High voltage tolerant variable capacitor and method of use thereof

Abstract

This invention provides a high-voltage variable capacitor and its method of use, comprising: a sealable housing assembly with ports; an electrode assembly mounted within the cavity of the housing assembly, the capacitance value of which is adjusted by changing the effective overlap area between the electrodes; and an insulating fluid dielectric filling the cavity to immerse the electrode assembly; the fluid dielectric is a liquid dielectric. This invention also provides a method for operating the capacitor, comprising draining the original first fluid dielectric from the cavity and injecting a second fluid dielectric with a different dielectric constant. Through this structure and method, the user can replace different types of fluid dielectrics, thereby changing the overall capacitance adjustment range and voltage rating of the capacitor. The capacitor of this invention has the advantages of high voltage resistance, small size, high power carrying capacity, flexible application, and relatively low cost.

Description

Technical Field

[0001] This invention relates to the field of electrical and electronic technology, and more specifically, to a high-voltage resistant variable capacitor and its method of use. Background Technology

[0002] In the electrical and electronic fields, a variable capacitor generally refers to a capacitor whose capacitance value can be adjusted. Currently, in this field, capacitors are mainly based on the parallel plate principle, and their capacitance values ​​follow these rules: (Formula 1) in Represents the capacitance value. The dielectric constant representing the dielectric between the plates. This represents the area of ​​overlap between parallel plates in the normal direction. This represents the spacing between the plates in the normal direction. According to Formula 1, the capacitance value of a capacitor can be changed (adjusted) by changing the dielectric material (different insulating materials between the plates correspond to different dielectric constant values), the overlap area between the plates, and the spacing between the plates.

[0003] Currently, variable capacitors mainly include vacuum variable capacitors, air variable capacitors, and piezoelectric variable capacitors. For specific models, the first two types of capacitors adjust their capacitance by changing the overlap area between the plates (i.e., the capacitor's electrode plates). Their dielectric constant and the spacing between the plates are fixed at the factory and cannot be freely changed by the user to alter the capacitance adjustment range; their capacitance value can only be adjusted within a specific range. Similarly, piezoelectric variable capacitors adjust their capacitance by changing the spacing between the plates. Their dielectric constant and the overlap area between the plates are fixed at the factory (and cannot be changed after packaging), and cannot be freely changed by the user to alter the capacitance adjustment range. Therefore, the capacitance value of these capacitors can only be adjusted within a specific range, limiting their application flexibility.

[0004] Vacuum variable capacitors are relatively large and inconvenient to use. Due to the high-voltage "field-induced breakdown" effect in a vacuum, the spacing between its plates (electrode plates) cannot be made infinitely small. Because the dielectric of this type of capacitor is a vacuum, its... The capacitance value is the lowest among dielectrics, therefore, according to Formula 1, the A value corresponding to commonly used capacitance values ​​is often large, meaning the size is larger. This is the main reason why vacuum variable capacitors are generally larger than other types of capacitors. Furthermore, the use of strict hermetic design and manufacturing processes results in higher procurement costs for users.

[0005] Air-filled variable capacitors have relatively low withstand voltages, typically not exceeding 10kV. This is due to the low breakdown voltage of air as the dielectric. Furthermore, the withstand voltage of these capacitors often decreases in humid weather, making them unsuitable for higher voltage applications. Because they use air as the dielectric, their... Because of their small size, it is difficult to miniaturize the electrode sheet size in high-voltage and high-capacitance applications.

[0006] Piezoelectric variable capacitors mainly include crystal oscillators, varactor diodes, etc. Due to their solid-state packaging, they are prone to failure due to heat, and their ultimate voltage withstand capability and power withstand capability are often smaller than those of air variable capacitors.

[0007] To comprehensively address the above problems, this invention proposes a high-voltage variable capacitor and its usage method. The capacitor's plate-shaped electrode array is filled with an insulating, non-polar fluid (typically liquid) of a suitable material. This solves the problems of high cost and large size associated with vacuum variable capacitors, as well as the insufficient high-voltage withstand capability and large size of air variable capacitors and piezoelectric variable capacitors. It also addresses the issues of insufficient high-voltage withstand capability and low power handling capacity of piezoelectric variable capacitors. Furthermore, unlike conventional variable capacitors, this invention's capacitor not only allows for changes in the overlap area of ​​the electrode plates but also alters the dielectric constant by changing the dielectric material. Therefore, this invention's capacitor possesses the unique ability to configure the capacitance adjustment range, thus broadening its application scope. Summary of the Invention

[0008] In view of the deficiencies in the prior art, the purpose of this invention is to provide a high-voltage resistant variable capacitor and its usage method.

[0009] A high-voltage resistant variable capacitor provided by the present invention comprises: The housing assembly is configured as a sealable cavity, and the housing assembly includes at least one medium port for discharging and injecting a fluid dielectric. An electrode assembly, mounted within the cavity of the housing assembly, includes a first electrode assembly and a second electrode assembly that are insulated from each other, wherein at least one electrode assembly is a movable electrode assembly for adjusting the capacitance value by changing the effective overlap area between the first electrode assembly and the second electrode assembly; and A fluid dielectric, an insulating fluid, is filled into the cavity of the housing assembly to immerse the electrode assembly; the fluid dielectric is a liquid dielectric.

