A magnetic fluid sealing shaft

Abstract

This invention discloses a magnetohydrodynamic (MHD) sealing shaft, comprising a bushing and a shaft body. The shaft body is mounted on the bushing and is rotatable relative to the bushing. A magnetohydrodynamic seal is provided between the shaft body and the bushing. The shaft body also includes a telescopic component, comprising a telescopic shaft built into the shaft body and capable of extending or retracting relative to the shaft body. The telescopic shaft and the shaft body are independent of each other. The shaft body cooperates with the bushing to achieve a rotational seal, while the telescopic shaft outputs linear displacement, allowing the shaft body to remain unaffected by the linear displacement output. This ensures the rotational seal between the shaft body and the bushing is not compromised. The introduction of the telescopic shaft compensates for the inability of conventional MHD sealing shafts to output linear displacement. Furthermore, the built-in design of the telescopic shaft avoids occupying external space, reducing the size of the device and improving its integration.

Description

Technical Field

[0001] This invention relates to the field of semiconductor processing equipment technology, and more specifically to a magnetic fluid sealing shaft. Background Technology

[0002] Conventional magnetohydrodynamic (MHD) sealing shafts can only achieve rotary sealing. However, in certain specific scenarios, it is also desirable for the MHD sealing shaft to output linear displacement. If a drive mechanism is directly added to the MHD sealing shaft, the reliability of the rotary seal will be affected. Summary of the Invention

[0003] The purpose of this invention is to provide a magnetohydrodynamic sealing shaft that can output linear displacement while achieving rotary sealing.

[0004] To solve the above-mentioned technical problems, the present invention provides a magnetic fluid sealing shaft, including a bushing and a shaft body, wherein the shaft body is installed on the bushing and the shaft body is rotatable relative to the bushing, and a magnetic fluid is provided between the shaft body and the bushing for sealing; it also includes a telescopic component, wherein the telescopic component includes a telescopic shaft, the telescopic shaft is built into the shaft body and is capable of extending or retracting relative to the shaft body.

[0005] With the above structure, the telescopic shaft and the shaft body are independent of each other. The shaft body is used to cooperate with the bushing to achieve a rotary seal, while the telescopic shaft is used to output linear displacement. This allows the shaft body to not participate in the output of linear displacement, so that the rotary seal between the shaft body and the bushing is not affected. The introduction of the telescopic shaft can make up for the deficiency that conventional magnetic fluid sealing shafts cannot output linear displacement. At the same time, the telescopic shaft is designed to be built into the shaft body, which can avoid occupying the external space of the magnetic fluid sealing shaft, thereby reducing the size of the equipment and improving the integration of the equipment.

[0006] Optionally, the shaft body is provided with a slot extending from one axial end face to the other axial end face but not penetrating through it. The slot includes a bottom wall and a peripheral wall. A piston is fitted onto the telescopic shaft, and the piston slides and seals against the peripheral wall of the slot. The shaft body also includes a cap, a first sealing element, and a fluid supply and recovery component. The cap is sealed at the opening of the slot and has a through hole. The telescopic shaft extends out of the slot through the through hole. The first sealing element seals the gap between the through hole and the telescopic shaft. A first chamber is formed between the piston and the cap, and a second chamber is formed between the piston and the bottom wall of the slot. The fluid supply and recovery component communicates with at least one of the first chamber and the second chamber.

[0007] Optionally, the bottom wall of the groove is provided with a groove, and the telescopic shaft is inserted into the groove.

[0008] Optionally, the first sealing element is a bellows, which is sleeved on the telescopic shaft. One end of the bellows is connected to the cap, and the other end of the bellows is connected to the piston.

[0009] Optionally, the slot opening is provided with a stepped surface, the cover is installed on the stepped surface, and a second sealing element is provided between the cover and the stepped surface.

