Vacuum capacitor

Abstract

A vacuum container (10) comprises a mesh tubular conductive path (5) that is stretchable in the axial direction and that is coaxially provided on the outer circumference side of a tubular bellows (4) in the vacuum container (10). The mesh tubular conductive path (5) is obtained by superposing, in multiple stages in the axial direction, elastic conductors (6) that each extend in an undulating form along the circumferential direction of the mesh tubular conductive path (5). In a pair of stages that are adjacent to each other in the axial direction among the multiple stages in which the elastic conductors are superposed, a curved portion that protrudes in the adjacent direction among curved portions (61, 62) provided to one of the pair of stages and a curved portion that protrudes in the adjacent direction among curved portions (61, 62) provided to the other of the pair of stages face each other in the adjacent direction, and are fixed to each other to form a fixed portion (71). In the pair of stages, fixed portions (71) and gap portions (7(2) are alternately and repeatedly provided along the circumferential direction.

Description

Vacuum Capacitor

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

[0002] 2. Description of the Related Art Conventionally, various vacuum capacitors have been used for impedance adjustment in high-frequency devices such as high-frequency power supplies and high-power oscillator circuits in general semiconductor equipment.

[0003] A typical vacuum capacitor uses a vacuum container having a cylindrical body at least part of which is insulating, and this vacuum container is configured such that one side (hereinafter simply referred to as the one axial side) of the cylindrical body in the axial direction (hereinafter simply referred to as the axial direction) is closed with a fixed-side conductor, and the other side (hereinafter simply referred to as the other axial side) of the cylindrical body in the axial direction is closed with a movable-side conductor.

[0004] Within the vacuum vessel, there are provided a fixed electrode provided on one axial side (fixed conductor side) of the vacuum vessel, a movable electrode support part located opposite the fixed electrode within the vacuum vessel and movable in the axial direction, and a movable electrode provided opposite the fixed electrode on one axial side of the movable electrode support part and forming an electrostatic capacitance between it and the fixed electrode.

[0005] A cylindrical bellows, which is expandable and contractible in the axial direction and supports the movable electrode support on the movable conductor, is provided between the movable electrode support and the movable conductor. The bellows divides the interior of the vacuum vessel into a vacuum chamber on the outer periphery of the bellows and an atmospheric chamber on the inner periphery of the bellows.

[0006] In recent years, the load on high-frequency equipment has gradually increased, and the high-frequency current that can flow through such equipment has also increased. For this reason, vacuum capacitors used in such equipment are required to have a high ability to pass high-frequency current.

[0007] For example, in Patent Document 1, a conductive path portion that is larger in diameter than a bellows (a "first bellows" designated by reference numeral 16 in Patent Document 1) and is expandable and contractible in the axial direction is arranged coaxially on the outer periphery of the bellows, and is engaged (electrically connected) with both the movable electrode support portion and the movable-side conductor. This allows high-frequency current to flow more easily through the conductive path portion than through the bellows due to the skin effect.

[0008] Specific examples of conductive path sections include a configuration using a bellows-shaped tubular conductor (referred to in Patent Document 1 as the "second bellows" indicated by reference numeral 17) and a configuration using a spiral conductor (referred to in Patent Document 1 as the "spiral conductor" indicated by reference numeral 18).

[0009] For example, in the case of a conductive path portion made of a bellows-shaped tubular conductor, the number of stages in the axial direction (the number of stages arranged due to reduced diameter sections and expanded diameter sections) can be increased, and in the case of a conductive path portion made of a spiral conductor, the number of turns can be increased, thereby allowing each to expand and contract by the desired amount in the axial direction.

[0010] Japanese Patent Application Publication No. 10-284347

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

[0012] For example, if the diameter of the conductive path portion is increased in the radial direction or simply made thicker (in the case of a spiral conductor, the wire diameter is increased), the cross-sectional area of ​​the conductive path portion perpendicular to the current flow direction will increase, which may potentially reduce the amount of heat generated when current is passed through it.

[0013] However, since the conductive path portion needs to avoid interfering with the inner wall surface of the vacuum vessel (because it is limited to be less than the inner diameter of the vacuum vessel), it may be difficult to increase the diameter of the conductive path portion, which may result in an increase in the diameter of the vacuum vessel. Furthermore, if the conductive path portion is thickened, the elastic modulus (e.g., spring constant) increases, which may reduce the operability of the vacuum capacitor (e.g., the operating force required to move the movable electrode support portion and the movable electrode in the axial direction increases).

