Vacuum capacitor

Abstract

This technology contributes to making it easier to obtain the desired high-frequency current conduction capability and operability. [Solution] A mesh cylindrical conductive path section 5, which is expandable and contractible in the axial direction, is provided coaxially on the outer circumference of a cylindrical bellows 4 inside a vacuum container 10. The mesh cylindrical conductive path section 5 is made up of elastic conductors 6, which have a wavy shape extending along the circumferential direction of the mesh cylindrical conductive path section 5, superimposed in multiple stages in the axial direction. In each of the multiple stages superimposed, a pair of stages adjacent to each other in the axial direction are fixed together by the curvature of one of the curved sections 61, 62 provided on the pair of stages, which is convex in the direction of the adjacent stage, and the curvature of the other of the curved sections 61, 62 provided on the pair of stages, which is convex in the direction of the adjacent stage, being positioned opposite each other in the direction of the adjacent stage and being fixed together, thereby forming a fixed portion 71. In the stages, the fixed portion 71 and the gap portion 72 are provided alternately and repeatedly along the circumferential direction.

Description

Technical Field

[0001] The present invention relates to a vacuum capacitor, and more particularly to a technology of a vacuum capacitor applicable to impedance adjustment in high-frequency devices such as high-frequency power supplies of semiconductor equipment and large-power transmission circuits.

Background Art

[0002] Conventionally, various vacuum capacitors have been used for impedance adjustment in high-frequency devices such as high-frequency power supplies of general semiconductor equipment and large-power transmission circuits.

[0003] In a general vacuum capacitor, a vacuum vessel having a cylindrical body at least partially made of an insulating material is applied. This vacuum vessel is configured by closing the fixed side, which is one side in the axial direction of the cylindrical body (hereinafter simply referred to as the axial direction as appropriate), with a fixed-side conductor, and closing the movable side, which is the other side in the axial direction of the cylindrical body (hereinafter simply referred to as the other axial direction as appropriate), with a movable-side conductor.

[0004] Inside the vacuum vessel, a fixed electrode provided on one side in the axial direction (fixed-side conductor side) inside the vacuum vessel, a movable electrode support portion located opposite to the fixed electrode inside the vacuum vessel and movable in the axial direction, and a movable electrode provided opposite to the fixed electrode on one side in the axial direction of the movable electrode support portion and forming a capacitance with the fixed electrode are provided.

[0005] Between the movable electrode support portion and the movable-side conductor, a bellows that is cylindrical and stretchable in the axial direction and supports the movable electrode support portion on the movable-side conductor is provided. By this bellows, the inside of the vacuum vessel is divided into a vacuum chamber on the outer peripheral side of the bellows and an atmospheric chamber on the inner peripheral side of the bellows.

[0006] In recent years, the load on high-frequency equipment has been gradually increasing, and the high-frequency currents that can flow through such equipment have also increased. Therefore, vacuum capacitors used in such high-frequency equipment are required to have a high capacity to conduct high-frequency currents.

[0007] For example, in Patent Document 1, a conductive path section, which is larger in diameter than the bellows (referred to as "first bellows" by reference numeral 16 in Patent Document 1) and expandable and contractible in the axial direction, is arranged coaxially on the outer circumference of the bellows and engaged (electrically connected) with both the movable electrode support section and the movable side conductor. As a result, in the case of high-frequency current, the current flows more easily through the conductive path section than through the bellows due to the skin effect.

[0008] Specific examples of conductive paths include configurations using a bellows-shaped conductor (referred to as "second bellows" by reference numeral 17 in Patent Document 1) and configurations using a spiral conductor (referred to as "spiral wire" by reference numeral 18 in Patent Document 1).

[0009] For example, in the case of a conductive path consisting of a bellows-shaped cylindrical conductor, increasing the number of stages in the axial direction (number of stages arranged by reduced diameter and expanded diameter sections), and in the case of a conductive path consisting of a helical conductor, increasing the number of turns, allows for expansion and contraction by a desired amount in the axial direction. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 10-284347 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] As described above, increasing the number of stages in the bellows-shaped conductor or increasing the number of turns in the helical conductor tends to increase the current-carrying distance of the conductive path and the resistance value. Furthermore, the amount of heat generated when a high-frequency current flows through the conductive path (hereinafter simply referred to as the amount of heat generated during current flow) increases, which may make it difficult to obtain the desired current-carrying capacity.

[0012] For example, if the diameter of the conductive path is increased in the radial direction, or simply increased in thickness (in the case of a spiral conductor, the wire diameter is increased), the cross-sectional area perpendicular to the direction of current flow in the conductive path becomes larger, which may suppress the amount of heat generated when current is flowing.

[0013] However, in the conductive path section, it is necessary to avoid interference with the inner wall surface of the vacuum vessel (because it is limited to less than the inner diameter of the vacuum vessel), so it may be difficult to enlarge the diameter of the conductive path section, which could lead to an increase in the diameter of the vacuum vessel. In addition, if the wall thickness is increased, the elastic modulus (e.g., spring constant) will increase, which may reduce the operability of the vacuum capacitor (for example, the operating force required to move the movable electrode support and the movable electrode in the axial direction will increase).

