A magnetic fluid sealed shaft assembly, canned motor and canned pump

Abstract

The application discloses a magnetic fluid sealed shaft assembly, a shielded motor and a shielded pump. The shaft assembly comprises a shell provided with a containing cavity, a fixed structure arranged on the inner wall of the containing cavity, a rotating shaft supported and arranged in the containing cavity, a magnetic fluid sealing device arranged in the containing cavity, an inner sleeve sealingly and fixedly sleeved on the rotating shaft, a space reserved in the shell for the magnetic fluid sealing device to jump with the rotating shaft and / or adjust the installation angle and position, and an elastic member sealingly installed on the outer sleeve of the magnetic fluid sealing device and sealingly connected with the fixed structure. The structure compensates for the influence of insufficient precision of the flatness of the fixed structure, the perpendicularity of the rotating shaft and the fixed structure, the coaxiality and the axial and radial jumping of the rotating shaft by the elastic installation of the magnetic fluid sealing device, eliminates the additional axial force, radial force, external torsional force and static indeterminate force suffered by the bearing in the magnetic fluid sealing device during work, and enables the magnetic fluid sealing device to be applied to pump products and the like, so as to ensure the sealing effect of the pump products and the like.

Description

[0001] This application claims priority to Chinese Patent Application No. 202011559309.6, filed with the State Intellectual Property Office on December 25, 2020, entitled "A Magnetohydrodynamic Seal Shaft Assembly, a Shielded Motor, and a Shielded Pump," the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of shaft sealing technology, specifically to a magnetohydrodynamic (MHD) sealed shaft assembly, a shielded motor, and a shielded pump. Background Technology

[0003] Magnetofluidic sealing technology is a novel sealing method that utilizes a magnetic fluid with high saturation magnetic intensity to seal related mechanical equipment. Magnetofluidic sealing is a zero-leakage dynamic seal with excellent sealing performance. However, when using magnetic fluid sealing devices to seal the shafts of non-precision products such as fans, valves, steam turbines, and pumps, it has been found that these devices are very prone to damage after a period of use. This is because the magnetic fluid sealing device needs to be installed on the shaft and fixed to a fixed structure on the outer casing. Since the magnetic fluid sealing device itself is a precision component, its installation and use require high precision in terms of the perpendicularity, coaxiality, and radial runout of the shaft and the fixed structure. If the required precision is not met during installation and manufacturing, the service life of the magnetic fluid sealing device will be significantly reduced, or even directly damaged. For non-precision products such as fans, valves, steam turbines, and pumps, the installation accuracy and machining accuracy of their parts often do not meet the accuracy requirements of magnetic fluid sealing devices. This makes it impossible to directly apply magnetic fluid sealing devices to products such as fans, valves, steam turbines, and pumps.

[0004] Therefore, how to apply magnetic fluid sealing devices to products such as fans, valves, steam turbines, and pumps, and how to ensure the service life of magnetic fluid sealing devices in these products, has become an urgent problem to be solved. Summary of the Invention

[0005] The object of the present invention is to provide a magnetic fluid seal shaft assembly to at least solve one of the problems mentioned in the background art.

[0006] The present invention also provides a shielded motor and a shielded pump comprising a shaft assembly including the above-described magnetohydrodynamic seal.

[0007] To achieve the above objectives, the first aspect of the present invention provides a shaft assembly for a magnetohydrodynamic (MHD) seal, comprising: a housing with a receiving cavity inside, and a fixing structure on the inner wall of the receiving cavity; a rotating shaft supported and installed within the receiving cavity; a MHD seal device located within the receiving cavity and sleeved on the rotating shaft, wherein the housing provides space for the MHD seal device to move with the rotating shaft and / or adjust its installation angle and position according to the installation state of the rotating shaft; and an elastic element that is airtightly connected to both the MHD seal device and the fixing structure. After the MHD seal device is elastically and airtightly connected to the fixing structure via the elastic element, the MHD seal device can move with the rotating shaft and / or adjust its installation angle and position according to the installation state of the rotating shaft, thereby avoiding conflict between the MHD seal device and the fixing structure. Preferably, the elastic element is made of a non-metallic material with certain elasticity, tensile strength, fatigue strength, etc., to meet the operating conditions.

[0008] Furthermore, an external air-blocking cavity is provided inside the housing and below the magnetic fluid sealing device. After the bottom of the housing is sealed, that is, when the shaft assembly of the magnetic fluid seal is working, an air blockage can be formed in the external air-blocking cavity.

[0009] In the above technical solution, preferably, the shaft assembly of the magnetohydrodynamic seal is a vertical structure.

[0010] Furthermore, the shaft assembly of the magnetohydrodynamic seal has a vertical structure. Further, the housing includes a first outer shell and a second outer shell that are sealed together. A shaft through-hole is provided at the connection between the first and second outer shells. The shaft of the second outer shell extends from inside the first outer shell into the second outer shell and extends out from the bottom of the second outer shell. The magnetohydrodynamic seal device is installed at the shaft through-hole via an elastic element to seal the shaft through-hole. An external air-blocking cavity is provided inside the second outer shell, below the magnetohydrodynamic seal device. After the bottom of the second outer shell is sealed, an air-blocking cavity can be formed within the external air-blocking cavity. Further, the gas required to form the air-blocking cavity is natural air within the second outer shell of the external air-blocking cavity, or the shaft assembly of the magnetohydrodynamic seal also includes an air inlet channel. One end of the air inlet channel communicates with the second outer shell of the external air-blocking cavity, and the other end communicates with a gas source. The gas required to form the air-blocking cavity includes natural air within the second outer shell of the external air-blocking cavity and the gas input through the air inlet channel.

[0011] Furthermore, the shaft assembly of the magnetohydrodynamic seal also includes a bearing housing assembly for supporting the mounting shaft. The bearing housing assembly is installed within the housing and located above or below the magnetohydrodynamic seal device. The lower boundary of the formed airlock is located below both the magnetohydrodynamic seal device and the bearing housing assembly.

[0012] Furthermore, the lower end of the magnetic fluid sealing device is elastically connected to the fixed structure via an elastic element, or the upper end of the magnetic fluid sealing device is elastically connected to the fixed structure via an elastic element.

[0013] Furthermore, the shaft assembly of the magnetohydrodynamic seal also includes a waterproof protection device, installed on the shaft, located near the bottom of the housing, and situated below the magnetohydrodynamic seal device and the bearing housing assembly. This waterproof protection device provides initial protection against liquids such as water below the shaft, preventing them from directly impacting the magnetohydrodynamic seal device.

[0014] Preferably, the waterproof protection device includes: a water-blocking device, installed on the rotating shaft and located at the opening at the bottom of the housing; and a water-pressing sleeve, installed on the rotating shaft and located on the side of the water-blocking device away from the magnetic fluid sealing device, with water-pressing threads provided on the outer wall of the water-pressing sleeve.

[0015] In the above technical solution, preferably, the fixing structure is disposed on the inner wall of the housing, or the fixing structure is installed on one end structure of the housing. Specifically, the fixing structure may be a boss disposed on the inner wall of the housing or a cylindrical structure installed on one end structure of the housing. When the housing includes an axially detachable and sealed first outer shell and a second outer shell, the fixing structure is preferably disposed at the connection between the first outer shell and the second outer shell.

[0016] In the above technical solution, preferably, a radial gap is provided between the magnetic fluid sealing device and the fixed structure, and an axial gap is provided between the two ends of the housing and the magnetic fluid sealing device.

[0017] In the above technical solution, preferably, the elastic element is an elastic connecting cylinder, which includes a sleeve part and an installation part. The sleeve part is sleeved and installed on the magnetic fluid sealing device, and the installation part is disposed on the elastic sleeve and sealed and fixedly connected to the fixed structure. The sleeve part and the installation part are an integral structure, and a radial distance is provided between the sleeve part and the fixed structure. An axial distance is provided between the two ends of the housing and the magnetic fluid sealing device.

[0018] Preferably, the sleeve portion and the mounting portion are made of a material that can meet the preset strength and elasticity requirements. The mounting portion is an annular retaining ring disposed on the outer side wall of the sleeve portion along the circumferential direction.

[0019] In one specific embodiment, the annular retaining ring is located in the middle of the sleeve portion and is connected to the fixing structure by screws. Both ends of the sleeve portion are fixedly fitted onto the magnetic fluid sealing device by at least two clamping members.