[0010] Preferably, the medium port includes a threaded opening and a removable sealing plug.

[0011] Preferably, the relative permittivity of the liquid dielectric is greater than 2.

[0012] Preferably, the liquid dielectric is mineral oil or castor oil.

[0013] Preferably, the first electrode assembly is a fixed electrode assembly, and the second electrode assembly is a rotatable electrode assembly; The fixed electrode assembly is fixedly mounted inside the housing assembly via a fixed shaft; The rotatable electrode assembly is rotatably disposed within the housing assembly via a rotating shaft, thereby changing its overlap area with the fixed electrode assembly.

[0014] Preferably, it further includes a spring conductive sheet, which is used to maintain an electrical connection with the rotatable electrode assembly as it rotates.

[0015] Preferably, the housing assembly includes a lower housing, a cover, and a sealing ring disposed between the lower housing and the cover; A shaft sealing plug is provided at the point where the shaft protrudes from the housing assembly.

[0016] Preferably, the fixed electrode assembly includes a plurality of parallel rectangular metal electrode sheets; Multiple rectangular metal electrode plates are stacked at intervals and fixed inside the housing assembly by a fixed shaft; the fixed shaft is electrically connected to the rectangular metal electrode plates; One end of the fixed shaft is inserted into the fixed shaft blind hole on the lower housing; the other end of the fixed shaft passes through the lower housing and extends to the outside of the housing assembly, and a fixed shaft sealing plug is provided at the through position; The fixed shaft is provided with a terminal nut for fixing the electrode plate assembly, which is used for electrical connection with an external circuit. The rotatable electrode assembly includes multiple parallel semi-circular metal electrode sheets; Multiple semi-circular metal electrode plates are stacked at intervals and rotatably disposed inside the housing assembly via the rotating shaft; the rotating shaft is electrically connected to the semi-circular metal electrode plates. One end of the rotating shaft is inserted into the blind hole on the lower housing; the other end of the rotating shaft passes through the lower housing and extends to the outside of the housing assembly for connecting to an external drive mechanism, and a rotating shaft sealing plug is provided at the through position; A spring conductive sheet is provided on the lower housing. The spring conductive sheet is fixed to the lower housing by a rotatable electrode assembly wiring screw. The spring conductive sheet is electrically connected to the rotatable electrode assembly wiring screw, which is used to electrically connect to an external wire. The spring conductive sheet includes a spring sheet portion and a planar contact portion. The planar contact portion contacts the shoulder portion of the rotating shaft through the spring sheet portion, allowing the rotating shaft to rotate. The planar contact portion is electrically connected to the shoulder portion. The plurality of rectangular metal electrode pieces allow the plurality of semi-circular metal electrode pieces to be inserted rotatably; the fixed axis and the rotating axis are parallel, and during the rotation of the plurality of semi-circular metal electrode pieces, the projected overlap area of ​​the rectangular metal electrode pieces and the semi-circular metal electrode pieces along the axial direction of the fixed axis can be changed.

[0017] The present invention also provides a method of using a high-voltage resistant variable capacitor, applied to the aforementioned high-voltage resistant variable capacitor, wherein the cavity of the high-voltage resistant variable capacitor is pre-filled with a first fluid dielectric, comprising the following steps: The first fluid dielectric is discharged from the cavity of the housing assembly through the medium port; and A second fluid dielectric with a different dielectric constant than the first fluid dielectric is injected into the cavity through the dielectric port.

[0018] Preferably, the first fluid dielectric and the second fluid dielectric are two liquid dielectrics with different dielectric constants.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. The variable capacitor of the present invention has strong high voltage resistance and is suitable for high power scenarios. By using a liquid dielectric with a breakdown voltage much higher than that of air, the capacitor can withstand higher voltages. At the same time, the good thermal conductivity of the liquid dielectric effectively solves the heat dissipation problem during high power operation.

[0020] 2. The variable capacitor of the present invention has a small volume. By using a liquid dielectric with a dielectric constant much higher than that of air or vacuum, the required electrode area is greatly reduced when achieving the same capacitance value, thereby significantly reducing the overall volume of the capacitor.

[0021] 3. The variable capacitor of the present invention has a configurable capacitance adjustment range and is flexible in application. It allows users to change the overall adjustment range of the capacitor by changing the fluid dielectric with different dielectric constants, so that the same capacitor hardware can be adapted to a variety of different application requirements, greatly improving its versatility.

[0022] 4. The variable capacitor of the present invention has a relatively low cost. Compared with the vacuum variable capacitor that requires a complex vacuum process, the structure and manufacturing process of the present application are relatively simple, and have a lower cost advantage. Attached Figure Description

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 A cross-sectional schematic diagram of a high-voltage resistant variable capacitor with replaceable fluid medium provided in an embodiment of the present invention; Figure 2 A schematic diagram of the overall appearance of a high-voltage resistant variable capacitor with replaceable fluid medium provided in an embodiment of the present invention; Figure 3 An exploded view of a high-voltage resistant variable capacitor with replaceable fluid medium provided in an embodiment of the present invention; Figure 4 This is a partially enlarged schematic diagram of the rotating shaft conductive mechanism provided in an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the capacitance adjustment principle provided in an embodiment of the present invention; Figure 6 This is a flowchart illustrating a method for using a capacitor according to an embodiment of the present invention.