[0014] The present invention has been made in view of the aforementioned technical problems, and aims to provide a vacuum capacitor that can contribute to making it easier to obtain the desired high-frequency current conducting capability and operability. [Means for solving the problem]

[0015] The vacuum capacitor according to this invention is a creation that can solve the above-mentioned problems, and one embodiment thereof comprises a vacuum container formed by having a cylindrical body which is at least a part of which is insulating, closing one side of the cylindrical body which is a fixed side which is a fixed side conductor and closing the other side which is a movable side which is a movable side conductor, a fixed electrode provided on one side in the axial direction within the vacuum container, a movable electrode support portion which is positioned in the vacuum container opposite to the fixed electrode and is movable in the axial direction, a movable electrode provided on one side of the movable electrode support portion which is opposite to the fixed electrode and forms capacitance with the fixed electrode, a bellows which is cylindrical and expandable in the axial direction between the movable electrode support portion and the movable side conductor and supports the movable electrode support portion on the movable side conductor, and a conductive path portion which is cylindrical in shape which is expandable in the axial direction and has a larger diameter than the bellows and is positioned coaxially on the outer circumference of the bellows and engages with the movable electrode support portion and the movable side conductor.

[0016] The vacuum chamber is divided by the bellows into a vacuum chamber on the outer circumference side of the bellows and an atmospheric chamber on the inner circumference side of the bellows. The conductive path consists of elastic conductors, each having a shape that extends along the circumferential direction of the conductive path, superimposed in multiple stages with respect to the axial direction. The elastic conductors are provided with multiple alternating curved portions along the circumferential direction, each having a curved portion that is convex on one side of the axial direction and another curved portion that is convex on the other side of the axial direction.

[0017] In the case of pairs of steps that are adjacent in the axial direction among the steps that are superimposed in the multi-step manner, the curved portion on one of the steps that is convex in the direction of the adjacent step and the curved portion on the other of the steps that is convex in the direction of the adjacent step are positioned opposite each other in the direction of the adjacent step and are fixed to each other.

[0018] Furthermore, the curved portion provided on one of the steps, which is convex in the direction opposite to the adjacent direction, and the curved portion provided on the other of the steps, which is convex in the direction opposite to the adjacent direction, are each positioned opposite to each other in the adjacent direction with a gap in between.

[0019] In the second embodiment, a base portion is provided at the other side of the movable electrode support portion in the axial direction and on the outer circumference side of the bellows, the base portion having a shape that extends from that position to the other side in the axial direction, one side of the conductive path portion in the axial direction is joined to the end of the base portion in the extending direction, and the other side of the conductive path portion in the axial direction is joined to the movable side conductor.

[0020] In the third embodiment, the cylindrical body comprises at least an insulating tube made of an insulating material and a flange tube coaxially connected to the other side of the insulating tube in the axial direction. The inner circumferential surface of the flange tube is provided with a first base portion that extends radially inward from the cylindrical body, and the first base portion is located on one side in the axial direction from the conductive path portion.

[0021] A second base portion is provided on the other side of the movable electrode support portion in the axial direction, at a position between the bellows and the conductive path portion, and the second base portion is shaped to extend from that position to the other side in the axial direction, with the end of the second base portion in the extending direction protruding further than the conductive path portion in the axial direction and bent outward in the radial direction.

[0022] Furthermore, one side of the conductive path portion in the axial direction is joined to the first base portion, and the other side of the conductive path portion in the axial direction is joined to the end of the second base portion in the extension direction.

[0023] The elastic conductor may be characterized in that it is obtained by shaping a long strip-shaped metal material so as to extend along the circumferential direction. Further, the elastic conductor may be characterized in that it is shaped like a wave washer or a coiled wave spring.

Advantages of the Invention

[0024] As described above, according to the present invention, it is possible to contribute to easily obtaining the energization ability and operability of a desired high-frequency current.

Brief Description of the Drawings

[0025] [Figure 1] Schematic explanatory view (vertical sectional view in the axial direction) of the vacuum capacitor 1A in the embodiment. [Figure 2] Schematic configuration diagram (view facing the axial direction) of the wave washer-shaped elastic conductor 6. [Figure 3] Partial side view of the mesh cylindrical conductive path portion 5 viewed from the outside in the radial direction (perspective view viewed from a position offset to the other side in the axial direction). [Figure 4] Schematic explanatory view (vertical sectional view in the axial direction) of the vacuum capacitor 1B in the embodiment.

Modes for Carrying Out the Invention

[0026] The vacuum capacitor according to the embodiment of the present invention is completely different from a configuration using a bellows-shaped cylindrical conductor (hereinafter, simply referred to as a bellows-shaped cylindrical conductive path portion) as shown in Patent Document 1, for example.

[0027] That is, the vacuum capacitor of the present embodiment has a mesh cylindrical conductive path portion (hereinafter, simply referred to as a mesh cylindrical conductive path portion) that is axially telescopic and has a larger diameter than a bellows, and is arranged coaxially on the outer peripheral side of the bellows, and is engaged with a movable electrode support portion and the movable-side conductor.

[0028] The mesh-like tubular conductive path is formed by superimposing elastic conductors (for example, long, strip-shaped, elastic conductors along the circumferential direction) of the mesh-like tubular conductive path in a multi-stage manner relative to the axial direction.

[0029] The elastic conductor has a shape in which a convex curved portion on one side in the axial direction (hereinafter simply referred to as the one-sided curved portion) and a convex curved portion on the other side in the axial direction (hereinafter simply referred to as the other-sided curved portion) are alternately arranged along the circumferential direction, resulting in an overall wavy shape in the circumferential direction.