[0020] In another specific embodiment, an annular retaining ring is located at one end of the sleeve portion and connected to the fixing structure by screws. At the other end of the sleeve portion, a bottom mounting portion protrudes inward from the inner wall of the sleeve portion. The bottom mounting portion is fixedly mounted to the end face of the magnetic fluid sealing device by screws. The annular retaining ring, the sleeve portion, and the bottom mounting portion are an integral structure, and the bottom mounting portion has a through hole for the rotating shaft to pass through. Furthermore, a buffer pad is provided between the end of the magnetic fluid sealing device away from the bottom mounting portion and the housing. This buffer pad allows space for axial movement of the magnetic fluid sealing device.

[0021] In a preferred embodiment, the magnetohydrodynamic sealing device is provided with at least one mating structure that is installed in conjunction with a fixed structure. The elastic element includes a first elastic ring disposed between the at least one mating structure and the fixed structure and / or a second elastic ring located on the side of the mating structure away from the fixed structure. The at least one fixed structure, the mating structure, the first elastic ring and / or the second elastic ring are fixed by fasteners. After the at least one fixed structure, the mating structure, the first elastic ring and / or the second elastic ring are fixed by fasteners, the at least one mating structure and the fixed structure are elastically connected, so that the magnetohydrodynamic sealing device can follow the rotation of the shaft and / or adjust the installation angle and position according to the installation state of the shaft, so that the magnetohydrodynamic sealing device can jump relative to the fixed structure along the axial direction of the shaft or tilt relative to the shaft.

[0022] The preferred mating structure is a flange structure, which can be an annular structure arranged along the circumferential direction of the magnetic fluid sealing device. The annular structure has multiple mounting holes. Alternatively, there can be multiple mating structures spaced apart along the circumferential direction of the magnetic fluid sealing device. All mating structures can be protrusions or mounting plates with mounting holes. The first and / or second elastic rings can be rubber rings or silicone rings, etc., or other compressible structures. The fasteners are preferably bolts or screws. During installation, the first and / or second elastic rings need to be pre-compressed using the fasteners. It is also necessary to ensure that after pre-compression, the first and / or second elastic rings still have sufficient deformation to maintain an elastic connection between the fixed structure and the mating structure. This allows the mating structure to move the entire magnetic fluid sealing device.

[0023] Furthermore, the shaft assembly of the magnetic fluid seal also includes: an inner gas plug cover, which is installed inside the outer gas plug cavity and is airtightly connected to the lower end of the magnetic fluid seal device in the axial direction. The inner gas plug cover is arranged around the outside of the part of the rotating shaft that extends into the outer gas plug cavity. An inner gas plug cavity is formed between the inner gas plug cover and the rotating shaft. After the bottom of the housing is sealed, that is, when the shaft assembly of the magnetic fluid seal is working, a gas plug can be formed in the inner gas plug cavity.

[0024] Furthermore, the upper end of the internal air plug is provided with a mounting plate, and the elastic element is clamped between the mounting plate and the lower end of the magnetic fluid sealing device, or the elastic element is clamped between the mounting plate and the fixed structure.

[0025] More preferably, the magnetic fluid sealing device includes a magnetic fluid sealing element and a fixed sleeve disposed outside the magnetic fluid sealing element. The flange structure and other mating structures are disposed around the fixed sleeve, and preferably are an integral structure with the fixed sleeve.

[0026] In another embodiment, a radial gap is provided between the fixed structure and the magnetic fluid sealing device, the elastic element is an elastic connecting ring, part of the elastic connecting ring is fixedly installed on the first end of the magnetic fluid sealing device, and the other part of the elastic connecting ring is fixedly installed on the fixed structure; a positioning structure is provided inside the housing corresponding to the second end of the magnetic fluid sealing device, and a buffer pad is provided between the positioning structure and the second end of the magnetic fluid sealing device.

[0027] Furthermore, the fixing structure is a cylindrical structure installed on the inner wall of the housing and arranged axially. The magnetic fluid sealing device is located inside the cylindrical structure and is provided with a radial distance between it and the cylindrical structure. The inner part of the elastic connecting ring is fixedly installed on the end face of the first end of the magnetic fluid sealing device, and the outer part of the elastic connecting ring is fixedly installed on the end face of the cylindrical structure corresponding to the end face of the first end of the magnetic fluid sealing device.

[0028] Furthermore, the elastic connecting ring, the magnetic fluid sealing device, the cylindrical structure, and the buffer pad form a sealed first cooling chamber. The shaft assembly of the magnetic fluid seal also includes a first cooling medium channel with one end sealed and connected to the first cooling chamber, and the other end of the first cooling medium channel is connected to the outside of the housing.

[0029] In any of the above technical solutions, preferably, the magnetic fluid sealing device includes: a fixed sleeve; a magnetic fluid seal installed inside the fixed sleeve, and a sealed second cooling chamber is provided between the inner side wall of the fixed sleeve and the outer side wall of the magnetic fluid seal; a second cooling medium channel, one end of the second cooling medium channel communicating with the second cooling chamber, and the other end of the second cooling medium channel communicating with the outside of the housing; wherein, an elastic element is sealed and installed on the fixed sleeve and sealed and connected to the fixed structure.

[0030] More preferably, the retaining sleeve is made of metal.

[0031] More preferably, a limiting structure is provided on the inner sidewall of one end of the fixed sleeve, and a detachable blocking member is installed at the other end of the fixed sleeve. The magnetohydrodynamic seal is limited and installed between the blocking member and the limiting structure. Wherein, when the elastic member is an elastic connecting ring, the blocking member is preferably a part of the elastic connecting ring.

[0032] According to the magnetic fluid seal shaft assembly provided by the present invention, during installation, space is reserved within the housing for the magnetic fluid seal device and the rotating shaft to move together and / or for the magnetic fluid seal device to self-adjust its installation angle and position. Simultaneously, the magnetic fluid seal device and the housing's fixing structure are connected by an elastic element. This allows the magnetic fluid seal device to move with the rotating shaft when it experiences radial or axial runout, without being restricted by the housing. Furthermore, the elastic connection between the magnetic fluid seal device and the housing enables the magnetic fluid seal device to automatically correct its installation angle based on the elastic deformation of the elastic element when there is a significant difference in perpendicularity or coaxiality between the rotating shaft and the fixing structure. This avoids the phenomenon of tilted installation when there is a large difference in perpendicularity or coaxiality between the rotating shaft and the fixing structure, thus achieving self-angle correction of the magnetic fluid seal device after tilted installation. In summary, this application, by reserving movement space for the magnetic fluid sealing device and enabling an elastic connection between the magnetic fluid sealing device and the housing, allows the magnetic fluid sealing device to dynamically adjust its installation angle and / or position according to actual conditions. This compensates for the effects of insufficient precision in the perpendicularity, coaxiality, and radial runout of the shaft and the fixed structure. This avoids interference from the fixed structure on the housing during the installation and operation of the magnetic fluid seal shaft assembly, reduces fatigue damage during operation, and eliminates additional radial forces, external torque, and static indeterminate forces on the bearings within the magnetic fluid seal during operation. This allows the magnetic fluid sealing device to be used in products with low precision requirements, such as pumps, ensuring its service life and reducing its failure rate. Ultimately, this ensures the sealing effect of products such as fans, valves, steam turbines, and pumps.

[0033] Furthermore, when the magnetic fluid seal shaft assembly of this application is used in vertical products such as vertical pumps, the use of the magnetic fluid seal device provides a fundamental guarantee against the formation of airlocks in the lower end of the housing. This is because the absolute airtightness of the magnetic fluid seal within a certain pressure range is fundamental to the existence of airlock cavities.

[0034] Furthermore, the magnetohydrodynamic sealing device includes an inner sleeve and an outer sleeve, the inner sleeve being fixed to the rotating shaft, and the outer sleeve being connected to the fixed structure via an elastic element.

[0035] A second aspect of the present invention provides a shielded motor, including a motor configuration assembly and a magnetohydrodynamically sealed shaft assembly provided in any embodiment of the first aspect, wherein the shaft of the magnetohydrodynamically sealed shaft assembly serves as the motor shaft of the shielded motor.

