Micro-nano magnetic medium sealing device and leakage rate detection method

Abstract

The invention discloses a micro-nano magnetic medium sealing device and a leakage rate detection method. The device comprises a shell, an end cover, a rotating shaft, a first pole shoe, a magnetic piece and a second pole shoe. The method comprises the steps that an unprocessed first pole shoe is installed in a shell, leakage is detected after sealing is conducted in a welding mode, if leakage does not exist, a magnetic piece and an unprocessed second pole shoe are sequentially installed in the shell, leakage is detected after sealing is conducted in the welding mode, and if leakage does not exist, the magnetic piece and the unprocessed second pole shoe are sealed in the shell. The unprocessed first pole shoe and the unprocessed second pole shoe are perforated, pole teeth are processed, the pole teeth are filled with micro-nano magnetic media, the shell, the first pole shoe, the magnet and the second pole shoe are installed on the rotating shaft, the end cover is installed on the shell, and the leakage rate of the magnetic sealing position is detected on the low-pressure side. According to the invention, the leakage channel at the rubber ring sealing position between the pole shoe and the shell in the related technology is blocked by using a welding method, so that the detected leakage rate is the leakage rate of the micro-nano magnetic medium sealing.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical engineering sealing, and in particular to a micro-nano magnetic medium sealing device and a leakage rate detection method. Background Art

[0002] In magnetic fluid sealing technology, magnetic fluid forms an O-ring under the influence of an uneven magnetic field, sealing the medium. This technology offers significant advantages, including zero leakage, long life, and low friction, making it an irreplaceable tool in high-end equipment such as aerospace and nuclear power. However, in extreme operating conditions, such as low temperatures, static sealing components like rubber rings can fail and leak, significantly impacting the detection of magnetic fluid seal leakage rates.

[0003] In the relevant technology for detecting the leakage rate of magnetic liquid seals, the leakage of static seals such as the sealing ring in the sealing structure is not taken into account. It is believed that the leakage rate measured by the helium mass spectrometer leak detector is the leakage rate of the magnetic liquid seal, which leads to errors in the detection results. Summary of the Invention

[0004] The present invention is based on the inventor's discovery and understanding of the following facts and problems:

[0005] The prior art lacks a specific method for detecting the leakage rate of magnetic fluid seals. A major reason for this is that, under normal operating conditions, static seals like rubber rings are assumed to be leak-proof, so any detected leakage is attributed to the magnetic fluid seal. However, under special operating conditions, such as low temperatures, static seals can leak, interfering with the detection of magnetic fluid seal leakage rates.

[0006] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0007] To this end, an embodiment of the present invention provides a micro-nano magnetic medium sealing device, which can adapt to special working conditions and avoid affecting the detection of the leakage rate of the micro-nano magnetic medium sealing part.

[0008] The micro-nano magnetic medium sealing device according to an embodiment of the present invention comprises:

[0009] A housing and an end cover provided on one side of the housing, wherein the housing and the end cover define a sealed cavity, a sealing ring is provided on the interface between the housing and the end cover, and a pressurizing hole communicating with the sealed cavity is provided on the end cover;

[0010] a sealing assembly disposed within the housing and located on a side of the sealed cavity away from the end cover, the sealing assembly comprising a plurality of pole shoes and a magnetic member disposed between any two of the pole shoes, the pole shoes and the housing being welded to each other to seal a gap therebetween;

[0011] The sealing assembly is mounted on the rotating shaft, and a micro-nano magnetic medium is filled between the pole teeth of the pole shoe and the rotating shaft.

[0012] The micro-nano magnetic medium sealing device of the embodiment of the present invention seals the gap between the pole piece and the housing by welding, thereby avoiding affecting the detection of the micro-nano magnetic medium sealing leakage rate under special working conditions and improving the accuracy of the detection.

[0013] In some embodiments, the housing and the end cover are made of non-magnetic conductive material, and the pole shoe is made of magnetic conductive material.

[0014] In some embodiments, the magnetic member is a permanent magnet, and the cross-sectional shape of the magnetic member is annular.

[0015] In some embodiments, the sealing gap between the pole teeth of the pole shoe and the rotating shaft is 0.05-0.3 mm.

[0016] An embodiment of the present invention also proposes a leakage rate detection method, which is applicable to the micro-nano magnetic medium sealing device described in the above embodiment. The multiple pole shoes of the micro-nano magnetic medium sealing device include a first pole shoe and a second pole shoe, and the first pole shoe and the second pole shoe are arranged at intervals in a direction away from the sealing cavity.