[0030] Furthermore, in each of the steps in which the elastic conductors are superimposed in a multi-stage manner as described above, a pair of steps adjacent to each other in the axial direction (hereinafter simply referred to as adjacent steps as appropriate) is assumed to have a fixed portion formed when a curved portion provided on one of the adjacent steps that is convex in the direction of the adjacent step (hereinafter simply referred to as the adjacent direction as appropriate) and a curved portion provided on the other of the adjacent steps that is convex in the direction of the adjacent step are positioned opposite each other in the adjacent direction and fixed to each other.

[0031] On the other hand, assume that a curved portion on one of the adjacent steps, which is convex on the opposite side in the adjacent direction, and a curved portion on the other of the adjacent steps, which is convex on the opposite side in the adjacent direction, are each positioned opposite each other in the adjacent direction with a gap in between (i.e., positioned to form a gap).

[0032] In other words, the mesh-like tubular conductive path section has a configuration in which fixed portions and gap portions are alternately and repeatedly provided along the circumferential direction between adjacent stages.

[0033] In a mesh-like cylindrical conductive path with this configuration, the gaps between adjacent stages compress and expand in the axial direction, causing elastic deformation and resulting in the entire structure expanding and contracting in the axial direction. Furthermore, high-frequency currents can flow in the axial direction while passing through the fixed portions between adjacent stages.

[0034] Comparing the mesh-type tubular conductive path with the bellows-type tubular conductive path, the following differences can be observed. First, in the bellows-type tubular conductive path, the entire structure expands and contracts axially as the reduced-diameter and expanded-diameter sections flex and expand in the axial direction, which can make it prone to buckling and fracture. Methods to suppress this buckling and fracture include, for example, (1) increasing the wall thickness of the reduced-diameter and expanded-diameter sections, and (2) reducing the radius of curvature to limit the amount of flexing and expanding motion (flexing and expanding within the range where buckling does not occur).

[0035] However, applying method (1) above may increase the elastic modulus of the reduced-diameter and expanded-diameter sections, potentially leading to increased bending stress. Furthermore, applying method (2) above may increase the number of axial steps when configuring the bellows-shaped conductive path to expand and contract by a desired amount.

[0036] Furthermore, the radial dimensions of the bellows-shaped conductive path change due to the axial bending and expanding movements of the reduced and expanded diameter sections. For this reason, one approach is to provide sufficient clearance between the bellows-shaped conductive path and the inner wall surface of the vacuum vessel to suppress interference between the two. However, this may make it difficult to increase the diameter of the bellows-shaped conductive path or may lead to an increase in the diameter of the vacuum vessel.

[0037] In contrast, the mesh-type tubular conductive path is designed so that the gaps between adjacent stages compress and expand in the axial direction, resulting in elastic deformation. Compared to the bellows-type tubular conductive path, this design is more susceptible to buckling and breakage. Furthermore, the gaps can be compressed until the curved sections forming the gaps are joined together (i.e., flat). In other words, the gaps between adjacent stages can undergo elastic deformation (compression and expansion) with a larger change in diameter compared to the reduced-diameter and expanded-diameter sections of a bellows-type conductor.

[0038] Therefore, since there is no need to employ the methods described in (1) and (2) above, the modulus of elasticity can be reduced, making it easier to suppress bending stress. Furthermore, in the mesh-type tubular conductive path section, it is entirely possible to expand and contract the desired amount even with fewer steps than in the bellows-type tubular conductive path section.

[0039] Furthermore, even if the gaps between adjacent stages are compressed or expanded in the axial direction, the radial dimensions can be suppressed to prevent changes. As a result, interference between the mesh-like tubular conductive path and the inner wall surface of the vacuum vessel can be easily suppressed without providing the aforementioned clearance.

[0040] Therefore, it can be seen that in a vacuum capacitor using a mesh-type cylindrical conductive path, the desired operability is easier to obtain and the product life is easier to extend compared to a configuration using a bellows-type cylindrical conductive path. Furthermore, it can be seen that the creepage distance in the axial direction of the mesh-type cylindrical conductive path is easier to shorten, resulting in lower resistance and heat generation during current flow, making it easier to obtain the desired current-carrying capacity. In addition, it can be seen that it is easier to increase the diameter of the mesh-type cylindrical conductive path and to miniaturize the vacuum vessel.

[0041] The vacuum capacitor of this embodiment has a configuration in which a mesh-like cylindrical conductive path is applied as described above, and it is sufficient that the gap between adjacent stages can be compressed and expanded in the axial direction to undergo elastic deformation, and that high-frequency current can flow in the axial direction while passing through the fixed parts between adjacent stages, allowing for a variety of design modifications. In other words, it is possible to appropriately apply common technical knowledge from various fields (for example, the vacuum capacitor field, the bellows field, the elastic conductor field, etc.) and modify the design by appropriately referring to prior art documents as needed, and the following embodiment is given as an example.

[0042] In the following embodiments, detailed explanations are omitted as appropriate, for example, by referring to the same reference numerals for similar content.