[0024] The diagram shows: 1-Lower housing; 2-Cover; 3-Rotating shaft; 4-Fixed shaft; 5-Rotable electrode assembly; 6-Fixed electrode assembly; 7-Rotable electrode assembly wiring screw; 8-Fixed electrode assembly wiring nut; 9-Spring conductive plate; 10-Rotating shaft sealing plug; 11-Sealing ring; 12-Fluorescent dielectric; 13-Housing screw; 14-Mounting base; 15-Fixed shaft blind hole; 16-Fixed shaft sealing plug; 17-Rotating shaft blind hole; 18-Shoulder area; 19-Spring plate area; 20-Plane contact area; S101 - Select and inject fluid dielectric step; S102 - Connect capacitor to external circuit step; S103 - Connect drive mechanism to shaft step; S104 - Adjust shaft to change capacitance value step; S105 - Monitor circuit performance step; S106 - Reach target state step. Detailed Implementation

[0025] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0026] Example 1 This application provides a high-voltage resistant variable capacitor with replaceable fluid medium, which is particularly suitable for antenna tuning units in high-power high-frequency communication equipment, such as the tuning circuit of a high-power loop antenna. It aims to utilize the advantages of high-performance liquid dielectric to achieve excellent high-voltage resistance, power carrying capacity and compact structural design.

[0027] Figure 1 This is a schematic diagram of the cross-sectional structure of the capacitor in an embodiment of this application. Figure 2 This is a schematic diagram of its overall appearance, and Figure 3 The diagram shows its exploded structure. The capacitor mainly includes a housing assembly, an electrode assembly housed inside the housing assembly, and a fluid dielectric 12 filling the cavity of the housing assembly.

[0028] Specifically, the housing assembly forms a reliably sealable cavity, primarily composed of a lower housing 1 and a cover 2. The lower housing 1 and cover 2 may be made of high-strength insulating materials (e.g., engineering plastics or ceramics) to ensure overall insulation performance and mechanical strength. An annular sealing ring 11 is provided between the mating surfaces of the lower housing 1 and cover 2. When secured by a housing screw 13 (see...) Figure 3 When the cover 2 is secured to the lower housing 1 with fasteners such as [insert fastener name here], the sealing ring 11 is compressed, thereby forming a reliable static seal between the two to prevent leakage of the internal fluid dielectric 12. Furthermore, to facilitate the replacement of the fluid dielectric 12, at least one port is provided on the housing assembly (e.g., at a suitable location on the cover 2 or the lower housing 1). As an optional implementation, this port can be a threaded opening equipped with a removable sealing plug. When the medium needs to be replaced, the sealing plug can be unscrewed, the old medium can be drained through the port, and the new medium can be injected. After the operation is completed, the sealing plug can be tightened to ensure a seal. Near the bottom of the lower housing 1 is a mounting base 14 for mounting and securing the capacitor in this embodiment.

[0029] The electrode assembly is housed within an inner cavity formed by the housing assembly, and the electrode assembly includes a first electrode assembly and a second electrode assembly that are insulated from each other. In one embodiment of this application, as a preferred structure, the first electrode assembly is a fixed electrode assembly, and the second electrode assembly is a rotatable electrode assembly.

[0030] Combination Figure 1 and Figure 3As shown, the fixed electrode assembly specifically includes a fixed electrode group 6. This fixed electrode group 6 is composed of multiple parallel rectangular metal electrode sheets stacked at certain intervals and fixed inside the housing assembly, for example, fixed to the base of the lower housing 1 by a fixed shaft 4. One end of the fixed shaft 4 is inserted into a fixed shaft blind hole 15 on the lower housing 1, and the other end of the fixed shaft 4 passes through the lower housing 1, with a fixed shaft sealing plug 16 provided at the through-hole position. The fixed electrode assembly is connected to an external circuit via a lead-out terminal, such as... Figure 2 The fixed shaft 4 and the fixed electrode assembly wiring nut 8 are shown. The fixed shaft 4 is electrically connected to the fixed electrode assembly 6 and passes through the wall of the housing assembly (e.g., the bottom of the lower housing 1) while ensuring the sealing of the passage position. The fixed electrode assembly wiring nut 8 is mounted on the fixed shaft 4.