[0017] The leakage rate detection method according to the embodiment of the present invention includes:

[0018] Installing the unprocessed first pole piece into the housing, and sealing the gap between the housing and the unprocessed first pole piece by welding;

[0019] Assemble the sealing ring and the end cap on the housing, introduce helium at the target pressure into the sealed cavity and maintain the pressure, and use a helium mass spectrometer leak detector to detect whether there is any gas leakage on the low-pressure side of the unprocessed first pole piece;

[0020] If there is no gas leakage, release the pressure in the sealed chamber, remove the sealing ring and end cover, and machine a circular hole in the center of the unmachined first pole shoe, with the diameter of the circular hole being smaller than the diameter of the rotating shaft;

[0021] The magnetic component and the unprocessed second pole piece are sequentially installed into the housing, and the gap between the housing and the unprocessed second pole piece is sealed by welding;

[0022] Assemble the sealing ring and the end cap on the housing, introduce helium at the target pressure into the sealed cavity and maintain the pressure, and use a helium mass spectrometer leak detector to detect whether there is any gas leakage on the low-pressure side of the unprocessed second pole piece;

[0023] If there is no gas leakage, release the pressure in the sealed chamber, remove the sealing ring and the end cover, open an assembly hole at the center of the unprocessed second pole shoe, expand the circular hole of the unprocessed first pole shoe to form an assembly hole, and process pole teeth in the assembly hole to form the first pole shoe and the second pole shoe;

[0024] Adding micro-nano magnetic medium to the pole teeth of the processed first pole shoe and the second pole shoe, and installing the housing, the first pole shoe, the magnetic member, and the second pole shoe on the rotating shaft;

[0025] The sealing ring and the end cover are assembled on the housing, helium at the target pressure is introduced into the sealing cavity and the pressure is maintained, and the leakage rate of the micro-nano magnetic medium seal is detected on the low-pressure side using a helium mass spectrometer leak detector.

[0026] The leakage rate detection method of the embodiment of the present invention uses welding to block the leakage channel at the rubber ring seal between the pole shoe and the housing in the related art, so that the detected leakage rate is the leakage rate of the micro-nano magnetic medium seal, providing an accurate basis for the stable and reliable operation of the micro-nano magnetic medium seal under extreme working conditions.

[0027] In some embodiments, the target pressure refers to 1-1.5 times the pressure that the micro-nano magnetic medium sealing device withstands during normal operation.

[0028] In some embodiments, no gas leakage refers to a leak rate lower than a minimum leak rate detectable by a helium mass spectrometer leak detector.

[0029] In some embodiments, when detecting leaks using a helium mass spectrometer leak detector, a temporary sealed chamber is formed on the low-pressure side by pre-sealing and evacuated, and the detection head of the helium mass spectrometer leak detector is placed in the temporary sealed chamber.

[0030] In some embodiments, after welding the gap between the housing and the unmachined first pole piece, the weld on the low-pressure side is ground.

[0031] In some embodiments, if the pole shoes and magnetic members of the micro-nano magnetic medium sealing device have multiple levels of alternating arrangement, the detection logic of the subsequent pole shoes is consistent with the detection logic of the first pole shoe and the second pole shoe. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of a micro-nano magnetic medium sealing device according to an embodiment of the present invention.

[0033] Figure 2Schematic diagram of an unprocessed first pole shoe and a second pole shoe according to an embodiment of the present invention.

[0034] Reference numerals:

[0035] 11-housing, 12-end cover, 13-sealing ring, 101-sealing chamber, 102-pressurized hole, 21-first pole shoe, 211-unprocessed first pole shoe, 22-second pole shoe, 221-unprocessed second pole shoe, 23-magnetic part, 24-micro-nano magnetic medium, 31-rotating shaft, 41-helium mass spectrometer leak detector. DETAILED DESCRIPTION

[0036] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0037] The micro-nano magnetic medium sealing device according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0038] like Figure 1 and Figure 2 As shown, the micro-nano magnetic medium sealing device according to the embodiment of the present invention includes a housing 11, an end cover 12, a rotating shaft 31 and a sealing assembly.