[0043] Examples <Main components of vacuum capacitor 1A> Figures 1 to 3 illustrate the configuration of a vacuum capacitor 1A according to an embodiment. In this vacuum capacitor 1A, a vacuum container 10 is formed by closing both ends (one side in the axial direction and the other side in the axial direction) of a cylindrical body 1, which is at least partially insulating, with a fixed conductor 2 and a movable conductor 3, respectively.

[0044] The vacuum container 10 is equipped with a fixed electrode 21 provided on the fixed-side conductor 2 side within the vacuum container 10, a movable electrode support 30 positioned opposite the fixed electrode 21 within the vacuum container 10 and movable in the axial direction (towards both ends of the cylindrical body 1), and a movable electrode 31 provided opposite the fixed electrode 21 on one side of the movable electrode support 30 in the axial direction, forming capacitance between it and the fixed electrode 21.

[0045] Between the movable electrode support portion 30 and the movable conductor 3 within the vacuum vessel 10, there is a bellows 4 that is cylindrical and expandable in the axial direction, supporting the movable electrode support portion 30 on the movable conductor 3. One side of the bellows 4 in the axial direction is joined to the other side of the movable electrode support portion 30 in the axial direction, and the other side of the bellows 4 in the axial direction is joined to the inner wall side of the movable conductor 3.

[0046] With this bellows 4, the outer circumference of the bellows 4 within the vacuum vessel 10, that is, the space (hereinafter referred to as the vacuum chamber) 11 surrounded by the cylindrical body 1, the fixed-side conductor 2, the movable-side conductor 3, the bellows 4, and the movable electrode support part 30, is kept airtight (airtight enough to create a vacuum), while the movable electrode 31 and the movable electrode support part 30 are configured to move in the axial direction. Furthermore, an atmospheric pressure space (hereinafter referred to as the atmospheric chamber) 12 is formed on the inner circumference of the bellows 4 within the vacuum vessel 10.

[0047] On the outer circumference of the bellows 4 in the vacuum chamber 11, there is a mesh-like cylindrical conductive path section 5 that is expandable and contractible in the axial direction and has a larger diameter than the bellows 4. This mesh-like cylindrical conductive path section 5 is positioned coaxially on the outer circumference of the bellows 4, and both ends of the mesh-like cylindrical conductive path section 5 in the axial direction engage with the movable electrode support section 30 and the movable side conductor 3, respectively, making them electrically connected. In the case of the mesh-like cylindrical conductive path section 5 shown in Figure 1, one end 5a in the axial direction engages with the movable electrode support section 30 (in the case of Figure 1, it engages indirectly via the base section 81 described later), and the other end 5b in the axial direction engages with the movable side conductor 3, making them electrically connected.

[0048] This mesh-like cylindrical conductive path section 5 has elastic conductors 6 that extend along the circumferential direction of the mesh-like cylindrical conductive path section 5, and these elastic conductors 6 are superimposed in a multi-stage manner with respect to the axial direction (in the case of Figure 3, N stages (where N is a natural number of 2 or more) are superimposed).

[0049] The elastic conductor 6 has a shape in which a curved portion 61 that is convex on one side in the axial direction and a curved portion 62 that is convex on the other side in the axial direction are alternately arranged along the circumferential direction, resulting in an overall wavy shape that extends in the circumferential direction. In the case of the elastic conductor 6 shown in Figure 2, the central part of the curved portion 61 is located in the area indicated by the dashed line in the figure, and the central part of the curved portion 62 is located in the area indicated by the dashed line in the figure.

[0050] As described above, in the case of adjacent stages, which are pairs of stages adjacent to each other in the axial direction among the stages in which the elastic conductor 6 is superimposed in a multi-stage manner, the curved portion that is convex in the adjacent direction of the one-sided curved portion 61 and2 provided on one of the adjacent stages are positioned opposite each other in the adjacent direction and are fixed to each other, thereby forming a fixing portion 71.

[0051] Furthermore, the curved portion 61 on one side and the curved portion 62 on the other side of adjacent steps, which are convex on the opposite side in the adjacent direction, and the curved portion 61 on one side and the curved portion 62 on the other side of the adjacent steps, which are convex on the opposite side in the adjacent direction, are each positioned opposite each other in the adjacent direction with a gap 72 in between.

[0052] As a result, the mesh-like cylindrical conductive path section 5 has a configuration in which fixing portions 71 and gap portions 72 are alternately provided along the circumferential direction between adjacent stages. Furthermore, the gap portions 72 between adjacent stages are compressed and expanded in the axial direction, causing elastic deformation, so that the entire structure can expand and contract in the axial direction. In addition, high-frequency currents that can flow through the mesh-like cylindrical conductive path section 5 can flow in the axial direction while passing through the fixing portions between adjacent stages. For example, as shown by arrows Y1 and Y2 in Figure 3, high-frequency currents will flow in a meandering manner in the axial direction.

[0053] The materials (electrode materials, metal materials, conductive materials, insulating materials, etc.), shapes, and processing and assembly methods of each component of the vacuum capacitor 1A described above can be appropriately applied in various forms depending on the intended use of the vacuum capacitor 1A, as long as the structure is appropriately designed so that each component does not interfere with one another. One example is shown below.

[0054] <An example of a vacuum container 10> The vacuum container 10 can be formed by closing both ends in the axial direction of a cylindrical body 1, at least a portion of which is insulating, with a fixed conductor 2 and a movable conductor 3, respectively, and by forming a vacuum chamber 11 and an atmospheric chamber 12 within the vacuum container 10 via a bellows 4 or the like, and various configurations can be applied.

