Variable vacuum capacitor

Abstract

This invention discloses a variable vacuum capacitor, comprising a base, two electrode groups, a positioning rod, and a transmission mechanism connected to the positioning rod. The positioning rod is fixedly connected to one of the electrode groups and drives that electrode group to move axially, thereby changing the coupling length between it and the other electrode group. A support sleeve is fixed on the base, and the support sleeve has an integrally connected guide sleeve and a sleeve portion. The positioning rod is slidably fitted inside the guide sleeve portion. The transmission mechanism includes a rotating screw and a positioning nut. The positioning nut is movably disposed inside the sleeve portion and fixedly connected to the positioning rod. The rotating screw is mounted inside the sleeve portion via a bearing and threadedly connected to the positioning nut. A limiting member is provided on the sleeve portion to restrict the axial movement of the rotating screw. This invention can effectively prevent the rotating screw from dislodging from the positioning nut due to exceeding the capacitance range, thus preventing damage to the variable vacuum capacitor and sudden changes in capacitance value, meeting the requirements for capacitance stability in the semiconductor manufacturing equipment field.

Description

Technical Field

[0001] This utility model relates to the field of capacitor technology, and in particular to a variable vacuum capacitor. Background Technology

[0002] The variable vacuum capacitor includes two sets of electrodes sealed in a vacuum. The moving electrode set is connected to the motor via an internal positioning rod and a transmission mechanism. The transmission mechanism includes a positioning nut and a rotating screw. The positioning nut is fixed to the positioning rod. The motor is connected to the rotating screw via a coupling. The motor drives the rotating screw to rotate, which in turn moves the moving electrode set axially through the positioning nut and the positioning rod. This changes the coupling length of the two sets of electrodes, thereby changing and adjusting the capacitance value. Therefore, the position of the rotating screw determines the capacitance value of the capacitor.

[0003] Generally, a support sleeve needs to be installed at the base end of a variable vacuum capacitor to support the rotating screw. The rotating screw is rotatably mounted on the support sleeve via bearings. In traditional variable vacuum capacitors, the support sleeve is usually not fixed; its left end is fitted onto a boss on the guide sleeve for positioning, and its right end is matched with a boss on the rotating screw via a bearing to form a limit.

[0004] Figure 1 The diagram illustrates a situation where a conventional variable vacuum capacitor, in a horizontally mounted state, experiences a disengagement of the rotating screw 4 and tilting of the support sleeve 15 due to gravity caused by the motor exceeding its rotation range. Specifically, when the motor drives the rotating screw 4 to rotate counterclockwise, the positioning nut 5 moves axially to the left. When the end face of the positioning nut 5 contacts the end face of the guide sleeve 14, it is stopped, and the capacitor capacitance no longer increases; this is the maximum capacitance position of the variable vacuum capacitor. If, due to improper operation or other special circumstances, the motor continues to rotate counterclockwise, the rotating screw 4 will move axially to the right (the coupling provides space for the axial movement of the rotating screw 4). Once the axial movement distance of the rotating screw 4 exceeds its engagement length with the positioning nut 5, the rotating screw 4 will disengage from the threaded hole of the positioning nut 5, causing a sudden change in the capacitor capacitance.

[0005] Furthermore, rotating the screw 4 can cause the support sleeve 15 to disengage from the boss of the guide sleeve 14. Especially when the variable vacuum capacitor is installed horizontally or in reverse, the support sleeve 15 tilts under the influence of gravity. This tilting causes the rotating screw 4 to be subjected to radial force, which can easily lead to jamming between the rotating screw 4 and the positioning nut 5, as well as between the positioning rod and the guide sleeve, resulting in irreversible damage to the vacuum capacitor. Therefore, users wish to restrict the position of the rotating screw 4 and the support sleeve 15 to avoid the aforementioned problems. Utility Model Content

[0006] The problem to be solved by this utility model is to provide a variable vacuum capacitor to overcome the defects of variable vacuum capacitor being damaged and having sudden changes in capacitance due to use outside the capacitance range.

[0007] The technical solution adopted by this utility model to solve its technical problem is as follows: a variable vacuum capacitor, including a base, two electrode groups, a positioning rod, and a transmission mechanism connected to the positioning rod. The positioning rod is fixedly connected to one of the electrode groups and is used to drive the electrode group to move axially to change the coupling length between it and the other electrode group. A support sleeve is fixed on the base. The support sleeve has an integrally connected guide sleeve and a sleeve. The positioning rod is slidably fitted in the guide sleeve. The transmission mechanism includes a rotating screw and a positioning nut. The positioning nut is movably disposed in the sleeve and fixedly connected to the positioning rod. The rotating screw is installed in the sleeve through a bearing and threadedly connected to the positioning nut. A limiting member is provided on the sleeve to restrict the axial movement of the rotating screw.