[0014] The present invention has been made in consideration of the above-mentioned technical problems, and has an object to provide a vacuum capacitor that can contribute to making it easier to obtain the desired high-frequency current carrying capacity and operability.

[0015] The vacuum capacitor of the present invention is an invention that can solve the above-mentioned problems, and one aspect thereof comprises: a vacuum container having a cylindrical body at least partially insulating, the fixed side of the cylindrical body being blocked with a fixed conductor and the movable side of the cylindrical body being blocked with a movable conductor; a fixed electrode provided on one side of the vacuum container in the axial direction; a movable electrode support part located opposite the fixed electrode within the vacuum container and movable in the axial direction; a movable electrode provided on one side of the movable electrode support part in the axial direction opposite the fixed electrode and forming a capacitance between it and the fixed electrode; a bellows that is cylindrical and expandable in the axial direction between the movable electrode support part and the movable conductor, and supports the movable electrode support part on the movable conductor; and a mesh cylindrical part that is expandable in the axial direction and has a larger diameter than the bellows, is positioned coaxially on the outer periphery of the bellows, and engages with the movable electrode support part and the movable conductor.

[0016] The interior of the vacuum vessel is divided by the bellows into a vacuum chamber on the outer periphery of the bellows and an atmospheric chamber on the inner periphery of the bellows, and the conductive path portion is formed by elastic conductors extending along the circumferential direction of the conductive path portion, stacked in multiple stages in the axial direction, and the elastic conductors have convex curved portions on one side of the axial direction and convex curved portions on the other side of the axial direction, which are alternately arranged multiple times along the circumferential direction.

[0017] In each pair of adjacent stages in the axial direction among the stages stacked in multiple stages, the curved portion provided on one of the stages that is convex in the adjacent direction and the curved portion provided on the other of the stages that is convex in the adjacent direction are positioned opposite each other in the adjacent direction and are fixed to each other.

[0018] The present invention is characterized in that the curved portion provided on one of the steps that is convex on the opposite side of the adjacent direction, and the curved portion provided on the other of the steps that is convex on the opposite side of the adjacent direction, are positioned opposite each other in the adjacent direction with a gap between them.

[0019] In the second aspect, a base portion having a shape extending from the other side of the axial direction of the movable electrode support portion on the outer periphery of the bellows is provided, and 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 a third aspect, the cylindrical body includes at least an insulating pipe made of an insulating material and a flange pipe coaxially connected to the insulating pipe on the other side in the axial direction, and a first pedestal portion is provided on an inner peripheral surface of the flange pipe and extends radially inward of the cylindrical body, and the first pedestal portion is located on one side in the axial direction of the conductive path portion.

[0021] A second base portion having a shape extending from the other side in the axial direction of the movable electrode support portion, between the bellows and the conductive path portion, is provided at the other side in the axial direction, and the end of the second base portion in the extending direction protrudes further to the other side in the axial direction than the conductive path portion and is bent radially outward.

[0022] The conductive path portion is characterized in that 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 obtained by forming a long strip of metal material so as to extend in the circumferential direction, or may be formed into a wave washer shape or a coiled wave spring shape.

[0024] As described above, the present invention can contribute to making it easier to obtain the desired high-frequency current carrying capacity and operability.

[0025] 1A is a schematic diagram of a vacuum capacitor 1A according to an embodiment (longitudinal cross-sectional view in the axial direction); FIG. 2A is a schematic diagram of a wave washer-shaped elastic conductor 6 (viewed in the axial direction); FIG. 3A is a partial side view of a mesh tubular conductive path portion 5 viewed from the outside in the radial direction (a perspective view viewed from a position offset to the other side in the axial direction); and FIG. 4B is a schematic diagram of a vacuum capacitor 1B according to an embodiment (longitudinal cross-sectional view in the axial direction).

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

[0027] That is, the vacuum capacitor of this embodiment has a configuration in which a meshed tubular conductive path portion (hereinafter simply referred to as a meshed tubular conductive path portion) that is expandable in the axial direction and has a larger diameter than the bellows is arranged coaxially on the outer periphery of the bellows and is engaged with the movable electrode support portion and the movable side conductor.