[0010] Optionally, it also includes an adapter sleeve, which is fixedly disposed and rotatably sealed with the shaft body. The adapter sleeve is provided with a first flow port and a second flow port, both of which are connected to the fluid supply and recovery components. The shaft body is provided with a first fluid channel and a second fluid channel, the first fluid channel being used to connect the first chamber and the first flow port, and the second fluid channel being used to connect the second chamber and the second flow port.

[0011] Optionally, a third sealing element is provided between the adapter sleeve and the shaft body, and the first flow port and the second flow port are both located between two adjacent third sealing elements.

[0012] Optionally, a first annular flow channel and a second annular flow channel are provided between the shaft and the adapter sleeve, which are spaced apart along the axial direction. The first flow port is connected to the first fluid channel through the first annular flow channel, and the second flow port is connected to the second fluid channel through the second annular flow channel.

[0013] Optionally, two bearings spaced apart are provided between the bushing and the shaft body, and the magnetofluid is arranged between the two bearings.

[0014] Optionally, the telescopic shaft is arranged coaxially with the shaft body. Attached Figure Description

[0015] Figure 1 This is a perspective structural diagram of a specific embodiment of the magnetohydrodynamic sealing shaft provided by the present invention (without an adapter sleeve);

[0016] Figure 2 A cross-sectional view of a specific embodiment of the magnetohydrodynamic sealing shaft provided by the present invention (configured with an adapter sleeve);

[0017] Figure 3 This is a schematic diagram of a specific embodiment of the magnetohydrodynamic sealing shaft provided by the present invention when the rotating shaft is in the retracted state;

[0018] Figure 4 This is a schematic diagram of a specific embodiment of the magnetohydrodynamic sealing shaft provided by the present invention when the rotating shaft is in the extended state.

[0019] Figures 1-4 The annotations in the accompanying drawings are explained as follows:

[0020] 1. Bushing, 11. Magnetofluid, 12. Bearing, 13. Flange connection;

[0021] 2 shaft body, 21 slot, 211 groove, 21a first chamber, 21b second chamber, 22 cover, 23 second seal, 24 first fluid channel, 25 second fluid channel;

[0022] 3. Telescopic component; 31. Telescopic shaft; 32. Piston; 33. First seal;

[0023] 4. Adapter sleeve, 41. First flow port, 42. Second flow port, 43. Third seal. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] The terms "first" and "second" used in this article are used only for the convenience of describing two or more structures or components that are identical or similar in structure and / or function, and do not indicate any special limitation on order and / or importance.

[0026] Please refer to Figures 1-4 , Figure 1 This is a perspective structural diagram of a specific embodiment (without an adapter sleeve) of the magnetohydrodynamic sealing shaft provided by the present invention. Figure 2 This is a cross-sectional view of a specific embodiment (equipped with an adapter sleeve) of the magnetohydrodynamic sealing shaft provided by the present invention. Figure 3 This is a schematic diagram of a specific embodiment of the magnetohydrodynamic sealing shaft provided by the present invention when the rotating shaft is in the retracted state. Figure 4 This is a schematic diagram of a specific embodiment of the magnetohydrodynamic sealing shaft provided by the present invention when the rotating shaft is in the extended state.

[0027] like Figure 1 , Figure 2 As shown, the present invention provides a magnetic fluid sealing shaft, including a bushing 1 and a shaft body 2. The shaft body 2 is installed on the bushing 1 and can rotate relative to the bushing 1. A magnetic fluid 11 is provided between the shaft body 2 and the bushing 1 for sealing.

[0028] Magnetofluid, also known as magnetic liquid or ferrofluid, is a colloidal material composed of two phases: a solid phase, which mainly refers to magnetic solid nanoparticles, and a liquid phase, which refers to the liquid that can carry the solid magnetic nanoparticles. Magnetofluid has the fluidity, lubricity, and sealing properties of a liquid carrier, while also possessing the strong magnetism and other properties of solid nanoparticles.

[0029] Magnetofluid sealing uses permanent magnets to fix the magnetofluid around the shaft 2. Because the gap between the shaft 2 and the bushing 1 is very small and its magnetic field strength is particularly large, it can withstand a large thrust along the axial direction to achieve a sealing effect.