[0036] Furthermore, the housing includes a first outer shell and a second outer shell that are sealed together. The first outer shell is a motor housing, and the motor assembly is disposed within the first outer shell. The output end of the motor shaft extends from the motor housing and inserts into the second outer shell. The magnetohydrodynamic sealing device of the shaft assembly is installed within either the motor housing or the second outer shell. Specifically,

[0037] A shaft passage hole is provided at the connection between the first and second housings. The motor shaft extends from the motor housing into the second housing through the shaft passage hole. A shaft inlet / outlet hole is provided on the end of the second housing away from the first housing. A magnetic fluid sealing device is installed at the shaft passage hole via an elastic element to seal the shaft passage hole. A bearing assembly supporting the motor shaft is also installed at the shaft passage hole, above or below the magnetic fluid sealing device. The motor configuration assembly is located inside the first housing to realize the motor function. Specifically, the magnetic fluid sealing device can be installed inside the first housing, which serves as the motor housing, and placed near the shaft outlet of the motor housing. Then, an elastic ring can be fixed to the outer end of the motor housing to elastically connect the magnetic fluid sealing device to the motor housing.

[0038] Furthermore, the shielded motor is a vertical motor, and after the end of the second housing away from the motor housing (first housing) is sealed and connected to the load device, an airlock can be formed inside it.

[0039] The shielded motor provided by the present invention includes a motor configuration assembly and a magnetohydrodynamic (MHD) sealed shaft assembly as provided in any embodiment of the first aspect. During installation, the motor housing of the motor body can be sealed and connected to a second housing, and the output end of the motor shaft can be inserted into the second housing through a shaft through-hole at the connection between the motor body and the second housing. This structure, which sets the shielded motor to a structure similar to the MHD sealed shaft assembly provided in any embodiment of the first aspect, enables axial surface sealing and shielding of the motor shaft. Therefore, it possesses the beneficial effects of the MHD sealed shaft assembly provided in any embodiment of the first aspect, which will not be elaborated further here.

[0040] Further, preferably, the magnetic fluid seal shaft assembly also includes an air inlet channel communicating with the second housing and introducing gas into the second housing, allowing an airlock to form inside the second housing. This airlock prevents water from entering the motor through the shaft inlet / outlet holes when the shielded motor is connected to the pump. The gas required to form the airlock can be either natural air inside the second housing or gas introduced into the second housing via the air inlet channel. To facilitate the input of external gas, an air inlet channel can be provided on the second housing, with one end connected to the lower end of the second housing and the other end connected to a gas source. A third aspect of the invention provides a shielded pump, including a pump body and a shielded motor connected to each other. The pump body includes the magnetic fluid seal shaft assembly provided in any embodiment of the first aspect, or the shielded motor is the shielded motor provided in any embodiment of the second aspect. Of course, the shielded motor can also be other motors with shielding functions, or a conventional motor.

[0041] The canned pump provided according to an embodiment of the present invention includes a pump body and a canned motor connected to each other. When the pump body includes the magnetic fluid seal shaft assembly provided in any embodiment of the first aspect, the pump can be a vertical pump such as a long-shaft submersible pump or a long-shaft deep well pump. When the canned motor is the canned motor provided in any embodiment of the second aspect, the pump body can be directly and airtightly installed on the end of the second housing away from the motor body, and the motor shaft is connected to the rotating part of the pump body, so that the rotating part of the pump body can be driven to operate through the motor shaft. At the same time, an air inlet channel for inputting gas into the second housing can be provided on the second housing, and the outer end of the air inlet channel is connected to a gas source. At this time, the lower end of the second housing is water-sealed by the pump body. Therefore, when gas is input into the second housing through the gas source, an airlock can be formed in the second housing. In this way, when the canned motor is connected to the pump body, water in the pump body can be prevented from entering the motor through the shaft inlet and outlet holes, thus ensuring that the magnetic fluid seal device does not come into contact with water, thereby achieving waterproof protection for the magnetic fluid seal device.

[0042] Furthermore, the shaft assembly of the magnetic fluid seal in this application is used in a motor / shielded motor, and the motor / shielded motor is an airtight motor with an independent fan. The airtight motor's interior can form an airlock shield. That is, the motor interior can be filled with natural air or an external air source (nitrogen, air, etc.). If the magnetic fluid seal fails, the liquid level rises, and the gas in the external and internal airlock cavities enters the upper motor cavity through the failed magnetic fluid seal. Simultaneously, the medium also rises, flowing into the air cavity surrounding the magnetic fluid. As the liquid level rises, the gas in the motor cavity is continuously compressed until the gas pressure inside the motor cavity equals the medium pressure, forming an equilibrium and thus an airlock, preventing the liquid level from rising further. The airtight motor's interior collects the gas from the airlock cavity and part or all of the gas from the cavities surrounding the magnetic fluid seal, resulting in a significant increase in gas pressure within the motor cavity. Due to the spatial design, the liquid level can be balanced at the bottom of the motor coil. Therefore, even if the magnetic fluid seal fails, the medium cannot rise to the motor coil outlet, ensuring the motor is not damaged.

[0043] It should be understood that the content described in this disclosure is not intended to limit the key or essential features of the embodiments of the present invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0044] Figure 1 A schematic diagram of the structure of a shielded pump provided for an embodiment of the present invention;

[0045] Figure 2 for Figure 1 A magnified schematic diagram of the partial structure at point A in the middle;

[0046] Figure 3 A schematic diagram of the structure of a shielded pump provided for another embodiment of the present invention;

[0047] Figure 4 A schematic diagram of the structure of a shielded pump provided for the third embodiment of the present invention;

[0048] Figure 5 This is a schematic diagram of the structure of a shielded pump provided in the fourth embodiment of the present invention;

[0049] Figure 6 for Figure 5 A magnified schematic diagram of the local structure at point B;

[0050] Figure 7 A schematic diagram of the structure of a shielded pump provided in the fifth embodiment of the present invention;

[0051] Figure 8 A schematic diagram of the structure of a shielded pump provided in the sixth embodiment of the present invention;

[0052] Figure 9 for Figure 8 A magnified schematic diagram of the local structure at point C;

[0053] Figure 10 A partial structural schematic diagram of a shielded pump provided in the seventh embodiment of the present invention;

[0054] Figure 11 A partial structural schematic diagram of a shielded pump provided in the eighth embodiment of the present invention;

[0055] Figure 12 A schematic diagram of the structure of a shielded pump provided in the ninth embodiment of the present invention;

[0056] Figure 13 This is a schematic diagram of the structure of a shielded pump provided in the tenth embodiment of the present invention;

[0057] Figure 14 A partial structural schematic diagram of a canned pump provided in one of the eleven embodiments of the present invention;

[0058] Figure 15 This is a partial structural schematic diagram of a shielded pump provided in twelve embodiments of the present invention.

[0059] in, Figures 1 to 15 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0060] 1. Housing, 12. Receiving cavity, 14. Fixing structure, 16. Positioning structure, 18. External air plugging cavity, 2. Rotating shaft, 3. Magnetorheological fluid sealing device, 30. Fitting structure, 32. Fixing sleeve, 32. Limiting structure, 34. Magnetorheological fluid sealing element, 36. Second cooling cavity, 38. Second cooling medium channel, 39. Blocking element, 4. Elastic connecting cylinder, 42. Sleeve part, 44. Mounting part, 46. Bottom mounting part, 5. Internal air plug cover, 6. Elastic connecting ring, 72. First elastic ring, 74. Second elastic ring, 8. Air inlet channel, 90. Buffer pad, 92. First cooling cavity, 94. First cooling medium channel, 96. Water pressure sleeve, 98. Water blocking device. Detailed Implementation

[0061] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0062] The following reference Figures 1 to 15This application describes a magnetic fluid seal shaft assembly provided by an embodiment of the present invention. The magnetic fluid seal shaft assembly provided in this application can be applied to non-precision products requiring sealing, such as pumps, canned motors, canned pumps, fans, valves, steam turbines, and nuclear submarines. This application primarily uses the application of the magnetic fluid seal shaft assembly in canned motors and canned pumps as examples to introduce the magnetic fluid seal shaft assembly.

[0063] like Figures 1 to 15 As shown, an embodiment of the first aspect of the present invention provides a magnetic fluid seal shaft assembly, including a housing 1, a rotating shaft 2, a magnetic fluid seal device 3, and an elastic element, wherein the elastic element may specifically be... Figure 5 , Figure 6 , Figure 10 , Figure 12 The elastic connecting cylinder 4 or Figures 1 to 4 as well as Figures 7 to 9 , Figure 11 , Figure 13 and Figure 14 The elastic connecting ring 6 or Figure 15 The first elastic coil 72 and the second elastic coil 74 are in the middle. Specifically:

[0064] The housing 1 is provided with a receiving cavity 12, and a fixing structure 14 is provided on the inner wall of the receiving cavity 12. The housing 1 can be specifically formed by connecting a first outer shell and a second outer shell, or it can be an integral structure. The first outer shell and the second outer shell are preferably arranged vertically, but they can also be arranged front-back or left-right.