[0039] The end cover 12 is located on the left side of the housing 11. The end cover 12 is detachably connected to the housing 11 via bolts. Specifically, corresponding lugs are provided on the housing 11 and the end cover 12, and mounting holes for mounting bolts are provided on the lugs. The housing 11 and the end cover 12 define a sealed chamber 101. The sealed chamber 101 is located on the left side of the sealing assembly. That is, the chamber on the left side of the sealing assembly is the sealed chamber 101. A sealing ring 13 is provided on the mating surface between the housing 11 and the end cover 12. Specifically, corresponding annular sealing grooves are provided on the left end surface of the housing 11 and the right end surface of the end cover 12, and the sealing ring 13 is installed in the two sealing grooves. A pressurized hole 102 is provided on the end cover 12, which is connected to the sealed chamber 101.

[0040] The sealing assembly is disposed within the housing 11, located on the side (right side) of the sealed cavity 101 away from the end cap 12. The sealing assembly includes multiple pole shoes and a magnetic member 23 disposed between any two pole shoes. Optionally, the multiple pole shoes are spaced apart in the left-right direction, with a magnetic member 23 disposed between adjacent pole shoes. A boss is provided on the inner circumferential wall of the housing 11 to form a stepped surface for positioning the leftmost pole shoe.

[0041] The pole shoe and the housing 11 are fixedly connected by welding to seal the gap between them. Compared with the related art that uses a rubber ring to seal the pole shoe and the housing 11, the sealing method of the present invention can ensure that there will be no leakage under special working conditions such as low temperature.

[0042] It should be noted that the housing 11 and end cap 12 are made of non-magnetic materials, such as austenitic stainless steel (such as 304 and 316 series), aluminum and aluminum alloys, copper and copper alloys, titanium alloys, or engineering plastics (such as polytetrafluoroethylene). These materials have extremely low magnetic permeability (close to that of air), making it difficult for magnetic fields to penetrate or form a magnetic circuit.

[0043] The pole shoe is a ring-shaped structure made of a magnetically conductive material, such as low-carbon steel (such as 10# steel), silicon steel (such as DW540), iron-nickel soft magnetic alloy (such as Permalloy 1J50), or iron-based amorphous alloy. Its high magnetic permeability and low coercivity allow for efficient conduction and concentration of magnetic flux lines.

[0044] The cross-section of the magnetic member 23 is annular, for example, a ring formed by a plurality of magnetic columns, or a complete magnetic ring. The magnetic member 23 is a permanent magnet, for example, neodymium iron boron.

[0045] The sealing assembly is mounted on the rotating shaft 31, and the space between the pole piece's pole teeth and the rotating shaft 31 is filled with a micro-nano magnetic medium 24. This micro-nano magnetic medium 24 can be a magnetic liquid, magnetorheological fluid, magnetic grease, magnetic particles, or other materials, and refers to any liquid or solid with magnetic properties that can provide a sealing function. Optionally, the sealing gap between the pole piece's pole teeth and the rotating shaft 31 is 0.05-0.3mm. This is achieved by comprehensively optimizing magnetic field strength, mechanical stability, and fluid dynamics to achieve a balance between efficient sealing and long-term reliable operation.

[0046] The micro-nano magnetic medium sealing device of the embodiment of the present invention seals the gap between the pole piece and the housing 11 by welding, thereby avoiding affecting the detection of the leakage rate at the micro-nano magnetic medium seal under special working conditions and improving the accuracy of the detection.

[0047] The following describes a leakage rate detection method according to an embodiment of the present invention with reference to the accompanying drawings.

[0048] The leakage rate detection method of the present embodiment is applicable to the micro-nano magnetic medium sealing device of the above-described embodiment. The following describes the leakage rate detection method of the present embodiment using a configuration where the pole piece and magnetic element are arranged in a single layer. The multiple pole pieces of the micro-nano magnetic medium sealing device include a first pole piece 21 and a second pole piece 22, which are spaced apart and arranged away from the sealed cavity 101.

[0049] The leakage rate detection method according to the embodiment of the present invention includes:

[0050] S1: Install the unprocessed first pole piece 211 into the housing 11, position it using the bosses within the housing 11, and seal the gap between the housing 11 and the unprocessed first pole piece 211 by welding to block the leakage path between the housing 11 and the unprocessed first pole piece 211. Subsequently, to facilitate assembly of the magnetic component 23, the weld on the right side of the unprocessed first pole piece 211 is polished.