[0030] In detail, two spaced-apart bearings 12 can be provided between the bushing 1 and the shaft 2. The bearings 12 can be ball bearings, roller bearings, etc., to achieve relative rotation between the bushing 1 and the shaft 2. Magnetorheological fluid 11 can be arranged in the area between the two bearings 12. The magnetorheological fluid 11 can be arranged in a single channel or multiple channels. When multiple channels are arranged, the magnetorheological fluid 11 can also be distributed at intervals along the axial direction. Figure 2 In this embodiment, there are two channels of magnetic fluid 11.

[0031] The bushing 1 may be provided with a flange connection part 13. Specifically, the flange connection part 13 may be located at one axial end of the bushing 1, or it may be located at other axial positions of the bushing 1. It may be provided with a connecting hole for connecting with other components such as screws or bolts, thereby fixing the bushing 1. In practice, the bushing 1 does not rotate, while the shaft 2 can rotate.

[0032] Furthermore, the magnetic fluid sealing shaft provided by the present invention may also include a telescopic component 3, which includes a telescopic shaft 31. The telescopic shaft 31 is built into the shaft body 2 and can extend or retract relative to the shaft body 2. It should be noted that the extension or retraction here is a state of "extending" or "retracting" relative to the shaft body 2 caused by the telescopic shaft 31 being able to move relative to the shaft body 2, and does not mean that the length of the telescopic shaft 31 itself can be extended or shortened.

[0033] With the above structure, the telescopic shaft 31 and the shaft body 2 are independent of each other. The shaft body 2 is used to cooperate with the bushing 1 to achieve a rotary seal, while the telescopic shaft 31 is used to output linear displacement, so that the shaft body 2 does not participate in the output of linear displacement. In this way, the rotary seal between the shaft body 2 and the bushing 1 will not be affected. The introduction of the telescopic shaft 31 can make up for the defect that conventional magnetic fluid sealing shafts cannot output linear displacement. At the same time, the design of the telescopic shaft 31 being built into the shaft body 2 can avoid occupying the external space of the magnetic fluid sealing shaft, thereby reducing the size of the equipment and improving the integration of the equipment.

[0034] The telescopic shaft 31 and the shaft body 2 can be coaxially arranged. In this case, if the shaft body 2 rotates, the telescopic shaft 31 can also rotate around its own axis. Alternatively, the telescopic shaft 31 and the shaft body 2 can be non-coaxial, meaning there can be a certain amount of eccentricity between the central axis of the telescopic shaft 31 and the central axis of the shaft body 2. In this case, if the shaft body 2 rotates, the telescopic shaft 31 can revolve relative to the central axis of the shaft body 2. In practice, both of the above solutions can be adopted, and those skilled in the art can choose flexibly according to their needs.

[0035] In fact, the axial direction of the telescopic shaft 31 can also be set at an angle to the axial direction of the shaft body 2, which is also acceptable. In other words, the installation method of the telescopic shaft 31 relative to the shaft body 2 can be varied, and the specific configuration can be determined according to actual needs.

[0036] The telescopic component 3 may also include a power component, which provides power to the telescopic shaft 31 to drive the telescopic shaft 31 to complete axial displacement.

[0037] There are many possible structural options for the aforementioned power component. For example, the power component can be a power element in the form of a cylinder, hydraulic cylinder, or other power cylinder. In this case, the telescopic shaft 31 can be equivalent to the piston rod of the power cylinder, capable of directly outputting linear displacement. Alternatively, the power component can also include a power element in the form of a motor. However, since the displacement directly output by this type of power element is rotational displacement, a power conversion structure in the form of a gear rack structure or a lead screw structure is required to convert the rotational displacement directly output by the power element into the linear displacement required by the telescopic shaft 31.

[0038] In specific embodiments of the present invention, power components in the form of cylinders or hydraulic cylinders can be used to reduce the number of parts and simplify the structure.