[0031] The rotatable electrode assembly includes a rotatable electrode group 5 and a rotating shaft 3 for driving its rotation. The rotatable electrode group 5 is also composed of multiple parallel semi-circular metal electrode plates stacked at certain intervals, their size and spacing matching the fixed electrode group 6, allowing the electrode plates of the rotatable electrode group 5 to be smoothly inserted into the gaps between the electrode plates of the fixed electrode group 6. The rotatable electrode group 5 is securely mounted on the rotating shaft 3 and rotates with it. One end of the rotating shaft 3 is inserted into a blind hole 17 on the lower housing 1, and the other end of the rotating shaft 3 extends through the lower housing 1 to the outside of the housing assembly for connection to an external drive mechanism, such as a motor or a manual knob. A rotating shaft sealing plug 10, such as an O-ring or a dedicated rotary seal, is provided at the location where the rotating shaft 3 passes through the lower housing 1 to ensure a dynamic seal is maintained at this point during rotation of the rotating shaft 3, preventing leakage of the fluid dielectric 12 from the shaft gap.

[0032] To connect the rotatable electrode assembly 5 to an external circuit, this embodiment employs a reliable rotating conductive structure. See also... Figure 2 and Figure 4 ,in Figure 4 This is a partially enlarged schematic diagram of the rotating shaft conductive mechanism. On the exterior of the housing assembly, a rotatable electrode assembly wiring screw 7 is provided for connecting external wires. This wiring screw 7 also serves to secure the spring conductive piece 9. The spring conductive piece 9 is a metal component with good elasticity and conductivity. One of its spring portions 19, through its own elastic force, presses a planar contact portion 20 tightly against the shoulder portion 18 of the rotating shaft 3. The shoulder portion 18 of the rotating shaft 3 is a smooth, surface-treated conductive annular area on the rotating shaft 3. In this way, regardless of how the rotating shaft 3 rotates, the contact portion of the spring conductive piece 9 always maintains stable sliding electrical contact with it, thereby establishing a complete, low-resistance electrical path from the wiring screw 7 to the spring conductive piece 9, then to the rotating shaft 3, and finally to the rotatable electrode assembly 5.

[0033] In this embodiment, to achieve extremely high withstand voltage and a compact size, a high-performance liquid dielectric, namely castor oil, was selected as the fluid dielectric 12. Castor oil is an insulating, non-polar liquid with a relative permittivity of approximately 4.7, much higher than that of air (approximately 1.0) and vacuum (1.0). Simultaneously, its breakdown voltage is as high as approximately 7.0 kV / cm, while the breakdown voltage of air is only approximately 0.3 kV / cm. The castor oil is filled into the entire cavity of the housing assembly through a pre-designed port, completely immersing the fixed electrode assembly 6 and the rotatable electrode assembly 5 within it.

[0034] The working principle of this capacitor is based on the capacitance formula of a parallel plate capacitor. The capacitance is given, where C is the capacitance value, ε is the dielectric constant of the medium between the electrodes, A is the effective overlap area of ​​the electrode plates, and d is the distance between the electrode plates. In the structure of this application, d is a fixed value, while ε is determined by the selected fluid dielectric 12. The capacitance value is adjusted by changing the effective overlap area A.

[0035] Figure 5 The process of adjusting the capacitance value is illustrated schematically. When the external drive mechanism drives the rotating shaft 3 to rotate, the rotatable electrode assembly 5 mounted on it also rotates accordingly. Figure 5 (a) shows the state where the rotatable electrode assembly 5 and the fixed electrode assembly 6 are completely offset, at which point the effective overlap area A between them is close to zero, and the capacitance value reaches its minimum. As the rotating shaft 3 rotates, the electrode pieces of the rotatable electrode assembly 5 gradually insert into the gaps of the fixed electrode assembly 6, as shown... Figure 5 (b) and Figure 5 As shown in (c), the effective overlapping area A gradually increases, and the capacitance value also increases linearly. When rotated to... Figure 5 At the position shown in (d), the overlap area A between the rotatable electrode group 5 and the fixed electrode group 6 reaches its maximum, and the capacitance value reaches its maximum value accordingly. By controlling the rotation angle of the rotating shaft 3, the capacitance value can be smoothly and continuously adjusted between the minimum and maximum values.

[0036] The following is combined Figure 6 The flowchart shown illustrates the method of using the capacitor in the high-power loop antenna tuning of this embodiment. First, in step S101, castor oil is selected as the fluid dielectric 12 according to the application requirements of high power and high voltage resistance, and it is injected into the inner cavity of the capacitor and sealed. Next, in step S102, the capacitor is connected in series to the radiation loop of the loop antenna. Specifically, the antenna loop is disconnected, and both ends are connected to the fixed electrode assembly wiring nut 8 and the rotatable electrode assembly wiring screw 7 of the capacitor, respectively. Next, in step S103, a precision drive mechanism such as a stepper motor or servo motor is connected to the exposed rotating shaft 3 of the capacitor.

[0037] After installation, tuning begins. The transmitter transmits a signal at low power, while the drive mechanism executes step S104, slowly rotating shaft 3 to change the capacitance value. Simultaneously, step S105 is executed in real-time using an antenna analyzer or VSWR meter to monitor the antenna's VSWR. If the VSWR does not reach the ideal value (e.g., greater than 1.5), the process returns to step S104 to continue adjusting the capacitance value. When the VSWR reaches its minimum value (ideally close to 1.1), it indicates that the antenna has reached resonance at that frequency. At this point, the process proceeds to step S106, the tuning process is complete, and the drive mechanism stops rotating.