[0008] As a further improvement of this utility model, the limiting member is a nut, which is threadedly connected to the end of the sleeve portion away from the guide sleeve portion.

[0009] As a further improvement of this utility model, the middle part of the rotating screw has a radially outward protruding support boss, the support boss is located on the side of the limiting member facing the sleeve part, the limiting member is provided with a through hole for the rotating screw to pass through, and the diameter of the through hole is smaller than the diameter of the support boss.

[0010] As a further improvement of this utility model, the end of the sleeve portion away from the guide sleeve portion is provided with a first positioning step along the inner wall, the bearing is supported on the first positioning step, and the support boss is fitted into the inner hole of the bearing.

[0011] As a further improvement of this utility model, the bearing is a planar thrust ball bearing, which includes two races, one of which is tightly fitted to the inner wall of the sleeve portion, and the other race is tightly fitted to the outer wall of the support boss. At the same time, the support boss is provided with a fourth positioning step that protrudes radially outward, and the fourth positioning step is used to stop and position itself on the corresponding race.

[0012] As a further improvement of this utility model, a second positioning step is provided along the inner wall of one end of the sleeve portion near the guide sleeve portion, and the positioning nut reciprocates between the second positioning step and the bearing.

[0013] As a further improvement of this utility model, the outer diameter of the sleeve portion is larger than the outer diameter of the guide sleeve portion, thereby forming a third positioning step at the connection position between the sleeve portion and the guide sleeve portion. The base has a mounting hole in the middle, the guide sleeve portion is inserted into the mounting hole, the third positioning step is positioned on the end face of the base, and the sleeve portion is located on the outside of the base.

[0014] As a further improvement of this utility model, one of the electrode groups includes a moving disk and a moving electrode ring group fixed to the moving disk, and the other electrode group includes a stator disk and a stationary electrode ring group fixed to the stator disk. The variable vacuum capacitor also includes a ceramic tube, and the base and the stator disk are respectively sealed and fixed to both ends of the ceramic tube. The moving disk and the moving electrode ring group are both located inside the ceramic tube, and the moving electrode ring group and the stationary electrode ring group are coupled to each other. A bellows is sealed between the base and the stator disk, and the positioning rod and the guide sleeve both extend into the bellows.

[0015] As a further improvement of this utility model, the sleeve part is provided with an exhaust hole that connects its interior to the outside atmosphere, and the exhaust hole is connected to the interior of the bellows through the fitting gap between the positioning rod and the guide sleeve part.

[0016] As a further improvement of this utility model, the limiting member is provided with a cover plate portion and a connecting ring with internal threads formed by extending axially from the outer circumference of the cover plate portion. The end of the sleeve portion away from the guide sleeve portion is provided with external threads along the outer wall. The connecting ring is threaded to the external threads of the sleeve portion, so that the cover plate portion covers one end of the sleeve portion.

[0017] The beneficial effects of this utility model are as follows: This utility model provides a variable vacuum capacitor by designing the support sleeve as an integrally connected guide sleeve and sleeve. The guide sleeve guides the axial sliding of the positioning rod, and the sleeve supports the rotating screw. The sleeve remains relatively fixed to the base. At the same time, the axial position of the rotating screw is limited by the limiting member set on the sleeve, thereby effectively preventing the rotating screw from coming off the positioning nut due to the user using it beyond the capacitance range when the capacitor is installed horizontally or in reverse, which would cause damage to the variable vacuum capacitor and sudden changes in capacitance. In addition, the guide sleeve and sleeve adopt an integral structure design, which can ensure the coaxiality and perpendicularity of the first positioning step, the second positioning step and the third positioning step during the processing, thereby ensuring the assembly accuracy of each component and improving the stability of the capacitance during the adjustment process, meeting the requirements of the field of semiconductor manufacturing equipment for the capacitance stability of variable vacuum capacitors. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a cross-sectional view of a traditional variable vacuum capacitor. Figure 2 This is a perspective view of the variable vacuum capacitor of this utility model; Figure 3 This is a cross-sectional view of the variable vacuum capacitor of this utility model; Figure 4 This utility model Figure 3 Enlarged view of section A; Figure 5 This utility model Figure 3 Enlarged view of section B in the middle.