[0028] The mesh tubular conductive path portion is formed by stacking elastic conductors (for example, long, strip-shaped elastic conductors extending along the circumferential direction of the mesh tubular conductive path portion (hereinafter simply referred to as the circumferential direction) in multiple stages in 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-side curved portion) and a convex curved portion on the other side in the axial direction (hereinafter simply referred to as the other-side curved portion) are arranged alternately along the circumferential direction, giving the conductor an overall circumferentially wavy shape.

[0030] Furthermore, in a pair of adjacent stages (hereinafter simply referred to as adjacent stages) in the axial direction among the stages in which the elastic conductors are stacked in multiple stages as described above, a curved portion provided on one of the adjacent stages that is convex in the adjacent direction (hereinafter simply referred to as the adjacent direction) and a curved portion provided on the other of the adjacent stages that is convex in the adjacent direction are positioned opposite each other in the adjacent direction and fixed to each other, thereby forming a fixed portion.

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

[0032] That is, the mesh tubular conductive path portion has a configuration in which fixed portions and gap portions are alternately provided in adjacent stages along the circumferential direction.

[0033] In a mesh tubular conductive path section having such a configuration, the gaps between adjacent stages are elastically deformed by compressing and expanding in the axial direction, so that the entire section expands and contracts in the axial direction.Furthermore, high-frequency current can flow in the axial direction via the fixed portions between the adjacent stages.

[0034] Here, when comparing a mesh tubular conductive path portion with a bellows tubular conductive path portion, the following differences are found. First, in a bellows tubular conductive path portion, the reduced diameter portion and the expanded diameter portion bend and stretch in the axial direction, causing the entire portion to expand and contract in the axial direction, which can easily cause buckling, breakage, etc. Methods for suppressing this buckling, breakage, etc. include, for example, (1) thickening the walls of the reduced diameter portion and the expanded diameter portion, and (2) reducing the radius of curvature to limit the amount of bending and stretching (bending and stretching within a range that does not buckle).

[0035] However, when the method (1) is applied, the elastic modulus of the reduced diameter portion and the expanded diameter portion may increase, which may result in an increase in bending stress. Also, when the method (2) is applied, when the bellows-shaped tubular conductive path portion is configured to be able to expand and contract by a desired amount, the number of stages in the axial direction may increase.

[0036] Furthermore, the radial dimension of the bellows-shaped tubular conductive path portion changes due to the axial bending and stretching of the diameter-reducing portion and the diameter-expanding portion. For this reason, for example, sufficient clearance can be provided between the bellows-shaped tubular conductive path portion and the inner wall surface of the vacuum vessel to suppress interference between them, but this makes it difficult to increase the diameter of the bellows-shaped tubular conductive path portion or may result in an increase in the diameter of the vacuum vessel.

[0037] In contrast, in a mesh tubular conductive path section, the gaps between adjacent sections are configured to compress and expand in the axial direction and elastically deform, which can be said to be a configuration that is easier to suppress buckling, breakage, etc., compared to a bellows tubular conductive path section. Furthermore, the gaps can be compressed until the curved sections forming the gaps are joined to each other (i.e., flat). In other words, the gaps between adjacent sections can be elastically deformed (compressed and expanded) by a larger amount than the narrowing and widening sections of the bellows tubular conductor.

[0038] Therefore, since there is no need to adopt the methods (1) and (2) above, the elastic modulus can be reduced, and bending stress can be easily suppressed. Furthermore, even if the mesh tubular conductive path section has fewer stages than the bellows tubular conductive path section, it is still possible to expand and contract the mesh tubular conductive path section by a desired amount.

[0039] Furthermore, even if the gaps between adjacent stages are compressed or expanded in the axial direction, the radial dimension can be kept constant, which makes it easy to suppress interference between the mesh tubular conductive path portion and the inner wall surface of the vacuum vessel, etc., without providing the above-mentioned clearance between them.

[0040] Therefore, it can be seen that vacuum capacitors using meshed tubular conductive paths are more likely to achieve the desired operability and contribute to a longer product life than those using bellows-shaped tubular conductive paths. Furthermore, it is easier to shorten the axial creepage distance of the meshed tubular conductive path, which reduces the resistance and heat generation during current flow, making it easier to achieve the desired current-carrying capacity. It can also be seen that this contributes to the increased diameter of the meshed tubular conductive path and the miniaturization of the vacuum vessel.