[0065] The rotating shaft 2 is supported and installed within the receiving cavity 12. The magnetic fluid sealing device 3 is located within the receiving cavity 12 and is sleeved on the rotating shaft 2. The housing 1 is provided with space for the magnetic fluid sealing device 3 to move with the rotating shaft 2 and / or to adjust its installation angle and position according to the installation state of the rotating shaft 2. An elastic element is airtightly installed on the magnetic fluid sealing device 3 and airtightly connected to the fixed structure 14. The elastic element allows for an elastic and airtight connection between the magnetic fluid sealing device 3 and the fixed structure 14, enabling the magnetic fluid sealing device 3 to move with the rotating shaft 2 and / or to adjust its installation angle and position according to the installation state of the rotating shaft 2. The elastic element is preferably made of a material with fabric or reinforcing cloth that meets the preset strength and elasticity requirements. Of course, the elastic element can also be made of a material without fabric or reinforcing cloth.

[0066] The magnetic fluid seal shaft assembly provided by the present invention includes a housing 1, a rotating shaft 2, a magnetic fluid seal device 3, and an elastic element. During installation, space is reserved within the housing 1 for the magnetic fluid seal device 3 and the rotating shaft 2 to move together and / or for the magnetic fluid seal device 3 to self-adjust its installation angle and position. For example, space is reserved for the magnetic fluid seal device 3 to move radially or axially, or for adjusting the magnetic fluid seal device 3 from an inclined installation state to a vertical installation state. Simultaneously, the magnetic fluid seal device 3 and the fixing structure 14 of the housing 1 are connected by an elastic element, thus achieving an elastic connection between the magnetic fluid seal device 3 and the housing 1. This allows the magnetic fluid seal device 3 to move along with the rotating shaft 2 when the rotating shaft 2 experiences radial or axial movement, without being restricted by the housing 1 and unable to move together with the rotating shaft 2. On the other hand, through the elastic connection between the magnetic fluid sealing device 3 and the housing 1, the magnetic fluid sealing device 3 can automatically correct its installation angle based on the elastic deformation of the elastic element when the perpendicularity and coaxiality of the rotating shaft 2 and the fixed structure 14 are significantly different. This avoids the phenomenon of tilted installation of the magnetic fluid sealing device 3 when the perpendicularity and coaxiality of the rotating shaft 2 and the fixed structure 14 are significantly different, thus realizing the self-angle correction of the magnetic fluid sealing device 3 after tilted installation. In summary, this application, by reserving movement space for the magnetic fluid sealing device 3 and elastically connecting the magnetic fluid sealing device 3 and the housing 1, enables the magnetic fluid sealing device 3 to dynamically adjust its installation angle and / or installation position according to actual conditions. This compensates for the insufficient precision of the shaft 2 and the fixed structure 14, such as perpendicularity, coaxiality, and radial runout of the shaft 2. This avoids interference from the fixed structure 14 on the housing 1 during the installation and operation of the magnetic fluid seal shaft assembly, reduces fatigue damage to the magnetic fluid sealing device 3 during operation, and eliminates additional radial force, external torque, and static indeterminate force on the bearings within the magnetic fluid sealing device 3 during operation. This allows the magnetic fluid sealing device 3 to be applied to products with low precision requirements, such as fans, valves, steam turbines, and pumps, and ensures its service life when applied to these products, reducing the failure rate.

[0067] Furthermore, such as Figures 1 to 14 As shown, an external air plugging cavity 18 is provided inside the housing 1 and below the magnetic fluid sealing device 3. When the shaft assembly of the magnetic fluid seal is working, an air plug can be formed in the external air plugging cavity 18.

[0068] In this embodiment, the magnetohydrodynamic sealing device 3 is a zero-leakage dynamic seal. On the one hand, it can dynamically seal the rotating shaft 2; on the other hand, it can also strictly seal the upper end of the external air-blocking cavity 18, thereby forming an airtight seal and allowing the upper end of the external air-blocking cavity 18 to seal the gas. The lower end of the external air-blocking cavity 18 can be airtightly connected to all rotating equipment such as water pumps that require pressure sealing. The internal cavity of the external air-blocking cavity 18 is completely sealed except for the shaft inlet and outlet, and is not connected to the inside of the housing 1. In this way, an independent air-blocking cavity can be formed around the output end of the shaft. In this structure, during operation, the upper part of the external gas plugging cavity 18 is sealed by the magnetohydrodynamic sealing device 3, thus achieving airtightness. The lower end of the external gas plugging cavity 18 is sealed by liquid, resulting in a highly airtight structure. Therefore, when liquid from outside the external gas plugging cavity 18 enters it, the gas inside the external gas plugging cavity 18 cannot leak. This allows the external liquid to gradually compress the gas inside the external gas plugging cavity 18 until the gas pressure equals the liquid pressure. Afterwards, the liquid level in the external air-blocking cavity 18 will not rise further. Once the liquid level stops rising, the magnetic fluid sealing device 3 will always be separated from the liquid by compressed gas. This creates a seal on the liquid through the compressed gas in the external air-blocking cavity 18. This blocking effect of gas on the liquid is what this application refers to as airlocking. Thus, the airlock in the external air-blocking cavity 18 prevents the magnetic fluid sealing device 3 from contacting the liquid, ensuring the working performance of the magnetic fluid sealing device 3. This allows the magnetic fluid sealing shaft assembly to be used for sealing and shielding the drive shaft of pumps, etc. Simultaneously, this vertical shielding device achieves highly efficient and leak-free sealing and shielding performance through the magnetic fluid sealing device 3 and the external air-blocking cavity 18, achieving true zero leakage.

[0069] Furthermore, such as Figures 1 to 6 As shown, the shielded pump includes a motor, a pump, and a housing 1 installed between the electrodes and the pump. The housing 1 is airtightly installed between the motor housing and the pump housing. The motor shaft extends from the motor housing and passes through the housing 1, then is driven to connect with the rotating parts of the pump. The lower end of the magnetohydrodynamic sealing device 1 is elastically and airtightly connected to the fixed structure 14 inside the housing 1 via an elastic element. The elastic element is an elastic connecting ring 6, and the inner edge of the elastic connecting ring 6 is fixed to the lower end of the magnetohydrodynamic sealing device 1 by screws. The outer edge of the elastic connecting ring 6 is fixed to the fixed structure 14 by screws. A preset space is formed between the housing 1, the fixed structure 14, the elastic element, and the lower end of the magnetohydrodynamic sealing device. This preset space is an external air-blocking cavity 18 capable of forming an airlock. The elastic connecting ring 6 can be fixed to the upper surface of the fixed structure 14. At this time, screws or bolts connect the fixed structure 14 and the elastic connecting ring 6 from above (e.g., Figure 2(As shown). Of course, the elastic connecting ring 6 can also be fixed to the lower surface of the fixing structure 14. In this case, screws or bolts connect the fixing structure 14 and the elastic connecting ring 6 from below (as shown). Figure 3 (As shown).

[0070] Furthermore, such as Figure 4 As shown, a barrier structure is also installed below the magnetohydrodynamic sealing device 3 inside the housing 1, and the external air plugging cavity 18 is formed by the barrier structure and the lower end of the housing.

[0071] Furthermore, such as Figure 7 , Figure 10 , Figure 11 and Figure 14 As shown, the shaft assembly of the magnetic fluid seal also includes: an inner air plug 5, which is installed in the outer air plug cavity 18 and is airtightly connected to the lower end of the magnetic fluid seal device 3 in the axial direction. The inner air plug 5 is arranged around the outside of the part of the rotating shaft 2 that extends into the outer air plug cavity 18. An inner air plug cavity is formed between the inner air plug 5 and the rotating shaft 2. An air plug can be formed in the inner air plug cavity when the shaft assembly of the magnetic fluid seal is working.