[0038] Understandably, because this embodiment uses castor oil with extremely high breakdown voltage, the capacitor's ability to withstand the high voltage generated by the antenna loop during high-power transmission is approximately 23 times that of an air-based variable capacitor, and it can withstand hundreds of kilovolts of radio frequency voltage without breakdown. Experimental data shows that the antenna system using the capacitor of this embodiment can stably increase its operating power from the 125 watts limited by conventional air-based variable capacitors to over 500 watts. Furthermore, as a liquid, castor oil has far superior thermal conductivity than air, effectively conducting the heat generated by the electrode plates under high current to the housing assembly and dissipating it, ensuring the stability of the capacitor during long-term high-power operation. Simultaneously, due to the high relative permittivity of castor oil (4.7), while achieving the same capacitance adjustment range as conventional large air-based variable capacitors, the electrode plate area and overall volume of the capacitor in this embodiment can be significantly reduced, to approximately 1 / 4.7 of the latter, thus achieving significant miniaturization and weight reduction.

[0039] Example 2 Those skilled in the art can understand this embodiment as a more specific description of Embodiment 1.

[0040] This embodiment provides a high-voltage resistant variable capacitor and its usage method. The variable capacitor provided in this embodiment is mainly composed of a housing assembly, an electrode assembly, and a fluid dielectric.

[0041] like Figure 1 The figure shown is a cross-sectional view of the high-voltage variable capacitor in normal operating condition on the central axis plane, as proposed in this embodiment. Figure 2 The image shown is an overall appearance diagram of a high-voltage resistant variable capacitor proposed in this embodiment. Figure 3 The diagram shown is a hypothetical disassembled and unfolded schematic of a high-voltage variable capacitor in operation, with the cover in the open position and the electrode assembly hypothetically removed from the lower housing and located below the lower housing.

[0042] The aforementioned housing assembly is the main support and enclosure structure of this capacitor, primarily composed of a lower housing, a cover, a sealing ring, a rotating shaft sealing plug, housing screws, etc. (see...) Figure 1 , Figure 3 Except for the housing screws, all other materials are insulating; there is a mounting base near the bottom of the lower housing (see...). Figure 2 The capacitor is installed and fixed in this embodiment; the inner cavity of the housing assembly is filled with fluid dielectric; the sealing ring is pressed between the lower housing and the cover by the tightening force of the housing screw to achieve a sealing effect and prevent the fluid dielectric in the cavity of the housing assembly from flowing out between the lower housing and the cover.

[0043] The electrode assembly mainly consists of a fixed electrode assembly and a rotatable electrode assembly. The main body of the electrode assembly is installed in the cavity of the housing assembly, and the fixed electrode assembly and the rotatable electrode assembly are mutually insulated in this capacitor.

[0044] The fixed electrode assembly mainly consists of one set of fixed electrode plates, two fixed shafts, and two fixing electrode assembly wiring nuts. (Reference) Figure 1 and Figure 3 The fixed electrode assembly comprises several flat electrode plates arranged face-to-face, parallel, and equidistant from each other, forming the fixed electrode assembly. The fixed electrode assembly is fixedly mounted on two parallel fixed shafts, with the planes of the electrode plates perpendicular to the fixed shafts. Two fixed electrode assembly wiring nuts are screwed onto the two fixed shafts respectively. All components in the fixed electrode assembly are made of conductive material, forming an electrical path. Therefore, the electrical signal from the external wire connected to the capacitor can be conducted to the fixed electrode assembly after being compressed by the wiring nuts. One end of the fixed shaft is inserted into the fixed shaft blind hole 15 located in the lower housing, and the other end protrudes from the lower housing. The joint between the shaft and the lower housing is sealed with adhesive or by a fixed shaft sealing plug 16. The exposed parts of the two fixed shafts after protruding from the lower housing are their wiring points, each equipped with a fixed electrode assembly wiring nut, and the external wire is fixed by the compression of either nut.

[0045] The rotatable electrode assembly mainly consists of one set of rotatable electrode plates, one rotating shaft, four rotatable electrode plate assembly wiring screws, and one spring conductive plate. (Reference) Figure 1 and Figure 3 The rotatable electrode assembly comprises several flat electrode plates arranged face-to-face, parallel to each other, and at equal distances to form the rotatable electrode assembly. The rotatable electrode assembly is fixedly mounted on a rotating shaft, with the planes of the electrode plates perpendicular to the rotating shaft. One end of the rotating shaft is inserted into a blind hole 17 located in the cavity wall of the lower housing (acting as a sliding bearing seat), and the other end protrudes from the lower housing through a through hole. A rotating shaft sealing plug is installed between the rotating shaft and the through hole of the lower housing to prevent the fluid dielectric in the housing assembly cavity from flowing out from here. Figure 4 The image shown is a partially enlarged view of the axial cross-section of this capacitor. (Refer to...) Figure 4The rotating shaft located on the outside of the lower housing has a shoulder, which serves as a limit and conducts electricity. Four rotatable electrode assembly wiring screws are screwed to the lower housing, and the spring conductive sheet is pressed between the lower housing and the four screws by the tightening force of these four screws. While being pressed, the spring in the spring conductive sheet is pressed against the shoulder of the rotating shaft by its elastic force. The part of the spring conductive sheet that contacts the shoulder of the rotating shaft is planar. All the above-mentioned parts contained in the electrode assembly are made of conductive material and thus form an electrical path between them. Therefore, after the external wire connected to the capacitor is pressed against the spring conductive sheet by any of the above-mentioned rotatable electrode assembly wiring screws, electricity can be conducted to the rotating shaft and then to the rotatable electrode assembly.