[0041] The vacuum capacitor of this embodiment is capable of various design modifications as long as it has a configuration that uses a mesh tubular conductive path portion as described above, can elastically deform by compressing and expanding the gaps between adjacent stages in the axial direction, and allows high-frequency current to flow in the axial direction via the fixed portions between adjacent stages. That is, the design can be modified by appropriately applying common technical knowledge in various fields (e.g., the vacuum capacitor field, the bellows field, the elastic conductor field, etc.) and by appropriately referring to prior art documents as necessary. The following examples are examples of such modifications.

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

[0043] 1 to 3 illustrate the configuration of a vacuum capacitor 1A according to an embodiment. In this vacuum capacitor 1A, both axial ends (one axial side and the other axial side) of a cylindrical body 1, at least a portion of which is insulating, are closed by a fixed conductor 2 and a movable conductor 3, respectively, to form a vacuum vessel 10.

[0044] Within the vacuum vessel 10, there are provided a fixed electrode 21 provided on the side of the fixed side conductor 2 within the vacuum vessel 10, a movable electrode support part 30 arranged opposite the fixed electrode 21 within the vacuum vessel 10 and movable in the axial direction (towards both ends of the cylindrical body 1), and a movable electrode 31 arranged opposite the fixed electrode 21 on one side of the axial direction of the movable electrode support part 30 and forming an electrostatic capacitance between it and the fixed electrode 21.

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

[0046] The bellows 4 allows the movable electrode 31 and the movable electrode support part 30 to move axially while maintaining an airtight (airtight so as to create a vacuum) space 11 (hereinafter referred to as the vacuum chamber) surrounded by the outer periphery of the bellows 4 within the vacuum vessel 10, i.e., the cylindrical body 1, the fixed conductor 2, the movable conductor 3, the bellows 4, and the movable electrode support part 30. Inside the vacuum vessel 10, an atmospheric pressure space 12 (hereinafter referred to as the atmospheric chamber) is formed on the inner periphery of the bellows 4.

[0047] A meshed tubular conductive path portion 5 that is expandable and contractible in the axial direction and has a larger diameter than the bellows 4 is provided on the outer periphery of the bellows 4 in the vacuum chamber 11. The meshed tubular conductive path portion 5 is coaxially positioned on the outer periphery of the bellows 4, and both ends of the meshed tubular conductive path portion 5 in the axial direction are engaged with and electrically connected to the movable electrode support portion 30 and the movable-side conductor 3, respectively. In the case of the meshed tubular conductive path portion 5 shown in Figure 1, an end portion 5a on one side in the axial direction is engaged with the movable electrode support portion 30 (in the case of Figure 1, it is indirectly engaged via a pedestal portion 81, which will be described later), and an end portion 5b on the other side in the axial direction is engaged with the movable-side conductor 3, thereby providing electrical connection.

[0048] This mesh tubular conductive path portion 5 has elastic conductors 6 extending in the circumferential direction of the mesh tubular conductive path portion 5, and the elastic conductors 6 are stacked in multiple stages in the axial direction (in the case of Figure 3, they are stacked in N stages (N is a natural number of 2 or more)).

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

[0050] As described above, in each of the adjacent stages, which are a pair of stages adjacent to each other in the axial direction among the stages in which the elastic conductor 6 is stacked in multiple stages, the curved portion of one side curved portion 61 and the other side curved portion 62 provided on one of the adjacent stages that is convex in the adjacent direction, and the curved portion of one side curved portion 61 and the other side curved portion 62 provided on the other of the adjacent stages that is convex in the adjacent direction are positioned opposite each other in the adjacent direction and fixed to each other, thereby forming a fixed portion 71.

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

[0052] As a result, the mesh tubular conductive path portion 5 has a configuration in which fixed portions 71 and gaps 72 are alternately provided in the circumferential direction between adjacent stages. The gaps 72 between adjacent stages are compressed and expanded in the axial direction, thereby elastically deforming, allowing the mesh tubular conductive path portion 5 as a whole to expand and contract in the axial direction. Furthermore, high-frequency current that can flow through the mesh tubular conductive path portion 5 can flow in the axial direction while passing through the fixed portions between adjacent stages. For example, as shown by arrows Y1 and Y2 in FIG. 3, the high-frequency current flows in a meandering pattern in the axial direction.