[0072] In this embodiment, the inner gas plug 5 is axially and airtightly connected to the lower end of the magnetic fluid sealing device 3, allowing the upper end of the inner gas plug 5 to be sealed by the magnetic fluid sealing device 3 to form an airtight seal. This ensures that the inner gas plug 5, once sealed by liquid at its lower end, can lock in the gas. Thus, when liquid from outside the inner gas plug 5 enters the inner gas plug 5, the gas inside cannot leak. The external liquid can only gradually compress the gas inside the inner gas plug 5, forming an airlock within it. This airlock further seals the magnetic fluid sealing device 3 axially within the outer gas plug cavity 18. This prevents liquid or volatile gas from contacting the magnetic fluid sealing device 3 after the shaft is connected to the fluid pumping device, thus protecting the magnetic fluid sealing device 3 from the liquid outside the inner gas plug 5. This structure combines the magnetic fluid sealing device 3, the outer gas plugging cavity 18, and the inner gas plugging cover 5. The combined structure not only has the completely leak-free sealing effect of the magnetic fluid sealing device 3, but also, during sealing and shielding, the outer gas plugging cavity 18 is made into a larger gas plugging cavity by sealing it with the external liquid. At the same time, the lower end of the inner gas plugging cover 5 is sealed by sealing it with the external liquid, thus achieving the sealing of the sealed cavity formed by the internal space of the magnetic fluid sealing device 3 and the internal space of the inner gas plugging cover 5. In this way, the compression of the gas in the sealed cavity by the external liquid can make the sealed cavity form a smaller gas plugging cavity. The gas plugging of the inner and outer double-layer gas plugging cavities ensures that the magnetic fluid sealing device 3 will not come into contact with the liquid during use.

[0073] Furthermore, the internal air plug 5 is trumpet-shaped or cylindrical.

[0074] Furthermore, such as with Figure 11 and Figure 14 As shown, the upper end of the internal air plug 5 is provided with a mounting plate. The elastic element is clamped and installed between the mounting plate and the lower end of the magnetic fluid sealing device 3, or the elastic element is clamped and installed between the mounting plate and the fixed structure. That is, the internal air plug 5 can be directly installed onto the fixed structure through the mounting plate. In this case, the elastic element can be clamped and installed through the mounting plate and the fixed structure. Of course, as... Figure 10 As shown, the mounting plate can also be directly installed at the lower end of the magnetic fluid sealing device 3, or it can be fixedly installed at the lower end of the magnetic fluid sealing device 3 together with the elastic element.

[0075] In the above embodiments, preferably, as follows: Figure 5 , Figure 7 , Figure 9 and Figure 11 As shown, the shaft assembly of the magnetic fluid seal has a vertical structure. The housing includes a first outer shell and a second outer shell that are sealed to each other. A shaft through hole is provided at the connection of the upper second outer shell, and a shaft inlet / outlet hole is provided at the bottom of the second outer shell. The rotating shaft extends from the first outer shell into the second outer shell through the shaft through hole and extends out through the shaft inlet / outlet hole. The magnetic fluid seal device 3 is installed at the shaft through hole through an elastic element to seal the shaft through hole. After the shaft inlet / outlet hole of the second outer shell is sealed, an air plug can be formed in the lower end of the second outer shell, and the lower boundary of the air plug is located below the magnetic fluid seal device. The gas required to form the air plug is the natural air in the second outer shell. Alternatively, the shaft assembly of the magnetic fluid seal also includes an air inlet channel 8. One end of the air inlet channel 8 is connected to the lower end of the second outer shell, and the other end of the air inlet channel 8 is connected to an air source. The gas required to form the air plug includes the natural air in the second outer shell and the gas input through the air inlet channel 8.

[0076] In this embodiment, when the magnetic fluid seal shaft assembly is used in structures such as pumps, each part of the second housing can be strictly sealed to form an airlock at the lower end of the second housing. During operation, this airlock creates a sealed barrier against liquids, preventing external liquids from entering the second housing and thus providing waterproof protection for the magnetic fluid seal device 3. For example, when this magnetic fluid seal shaft assembly is used in a vertical canned motor pump, the first housing serves as the motor housing, while the second housing seals the connection between the motor housing and the pump. The rotating shaft 2 serves as the motor shaft, extending out of the shaft inlet / outlet hole and connecting to the rotating part of the pump body. In this structure, after the vertical canned motor pump is installed, the lower end of the second housing is water-sealed by the pump body. Therefore, natural air inside the second housing and external air can form an airlock below the magnetic fluid seal device 3, preventing water from the pump body from entering the motor through the shaft inlet / outlet hole. This ensures that the magnetic fluid seal device 3 does not come into contact with water, thus achieving waterproof protection for the magnetic fluid seal device 3. By providing an air intake channel on the second housing, external air can be easily introduced into the second housing, thereby increasing the pressure of the airlock formed. Of course, if the airlock pressure formed by natural air meets the required operating conditions, the air intake channel 8 may not be provided.

[0077] More preferably, the shaft assembly of the magnetohydrodynamic seal further includes a bearing housing assembly for supporting the rotating shaft 2, and the magnetohydrodynamic seal device 3 can be installed on either side of the bearing housing assembly axially via an elastic element. Figure 1 , Figure 4 , Figure 5 In the provided shielded pump, the magnetohydrodynamic seal device 3 is mounted below the bearing body assembly via an elastic element. Figure 15 In this configuration, the magnetohydrodynamic sealing device 3 is mounted above the bearing body assembly via an elastic element. In short, the specific installation positions of the magnetohydrodynamic sealing device 3 and the bearing body assembly can be reasonably set according to structural requirements, and are not specifically limited here.

[0078] The first and second housings are preferably separate structures, but they can also be integrated. In one specific embodiment, the magnetohydrodynamic sealed shaft assembly is used for a motor. In this case, the first housing is the motor housing, and the second housing is sealed between the motor housing and the load (e.g., a pump body). The motor is preferably a water-cooled, shielded motor. Figure 14 and Figure 15As shown, when the magnetic fluid sealing device 3 is installed inside the motor housing of the motor body, the lower bearing assembly of the motor can be located either above or below the magnetic fluid sealing device 3. At the same time, a magnetic shielding device is also provided on the side of the magnetic fluid sealing device 3 away from the lower bearing assembly. The magnetic shielding device is installed on the motor shaft. Specifically, the magnetic shielding device can be a magnetic shielding cover that can cover the magnetic fluid sealing device 3, or a relatively simple magnetic shielding plate.

[0079] Preferably, such as Figure 1 , Figure 5 and Figure 6 , Figure 14 As shown, the fixing structure 14 is disposed on the inner wall of the housing 1. For example, the fixing structure 14 can be a boss disposed on the inner wall of the housing 1. In this case, the magnetic fluid sealing device 3 is elastically connected to the inner wall of the housing 1 through an elastic element. This structure is suitable for installing the magnetic fluid sealing device 3 in the middle of the housing 1. In another embodiment, as shown... Figure 4 , Figures 7 to 10 to Figure 12 as well as Figure 15 As shown, the fixing structure 14 is installed on one end structure (such as an end cap) of the housing 1. For example, the fixing structure 14 can be a cylindrical structure installed on the end cap. In this case, the magnetic fluid sealing device 3 is directly elastically connected to the end structure such as the end cap through an elastic element. This structure is suitable for installing the magnetic fluid sealing device 3 to the end of the housing 1.

[0080] In the above embodiments, a radial gap is provided between the magnetic fluid sealing device 3 and the fixed structure 14, and an axial gap is provided between the housing 1 and the two ends of the magnetic fluid sealing device 3. This allows the magnetic fluid sealing device 3 to move radially or axially together with the rotating shaft 2 during installation and use, and also to tilt and rotate along the rotating shaft 2 to correct and adjust its installation angle and position. This avoids damage to the magnetic fluid sealing device 3 due to insufficient installation and machining accuracy of the housing 1 or the rotating shaft 2.

[0081] In the above embodiments, preferably, as follows: Figure 5 , Figure 6 , Figure 10 , Figure 12 As shown, the elastic element is an elastic connecting cylinder 4, which includes a sleeve portion 42 and a mounting portion 44. The sleeve portion 42 is sleeved and mounted on the magnetic fluid sealing device 3, and the mounting portion 44 is disposed on the sleeve portion 42 and is sealed and fixedly connected to the fixing structure 14. The sleeve portion 42 and the mounting portion 44 are integral structures. A radial distance is provided between the sleeve portion 42 and the fixing structure 14, and an axial distance is provided between the two ends of the housing 1 and the magnetic fluid sealing device 3.