[0046] Furthermore, the rotating shaft and the two fixed shafts are parallel to each other, so the electrode plates in the rotatable electrode plate group and the fixed electrode plate group are parallel to each other. Furthermore, based on the above-described features, the rotatable electrode assembly can rotate around the axis of rotation; within a certain rotation angle range, the rotatable electrode assembly can be inserted into the gap between the electrodes in the fixed electrode assembly; there is an equidistant spacing between the parallel electrodes in the rotatable and fixed electrode assemblies. Different rotation angles of the axis will create different overlap areas between the two electrode assemblies in the normal direction of the electrodes, with different overlap areas corresponding to different capacitance values ​​(according to Formula 1), thereby achieving capacitance adjustment. It should be noted that, as a common understanding in the field of variable capacitors, the total area of ​​the electrodes in a given electrode assembly is equivalent to the area of ​​a certain plate in Formula 1, and the overlap area between two electrode assemblies in the normal direction is equivalent to the overlap area between parallel plates in the normal direction in Formula 1.

[0047] The fluid dielectric is an insulating, non-polar fluid, and therefore serves as the dielectric material for this capacitor. In the capacitor's operating state, the fluid dielectric fills the inner cavity of the housing assembly, and both the fixed and rotatable electrode groups are completely immersed in the insulating, non-polar fluid dielectric. The fluid dielectric located in the spacer region between the electrode groups acts as the capacitor's dielectric. As shown in Formula 1, the capacitor's capacitance can be changed (adjusted) by altering the dielectric material (different insulating materials between the plates correspond to different dielectric constant values), the overlap area between the plates (between the electrode groups of this capacitor), and the spacing between the plates. Therefore, this capacitor adjusts the dielectric constant by changing the fluid dielectric, thereby changing the capacitance adjustment range. This is one of the main differences between this capacitor and traditional capacitors. Users can flexibly calculate the dielectric constant range according to Formula 1 based on the capacitor's operating capacitance range and then select any insulating, non-polar fluid within the corresponding dielectric constant range as the fluid dielectric. The fluid dielectric is a liquid; in a preferred embodiment, the fluid dielectric is mineral oil or castor oil.

[0048] Furthermore, liquid insulating, non-polar fluids are the typical and primary material types for the dielectric of this capacitor, which is also the main way to leverage the performance advantages of this capacitor. The dielectric constant of liquid insulating, non-polar fluids is significantly greater than that of vacuum and air. For example, the dielectric constant of mineral oil is approximately 2.2 to 2.5 times that of vacuum, castor oil is approximately 4.7 times that of vacuum, and air is 1.0006 times that of vacuum. According to Formula 1, for the same capacitance value, area and dielectric constant are inversely proportional. Therefore, in a typical scenario for this capacitor, when using a liquid dielectric, such as when the capacitor cavity is filled with mineral oil as the dielectric material, the electrode area of ​​this capacitor will be approximately 1 / 2.5 to 1 / 2.2 of that of a vacuum variable capacitor and an air variable capacitor; while when castor oil is used, the size of this capacitor is approximately 1 / 4.7 of that of a vacuum variable capacitor and an air variable capacitor. Thus, the size of this capacitor will be significantly smaller than that of vacuum variable capacitors and air variable capacitors, which is beneficial for easier use of the capacitor and reducing the size of the circuit.

[0049] Furthermore, because this capacitor can use liquid-based insulating, non-polar fluid dielectric materials, its breakdown voltage (high-voltage withstand capability) is significantly greater than that of air. For example, the breakdown voltage of air is approximately 0.3 kV / cm (lower in humid environments), resulting in the high-voltage withstand capability of air-based variable capacitors generally not exceeding 10 kV. In contrast, the breakdown voltage of mineral oil is typically not less than 1.2 kV / cm, and that of castor oil is typically not less than 7.0 kV / cm. Therefore, when the inner cavity of this capacitor is filled with castor oil as the dielectric material, its high-voltage withstand capability limit will be 23 times that of an air-based variable capacitor, far exceeding that of piezoelectric variable capacitors (such as crystal oscillators and varactor diodes, which generally do not exceed 100V). Thus, this capacitor belongs to the category of high-voltage variable capacitors.

[0050] Furthermore, since this capacitor uses a fluid as the dielectric and does not employ integrated circuit packaging technology, it typically exhibits excellent thermal conductivity when using a liquid fluid dielectric. Therefore, heat dissipation is not a concern during high-power operation, making it suitable for high-power applications. Its operating power is significantly greater than that of piezoelectric variable capacitors (generally used in small-signal scenarios), and its high-power operating capability is comparable to that of vacuum variable capacitors and air variable capacitors.