[0053] The materials (electrode materials, metal materials, conductive materials, insulating materials, etc.) and shapes of the components of the vacuum capacitor 1A described above, as well as the processing and assembly methods of the components, can be suitably applied in various ways depending on the intended use of the vacuum capacitor 1A, as long as the components are designed appropriately so as not to interfere with each other.

[0054] <Example of vacuum vessel 10> The vacuum vessel 10 can be configured in various ways as long as both axial ends of a cylindrical body 1, at least a portion of which is insulating, can be closed by a fixed conductor 2 and a movable conductor 3, and a vacuum chamber 11 and an atmospheric chamber 12 can be formed within the vacuum vessel 10 via a bellows 4 or the like.

[0055] In the case of the cylindrical body 1 shown in Figure 1, flange tubes 14 (fixed conductor 2 side) and 15 (movable conductor 3 side) made of a metal material (for example, metal materials such as copper, stainless steel (SUS), various alloys (beryllium copper, etc.), and metal materials that have been subjected to various processing processes (copper plating, copper clad lamination, etc.)) are coaxially connected to both axial ends of an insulating tube 13 made of an insulating material (for example, a ceramic material, etc.). Both ends of the cylindrical body 1 are closed by flat plate-shaped fixed conductor 2 and movable conductor 3 made of metal material, respectively.

[0056] Such a cylindrical body 1 is preferably configured to easily maintain the vacuum state (suppress vacuum leaks) in the vacuum chamber 11. One example of this is to make the radial thickness of the insulating tube 13 larger than the radial thickness of the flange pipes 14, 15, but it is preferable to design it appropriately so that the insulating tube 13 does not interfere with other components adjacent to it.

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

[0058] It should be noted that the cylindrical body 1 can be constructed using only the insulating tube 13 (i.e., omitting the flange pipes 14 and 15), but as mentioned above, in order to prevent interference with other components adjacent to the insulating tube 13, it is advisable to construct the cylindrical body 1 using at least the insulating tube 13 and the flange pipe 15.

[0059] <Example of Fixed Electrode 21 and Movable Electrode 31> Both the fixed electrode 21 and the movable electrode 31 (hereinafter simply referred to as the two electrodes) can form a capacitance between them, and various configurations can be applied to each of them as long as the capacitance changes in accordance with the axial movement of the movable electrode 31. One example is a configuration in which the two electrodes can cross each other in the axial direction without contacting each other, and a desired capacitance is formed between the two electrodes in accordance with the amount of crossing (crossing area) in the axial direction.

[0060] 1, the electrodes are configured as an electrode group in which a plurality of substantially cylindrical electrode members (thin-walled electrode members with small radial thicknesses) 21a, 31a, each having a different inner diameter, are concentrically arranged at regular intervals. The electrode members of both electrodes can cross each other in the axial direction without contacting each other, and a desired capacitance can be formed between the electrodes depending on the amount of crossing in the axial direction.

[0061] Instead of the plurality of substantially cylindrical electrode members as described above, the electrodes may each be formed of an electrode member extending in a spiral shape. In this case, the electrode members of the electrodes can cross each other in the axial direction without contacting each other, and a desired capacitance can be formed between the electrodes depending on the amount of crossing in the axial direction.

[0062] <Example of Movable Electrode Supporting Section 30> The movable electrode supporting section 30 may be configured to be movable in the axial direction while supporting the movable electrode 31, and various configurations are applicable.

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

[0064] A movable rod (cylindrical movable rod in Figure 1) 32 is provided in the center of the back side of the movable electrode support part 30 (the other axial side where the movable electrode 31 is not provided) and has a shape extending from the center to the other axial side (in Figure 1, it has a shape extending so as to penetrate through the movable side conductor 3 side of the vacuum vessel 10 and protrude).

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

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

[0067] Reference numeral 35 in Fig. 1 denotes a rod (hereinafter referred to as the insulation operating rod) that moves while guiding the movable rod 32 in the axial direction by the bearing member 34, and that adjusts the capacitance of the vacuum capacitor 1A to perform insulation operation. In the case of the insulation operating rod 35 shown in Fig. 1, one end side (the side on which the male thread portion 35b is formed in Fig. 1) is threadedly engaged with the other side of the movable rod 32 in the axial direction (in Fig. 1, the male thread portion 35b formed on the insulation operating rod 35 is threadedly engaged with the female thread portion 32a formed on the inner wall of the one end side of the movable rod 32). In addition, the other end side of the insulation operating rod 35 (the side on which the head portion 35a made of an insulating material is formed in Fig. 1) is configured so that a drive source (such as a motor) not shown can be connected.