[0055] In the case of the cylindrical body 1 shown in Figure 1, an insulating tube 13 made of an insulating material (e.g., ceramic material) has flange tubes 14 (for the fixed conductor 2 side) and 15 (for the movable conductor 3 side) made of a metal material (e.g., copper, stainless steel (SUS), various alloys (e.g., beryllium copper), and metal materials that have undergone various processing treatments (copper plating, copper lamination, etc.). The same applies hereinafter) connected coaxially to both ends of the insulating tube 13 in the axial direction. The ends of the cylindrical body 1 are closed by flat plate-shaped fixed conductor 2 and movable conductor 3, respectively, made of a metal material.

[0056] In such a cylindrical body 1, it is preferable to have a configuration that makes it easy to maintain the vacuum state of the vacuum chamber 11 (suppress vacuum leakage). As an example, the radial wall thickness dimension of the insulating tube 13 can be made larger than the radial wall thickness dimension of the flange tubes 14 and 15, but it is preferable to design it appropriately so as not to interfere with other components adjacent to the insulating tube 13.

[0057] In particular, the other side of the cylindrical body 1 in the axial direction must be designed appropriately so as not to hinder the axial movement of the movable electrode support portion 30 and the movable electrode 31, and so as not to hinder the axial expansion and contraction of the mesh cylindrical conductive path portion 5. A specific example is to provide the insulating tube 13 of the cylindrical body 1 shown in Figure 1 at a position offset to one side in the axial direction of the cylindrical body 1.

[0058] In addition, while it is possible to construct the cylindrical body 1 using only the insulating pipe 13 (i.e., omitting the flange pipes 14 and 15), as mentioned above, in order to suppress interference with other components adjacent to the insulating pipe 13, it is recommended to construct it using at least the insulating pipe 13 and the flange pipe 15.

[0059] <An example of a fixed electrode 21 and a movable electrode 31> Both the fixed electrode 21 and the movable electrode 31 (hereinafter simply referred to as "both electrodes" as appropriate) are capable of forming a capacitance between them, and the capacitance changes according to the axial movement of the movable electrode 31. Various configurations can be applied to each. One example is a configuration in which both electrodes can intersect axially in a non-contact state, and a desired capacitance is formed between the two electrodes according to the amount of intersection (intersection area) in the axial direction.

[0060] In the case of the two electrodes shown in Figure 1, the electrode group consists of multiple substantially cylindrical electrode members (thin-walled electrode members with small radial thickness) 21a, 31a, each with a different inner diameter, arranged concentrically at regular intervals. The electrode members of both electrodes can intersect axially without contacting each other, and a desired capacitance can be formed between the two electrodes depending on the amount of axial intersection.

[0061] Instead of the multiple substantially cylindrical electrode members described above, each electrode may be fitted with an electrode member that extends in a spiral shape. In this case as well, the electrode members of both electrodes can intersect axially in a non-contact state, and a desired capacitance can be formed between the two electrodes depending on the amount of intersection in the axial direction.

[0062] <An example of a movable electrode support part 30> The movable electrode support portion 30 only needs to be configured to be movable in the axial direction while supporting the movable electrode 31, and various configurations can be applied.

[0063] In the case of the movable electrode support portion 30 shown in Figure 1, it is made of a metal material and is a flat plate shape extending in the radial direction, with the central part being thickened in the axial direction. The movable electrode 31 is supported on one side of the movable electrode support portion 30 in the axial direction.

[0064] A movable rod (a cylindrical movable rod in Figure 1) 32 is provided in the center of the rear side of the movable electrode support portion 30 (the other side in the axial direction where the movable electrode 31 is not provided), with a shape that extends from the center in the other side in the axial direction (in Figure 1, it extends so as to penetrate and protrude through the movable conductor 3 side of the vacuum container 10).

[0065] In the case of the movable rod 32 shown in Figure 1, it is supported via a bearing member 34 provided in the vacuum container 10 (provided in the through hole 33 approximately in the center of the movable conductor 3 in Figure 1) so as to be able to slide freely in the axial direction (the outer surface of the movable rod 32 slides freely on the bearing member 34).

[0066] By moving this movable rod 32 in the axial direction via, for example, a drive source (motor, etc.) not shown, the movable electrode support portion 30 moves together with the movable electrode 31 in the axial direction.

[0067] Reference numeral 35 in Figure 1 indicates a rod (hereinafter referred to as the insulating operation rod) that moves the movable rod 32 while being guided in the axial direction by a bearing member 34, and adjusts the capacitance in the vacuum capacitor 1A to perform an insulating operation. In the case of the insulating operation rod 35 shown in Figure 1, one end of the insulating operation rod 35 (the side on which the male threaded portion 35b is formed in Figure 1) is screwed into the other side of the movable rod 32 in the axial direction (in Figure 1, the male threaded portion 35b formed on the insulating operation rod 35 is screwed into the female threaded portion 32a formed on the inner wall of one end of the movable rod 32). The other end of the insulating operation rod 35 (the side on which a head 35a made of, for example, an insulating material is formed in Figure 1) is configured to allow connection of a drive source (motor, etc.) not shown.