[0051] The adjustable capacitance range of the capacitor in this embodiment is significantly expanded compared to current variable capacitors, and its application is more flexible. The capacitor in this embodiment has a significantly higher high-voltage withstand capability than traditional capacitors such as air variable capacitors and piezoelectric variable capacitors. For a specific capacitance adjustment range, the size of the capacitor in this embodiment is significantly smaller than that of vacuum variable capacitors and air variable capacitors. The capacitor in this embodiment is suitable for high-power applications.

[0052] like Figure 5 The diagram illustrates the principle of different overlap areas (shaded areas) formed between the rotatable electrode assembly immersed in a fluid dielectric and the fixed electrode assembly when rotated at different angles, corresponding to different capacitance values ​​(the housing assembly is not shown for ease of understanding). Figure 5 (a) The overlap area between the rotatable electrode group and the fixed electrode group is zero, and the theoretical capacitance of the capacitor is zero. Figure 5 (b) The rotatable electrode assembly is inserted into the gap between the corresponding electrodes in the fixed electrode assembly, and the capacitance value is greater than [missing value]. Figure 5 The state in (a); Figure 5 (c) The overlap area of ​​the rotatable electrode group and the fixed electrode group is greater than [the specified value]. Figure 5 In state (b), the corresponding capacitance value is also greater than that in state 5(b); Figure 5(d) The rotatable electrode group has been fully inserted into the gap between the corresponding electrode pieces in the fixed electrode group. For the corresponding fluid dielectric, the capacitance value of this capacitor reaches its maximum value at this time.

[0053] To avoid affecting the readability of the image, the fluid dielectric in the image is not represented by a shaded line, but by a blank space, indicating that the inner cavity of the capacitor is filled with fluid dielectric when it is in operation.

[0054] This embodiment provides a high-voltage resistant variable capacitor and its usage method. The capacitor mainly consists of an electrode assembly, a housing assembly, and a fluid dielectric. The main body of the electrode assembly is installed in the inner cavity of the housing assembly, and the fluid dielectric is filled into the inner cavity of the housing assembly. The electrode assembly contains a spring-loaded conductive sheet and a rotatable electrode group, which are electrically connected. The housing assembly includes a lower housing, a cover, a sealing ring, a rotating shaft sealing plug, etc., all of which are made of insulating materials.

[0055] This embodiment also provides a method for using a high-voltage variable capacitor. According to the needs of the capacitance adjustment range, the user can replace the fluid dielectric of different materials and fill the inner cavity of the housing assembly with it to realize the configuration and change of the capacitance adjustment range. The fluid dielectric includes various insulating and non-polar fluids, typically liquid dielectrics.

[0056] This embodiment provides a high-voltage resistant variable capacitor and its usage method. The variable capacitor provided in this embodiment is mainly composed of a housing assembly, an electrode assembly, and a fluid dielectric. The electrode assembly is mainly composed of a fixed electrode assembly and a rotatable electrode assembly. The fixed electrode assembly includes several flat electrode sheets arranged face-to-face in parallel and at equal distances to form a fixed electrode sheet group. The rotatable electrode sheet assembly includes several flat electrode sheets arranged face-to-face in parallel and at equal distances to form a rotatable electrode sheet group.

[0057] The two electrode assemblies described above are installed inside the housing assembly. This capacitor configures its dielectric material by filling the housing assembly with a corresponding insulating, non-polar fluid (typically liquid) according to actual usage requirements, thereby flexibly configuring the adjustment range of the capacitance value of this variable capacitor. The rotatable electrode assembly of this capacitor can be rotated and inserted into the gap between the electrodes in the fixed electrode assembly. Different rotation angles will create different overlap areas between the two electrode assemblies in the normal direction of the electrode assemblies. Different overlap areas correspond to different capacitance values ​​(according to relevant physical formulas), thereby achieving capacitance adjustment.

[0058] This embodiment provides a high-voltage resistant variable capacitor, which, due to its design and method of using a replaceable fluid dielectric, brings the following significant benefits: a) the adjustable capacitance range of the capacitor is significantly expanded, and its application is more flexible; b) its high-voltage withstand capability is significantly higher than that of traditional capacitors such as air variable capacitors and piezoelectric variable capacitors; c) for the same capacitance adjustment range, the size of this capacitor is significantly smaller than that of vacuum variable capacitors and air variable capacitors; d) it is suitable for high-power applications; e) the solution provided in this embodiment can solve the problems of large size and high cost of current vacuum variable capacitors, and solve the problem of insufficient high-voltage withstand capability of air variable capacitors and piezoelectric variable capacitors.

[0059] Unlike traditional variable capacitors, the capacitor in this embodiment can not only change the overlapping area of ​​the electrode assembly, but also change the dielectric constant of the capacitor by changing the dielectric. Therefore, this capacitor also has the unique ability to adjust the capacitance range, making it more widely applicable.