[0039] like Figure 2 As shown, the shaft 2 may be provided with a slot 21 extending from one axial end face to the other axial end face but not penetrating through it. The slot 21 includes a bottom wall and a peripheral wall. A piston 32 may be sleeved on the telescopic shaft 31, and the piston 32 can slide and seal against the peripheral wall of the slot 21. That is, the piston 32 and the peripheral wall of the slot 21 can be in close contact, which can prevent fluid on both sides of the piston 32 from communicating through the gap between the piston 32 and the peripheral wall of the slot. At the same time, the piston 32 can slide axially within the slot 21.

[0040] Furthermore, it may also include a cover 22, which can be sealed at the opening of the slot 21. In this case, the cover 22 and the inner wall of the slot 21 can enclose and form the cylinder cavity. The piston 32 can divide the cylinder cavity into two parts along the axial direction. For ease of description, the space between the piston 32 and the cover 22 can be referred to as the first chamber 21a, and the space between the piston 32 and the bottom wall of the slot can be referred to as the second chamber 21b.

[0041] The cover 22 and the shaft 2 can be connected using fasteners such as screws. Specifically, the slot 21 can have a stepped surface (not shown in the figure) at the slot opening. The cover 22 can be installed on the stepped surface, and a second sealing element 23 can be provided between the cover 22 and the stepped surface to seal the gap between them. The second sealing element 23 can be a rubber ring or the like. Of course, the stepped surface can also be omitted, in which case the cover 22 can be directly mated to the axial end face of the shaft 2.

[0042] The cover 22 may be provided with a through hole (not marked in the figure), and the telescopic shaft 31 may extend out of the slot 21 through the through hole to output linear displacement to the outside.

[0043] Furthermore, it may also include a first seal 33, which can seal the radial gap (hereinafter referred to as the hole-shaft gap) between the through hole and the telescopic shaft 31 to prevent the first chamber 21a from being connected to the outside through the hole-shaft gap, thereby ensuring the sealing performance of the first chamber 21a.

[0044] The type of the first sealing element 33 is not limited here, as long as it can achieve the above-mentioned sealing effect. In an exemplary solution, the first sealing element 33 can be a bellows, which can be sleeved on the telescopic shaft 31. One end of the bellows can be connected to the cover 22, and the other end of the bellows can be connected to the piston 32, thereby isolating the first chamber 21a from the aforementioned hole-shaft gap. This arrangement not only achieves sealing isolation at the aforementioned hole-shaft gap, but also avoids wear on the first sealing element 33 during the operation of the telescopic shaft 31, and also helps to ensure the service life of the first sealing element 33 during long-term use.

[0045] Furthermore, it may also include a fluid supply and recovery component, which is connected to at least one of the first chamber 21a and the second chamber 21b. This component can supply fluid to the first chamber 21a or the second chamber 21b, or extract fluid from the first chamber 21a or the second chamber 21b to change the pressure on both sides of the piston 32 axially, thereby driving the telescopic rod 31 to move axially. The fluid supplied by the fluid supply and recovery component can be a gas or a liquid; the specific type of gas or liquid is not limited here.

[0046] Both the first chamber 21a and the second chamber 21b can be connected to fluid supply and recovery components. With this configuration, when fluid is filled into the first chamber 21a, the fluid in the second chamber 21b needs to be extracted, allowing the piston 32 and the telescopic shaft 31 to displace in the direction of compressing the second chamber 21b (displacement downwards in the attached diagram, as shown). Figure 3 (as shown in the figure); when fluid is filled into the second chamber 21b, the fluid in the first chamber 21a needs to be extracted, so that the piston 32 and the telescopic shaft 31 can be displaced in the direction of compressing the first chamber 21a (in the figure, the displacement is upward, as shown in the figure). Figure 4 (As shown). That is to say, when both the first chamber 21a and the second chamber 21b are connected to fluid supply and recovery components, the operations of extracting fluid and filling fluid in the two chambers are opposite.