[0068] Furthermore, the insulated operating rod 35 is rotatably supported by a support (in Figure 1, a support consisting of a screw receiving portion 36a and a thrust bearing 36b for reducing rotational torque) 36 provided on the vacuum vessel 10 (in Figure 1, it protrudes from the bearing member 34 and is fixed so as to cover the other side of the movable rod 32 in the axial direction).

[0069] <An example of bellows 4> The bellows 4 is a cylindrical shape that can expand and contract in the axial direction, and only needs to be able to support the movable electrode support portion 30 so as to be movable relative to the movable conductor 3 while maintaining an airtight seal on the vacuum chamber 11, and various configurations can be applied.

[0070] The bellows 4 shown in Figure 1 is a molded body formed from a metal material (for example, stainless steel) into a thin-walled bellows-like cylindrical shape, in which a reduced diameter section 41 and an expanded diameter section 42 are arranged alternately in multiple stages in the axial direction (for example, about 10 to 20 reduced diameter sections 41 and expanded diameter sections 42 are arranged alternately).

[0071] <An example of a mesh-type tubular conductive path section 5> The mesh-like cylindrical conductive path section 5 is a mesh-like cylindrical structure in which elastic conductors 6, which have a wavy shape extending in the circumferential direction, are superimposed in multiple stages in the axial direction, and the gaps 72 between adjacent stages are compressed and expanded in the axial direction, causing the whole to expand and contract in the axial direction, and a high-frequency current can flow in the axial direction while passing through the fixed parts 71 of adjacent stages. Various embodiments can be applied.

[0072] For example, in the case of the elastic conductor 6, it is possible to obtain a long, strip-shaped conductor (e.g., a long linear conductor, a long flat plate conductor, etc.) made of a metallic material (e.g., metallic materials such as copper and stainless steel (SUS), as well as various alloys (beryllium copper, etc.) and metallic materials that have undergone various processing treatments (copper plating, copper lamination, etc.)) by forming it to extend in a wavy pattern along the circumferential direction. A specific example is to obtain the long, strip-shaped conductor described above by forming it into a wave washer shape or a coiled wave spring shape along the circumferential direction. In the case of the elastic conductor 6 shown in Figure 2, the structure is such that a long flat plate conductor is formed into a wave washer shape.

[0073] The fixing portion 71 can be formed by appropriately fixing one curved portion 61 and the other curved portion 62 which are positioned opposite each other with a convex shape in the adjacent direction. Examples of such fixing methods include welding, brazing, riveting, etc.

[0074] In such a fixed portion 71, when a high-frequency current flows, both the curved portion 61 on one side and the curved portion 62 on the other side related to the fixed portion 71 generate heat through current, making vacuum adhesion between the two more likely. When this vacuum adhesion occurs, the resistance (contact resistance) of the fixed portion 71 is easily reduced, and the fixed structure is easily strengthened (self-recovered). In addition, when the mesh cylindrical conductive path portion 5 shrinks in the axial direction, the fixing force of the fixed portion 71 is increased, so similarly the resistance (contact resistance) of the fixed portion 71 is easily reduced. As a result, the ability to conduct high-frequency current is increased, and the reliability of the vacuum capacitor 1A is also increased.

[0075] The cross-sectional shape of the elastic conductor 6 is designed to allow the elastic conductor 6 to deform easily in the axial direction, such that the thickness dimension in the axial direction (dimension t1 in Figure 3) is small. For example, when forming using a long, flat conductor, it is possible to apply a shape with an extremely thin thickness dimension (for example, a shape as thin as metal foil) while maintaining the desired mechanical strength.

[0076] The shape and number of the curved portions 61 and 62 on one side of the elastic conductor 6, and the shape and number of stages of the mesh-like cylindrical conductive path 5 formed by superimposing the elastic conductors 6, can be appropriately set according to the target vacuum capacitor 1A, for example. In the case of the elastic conductor 6 shown in Figure 2, the curved portions 61 and 62 on one side are arranged alternately in the circumferential direction, with four of each provided, but the design is not limited to this configuration.

[0077] The ends 5a and 5b of the mesh cylindrical conductive path section 5 may have a plain end shape, which is a wavy shape extending in the circumferential direction, similar to the other steps, or they may have a shim end shape, which is a flat shape, as shown in Figure 3. In the case of the mesh cylindrical conductive path section 5 having shim end shapes 5a and 5b, adjacent steps containing these ends 5a and 5b will have a configuration in which the fixing portion 71 and the gap portion 72 are alternately provided along the circumferential direction, as shown in Figure 3. In addition, the area of ​​the engagement surface with the movable electrode support portion 30 and the movable side conductor 3 (or the engagement surface with the base portions 81, 82, and 83 described later) tends to be large. For this reason, when the elastic force acting on the engagement surface when the mesh cylindrical conductive path section 5 expands and contracts in the axial direction is applied, it tends to be uniformly dispersed.

[0078] When a wave washer-shaped elastic conductor 6 is applied, the number of stages in the mesh-tube conductive path 5 increases each time the elastic conductor 6 is superimposed coaxially. On the other hand, when a coiled wave spring-shaped elastic conductor 6 is applied, the elastic conductor 6 extends spirally along the circumferential direction, and the number of stages in the mesh-tube conductive path 5 increases each time one rotation in the circumferential direction is completed and the next rotation begins.