[0020] Referring to the accompanying drawings, the following explanations are provided: 1. Base; 2. Positioning rod; 3. Support sleeve; 301. Guide sleeve; 302. Sleeve; 3021. First positioning step; 3022. Second positioning step; 3023. Third positioning step; 3024. Vent hole; 4. Rotating screw; 401. Support boss; 402. Fourth positioning step; 5. Positioning nut; 6. Bearing; 601. Seat ring; 7. Limiting component; 701. Through hole; 702. Cover plate; 703. Connecting ring; 8. Moving plate; 9. Moving electrode ring assembly; 10. Stator plate; 11. Static electrode ring assembly; 12. Ceramic tube; 13. Bellows; 14. Guide sleeve; 15. Support sleeve. Detailed Implementation

[0021] The present application will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0022] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0024] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0025] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0026] The technical solutions provided by the various embodiments of this application are described below with reference to the accompanying drawings.

[0027] See Figures 2 to 5 This utility model provides a variable vacuum capacitor, including a vacuum capacitor body and a transmission assembly. The vacuum capacitor body includes a base 1 and two electrode groups. In this embodiment, one electrode group can move axially, while the other electrode group is fixed.

[0028] The term "axial direction" as used in this article refers to the direction of the central axis of the vacuum capacitor body.

[0029] Furthermore, the transmission assembly includes a positioning rod 2 and a transmission mechanism. The positioning rod 2 is arranged along the axial direction of the vacuum capacitor body, with its upper end connected to the transmission mechanism and its lower end fixed to an electrode group capable of axial movement. This electrode group is used to drive the electrode group to move axially, thereby changing the coupling length between it and another electrode group to achieve capacitance adjustment. The transmission mechanism includes a rotating screw 4 and a positioning nut 5.

[0030] As one of the important improvements of the present invention, a support sleeve 3 is fixed on the base 1. The support sleeve 3 is arranged along the axial direction of the vacuum capacitor body. The support sleeve 3 is provided with an integrally connected guide sleeve part 301 and sleeve part 302.

[0031] like Figure 3As shown, both the guide sleeve 301 and the sleeve 302 are cylindrical, with the guide sleeve 301 located at the bottom and the sleeve 302 at the top. The positioning rod 2 is slidably fitted inside the guide sleeve 301. The guide sleeve 301 guides the axial sliding of the positioning rod 2, ensuring the stability of the positioning rod 2's movement. At the same time, it constrains the radial position of the electrode group connected to the positioning rod 2, preventing radial offset and ensuring capacitance accuracy.

[0032] Furthermore, the positioning nut 5 is movably disposed within the sleeve portion 302 and fixedly connected to the positioning rod 2. The rotating screw 4 is rotatably installed within the sleeve portion 302 via the bearing 6 and threadedly connected to the positioning nut 5. When the rotating screw 4 rotates, the positioning nut 5 can move axially within the sleeve portion 302 under the drive of the rotating screw 4, and the positioning nut 5 synchronously drives the positioning rod 2 to move.

[0033] In addition, a limiting member 7 is provided on the sleeve part 302 to limit the axial movement of the rotating screw 4 and to prevent the rotating screw 4 from coming out of the positioning nut 5.

[0034] As can be seen, this utility model designs the support sleeve 3 as an integrally connected guide sleeve part 301 and sleeve part 302. The guide sleeve part 301 guides the axial sliding of the positioning rod 2, and the sleeve part 302 supports the rotating screw 4. The sleeve part 302 remains relatively fixed to the base 1. At the same time, the limiting member 7 provided on the sleeve part 302 restricts the axial position of the rotating screw 4, thereby effectively preventing the rotating screw 4 from dislodging from the positioning nut 5 due to the user exceeding the capacitance range when the capacitor is installed horizontally or in reverse, which would cause damage to the variable vacuum capacitor and sudden changes in capacitance. This meets the requirement for capacitance stability of variable vacuum capacitors in the semiconductor manufacturing equipment field. At the same time, the guide sleeve part 301 and sleeve part 302 adopt an integral structure design, reducing the cumulative effect of the form and position tolerances of parts in the traditional separate structure and improving capacitance stability.

