficiency and the effect of the magnetic field, and further enhance the sealing performance of the sealing device.

[0043] Furthermore, the different levels of permanent magnetic fields include a primary permanent magnetic field 61, a secondary permanent magnetic field 62 and a tertiary permanent magnetic field 63, the primary permanent magnetic field 61 is at the outermost side, the tertiary permanent magnetic field 63 is at the innermost side, and the secondary permanent magnetic field 62 is located between the primary permanent magnetic field 61 and the tertiary permanent magnetic field 63.

[0044] The permanent magnet 3 generates different levels of permanent magnetic fields through interaction with the left pole shoe 21 and the right pole shoe 22, including a primary permanent magnetic field 61, a secondary permanent magnetic field 62 and a tertiary permanent magnetic field 63. The layout of this graded magnetic field is designed based on the sealing requirements of the sealing device and the distribution characteristics of the magnetic liquid 41.

[0045] When the sealing device is working, when the sealing sleeve 5 rotates with the main shaft 1, the magnetic phase change material 4 between the sealing sleeve 5 and the pole shoe undergoes phase change due to frictional heat to form a magnetic liquid 41 and a micro gap. At this time, the three-level permanent magnetic field 63 first generates an attraction force on the magnetic liquid 41 in the micro gap, so that a compact layer of magnetic liquid 41 is formed on the inner side of the micro gap.

[0046] As the magnetic liquid 41 increases and flows, the secondary permanent magnetic field 62 begins to play a role, guiding part of the magnetic liquid 41 to the outside, so that the magnetic liquid 41 gradually forms a distribution state from inside to outside and from dense to sparse in the micro gap. This distribution state helps to improve the reliability of the seal because it can dynamically adjust the distribution of the magnetic liquid 41 according to the pressure changes and sealing requirements at different positions in the micro gap.

[0047] The primary permanent magnetic field 61 maintains the stability of the entire sealing area at the outermost side. It can prevent the magnetic liquid 41 from overflowing the micro gap under the action of centrifugal force or other external factors, and prevent foreign impurities from entering the micro gap. Through the synergistic effect of the three-level permanent magnetic field 63, an efficient and stable magnetic liquid 41 sealing structure can be formed between the sealing sleeve 5 and the pole shoe, effectively preventing the leakage of liquid or gas.

[0048] The present application also discloses the specific preparation and control process of the magnetic phase change material 4, as described below:

[0049] The magnetic phase change paraffin material is selected as the key material in the sealing device because of its unique performance advantages. Paraffin has good phase change characteristics, can change from solid to liquid within a certain temperature range, and can absorb or release a large amount of heat during the phase change process. At the same time, by adding ferroferric oxide nanoparticles, the material is magnetic and can form a specific distribution under the action of a magnetic field to achieve a sealing effect. The addition of surfactants helps to improve the dispersibility of ferroferric oxide nanoparticles in the base liquid and paraffin, ensuring the stable performance of the magnetic phase change paraffin material. This composite material has both the phase change characteristics of paraffin and magnetism, and can play an important role in sealing devices.

[0050] Ferroferric oxide nanoparticles with a diameter of 20-30 nm are prepared by chemical co-precipitation. Paraffin is melted in an environment of 50-75°, and the ferroferric oxide nanoparticles, base liquid, and surfactant are immersed in the melted paraffin. Through a specific process, a magnetic phase change paraffin material is developed.

[0051] The temperature at which the manufactured magnetic phase change wax material changes into the magnetic liquid 41 is 50° C. to 70° C. During the operation of the sealing device, when the temperature generated by the friction between the sealing sleeve 5 and the magnetic phase change wax material reaches this range, the material begins to change phase from solid to magnetic liquid 41, forming a micro gap and achieving sealing under the action of the magnetic field.

[0052] Controlling the phase change temperature within this range has the following important effects: First, this temperature range is relatively low and easy to achieve in practical applications, and will not cause excessive temperature impacts on other components of the sealing device. Secondly, this temperature range can be controlled by adjusting parameters such as the friction coefficient between the sealing sleeve 5 and the pole shoe, and the rotation speed of the main shaft 1, so that the sealing device can operate stably under different working conditions. Finally, the phase change temperature range of 50°C to 70°C can ensure the stable performance of the magnetic phase change paraffin material before and after the phase change, thereby improving the reliability and service life of the sealing device.