[0079] One method for increasing the current-carrying capacity of the mesh-like cylindrical conductive path 5 is to increase the outer diameter circumference of the mesh-like cylindrical conductive path 5, which is inversely proportional to the electrical resistance of the high-frequency current. Another method is to shorten the current path as shown by the arrows Y1 and Y2 in Figure 3.

[0080] Specific examples include reducing the number of stages in the mesh-like tubular conductive path section 5 (to at least less than the number of stages in the bellows 4), and / or shortening the distance between the apex of one curved section 61 and the apex of the other curved section 62 in each stage (elastic conductor 6).

[0081] <An example of a structure using a base> The ends 5a and 5b of the mesh-like cylindrical conductive path section 5 may be directly engaged with the movable electrode support section 30 and the movable side conductor 3, or they may be indirectly engaged with them.

[0082] In the case of the vacuum capacitor 1A shown in Figure 1, the end portion 5a of the mesh cylindrical conductive path portion 5 is indirectly engaged with the movable electrode support portion 30 via a base portion 81 provided on the other side of the axial direction of the movable electrode support portion 30 and on the outer circumference side of the bellows 4.

[0083] In the case of the base portion 81 shown in Figure 1, it is cylindrical with a larger diameter than the bellows 4 and is positioned coaxially with respect to the bellows 4 on the other side in the axial direction of the movable electrode support portion 30. As a result, the base portion 81 is configured to extend from the movable electrode support portion 30 to the other side in the axial direction. The end portion 5a of the mesh cylindrical conductive path portion 5 engages with the other end portion 8a of the base portion 81 in the axial direction. In the case of the end portion 8a shown in Figure 1, it has an enlarged diameter shape that is bent radially outward, and is configured to facilitate engagement with the end portion 5a of the mesh cylindrical conductive path portion 5.

[0084] By using such a base portion 81, it becomes possible to shorten the mesh cylindrical conductive path portion 5 in the axial direction according to the axial dimensions of the base portion 81. Furthermore, since the base portion 81 can have a shape that simply extends in the axial direction, rather than a stepped shape like the mesh cylindrical conductive path portion 5, the creepage distance in the axial direction becomes shorter. Consequently, the current path of the high-frequency current flowing between the movable electrode support portion 30 and the movable side conductor 3 is shortened.

[0085] Furthermore, since the mesh-like tubular conductive path section 5 is positioned offset to the other side in the axial direction between the movable electrode support section 30 and the movable conductor 3, interference with, for example, the insulating tube 13 is more easily suppressed.

[0086] <Other examples of structures using a base> The vacuum capacitor 1B shown in Figure 4 has the same configuration as the vacuum capacitor 1A, in which the end 5a of the mesh cylindrical conductive path 5 is indirectly engaged with the movable conductor 3 via the flange tube 15 and the base portion 82 (first base portion) located on the other side in the axial direction of the cylindrical body 1. Furthermore, the end 5b of the mesh cylindrical conductive path 5 is indirectly engaged with the movable electrode support portion 30 via the base portion 83 (second base portion) provided on the other side in the axial direction of the movable electrode support portion 30, between the bellows 4 and the mesh cylindrical conductive path 5.

[0087] In the case of the base portion 82 shown in Figure 4, it is flange-shaped, extending radially inward from the inner circumferential surface of the flange pipe 15 and extending circumferentially, and is positioned offset to one side in the axial direction from the end portion 5a of the mesh cylindrical conductive path portion 5. The end portion 5a of the mesh cylindrical conductive path portion 5 is engaged with the other side in the axial direction of the base portion 82.

[0088] Furthermore, in the case of the base portion 83 shown in Figure 4, it has a cylindrical shape with a larger diameter than the bellows 4, and is positioned coaxially (coaxial with both) between the bellows 4 and the mesh cylindrical conductive path portion 5 on the other side in the axial direction of the movable electrode support portion 30. As a result, the base portion 83 is configured to extend from the movable electrode support portion 30 to the other side in the axial direction.

[0089] The other end 8b of the base portion 83 in the axial direction protrudes further in the other axial direction than the end 5b of the mesh cylindrical conductive path portion 5, and is bent radially outward. In the case of the end 8b shown in Figure 4, it is bent so that it has approximately the same diameter as the mesh cylindrical conductive path portion 5. The end 5b of the mesh cylindrical conductive path portion 5 engages with one side of the end 8b in the axial direction.

[0090] By using the base portions 82 and 83 described above, it is possible to shorten the mesh cylindrical conductive path portion 5 in the axial direction depending on the installation position of the base portion 82 on the flange pipe 15 and the axial dimensions of the base portion 83. Furthermore, the base portion 82 is simply an extension from the flange pipe 15, and the base portion 83 can be simply an extension in the axial direction, similar to the base portion 81. For this reason, even when the base portions 82 and 83 are applied, there is a good chance that the length of the current path of the high-frequency current flowing between the movable electrode support portion 30 and the movable side conductor 3 can be suppressed.

[0091] Furthermore, since the mesh-like tubular conductive path section 5 is always positioned offset to the other side in the axial direction from the insulating tube 13, interference with the insulating tube 13 can be avoided.

[0092] Furthermore, the elastic force of the bellows 4 when it expands and contracts and the elastic force of the mesh tubular conductive path section 5 when it expands and contracts act in opposite directions in the axial direction and tend to cancel each other out. As a result, the operating force required to move, for example, the movable electrode support section 30 and the movable electrode 31 in the axial direction is easily reduced.