[0047] For this scheme, there can be two fluid supply and recovery components. The two fluid supply and recovery components can be connected to the first chamber 21a and the second chamber 21b in a one-to-one correspondence, and then operate the two chambers respectively. Alternatively, there can be only one fluid supply and recovery component, which can include a supply part and a recovery part. The two can be equipped with certain valve bodies and pipelines that are connected to the first chamber 21a and the second chamber 21b. When the supply part supplies fluid to the first chamber 21a, the recovery part can recover the fluid in the second chamber 21b. When the supply part supplies fluid to the second chamber 21b, the recovery part can recover the fluid in the first chamber 21a.

[0048] Alternatively, only one of the first chamber 21a and the second chamber 21b may be connected to the fluid supply and recovery component. For simplicity, this description will only take the connection of the first chamber 21a to the fluid supply and recovery component as an example. The second chamber 21b may contain a certain amount of compressible fluid (such as gas) or a pre-installed elastic element. In this way, when fluid is filled into the first chamber 21a, the pressure in the first chamber 21a can increase, which can drive the piston 32 together with the telescopic rod 31 to move in the direction of compressing the second chamber 21b. The compressible fluid or elastic element in the second chamber 21b can be in a compressed state to accumulate energy. When the fluid in the first chamber 21a is extracted, the energy accumulated by the compressible fluid or elastic element in the second chamber 21b can be released to push the piston 32 together with the telescopic rod 31 to move in the direction of compressing the first chamber 21a. The elastic element can be a spring, tension rope, or other types of elastic elements, which are not limited here; taking a spring as an example, it can be sleeved on the telescopic shaft 31.

[0049] Furthermore, it may also include an adapter sleeve 4, which can be fixedly installed and can be rotatably sealed with the shaft 2. The adapter sleeve 4 may be provided with a first flow port 41 and a second flow port 42. Both the first flow port 41 and the second flow port 42 may be connected to fluid supply and recovery components. The number and connection method of the fluid supply and recovery components can be referred to the foregoing description. The shaft 2 may be provided with a first fluid channel 24 and a second fluid channel 25. The first fluid channel 24 is used to connect the first chamber 21a and the first flow port 41, and the second fluid channel 25 is used to connect the second chamber 21b and the second flow port 42.

[0050] With this structure, the adapter sleeve 4 does not rotate, and the connection pipeline between the fluid supply and recovery components and the adapter sleeve 4 will not twist, which is more conducive to ensuring the reliability of the connection.

[0051] In more detail, the inner ends of both the first flow port 41 and the second flow port 42 can be connected to an annular flow channel, which can be disposed on the inner wall surface of the adapter sleeve 4 and / or the outer wall surface of the shaft 2. For ease of description, the annular flow channel connected to the first flow port 41 can be referred to as the first annular flow channel, and the annular flow channel connected to the second flow port 42 can be referred to as the second annular flow channel. The first flow port 41 can be connected to the first fluid channel 24 through the first annular flow channel, and the second flow port 42 can be connected to the second fluid channel 25 through the second annular flow channel. With this arrangement, even if the shaft 2 rotates relative to the adapter sleeve 4, it will not affect the normal connection between the first flow port 41 and the first fluid channel 24, or the normal connection between the second connection port 42 and the second fluid channel 25.

[0052] A third sealing element 43 can also be provided between the adapter sleeve 4 and the shaft 2. The first flow port 41 and the second flow port 42 are located between two adjacent third sealing elements 43 to seal the gaps between the adapter sleeve 4 and the shaft 2 on both sides of the first flow port 41 and on both sides of the second flow port 42.

[0053] The third seal 43 can also be a sealing element in the form of a rubber ring or the like. Alternatively, the third seal 43 can also adopt a magnetohydrodynamic sealing structure similar to that between the bushing 1 and the shaft 2.