[0053] When the friction between the magnetic phase change wax material and the sealing sleeve 5 generates a temperature of 50°C to 70°C, the rotation speed of the main shaft 1 is 10 to 40 r / s. The rotation speed of the main shaft 1 directly affects the friction between the sealing sleeve 5 and the magnetic phase change wax material, thereby affecting the generated temperature.

[0054] In practical applications, the rotation speed of the main shaft 1 can be adjusted to control the temperature generated by friction according to the specific requirements and working conditions of the sealing device. For example, when higher sealing performance is required, the rotation speed of the main shaft 1 can be appropriately increased to increase the temperature generated by friction, so as to prompt the magnetic phase change paraffin material to change phase faster to form magnetic liquid 41. However, the rotation speed of the main shaft 1 cannot be too high, otherwise it may cause problems such as increased wear of the sealing device and increased energy consumption. Therefore, it is necessary to make a reasonable selection within the rotation speed range of 10 to 40 r / s to achieve the best sealing effect and work efficiency.

[0055] The magnetic phase-change wax material has many application advantages in the sealing device that generates magnetic liquid 41 in situ to form a micro-gap. It can automatically adjust the phase change state according to the working conditions to achieve dynamic sealing; the preparation of the material is relatively simple and the cost is low; it has good stability and reliability and can work for a long time in different environments.

[0056] The above is a detailed introduction to a sealing device for in-situ generation of magnetic liquid to form a micro-gap provided by an embodiment of the present application. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A sealing device for in-situ generation of magnetic liquid to form a micro-gap, characterized in that: include: The main shaft is the central axis of the sealing device; A sealing sleeve is installed on the outer surface of the main shaft and rotates with the main shaft; A permanent magnet is arranged outside the sealed magnetic sleeve and is used to generate a magnetic field; a step shoe, in contact with the permanent magnet, and used to form permanent magnetic fields of different levels under the action of the magnetic field of the permanent magnet; The magnetic phase change material is filled between the sealing sleeve and the pole shoe. After the contact surface is heated, the phase change becomes a magnetic liquid to form a tiny gap, and a seal is formed under the action of the permanent magnetic field of different levels.

2. The sealing device for forming a micro-gap by in-situ generation of magnetic liquid according to claim 1, characterized in that: The sealing sleeve is installed on the outer surface of the main shaft in an interference fit manner.

3. The sealing device for forming a micro-gap by in-situ generation of magnetic liquid according to claim 1, characterized in that: The pole shoe comprises a left pole shoe and a right pole shoe, and the permanent magnet contacts the left pole shoe and the right pole shoe through the action of a magnetic field and is located between the left pole shoe and the right pole shoe.

4. The sealing device for forming a micro-gap by in-situ generation of magnetic liquid according to claim 1, characterized in that: The pole shoe and the sealing sleeve form a filling gap, and the magnetic phase change material is filled in the filling gap.

5. The sealing device for forming a micro-gap by in-situ generation of magnetic liquid according to claim 4, characterized in that: The side of the filling gap close to the sealing sleeve is a flat contact surface, and the side of the filling gap close to the pole shoe is a non-flat contact surface.

6. The sealing device for forming a micro-gap by in-situ generation of magnetic liquid according to claim 1, characterized in that: The different levels of permanent magnetic fields include a primary permanent magnetic field, a secondary permanent magnetic field and a tertiary permanent magnetic field. The primary permanent magnetic field is on the outermost side, the tertiary permanent magnetic field is on the innermost side, and the secondary permanent magnetic field is located between the primary permanent magnetic field and the tertiary permanent magnetic field.

7. The sealing device for forming a micro-gap by in-situ generation of magnetic liquid according to claim 1, characterized in that: The magnetic phase change material is a magnetic phase change paraffin material.

8. The sealing device for forming a micro-gap by in-situ generation of magnetic liquid according to claim 7, characterized in that: The magnetic phase-change paraffin material is made of ferroferric oxide nanometers, base liquid, surfactant and paraffin.

9. The sealing device for forming a micro-gap by in-situ generation of magnetic liquid according to claim 8, characterized in that: The temperature at which the prepared magnetic phase-change paraffin material changes into a magnetic liquid is 50° C. to 70° C.

10. The sealing device for forming a micro-gap by in-situ generation of magnetic liquid according to claim 9, characterized in that: When the friction between the magnetic phase-change wax material and the sealing sleeve generates a temperature of 50° C. to 70° C., the rotation speed of the main shaft is 10 to 40 r / s.

Images