[0035] See Figure 3 The limiting component 7 is a nut, which is threadedly connected to the end of the sleeve portion 302 away from the guide sleeve portion 301, i.e. Figure 3 The upper end of the sleeve portion 302 is shown. The limiting member 7 in this utility model is a nut and threadedly connected to the sleeve portion 302. This structure is simple, easy to install and disassemble, and convenient for later maintenance and adjustment. At the same time, the threaded connection can ensure that the limiting member 7 is firmly fixed, reliably restricting the axial position of the rotating screw 4, effectively preventing it from coming off, and improving the stability of the capacitor.

[0036] Specifically, see Figure 4The limiting member 7 is provided with a circular cover plate portion 702 and a connecting ring 703 with internal threads extending axially downward from the outer circumference of the cover plate portion 702. The sleeve portion 302 is provided with external threads along the outer wall at one end away from the guide sleeve portion 301. The connecting ring 703 is threaded to the external threads of the sleeve portion 302, so that the cover plate portion 702 covers the upper end of the sleeve portion 302.

[0037] The rotating screw 4 has a radially outwardly protruding annular support boss 401 in its middle. The support boss 401 is located on the side of the limiting member 7 facing the sleeve portion 302. The cover portion 702 of the limiting member 7 has a through hole 701 in the middle for the upper part of the rotating screw 4 used for connecting the coupling to pass through, and the diameter of the through hole 701 is smaller than the diameter of the support boss 401. This utility model forms a mechanical hard limit by cooperating between the support boss 401 of the rotating screw 4 and the limiting member 7, which can accurately limit the axial movement range of the rotating screw 4 and prevent it from disengaging from the positioning nut 5 due to excessive rotation.

[0038] Continue reading Figure 4 The sleeve portion 302, away from the guide sleeve portion 301, has a first positioning step 3021 along its inner wall. The bearing 6 is supported on the first positioning step 3021, and the support boss 401 fits into the inner hole of the bearing 6. The first positioning step 3021 of the sleeve portion 302 provides stable support for the bearing 6, ensuring accurate installation of the bearing 6 and reducing displacement of the bearing 6 during operation. The connection between the bearing 6 and the support boss 401 ensures smooth rotation of the rotating screw 4.

[0039] Preferably, the bearing 6 is a planar thrust ball bearing, which includes two races 601 and balls distributed between the two races 601. One race 601 is tightly fitted to the inner wall of the sleeve portion 302, and the other race 601 is tightly fitted to the outer wall of the support boss 401. The support boss 401 is provided with a radially outwardly protruding fourth positioning step 402, which is used to stop and position the bearing 601 on the corresponding race, ensuring accurate installation of the rotating screw 4. This invention, by using a planar thrust ball bearing, can effectively withstand the axial thrust of the rotating screw 4, reduce frictional loss, and improve transmission efficiency. The two races 601 of the bearing 6 are tightly fitted to the inner wall of the sleeve portion 302 and the outer wall of the support boss 401, respectively. Combined with the stop and positioning of the races 601 by the fourth positioning step 402 of the support boss 401, the stability of the rotating screw 4's rotation is further enhanced.

[0040] See Figure 5 The sleeve portion 302 is provided with a second positioning step 3022 along the inner wall at one end near the guide sleeve portion 301, and the positioning nut 5 reciprocates between the second positioning step 3022 and the bearing 6.

[0041] When the screw 4 rotates clockwise, the positioning nut 5 moves upward. When the upper end face of the positioning nut 5 moves to abut against the lower end face of the bearing 6, the positioning nut 5 is stopped, and the capacitance value no longer decreases. This is the minimum capacitance value position of the vacuum variable capacitor. When the screw 4 rotates counterclockwise, the positioning nut 5 moves downward. When the lower end face of the boss of the positioning nut 5 moves to abut against the second positioning step 3022, the positioning nut 5 is stopped, and the capacitance value no longer increases. This is the maximum capacitance value position of the vacuum variable capacitor.

[0042] This application defines the reciprocating range of the positioning nut 5 by using the second positioning step 3022 of the sleeve portion 302 and the bearing 6 together, thus clarifying the adjustment range of the capacitor value and preventing the positioning nut 5 from moving beyond the range, which could lead to abnormal coupling length of the electrode group and avoid sudden changes in capacitance.