[0068] The insulating operating rod 35 is rotatably supported by a support 36 (in FIG. 1, the support is made up of a screw receiving portion 36a and a thrust bearing 36b for reducing rotational torque) provided in the vacuum vessel 10 (in FIG. 1, the support 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] <Example of Bellows 4> The bellows 4 is cylindrical and can expand and contract in the axial direction, and can support the movable electrode support part 30 so that it can move freely relative to the movable-side conductor 3 while keeping the vacuum chamber 11 airtight, and various configurations are possible.

[0070] The bellows 4 shown in FIG. 1 is a molded body formed from a metal material (e.g., stainless steel) into a thin-walled bellows-like cylindrical shape, and has a configuration in which reduced diameter portions 41 and expanded diameter portions 42 are alternately arranged in multiple stages in the axial direction (e.g., approximately 10 to 20 reduced diameter portions 41 and approximately 10 to 20 expanded diameter portions 42 are alternately arranged).

[0071] <An example of mesh tubular conductive path portion 5> The mesh tubular conductive path portion 5 has a mesh tube shape formed by overlapping elastic conductors 6, each shaped to undulate in the circumferential direction, in multiple stages in the axial direction, and the gaps 72 of adjacent stages are compressed and expanded in the axial direction to elastically deform, thereby allowing the entire portion to expand and contract in the axial direction, and any configuration is possible as long as it allows high-frequency current to flow in the axial direction while passing through the fixed portions 71 of adjacent stages.

[0072] For example, the elastic conductor 6 can be obtained by forming a long strip (e.g., long wire, long flat plate, etc.) conductor made of a metal material (e.g., copper, stainless steel (SUS), various alloys (e.g., beryllium copper), and metal materials that have been subjected to various processing processes (e.g., copper plating, copper clad lamination, etc.)) so that it extends in a wavy pattern along the circumferential direction. Specific examples include forming such a long strip conductor into a circumferential wave washer or coiled wave spring shape. The elastic conductor 6 shown in FIG. 2 has a configuration in which a long flat plate conductor is formed into a wave washer shape.

[0073] The fixing portion 71 may be formed by appropriately fixing one side curved portion 61 and the other side curved portion 62 that are convex in the adjacent direction and positioned opposite each other, and 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 one-side curved portion 61 and the other-side curved portion 62 associated with the fixed portion 71 generate heat through electrical current, making vacuum adhesion between them more likely to occur. When this vacuum adhesion occurs, the resistance (contact resistance) of the fixed portion 71 is more likely to decrease, and the fixed structure is more likely to be strengthened (self-healing). Furthermore, when the mesh tubular conductive path portion 5 shrinks in the axial direction, the adhesive strength of the fixed portion 71 is increased, which similarly makes it more likely to reduce the resistance (contact resistance) of the fixed portion 71. As a result, the high-frequency current carrying capacity is improved, and the reliability of the vacuum capacitor 1A is also improved.

[0075] The cross-sectional shape of the elastic conductor 6 can be designed to have a small axial thickness (dimension t1 in FIG. 3) to facilitate elastic deformation of the elastic conductor 6. For example, when molding using a long, flat conductor, it is possible to use a shape with an extremely thin thickness (for example, a shape as thin as a metal foil) within a range that maintains the desired mechanical strength.

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

[0077] The ends 5a, 5b of the mesh tubular conductive path portion 5 may have a plain end shape, which is a wavy shape extending in the circumferential direction, like the other steps, or may have a shim end shape, which is a flat shape, as shown in FIG. 3 . Even in the case of a mesh tubular conductive path portion 5 having shim end shapes, the adjacent steps including the ends 5a, 5b have a configuration in which the fixing portions 71 and the gap portions 72 are alternately provided along the circumferential direction, as shown in FIG. 3 . Furthermore, 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 pedestals 81, 82, 83 described below) tends to be large. Therefore, when the elastic force acting on the engagement surface when the mesh tubular conductive path portion 5 expands and contracts in the axial direction acts, the elastic force tends to be uniformly distributed.