[0082] In this embodiment, the elastic connecting cylinder 4 is fitted onto the magnetic fluid sealing device 3 via the sleeve portion 42, and then the elastic connection between it and the fixed structure 14 is achieved through the mounting portion 44. During installation, the elastic connecting cylinder 4 and the magnetic fluid sealing device 3 can be assembled into a single component, and then the entire component can be installed at the fixed position of the rotating shaft 2. Finally, the mounting portion 44 of the elastic connecting cylinder 4 is fixedly connected to the fixed structure 14 using screws or similar means.

[0083] Furthermore, the mounting portion 44 is an annular retaining ring disposed on the outer side wall of the sleeve portion 42 along the circumferential direction. In one specific embodiment, as shown... Figure 5 and Figure 6 As shown, the annular retaining ring is located in the middle of the sleeve portion 42 and is connected to the fixing structure 14 by screws. Both ends of the sleeve portion 42 are fixedly fitted onto the magnetic fluid sealing device 3 by at least two clamping members. In another specific embodiment, as... Figure 10 and Figure 12 As shown, an annular retaining ring is located at one end of the sleeve portion 42 and is connected to the fixing structure 14 by screws. At the other end of the sleeve portion 42, a bottom mounting portion 46 is provided, which fits against one end face of the magnetic fluid sealing device 3. The bottom mounting portion 46 is fixedly mounted to the end face of the magnetic fluid sealing device 3 by screws. The annular retaining ring, sleeve portion 42, and bottom mounting portion 46 are an integral structure. The bottom mounting portion 46 has a through hole for the rotating shaft 2 to pass through. Furthermore, a buffer pad 90 is provided between the end of the magnetic fluid sealing device 3 away from the bottom mounting portion 46 and the housing 1. This buffer pad 90 provides space for the magnetic fluid sealing device 3 to move axially or tilt relative to the rotating shaft 2.

[0084] In yet another embodiment, such as Figures 1 to 4 as well as Figures 7 to 9 , Figure 11 and Figure 14 As shown, a radial gap is provided between the fixed structure 14 and the magnetic fluid sealing device 3. The elastic element is an elastic connecting ring 6. Part of the elastic connecting ring 6 is fixedly installed on the end face of the first end of the magnetic fluid sealing device 3, and the other part of the elastic connecting ring 6 is fixedly installed on the fixed structure 14. Preferably, the elastic connecting ring 6 and the end of the magnetic fluid sealing device 3 can be fixed together by screws, and the elastic connecting ring 6 and the fixed structure 14 can also be fixed together by screws. When the magnetic fluid sealing device 3 has a structure including a fixed sleeve 32 and a magnetic fluid sealing element 34, the elastic connecting ring 6 extends to the end face of the magnetic fluid sealing element 34 to seal the magnetic fluid sealing element 34 inside the fixed sleeve 32.

[0085] Preferably, such as Figures 7 to 10As shown, the housing 1 is provided with a positioning structure 16 at the second end of the magnetic fluid sealing device 3, and a buffer pad 90 is provided between the positioning structure 16 and the second end of the magnetic fluid sealing device 3. The buffer pad 90 provides room for the axial runout of the magnetic fluid sealing device 3, and the buffer pad 90, together with the elastic connecting ring 6, can limit the two ends of the magnetic fluid sealing device 3.

[0086] Furthermore, such as Figures 7 to 9 and Figure 11 As shown, the fixing structure 14 is a cylindrical structure installed on the inner wall of the housing 1 and arranged axially. The magnetic fluid sealing device 3 is located inside the cylindrical structure and is provided with a radial distance between it and the cylindrical structure. The end face of the first end of the magnetic fluid sealing device 3 is flush with the end face of the corresponding cylindrical structure. The inner part of the elastic connecting ring 6 is fixedly installed on the end face of the first end of the magnetic fluid sealing device 3 by screws, and the outer part of the elastic connecting ring 6 is fixedly installed on the end face of the cylindrical structure corresponding to the end face of the first end of the magnetic fluid sealing device 3 by screws.

[0087] In one embodiment, such as Figures 1 to 6 As shown, the magnetic fluid sealing device 3 is a common structure without cooling function, for example, the magnetic fluid sealing device 3 is a structure without the fixed sleeve 32.

[0088] In another embodiment, preferably, as Figures 7 to 9 As shown, the elastic connecting ring 6, the magnetic fluid sealing device 3, the fixing structure 14 and the buffer pad 90 form a sealed first cooling chamber 92. The shaft assembly of the magnetic fluid seal also includes a first cooling medium channel 94 with one end sealed and connected to the first cooling chamber 92, and the other end of the first cooling medium channel 94 is connected to the outside of the housing 1.

[0089] In this embodiment, the magnetic fluid sealing device 3 can be cooled by supplying cooling medium into the first cooling chamber 92 through the first cooling medium channel 94, thus preventing the bearings in the magnetic fluid sealing device 3 from overheating during operation.

[0090] In a preferred embodiment, such as Figure 15As shown, the magnetic fluid sealing device 3 is provided with at least one mating structure 30 that is installed in conjunction with the fixed structure 14. The elastic element includes a first elastic ring 72 disposed between the at least one mating structure 30 and the fixed structure 14 and / or a second elastic ring 74 located on the side of the mating structure 30 away from the fixed structure 14. The at least one fixed structure 14, the mating structure 30, the first elastic ring 72 and / or the second elastic ring 74 are fixed by fasteners. After the at least one fixed structure 14, the mating structure 30, the first elastic ring 72 and / or the second elastic ring 74 are fixed by fasteners, the at least one mating structure 30 and the fixed structure 14 are elastically connected, so that the magnetic fluid sealing device 3 can jump relative to the fixed structure 14 in the axial direction of the rotating shaft or adjust its own installation angle and position according to the installation state of the rotating shaft. This allows the magnetic fluid sealing device 3 to dynamically adjust its own installation angle and / or installation position, avoiding mutual interference and conflict between the magnetic fluid sealing device 3 and the fixed structure 14. The mating structure 30 is preferably a flange structure. The mating structure 30 can be an annular structure arranged along the circumferential direction of the magnetic fluid sealing device 3, with multiple mounting holes on the annular structure. Alternatively, there can be multiple mating structures 30, spaced apart along the circumferential direction of the magnetic fluid sealing device 3. The shapes of the multiple mating structures 30 can all be protrusions or mounting plates with mounting holes. The first elastic ring 72 and / or the second elastic ring 74 can be rubber rings or silicone rings, etc. Of course, the first elastic ring 72 and / or the second elastic ring 74 can also be other structures capable of compression and deformation. The fasteners are preferably bolts or screws. During installation, the first elastic ring 72 and / or the second elastic ring 74 need to be pre-compressed by the fasteners to a certain extent. At the same time, it must be ensured that after the first elastic ring 72 and / or the second elastic ring 74 are pre-compressed by the fasteners, they still have sufficient deformation to maintain an elastic connection between the fixing structure 14 and the mating structure 30. This allows the mating structure 30 to move the entire magnetic fluid sealing device 3.

[0091] More preferably, the magnetic fluid sealing device 3 includes a magnetic fluid seal 34 and a fixed sleeve 32 disposed outside the magnetic fluid seal. The flange structure and other mating structures 30 are disposed around the fixed sleeve 32 and are preferably an integral structure with the fixed sleeve 32.

[0092] In yet another specific embodiment, such as Figure 12As shown, the structure of the magnetic fluid sealing device 3 includes a fixed sleeve 32, a magnetic fluid seal 34, and a second cooling medium channel 38. The magnetic fluid seal 34 is installed inside the fixed sleeve 32, and a sealed second cooling chamber 36 is provided between the inner side wall of the fixed sleeve 32 and the outer side wall of the magnetic fluid seal 34. One end of the second cooling medium channel 38 is connected to the second cooling chamber 36, and the other end of the second cooling medium channel 38 is connected to the outside of the housing 1. An elastic element is connected between the fixed sleeve 32 and the fixed structure 14, so that the fixed sleeve 32 and the fixed structure 14 are sealed and elastically connected.

[0093] In this embodiment, the magnetohydrodynamic sealing device 3 includes a fixed sleeve 32, a magnetohydrodynamic seal 34, and a second cooling medium channel 38 for conveying cooling medium. A sealed second cooling chamber 36 is formed between the fixed sleeve 32 and the magnetohydrodynamic seal 34. Cooling medium is supplied to the second cooling chamber 36 through the second cooling medium channel 38 to cool the magnetohydrodynamic sealing device 3, thus preventing overheating of the bearings during operation. In practical use, the outer end of the second cooling medium channel 38 can be connected to a cooling medium source (such as a water source).