[0043] See Figure 3 and Figure 5 The outer diameter of the sleeve portion 302 is larger than the outer diameter of the guide sleeve portion 301, thus forming a third positioning step 3023 at the connection position between the sleeve portion 302 and the guide sleeve portion 301. The base 1 has a mounting hole in the middle, and the guide sleeve portion 301 is fixedly inserted into the mounting hole. The third positioning step 3023 is positioned at the end face of the base 1, and the sleeve portion 302 is located on the outside of the base 1. The third positioning step 3023 formed by the sleeve portion 302 and the guide sleeve portion 301 can accurately position and install the support sleeve 3 in the mounting hole of the base 1, simplifying the assembly process and improving production efficiency. The sleeve portion 302 is located on the outside of the base 1, and the guide sleeve portion 301 is inserted into the base 1, which reasonably distributes the structural layout of the support sleeve 3 inside and outside the base 1, ensuring the compactness of the internal transmission structure and facilitating the connection between external components (such as motors) and the rotating screw 4.

[0044] By adopting an integrated structural design for the guide sleeve 301 and the sleeve 302, this application can ensure the coaxiality and perpendicularity of the first positioning step 3021, the second positioning step 3022 and the third positioning step 3023 during the processing, thereby ensuring the assembly accuracy of each component and improving the stability of the capacity during the adjustment process.

[0045] See again Figure 3 In this application, the two electrode groups are a moving electrode group and a stationary electrode group. The position of the moving electrode group within the vacuum capacitor body is adjustable to change the coupling length between it and the stationary electrode group, thereby changing the coupling area and achieving capacitance adjustment.

[0046] The moving electrode group includes a moving disk 8 and a moving electrode ring group 9 fixed to the moving disk 8, while the stationary electrode group includes a stator disk 10 and a stationary electrode ring group 11 fixed to the stator disk 10. Both the moving electrode ring group 9 and the stationary electrode ring group 11 are composed of multiple electrode rings of different diameters arranged concentrically at intervals. The electrode rings in the moving electrode ring group 9 and the electrode rings in the stationary electrode ring group 11 are alternately and concentrically arranged in the vacuum chamber inside the vacuum capacitor body, so that the moving electrode ring group 9 and the stationary electrode ring group 11 can couple with each other through the electric field formed between them.

[0047] The vacuum capacitor body also includes a ceramic tube 12, a base 1 and a stator disk 10, which are respectively sealed and fixed at both ends of the ceramic tube 12; the moving disk 8 and the moving electrode ring group 9 are both located inside the ceramic tube 12, and a bellows 13 is sealed between the base 1 and the stator disk 10, thereby forming a closed space between the ceramic tube 12, the base 1, the bellows 13, the moving disk 8 and the stator disk 10, and this closed space is configured as a vacuum chamber, in which the moving electrode ring group 9 and the stationary electrode ring group 11 are coupled to each other and housed in the vacuum chamber.

[0048] Furthermore, both the positioning rod 2 and the guide sleeve 301 extend into the interior of the bellows 13. When an external power device, such as a motor, drives the positioning rod 2 to move up and down axially through a transmission mechanism, the positioning rod 2 will synchronously drive the moving electrode group to move, and at the same time, the bellows 13 will be compressed / stretched accordingly, so that the coupling length between the moving electrode ring group 9 and the stationary electrode ring group 11 changes, thereby realizing the adjustment of the capacitance value of the vacuum capacitor.

[0049] It is worth mentioning that the sleeve part 302 is provided with an exhaust hole 3024 in the radial direction to connect its interior with the outside atmosphere. The exhaust hole 3024 is connected to the inside of the bellows 13 through the fitting gap between the positioning rod 2 and the guide sleeve part 301. This facilitates the discharge of gas inside the bellows 13 or the entry of outside gas into the bellows 13 during the adjustment of the vacuum capacitor capacitance value, thereby reducing the resistance of the internal air pressure to the expansion and contraction of the bellows 13 and reducing the rotational torque.

[0050] Therefore, the variable vacuum capacitor of this utility model, by making the guide sleeve 301 and the sleeve 302 into an integrated structure, and by limiting the axial position of the rotating screw 4 by the limiting member 7 provided on the sleeve 302, ensures that the rotating screw 4 will not disengage due to the motor rotating beyond the range, regardless of whether the variable vacuum capacitor is installed horizontally or in reverse. This avoids damage to the variable vacuum capacitor and sudden changes in capacitance, and meets the requirements for capacitance stability of variable vacuum capacitors in the field of semiconductor manufacturing equipment.