[0078] When a wave washer-shaped elastic conductor 6 is used, the number of stages in the mesh tubular conductive path portion 5 increases each time the elastic conductors 6 are coaxially stacked. On the other hand, when a coiled wave spring-shaped elastic conductor 6 is used, the elastic conductor 6 extends spirally in the circumferential direction, and the number of stages in the mesh tubular conductive path portion 5 increases each time one turn in the circumferential direction is completed and the next turn begins.

[0079] One method for increasing the high-frequency current-carrying capacity of the mesh tubular conductive path portion 5 described above is to increase the outer circumference of the mesh tubular conductive path portion 5, which is inversely proportional to the electrical resistance of the high-frequency current.Another method is to shorten the current path as indicated by arrows Y1 and Y2 in FIG. 3.

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

[0081] <Example of structure using a pedestal portion> The ends 5 a and 5 b of the mesh tubular conductive path portion 5 may be directly or indirectly engaged with the movable electrode support portion 30 and the movable-side conductor 3 .

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

[0083] 1 has a cylindrical shape with a larger diameter than the bellows 4, and is located on the other axial side of the movable electrode support part 30 so as to be coaxial with the bellows 4. As a result, the pedestal part 81 is configured to extend from the movable electrode support part 30 to the other axial side. The end part 5a of the mesh tubular conductive path part 5 engages with the end part 8a on the other axial side of the pedestal part 81. The end part 8a shown in FIG. 1 has an expanded diameter that is bent radially outward, and is configured to easily engage with the end part 5a of the mesh tubular conductive path part 5.

[0084] By using such a pedestal 81, it is possible to shorten the mesh tubular conductive path portion 5 in the axial direction in accordance with the axial dimension of the pedestal 81. Furthermore, the pedestal 81 can be formed in a shape that simply extends in the axial direction, rather than in a stepped shape like the mesh tubular conductive path portion 5, and therefore the creepage distance in the axial direction is short. Therefore, 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 tubular conductive path portion 5 is positioned between the movable electrode support portion 30 and the movable-side conductor 3, biased toward the other side in the axial direction, it becomes easier to suppress interference with, for example, the insulating tube 13.

[0086] 4 has the same configuration as vacuum capacitor 1A, and is configured such that end 5a of meshed tubular conductive path portion 5 is indirectly engaged with movable-side conductor 3 via flange pipe 15 and pedestal portion 82 (first pedestal portion) located on the other axial side of cylindrical body 1. Also, end 5b of meshed tubular conductive path portion 5 is indirectly engaged with movable electrode support portion 30 via pedestal portion 83 (second pedestal portion) provided on the other axial side of movable electrode support portion 30, between bellows 4 and meshed tubular conductive path portion 5.

[0087] 4, the pedestal portion 82 has a flange shape that extends radially inward from the inner peripheral surface of the flange pipe 15 and extends circumferentially, and is provided so as to be positioned biased to one side in the axial direction relative to the end portion 5a of the mesh tubular conductive path portion 5. The end portion 5a of the mesh tubular conductive path portion 5 engages with the other side in the axial direction of the pedestal portion 82.

[0088] 4 has a cylindrical shape with a larger diameter than the bellows 4, and is located on the other axial side of the movable electrode support part 30 so as to be coaxial with both the bellows 4 and the mesh tubular conductive path part 5 (coaxial with both of them). As a result, the pedestal part 83 is configured to extend from the movable electrode support part 30 to the other axial side.

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

[0090] By using the pedestal portions 82, 83 as described above, it is possible to shorten the mesh tubular conductive path portion 5 in the axial direction according to the installation position of the pedestal portion 82 relative to the flange pipe 15 and the axial dimension of the pedestal portion 83. Furthermore, the pedestal portion 82 has a shape that simply extends from the flange pipe 15, and the pedestal portion 83 can have a shape that simply extends in the axial direction, similar to the pedestal portion 81. Therefore, even when the pedestal portions 82, 83 are used, there is a good possibility 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 reduced.

[0091] Furthermore, since the mesh tubular conductive path portion 5 is always positioned biased toward the other side in the axial direction than the insulating tube 13 , interference with the insulating tube 13 can be avoided.

[0092] Furthermore, the elastic force generated when the bellows 4 expands and contracts and the elastic force generated when the mesh tubular conductive path portion 5 expands and contracts act in opposite directions in the axial direction and tend to cancel each other out, which makes it easier to reduce the operating force required when, for example, moving the movable electrode support portion 30 and the movable electrode 31 in the axial direction.