[0093] <Examples of operation of vacuum capacitors 1A and 1B> In vacuum capacitors 1A and 1B, the insulating operating rod 35 is operated via a drive source (not shown) to move the movable rod 32 in the axial direction, which changes the amount of intersection between the fixed electrode 21 and the movable electrode 31, thereby adjusting the capacitance and performing impedance adjustment.

[0094] Furthermore, when a voltage is applied between the two electrodes of the vacuum capacitor 1A to induce a high-frequency current, the high-frequency current flows through the following current-carrying path. Specifically, the high-frequency current first flows through the fixed conductor 2 and then the fixed electrode 21, and then flows to the movable electrode 31 via the capacitance between the two electrodes.

[0095] Subsequently, current can flow from the movable electrode 31 to the movable conductor 3 via the movable electrode support 30, bellows 4, movable rod 32, and mesh tubular conductive path 5. However, due to the skin effect, the current mainly flows to the movable conductor 3 via the mesh tubular conductive path 5.

[0096] Although the present invention has been described in detail only with respect to the specific examples described above, it will be obvious to those skilled in the art that a wide variety of modifications are possible within the scope of the technical concept of the present invention, and it is natural that such modifications fall within the scope of the claims. [Explanation of Symbols]

[0097] 1A, 1B... Vacuum capacitor, 10... Vacuum container, 1... Cylindrical body 21...Fixed electrode, 31...Movable electrode, 30...Movable electrode support part 4... Bellows 5…Mesh tubular conductive path section, 6…Elastic conductor 61...Curved section on one side, 62...Curved section on the other side 71...Fixed portion, 72...Gap portion 81, 82, 83... Base part

Claims

1. A vacuum vessel having a cylindrical body in which at least a portion is insulating, wherein one side of the cylindrical body in the axial direction, the fixed side, is closed with a fixed-side conductor, and the other side in the axial direction, the movable side, is closed with a movable-side conductor, A fixed electrode provided on one side in the axial direction within the vacuum vessel, A movable electrode support portion is positioned in the vacuum chamber opposite to the fixed electrode and is movable in the axial direction, A movable electrode is provided on one side of the movable electrode support portion in the axial direction, facing the fixed electrode, and forming capacitance between itself and the fixed electrode, A bellows is provided between the movable electrode support portion and the movable side conductor, which is cylindrical and expandable in the axial direction, and which supports the movable electrode support portion on the movable side conductor. A conductive path portion that is expandable and contractible in the axial direction, has a larger diameter than the bellows, is positioned coaxially on the outer circumference of the bellows, and engages with the movable electrode support portion and the movable side conductor, Equipped with, The vacuum chamber is divided by the bellows into a vacuum chamber on the outer circumference side of the bellows and an atmospheric chamber on the inner circumference side of the bellows. The conductive path portion is formed by elastic conductors, each having a shape that extends along the circumferential direction of the conductive path portion, being superimposed in a multi-stage manner with respect to the axial direction. The elastic conductor has multiple curved portions arranged alternately along the circumferential direction, with a convex curved portion on one side in the axial direction and a convex curved portion on the other side in the axial direction. Among the multi-stage superimposed stages, in pairs of stages that are adjacent in the axial direction, The curved portion on one of the steps that is convex in the direction of the adjacent step, and the curved portion on the other of the steps that is convex in the direction of the adjacent step, are each positioned facing each other in the direction of the adjacent step and are fixed to each other. A curved portion provided on one of the aforementioned steps, which is convex in the direction opposite to the adjacent direction, and a curved portion provided on the other of the aforementioned steps, which is convex in the direction opposite to the adjacent direction, are each positioned opposite to each other in the direction of the adjacent direction, with a gap in between. A vacuum capacitor characterized by the following features.

2. A base portion is provided on the other side of the movable electrode support portion in the axial direction, on the outer circumference side of the bellows, with a shape that extends from that position to the other side in the axial direction. One side of the conductive path portion in the axial direction is joined to the end of the base portion in the extension direction, The other side of the conductive path in the axial direction is joined to the movable conductor. The vacuum capacitor according to claim 1, characterized by its features.

3. The cylindrical body comprises at least, An insulating tube made of an insulating material, A flange pipe is coaxially connected to the other side of the insulating pipe in the axial direction, It consists of having, A first base portion is provided on the inner circumferential surface of the flange pipe, having a shape that extends radially inward from the cylindrical body. The first base portion is located on one side in the axial direction of the conductive path portion, A second base portion is provided on the other side of the movable electrode support portion in the axial direction, at a position between the bellows and the conductive path portion, with a shape that extends from that position to the other side in the axial direction. The end portion of the second base portion in the extending direction is shaped to protrude to the other side in the axial direction from the conductive path portion and be bent outward in the radial direction. One side of the conductive path in the axial direction is joined to the first base portion, The other side of the conductive path portion in the axial direction is joined to the end of the second base portion in the extension direction. The vacuum capacitor according to claim 1, characterized by its features.

4. The vacuum capacitor according to any one of claims 1 to 3, characterized in that the elastic conductor is obtained by shaping a long, strip-shaped metal material so that it extends along the circumferential direction.

5. The vacuum capacitor according to any one of claims 1 to 3, characterized in that the elastic conductor is formed in the shape of a wave washer or a coiled wave spring.

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