[0094] Preferably, the cooling medium is water, so that the magnetic fluid sealing device 3 can be cooled by water cooling.

[0095] More preferably, the fixing sleeve 32 is made of metal, which can ensure the strength of the fixing sleeve 32 and enhance the heat dissipation efficiency of the fixing sleeve 32.

[0096] More preferably, such as Figure 12 As shown, a limiting structure 322 is provided on the inner side wall of one end of the fixed sleeve 32, and a detachable blocking member 39 is installed on the other end of the fixed sleeve 32. The magnetic fluid seal 34 is limited and installed between the blocking member 39 and the limiting structure 322.

[0097] In this embodiment, the limiting structure 322 and the blocking member 39 achieve the limiting installation of the magnetic fluid seal 34 within the fixed sleeve 32. During installation, the magnetic fluid seal 34 can be inserted into the fixed sleeve 32 from the end without the limiting structure 322, and the magnetic fluid seal 34 can be made to abut against the limiting structure 322. Then, the blocking member 39 can be installed by screws or other means to block the other end of the magnetic fluid seal 34. Wherein, when the elastic member is the elastic connecting ring 6, the blocking member 39 is preferably a part of the elastic connecting ring 6.

[0098] like Figures 1 to 14As shown, the second aspect of the present invention provides a shielded motor, including a motor configuration component for realizing the motor function and a magnetic fluid seal shaft assembly provided in any embodiment of the first aspect. The shaft of the magnetic fluid seal shaft assembly is a motor shaft. The housing includes a first outer shell and a second outer shell that are sealed to each other. A shaft through hole is provided at the connection between the first outer shell and the second outer shell. The first outer shell is a motor housing. The motor shaft extends from the motor housing into the second outer shell through the shaft through hole. A shaft inlet and outlet hole is provided on the end of the second outer shell away from the first outer shell. A magnetic fluid seal device is installed at the shaft through hole through an elastic element for sealing the shaft through hole. A bearing body assembly supporting the motor shaft is also installed at the shaft through hole, on the upper or lower side of the magnetic fluid seal device. After the end of the second outer shell away from the motor housing is sealed to the load device, an air lock can be formed inside it.

[0099] The shielded motor provided according to embodiments of the present invention includes a motor configuration assembly and a magnetohydrodynamic (MHD) sealed shaft assembly provided in any embodiment of the first aspect. During installation, a new second housing can be extended from the existing motor housing of the motor body, and the output end of the motor shaft is inserted into the second housing through a shaft through-hole at the connection between the motor body and the second housing. This structure can utilize the MHD sealed shaft assembly provided in any embodiment of the first aspect to provide axial surface sealing and shielding for the motor shaft, thus possessing the beneficial effects of the MHD sealed shaft assembly provided in any embodiment of the first aspect, which will not be elaborated further here.

[0100] Furthermore, the shielded motor of this application is an airtight motor, and the interior of the airtight motor can form an airlock shield. The shielded motor is equipped with an independent fan.

[0101] Furthermore, preferably, the magnetohydrodynamic seal shaft assembly also includes an air inlet channel communicating with the second housing and introducing gas into the second housing, wherein an airlock can be formed inside the second housing. This airlock prevents water from the pump from entering the motor through the shaft inlet / outlet holes when the shielded motor is connected to the pump.

[0102] Furthermore, preferably, the shielded motor also includes an air source that communicates with the air intake channel 8 and provides gas.

[0103] like Figures 1 to 14 As shown, a third aspect of the present invention provides a shielded pump, including a pump body and a shielded motor connected to each other, the pump body including a magnetohydrodynamic sealed shaft assembly provided in any embodiment of the first aspect. In another embodiment, a third aspect of the present invention provides a shielded pump including a shielded motor provided in any embodiment of the second aspect.

[0104] Among them, in this application Figures 1 to 3In this design, the motor is an airtight motor with an independent fan, and its interior can be filled with natural air or an external air source (nitrogen, air, etc.). As a result, if the magnetic fluid sealing device 3 fails, the liquid level rises, and the gas in the external gas plugging cavity 18 enters the upper motor cavity through the failed magnetic fluid sealing device 3. Simultaneously, the medium also rises, flowing through the magnetic fluid sealing device 3 and first into the air cavity surrounding the magnetic fluid. As the liquid level rises, the gas in the motor cavity is continuously compressed until the gas pressure inside the motor cavity equals the medium pressure, reaching equilibrium, and the liquid level stops rising. (Because the motor cavity collects gas from the external gas plugging cavity 18 and part or all of the gas from the cavity surrounding the magnetic fluid seal, the gas pressure inside the motor cavity increases significantly.) Due to the spatial design, the liquid level can reach equilibrium below the motor coil, thus preventing the medium from rising to the motor coil even if the magnetic fluid seal fails, ensuring the motor is not damaged.

[0105] Of course, the motor can also be a regular motor (such as...) Figure 4 (as shown), or an airtight water-cooled motor (such as...) Figure 5 and Figure 8 (As shown).

[0106] According to embodiments of the present invention, when the shielded pump includes the magnetic fluid seal shaft assembly provided in any embodiment of the first aspect, the pump can be a vertical pump such as a long-shaft submersible pump or a long-shaft deep well pump. When the shielded pump includes the shielded motor provided in any embodiment of the second aspect, the pump body can be directly and airtightly installed on the end of the second housing away from the motor body, connecting the motor shaft to the rotating part of the pump body, thus enabling the rotating part of the pump body to be driven by the motor shaft. Simultaneously, an air inlet channel 8 for inputting gas into the second housing can be provided on the second housing, and the outer end of the air inlet channel 8 can be connected to a gas source. At this time, the lower end of the first receiving cavity 12 is water-sealed by the pump body. Therefore, when gas is input into the second housing through the gas source, an airlock can be formed in the end of the second housing near the shaft inlet / outlet hole. This prevents water inside the pump body from entering the motor through the shaft inlet / outlet hole when the shielded motor is connected to the pump body, thus ensuring that the magnetic fluid seal device 3 does not come into contact with water, thereby achieving waterproof protection for the magnetic fluid seal device 3.

[0107] In the aforementioned canned pumps, such as Figures 1 to 12 As shown, the canned motor pump is a vertical pump, comprising a pump body, a vertically arranged magnetohydrodynamic (MHD) sealed shaft assembly, and the pump body being airtightly mounted to the lower end of the second housing. The rotating shaft 2 is connected to the rotating part of the pump body. Preferably, as shown... Figure 5 and Figure 8As shown, the canned motor pump also includes one or more waterproof protection devices, including a water-pressing sleeve 96 and a water-blocking device 98. The water-pressing sleeve 96 is installed between the rotating shaft 2 and the pump casing. A water-pressing thread is provided on the upper outer wall of the water-pressing sleeve 96. The thread direction can be adjusted according to the rotation direction of the rotating shaft 2, so that when the rotating shaft 2 rotates, the water flowing upwards along the rotating shaft 2 can be pushed downwards, preventing water from entering the second housing and contacting the magnetic fluid sealing device 3. The water-blocking device 98 is installed on the rotating shaft 2, located at the shaft inlet / outlet hole of the second housing. This water-blocking device 98 can block the water flow that rapidly rushes into the second housing, preventing the sudden impact water flow generated in the pump body from directly splashing onto the magnetic fluid sealing device 3, thus preventing damage to the magnetic fluid sealing device 3 due to water contact. After the water is blocked by the water-blocking device 98, the water entering the second shell can only rise slowly and will not suddenly and rapidly penetrate the barrier formed by the gas and come into contact with the magnetic fluid sealing device 3. This allows the gas in the second shell to balance with the water pressure, thereby effectively shielding the magnetic fluid sealing device 3 from air pressure. Preferably, the water-blocking device 98 is a water-blocking plate or a trumpet-shaped water-blocking cover installed on the rotating shaft 2 and having a preset axial distance between it and the magnetic fluid sealing device 3, with the opening of the trumpet-shaped water-blocking cover facing upward.