[0051] S2: Assemble the sealing ring 13 and the end cover 12 on the outer shell 11 in sequence, introduce helium of target pressure into the sealing cavity 101 through the pressurization hole 102 and maintain the pressure, and use the helium mass spectrometer leak detector 41 to detect whether there is any gas leakage on the low-pressure side (right side) of the unprocessed first pole shoe 211.

[0052] S3: If there is no gas leakage, release the pressure of the sealed chamber 101, remove the sealing ring 13 and the end cover 12, and process a circular hole at the center of the unprocessed first pole shoe 211, and the diameter of the circular hole is smaller than the diameter of the rotating shaft 31, so as to facilitate the subsequent detection of leakage at the weld of the second pole shoe 22.

[0053] S4: The magnetic member 23 and the unprocessed second pole piece 221 are sequentially installed into the housing 11 , and the gap between the housing 11 and the unprocessed second pole piece 221 is sealed by welding.

[0054] S5: Assemble the sealing ring 13 and the end cover 12 on the outer shell 11 in sequence, introduce helium of target pressure into the sealed cavity 101 through the pressurized hole 102 and maintain the pressure, and use the helium mass spectrometer leak detector 41 to detect whether there is any gas leakage on the low-pressure side (right side) of the unprocessed second pole shoe 221.

[0055] S6: If there is no gas leakage, release the pressure in the sealed chamber 101, remove the sealing ring 13 and the end cover 12, open an assembly hole at the center of the unprocessed second pole shoe 221, expand the circular hole of the unprocessed first pole shoe 211 to form an assembly hole, and process pole teeth in the assembly hole to form the first pole shoe 21 and the second pole shoe 22.

[0056] S7: Add micro-nano magnetic medium 24 to the pole teeth of the first pole shoe 21 and the second pole shoe 22 after processing, and install the housing 11, the first pole shoe 21, the magnetic member 23, and the second pole shoe 22 on the rotating shaft 31.

[0057] S8: Seal ring 13 and end cap 12 are sequentially assembled on housing 11. Helium gas at the target pressure is introduced into sealed chamber 101 and maintained at this pressure. The leakage rate of the micro-nano magnetic medium seal is measured on the low-pressure side (right side) using a helium mass spectrometer leak detector 41. At this point, only one leakage path is detected at the micro-nano magnetic medium seal. The measured leakage rate is the leakage rate of the micro-nano magnetic medium seal.

[0058] The target pressure refers to 1-1.5 times the pressure that the micro-nano magnetic medium sealing device can withstand during normal operation. No gas leakage refers to a leakage rate lower than the minimum leakage rate detected by the helium mass spectrometer leak detector 41.

[0059] In related magnetic fluid seals, a rubber ring is used to seal between the pole piece and the housing. Under extreme operating conditions, such as low temperatures, the rubber ring seal fails. Leakage from the high-pressure side to the low-pressure side occurs through two channels: the rubber ring seal and the magnetic fluid seal. Therefore, it's impossible to effectively monitor the leakage rate of the magnetic fluid seal alone.

[0060] The leakage rate detection method of the embodiment of the present invention uses welding to block the leakage channel at the rubber ring seal between the pole shoe and the housing in the related art, so that the detected leakage rate is the leakage rate of the micro-nano magnetic medium seal, providing an accurate basis for the stable and reliable operation of the micro-nano magnetic medium seal under extreme working conditions.

[0061] It should be noted that if the pole shoes and magnetic members 23 of the micro-nano magnetic medium sealing device have multiple levels of alternating arrangement, the detection logic of the subsequent pole shoes is consistent with the detection logic of the first pole shoe 21 and the second pole shoe 22 .

[0062] In some embodiments, when detecting leaks using the helium mass spectrometer leak detector 41 , a temporary sealed chamber is formed on the low-pressure side by pre-sealing and evacuated, and the detection head of the helium mass spectrometer leak detector 41 is placed in the temporary sealed chamber.

[0063] It can be understood that in order to avoid the high helium background of the instrument caused by the helium component in the air, a temporary closed chamber is formed on the low-pressure side and vacuumed using methods including but not limited to lip sealing, and the detection head of the helium mass spectrometer leak detector 41 is placed in the temporary closed chamber to achieve high-precision detection.