[0054] The bottom wall of the slot 21 can also be provided with a groove 211, into which the telescopic shaft 31 can be inserted to avoid the movement of the telescopic shaft 31, so that the piston 32 can have a larger displacement space. Furthermore, the shape and size of the groove 211 can be designed so that the axial cross section of the groove 211 can match the axial cross section of the telescopic shaft 31, so that when the telescopic shaft 31 is inserted into the groove 211, the displacement of the telescopic shaft 31 can also be guided.

[0055] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A magnetohydrodynamic sealing shaft, characterized in that, It includes a bushing (1) and a shaft body (2), the shaft body (2) is installed on the bushing (1), and the shaft body (2) can rotate relative to the bushing (1). A magnetic fluid (11) is provided between the shaft body (2) and the bushing (1) for sealing. It also includes a telescopic component (3), which includes a telescopic shaft (31) that is built into the shaft body (2) and can extend or retract relative to the shaft body (2); The shaft (2) is provided with a slot (21) extending from one end of its axial direction to the other end of its axial direction but not penetrating through it. The slot (21) includes a bottom wall and a peripheral wall. The telescopic shaft (31) is fitted with a piston (32), and the piston (32) slides and seals with the peripheral wall of the slot (21). It also includes a cap (22), a first seal (33), and a fluid supply and recovery component. The cap (22) is sealed at the opening of the slot (21). The cap (22) has a through hole. The telescopic shaft (31) extends out of the slot (21) from the through hole. The first seal (33) can seal the gap between the through hole and the telescopic shaft (31). A first chamber (21a) is formed between the piston (32) and the cap (22). A second chamber (21b) is formed between the piston (32) and the bottom wall of the slot. The fluid supply and recovery component is connected to at least one of the first chamber (21a) and the second chamber (21b).

2. The magnetohydrodynamic sealing shaft according to claim 1, characterized in that, The bottom wall of the trough is provided with a groove (211), and the telescopic shaft (31) is inserted into the groove (211).

3. The magnetohydrodynamic sealing shaft according to claim 1, characterized in that, The first sealing element (33) is a bellows, which is sleeved on the telescopic shaft (31). One end of the bellows is connected to the cover (22), and the other end of the bellows is connected to the piston (32).

4. The magnetohydrodynamic sealing shaft according to claim 1, characterized in that, The slot (21) has a stepped surface at the slot opening, the cover (22) is installed on the stepped surface, and a second sealing element (23) is provided between the cover (22) and the stepped surface.

5. The magnetohydrodynamic sealing shaft according to claim 1, characterized in that, It also includes an adapter sleeve (4), which is fixedly installed and rotates and seals with the shaft (2). The adapter sleeve (4) is provided with a first flow port (41) and a second flow port (42), and the first flow port (41) and the second flow port (42) are both connected to the fluid supply and recovery components. The shaft (2) is provided with a first fluid channel (24) and a second fluid channel (25). The first fluid channel (24) is used to connect the first chamber (21a) and the first flow port (41), and the second fluid channel (25) is used to connect the second chamber (21b) and the second flow port (42).

6. The magnetohydrodynamic sealing shaft according to claim 5, characterized in that, A third seal (43) is provided between the adapter sleeve (4) and the shaft (2), and the first flow port (41) and the second flow port (42) are both located between two adjacent third seals (43).

7. The magnetohydrodynamic sealing shaft according to claim 5, characterized in that, A first annular flow channel and a second annular flow channel are provided between the shaft (2) and the adapter sleeve (4) at intervals along the axial direction. The first flow port (41) is connected to the first fluid channel (24) through the first annular flow channel, and the second flow port (42) is connected to the second fluid channel (25) through the second annular flow channel.

8. The magnetohydrodynamic sealing shaft according to any one of claims 1-7, characterized in that, Two bearings (12) spaced apart are provided between the bushing (1) and the shaft (2), and the magnetofluid (11) is arranged between the two bearings (12).

9. The magnetohydrodynamic sealing shaft according to any one of claims 1-7, characterized in that, The telescopic shaft (31) is arranged coaxially with the shaft body (2).

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