[0093] <Example of operation of vacuum capacitors 1A, 1B> In vacuum capacitors 1A, 1B, the insulating operating rod 35 is operated via a drive source not shown in the figure, and the movable rod 32 is moved in the axial direction, thereby changing the amount of intersection between the fixed electrode 21 and the movable electrode 31, and the electrostatic capacitance is increased or decreased, thereby adjusting the impedance.

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

[0095] After this, the current can further flow from the movable electrode 31 to the movable side conductor 3 via the movable electrode support portion 30, bellows 4, movable rod 32, and mesh tubular conductive path portion 5, but due to the skin effect, it will flow mainly via the mesh tubular conductive path portion 5 to the movable side conductor 3.

[0096] Although the present invention has been described in detail above only with respect to the specific examples, it will be apparent to those skilled in the art that various 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.

[0097] 1A, 1B... Vacuum capacitor, 10... Vacuum container, 1... Cylindrical body, 21... Fixed electrode, 31... Movable electrode, 30... Movable electrode support portion, 4... Bellows, 5... Meshed cylindrical conductive path portion, 6... Elastic conductor, 61... One side curved portion, 62... Other side curved portion, 71... Fixing portion, 72... Gap portion, 81, 82, 83... Base portion

Claims

1. A vacuum vessel having a cylindrical body at least a portion of which is insulating, the cylindrical body having one axial side, or fixed side, sealed with a fixed side conductor, and the other axial side, or movable side, sealed with a movable side conductor; a fixed electrode provided on one side of the vacuum vessel in the axial direction; a movable electrode support part located inside the vacuum vessel opposite the fixed electrode and movable in the axial direction; a movable electrode provided on one side of the movable electrode support part opposite the fixed electrode, and forming a capacitance between it and the fixed electrode; a bellows having a cylindrical shape that is expandable and contractible in the axial direction between the movable electrode support part and the movable conductor, and supporting the movable electrode support part on the movable conductor; and a mesh cylindrical part that is expandable and contractible in the axial direction, has a diameter larger than the bellows, is located coaxially on the outer periphery of the bellows, and engages with the movable electrode support part and the movable conductor. The interior of the vacuum vessel is divided by the bellows into a vacuum chamber on the outer periphery of the bellows and an atmospheric chamber on the inner periphery of the bellows, the conductive path portion is formed by elastic conductors extending along the circumferential direction of the conductive path portion being stacked in multiple stages in the axial direction, the elastic conductors have curved portions convex on one side of the axial direction and curved portions convex on the other side of the axial direction, and the elastic conductors are provided alternately along the circumferential direction in multiple repeated stages, and in each pair of stages adjacent to each other in the axial direction among the stages stacked in multiple stages, the curved portion of one of the stages that is convex in the adjacent direction and the curved portion of the other of the stages that is convex in the adjacent direction are positioned opposite each other in the adjacent direction and are fixed to each other, A vacuum capacitor characterized in that one of the curved portions provided on one of the steps is convex on the opposite side of the adjoining direction, and the other of the curved portions provided on the other of the steps is convex on the opposite side of the adjoining direction, and the curved portion is positioned opposite in the adjoining direction with a gap therebetween.

2. A vacuum capacitor as described in claim 1, characterized in that a pedestal portion is provided at a position on the other side of the movable electrode support portion in the axial direction and on the outer periphery of the bellows, the pedestal portion having a shape extending from said position to the other side in the axial direction, one side of the conductive path portion in the axial direction being joined to an end of the pedestal portion in the extending direction, and the other side of the conductive path portion in the axial direction being joined to the movable conductor.

3. 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, wherein a first pedestal portion is provided on an inner peripheral surface of the flange tube and extends radially inward of the cylindrical body, the first pedestal portion is located on one side of the conductive path portion in the axial direction, a second pedestal 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 extends from said position to the other side in the axial direction, an end of the second pedestal portion in the extending direction projects further on the other side in the axial direction than the conductive path portion and is bent radially outward, one side of the axial direction of the conductive path portion is joined to the first pedestal portion, and the other side of the axial direction of the conductive path portion is joined to the end of the second pedestal portion in the extending direction.

2. The vacuum capacitor according to claim 1.

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

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

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