[0064] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0065] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0066] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0067] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0068] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0069] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A micro-nano magnetic medium sealing device, characterized in that: include: A housing and an end cover provided on one side of the housing, wherein the housing and the end cover define a sealed cavity, a sealing ring is provided on the interface between the housing and the end cover, and a pressurizing hole communicating with the sealed cavity is provided on the end cover; a sealing assembly disposed within the housing and located on a side of the sealed cavity away from the end cover, the sealing assembly comprising a plurality of pole shoes and a magnetic member disposed between any two of the pole shoes, the pole shoes and the housing being welded to each other to seal a gap therebetween; The sealing assembly is mounted on the rotating shaft, and a micro-nano magnetic medium is filled between the pole teeth of the pole shoe and the rotating shaft.

2. The micro-nano magnetic medium sealing device according to claim 1, characterized in that: The shell and the end cover are made of non-magnetic conductive materials, and the pole shoe is made of magnetic conductive materials.

3. The micro-nano magnetic medium sealing device according to claim 1, characterized in that: The magnetic part is a permanent magnet, and the cross-section of the magnetic part is annular.

4. The micro-nano magnetic medium sealing device according to claim 1, characterized in that: The sealing gap between the pole teeth of the pole shoe and the rotating shaft is 0.05-0.3 mm.

5. A leakage rate detection method, characterized in that: The leakage rate detection method is applicable to the micro-nano magnetic medium sealing device according to any one of claims 1 to 4, wherein the plurality of pole shoes of the micro-nano magnetic medium sealing device include a first pole shoe and a second pole shoe, and the first pole shoe and the second pole shoe are spaced apart in a direction away from the sealed cavity. The leakage rate detection method includes: Installing the unprocessed first pole piece into the housing, and sealing the gap between the housing and the unprocessed first pole piece by welding; Assemble the sealing ring and the end cap on the housing, introduce helium at the target pressure into the sealed cavity and maintain the pressure, and use a helium mass spectrometer leak detector to detect whether there is any gas leakage on the low-pressure side of the unprocessed first pole piece; If there is no gas leakage, release the pressure in the sealed chamber, remove the sealing ring and end cover, and machine a circular hole in the center of the unmachined first pole shoe, with the diameter of the circular hole being smaller than the diameter of the rotating shaft; The magnetic component and the unprocessed second pole piece are sequentially installed into the housing, and the gap between the housing and the unprocessed second pole piece is sealed by welding; Assemble the sealing ring and the end cap on the housing, introduce helium at the target pressure into the sealed cavity and maintain the pressure, and use a helium mass spectrometer leak detector to detect whether there is any gas leakage on the low-pressure side of the unprocessed second pole piece; If there is no gas leakage, release the pressure in the sealed chamber, remove the sealing ring and the end cover, open an assembly hole at the center of the unprocessed second pole shoe, expand the circular hole of the unprocessed first pole shoe to form an assembly hole, and process pole teeth in the assembly hole to form the first pole shoe and the second pole shoe; Adding micro-nano magnetic medium to the pole teeth of the processed first pole shoe and the second pole shoe, and installing the housing, the first pole shoe, the magnetic member, and the second pole shoe on the rotating shaft; The sealing ring and the end cover are assembled on the housing, helium at the target pressure is introduced into the sealing cavity and the pressure is maintained, and the leakage rate of the micro-nano magnetic medium seal is detected on the low-pressure side using a helium mass spectrometer leak detector.

6. The leakage rate detection method according to claim 5, characterized in that: The target pressure refers to 1-1.5 times the pressure that the micro-nano magnetic medium sealing device withstands during normal operation.

7. The leakage rate detection method according to claim 5, characterized in that: No gas leakage means the leak rate is lower than the minimum leak rate that can be detected by a helium mass spectrometer leak detector.

8. The leakage rate detection method according to claim 5, characterized in that: When detecting leaks using a helium mass spectrometer leak detector, a temporary sealed chamber is formed on the low-pressure side using a pre-sealing method and evacuated, and the detection head of the helium mass spectrometer leak detector is placed in the temporary sealed chamber.

9. The leakage rate detection method according to claim 5, characterized in that: After welding the gap between the housing and the unmachined first pole piece, the weld seam on the low-pressure side is ground.

10. The leakage rate detection method according to any one of claims 5 to 9, characterized in that: If the pole shoes and magnetic members of the micro-nano magnetic medium sealing device have multiple levels of alternating arrangement, the detection logic of the subsequent pole shoes is consistent with the detection logic of the first pole shoe and the second pole shoe.

Images