[0108] In the description of this specification, the terms "connection," "installation," and "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0109] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A magnetic fluid sealed shaft assembly, characterized by, include: A housing, wherein a receiving cavity is provided inside the housing, and a fixing structure is provided on the inner wall of the receiving cavity; The rotating shaft is supported and installed within the receiving cavity; A magnetic fluid sealing device is located inside the receiving cavity and is sleeved on the rotating shaft. The housing is provided with space for the magnetic fluid sealing device to move with the rotating shaft and / or adjust the installation angle and position according to the installation state of the rotating shaft. The elastic element is airtightly connected to both the magnetic fluid sealing device and the fixed structure. After the magnetic fluid sealing device is elastically and airtightly connected to the fixed structure through the elastic element, the magnetic fluid sealing device can follow the rotation of the rotating shaft and / or adjust the installation angle and position according to the installation state of the rotating shaft. A radial gap is provided between the fixed structure and the magnetic fluid sealing device. The elastic element is an elastic connecting ring. Part of the elastic connecting ring is fixedly installed on the first end of the magnetic fluid sealing device, and the other part of the elastic connecting ring is fixedly installed on the fixed structure. A positioning structure is provided inside the housing corresponding to the second end of the magnetic fluid sealing device. A buffer pad is provided between the positioning structure and the second end of the magnetic fluid sealing device; or The fixing structure is disposed on the inner side wall of the housing, or the fixing structure is installed on one end structure of the housing, and / or a radial distance is provided between the magnetic fluid sealing device and the fixing structure, and an axial distance is provided between the two ends of the housing and the magnetic fluid sealing device; wherein, the elastic element is an elastic connecting cylinder, the elastic connecting cylinder includes a sleeve part and a mounting part, the sleeve part is sleeved and installed on the magnetic fluid sealing device, the mounting part is disposed on the sleeve part and is sealed and fixedly connected to the fixing structure, the sleeve part and the mounting part are an integral structure, a radial distance is provided between the sleeve part and the fixing structure, and an axial distance is provided between the two ends of the housing and the magnetic fluid sealing device.

2. The magnetic fluid sealed shaft assembly of claim 1, wherein, An external air-blocking cavity is provided inside the housing and below the magnetohydrodynamic sealing device. After the bottom of the housing is sealed, an air blockage can be formed in the external air-blocking cavity.

3. The magnetic fluid sealed shaft assembly of claim 1, wherein, The shaft assembly of the magnetic fluid seal is a vertical structure. The housing includes a first outer shell and a second outer shell that are sealed to each other. A shaft through hole is provided at the connection between the first outer shell and the second outer shell. The rotating shaft extends from the first outer shell into the second outer shell and extends out from the bottom of the second outer shell. The magnetic fluid seal device is installed at the shaft through hole through an elastic element to seal the shaft through hole. An external air-blocking cavity is provided inside the second housing and below the magnetic fluid sealing device. After the bottom of the second housing is sealed, an air blockage can be formed in the external air-blocking cavity. The gas required to form the air blockage is the natural air in the external air-blocking cavity. Alternatively, the shaft assembly of the magnetic fluid seal may also include an air inlet channel. One end of the air inlet channel is connected to the external air-blocking cavity, and the other end of the air inlet channel is connected to a gas source. The gas required to form the air blockage includes the natural air in the external air-blocking cavity and the gas input through the air inlet channel.

4. The magnetic fluid sealed shaft assembly of claim 3, wherein, The shaft assembly of the magnetohydrodynamic seal further includes a bearing housing assembly for supporting the rotating shaft, the bearing housing assembly being installed within the housing and located above or below the magnetohydrodynamic seal device; and / or The lower end of the magnetic fluid sealing device is elastically connected to the fixed structure via the elastic element, or the upper end of the magnetic fluid sealing device is elastically connected to the fixed structure via the elastic element.

5. The shaft assembly with a magnetohydrodynamic seal according to claim 1, characterized in that, In the case where the elastic connecting sleeve includes a sleeve portion and a mounting portion, The mounting portion is an annular retaining ring disposed on the outer side wall of the sleeve portion along the circumferential direction; wherein: The annular retaining ring is located in the middle of the sleeve and is connected to the fixing structure by screws. Both ends of the sleeve are fixedly fitted onto the magnetic fluid sealing device by at least two fasteners. Alternatively, the annular retaining ring is located at one end of the sleeve and is connected to the fixing structure by screws. A bottom mounting part protruding inward from the inner sidewall of the sleeve is provided at the other end of the sleeve. The bottom mounting part is fixedly installed on the end face of the magnetic fluid sealing device by screws. The annular retaining ring, the sleeve, and the bottom mounting part are an integral structure, and the bottom mounting part is provided with a through hole for the rotating shaft to pass through.

6. The shaft assembly with a magnetohydrodynamic seal according to claim 1, characterized in that, The magnetohydrodynamic sealing device is provided with a mating structure that cooperates with the fixed structure. The elastic element includes a first elastic ring disposed between the mating structure and the fixed structure and / or a second elastic ring located on the side of the mating structure away from the fixed structure. The fixed structure, the mating structure, the first elastic ring and / or the second elastic ring are fixed by fasteners. After the fixed structure, the mating structure, the first elastic ring and / or the second elastic ring are fixed by the fasteners, the mating structure and the fixed structure are elastically connected, so that the magnetohydrodynamic sealing device can follow the rotation of the shaft and / or adjust the installation angle and position according to the installation state of the shaft.

7. The shaft assembly with a magnetohydrodynamic seal according to claim 1, characterized in that, When the elastic element is an elastic connecting ring, the fixing structure is a cylindrical structure installed on the inner wall of the housing and arranged axially. The magnetic fluid sealing device is located inside the cylindrical structure and is provided with a radial distance between it and the cylindrical structure. The inner part of the elastic connecting ring is fixedly installed on the end face of the first end of the magnetic fluid sealing device, and the outer part of the elastic connecting ring is fixedly installed on the end face of the cylindrical structure corresponding to the end face of the first end of the magnetic fluid sealing device.

8. The shaft assembly with a magnetohydrodynamic seal according to claim 7, characterized in that, The elastic connecting ring, the magnetic fluid sealing device, the cylindrical structure, and the buffer pad form a sealed first cooling chamber. The shaft assembly of the magnetic fluid seal also includes a first cooling medium channel with one end sealed and connected to the first cooling chamber, and the other end of the first cooling medium channel is connected to the outside of the housing.

9. The magnetic fluid sealed shaft assembly of claim 2, wherein, Also includes: An inner gas plug is installed inside the outer gas plug cavity and is airtightly connected to the lower end of the magnetohydrodynamic sealing device in the axial direction. The inner gas plug is arranged around the outside of the part of the rotating shaft that extends into the outer gas plug cavity. An inner gas plug cavity is formed between the inner gas plug and the rotating shaft. After the bottom of the housing is sealed, a gas plug can be formed in the inner gas plug cavity.

10. The magnetic fluid sealed shaft assembly of claim 9, wherein, The upper end of the inner air plug is provided with a mounting plate, and the elastic element is clamped between the mounting plate and the lower end of the magnetohydrodynamic sealing device, or the elastic element is clamped between the mounting plate and the fixed structure.

11. The magnetic fluid sealed shaft assembly of any one of claims 1 to 10, wherein, The magnetohydrodynamic sealing device includes: Fixed sleeve; A magnetic fluid seal is installed inside the fixed sleeve, and a sealed second cooling chamber is provided between the inner side wall of the fixed sleeve and the outer side wall of the magnetic fluid seal. The second cooling medium channel has one end connected to the second cooling cavity and the other end connected to the outside of the housing. The elastic element is sealed and installed on the fixed sleeve and is sealed and connected to the fixed structure.

12. A shielded electric machine characterized by include: Motor configuration components; The shaft assembly of the magnetohydrodynamic seal as described in any one of claims 1 to 11, wherein the rotating shaft of the magnetohydrodynamic seal shaft assembly is a motor shaft; The housing of the magnetohydrodynamic seal shaft assembly includes a first outer shell and a second outer shell that are sealed to each other. The first outer shell is a motor housing, and the motor configuration assembly is disposed inside the first outer shell. The output end of the motor shaft extends from the motor housing and is inserted into the second housing. The magnetic fluid sealing device of the magnetic fluid sealed shaft assembly is installed inside the motor housing or the second housing.

13. A canned pump characterized by include: A pump body and a shielded motor are interconnected, wherein the pump body includes a shaft assembly with a magnetohydrodynamic seal as described in any one of claims 1 to 11, or the shielded motor is a shielded motor as described in claim 12.

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