[0051] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A variable vacuum capacitor, comprising a base (1), two electrode groups, a positioning rod (2), and a transmission mechanism connected to the positioning rod (2), wherein the positioning rod (1) is fixedly connected to one of the electrode groups and is used to drive the electrode group to move axially, thereby changing the coupling length between the electrode group and the other electrode group; characterized in that, A support sleeve (3) is fixed on the base (1). The support sleeve (3) is provided with an integrally connected guide sleeve part (301) and sleeve part (302). The positioning rod (2) is slidably fitted in the guide sleeve part (301). The transmission mechanism includes a rotating screw (4) and a positioning nut (5). The positioning nut (5) is movably disposed in the sleeve part (302) and fixedly connected to the positioning rod (2). The rotating screw (4) is installed in the sleeve part (302) through a bearing (6) and threadedly connected to the positioning nut (5). The sleeve part (302) is provided with a limiting member (7) for restricting the axial movement of the rotating screw (4).

2. The variable vacuum capacitor according to claim 1, characterized in that, The limiting member (7) is a nut, which is threadedly connected to the end of the sleeve (302) away from the guide sleeve (301).

3. The variable vacuum capacitor according to claim 2, characterized in that, The rotating screw (4) has a radially outward protruding support boss (401) in the middle. The support boss (401) is located on the side of the limiting member (7) facing the sleeve part (302). The limiting member (7) is provided with a through hole (701) through which the rotating screw (4) passes, and the diameter of the through hole (701) is smaller than the diameter of the support boss (401).

4. The variable vacuum capacitor according to claim 3, characterized in that, The sleeve portion (302) is provided with a first positioning step (3021) along the inner wall at one end away from the guide sleeve portion (301). The bearing (6) is supported on the first positioning step (3021), and the support boss (401) is fitted into the inner hole of the bearing (6).

5. The variable vacuum capacitor according to claim 4, characterized in that The bearing (6) is a planar thrust ball bearing, which includes two races (601). One race (601) is tightly fitted to the inner wall of the sleeve portion (302), and the other race (601) is tightly fitted to the outer wall of the support boss (401). The support boss (401) is provided with a radially outward protruding fourth positioning step (402), which is used to stop and position itself on the corresponding race (601).

6. The variable vacuum capacitor according to claim 1, wherein The sleeve portion (302) near the guide sleeve portion (301) has a second positioning step (3022) along its inner wall, and the positioning nut (5) reciprocates between the second positioning step (3022) and the bearing (6).

7. The variable vacuum capacitor according to claim 1, wherein The outer diameter of the sleeve portion (302) is larger than the outer diameter of the guide sleeve portion (301), thereby forming a third positioning step (3023) at the connection position between the sleeve portion (302) and the guide sleeve portion (301). The base (1) has a mounting hole in the middle, the guide sleeve portion (301) is inserted into the mounting hole, the third positioning step (3023) is positioned on the end face of the base (1), and the sleeve portion (302) is located on the outside of the base (1).

8. The variable vacuum capacitor according to claim 1, wherein One of the electrode groups includes a moving disk (8) and a moving electrode ring group (9) fixed to the moving disk (8), and the other electrode group includes a stator disk (10) and a stationary electrode ring group (11) fixed to the stator disk (10). The variable vacuum capacitor also includes a ceramic tube (12). The base (1) and the stator disk (10) are respectively sealed and fixed at both ends of the ceramic tube (12). The moving disk (8) and the moving electrode ring group (9) are both located inside the ceramic tube (12), and the moving electrode ring group (9) is coupled to the stationary electrode ring group (11). A bellows (13) is sealed between the base (1) and the stator disk (10). The positioning rod (2) and the guide sleeve (301) both extend into the bellows (13).

9. The variable vacuum capacitor according to claim 8, characterized in that The sleeve part (302) is provided with an exhaust hole (3024) that connects its interior to the outside atmosphere, and the exhaust hole (3024) is connected to the interior of the bellows (13) through the fitting gap between the positioning rod (2) and the guide sleeve part (301).

10. The variable vacuum capacitor according to claim 2, wherein The limiting member (7) is provided with a cover plate portion (702) and a connecting ring (703) with internal threads extending axially from the outer circumference of the cover plate portion (702). The sleeve portion (302) is provided with an external thread along the outer wall at one end away from the guide sleeve portion (301). The connecting ring (703) is threaded to the external thread of the sleeve portion (302), so that the cover plate portion (702) covers one end of the sleeve portion (302).

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