[0060] Example 3 The variable capacitor of this invention has significant advantages in applications such as high-power, high-voltage capacitor regulation. The specific implementation methods and unique advantages of the capacitor of this invention are described below, taking into account its practical application in high-power loop antenna tuning in the field of electronic communications.

[0061] The resistance and inductive reactance (impedance of an inductor) of a loop transceiver antenna used in communication are generally fixed. Therefore, the tuning of a loop antenna is achieved by connecting a variable capacitor in series in its loop. By adjusting the capacitance value (corresponding to different capacitance impedances, called capacitive reactance), the overall impedance of the loop antenna (i.e., the combined effect of resistance, inductive reactance, and capacitive reactance) is optimized. At this point, the standing wave ratio (VSWR) of the loop antenna reaches its minimum value, and the antenna is in a resonant state (the state of complete tuning), possessing the best transmission and reception performance for electromagnetic waves. The main challenge in tuning a loop transceiver antenna is its significantly high inductive reactance, which means that as the power increases, the voltage across the variable capacitor connected in series in the loop also increases significantly.

[0062] Currently, air-electrode variable capacitors are the primary choice for tuning loop antennas. It is well known that to ensure optimal communication performance, higher transmit power is generally desirable. However, air, the dielectric material of air-electrode variable capacitors, has a breakdown voltage of approximately 0.3 kV / cm (lower in humid environments), resulting in a high-voltage withstand capability of less than 10 kV. This significantly limits its high-power operation (generally not exceeding 125 W), becoming a power bottleneck for the entire communication system. Typically, when the capacitor's cavity is filled with castor oil and used as the dielectric material, its high-voltage operating limit is approximately 23 times that of air-electrode variable capacitors, thus enabling a power handling capacity of over 500 W, effectively solving the aforementioned bottleneck problem.

[0063] The following are the specific steps for using this variable capacitor in the field of communications for tuning loop antennas: 1. Preparations.

[0064] 1) Upon initial use, if the inner cavity of the housing assembly is not filled with fluid dielectric, the operator should fill the inner cavity of the capacitor housing assembly with castor oil, ensuring that the sealing ring is installed between the mating surfaces of the lower housing and the cover (see...). Figure 1 and Figure 3 ), put the cover on and tighten the 4 housing screws and press the sealing ring.

[0065] 2) Connect an external rotary drive mechanism to the exposed end of the capacitor shaft (for driving the capacitor shaft to rotate). For safety reasons, preferably, in high-power scenarios, the rotary drive mechanism is a motor drive mechanism. In low-power scenarios not exceeding 5W, an insulating knob cap can be installed on the exposed end of the shaft, and the shaft can be rotated manually by rotating the knob cap.

[0066] 3) Place the two wires of the loop antenna below the rotatable electrode assembly wiring screw and the fixed electrode assembly wiring nut of the variable capacitor (choose one of the two nuts); tighten the screw and nut to ensure that the two wires of the antenna are compressed, thereby completing the electrical connection between the capacitor and the external device, that is, the capacitor is connected in series in the loop of the loop antenna; connect the loop antenna to the communication radio station.

[0067] 2. Adjust the capacitor.

[0068] 1) The capacitance value of this capacitor is adjusted by rotating an external rotary drive mechanism. Specifically, the rotation of the external rotary drive mechanism drives the rotation of the capacitor's shaft, which in turn drives the rotatable electrode assembly to rotate around the shaft. When the rotatable electrode assembly rotates in the aforementioned direction, each of its flat electrode plates will be partially or completely inserted into the gap between the corresponding electrode plates in the fixed electrode assembly (at this time, there is a gap between the two electrode assembly groups). Therefore, different rotation angles of the shaft will create different electrode plate overlap areas between the fixed electrode assembly and the rotatable electrode assembly in the normal direction of the electrode plates. Different electrode plate overlap areas (i.e., the "overlap area between flat plates in the normal direction" in Formula 1) correspond to different capacitance values ​​(according to Formula 1), thereby achieving the adjustment of the capacitance value.

[0069] Specifically, Figure 5 This is a schematic diagram illustrating the principle that when a rotatable electrode assembly immersed in a fluid dielectric rotates at different angles, it forms different overlap areas with the fixed electrode assembly (the shaded area in the diagram), corresponding to different capacitance values ​​(the housing assembly is not shown for ease of understanding). Figure 5 (a) The overlap area between the rotatable electrode group and the fixed electrode group is zero, and the theoretical capacitance of the capacitor is zero. Figure 5 (b) The rotatable electrode assembly is inserted into the gap between the corresponding electrodes in the fixed electrode assembly, and the capacitance value is greater than [missing value]. Figure 5 The state in (a); Figure 5 (c) The overlap area of ​​the rotatable electrode group and the fixed electrode group is greater than [the specified value]. Figure 5 In state (b), the corresponding capacitance value is also greater than that in state 5(b); Figure 5 (d) The rotatable electrode group has been fully inserted into the gap between the corresponding electrode pieces in the fixed electrode group. For the corresponding fluid dielectric, the capacitance value of this capacitor reaches its maximum value at this time.

[0070] 2) As the capacitance value of this capacitor changes, there will be a range of values ​​within which the impedance (i.e., the combination of resistance, inductive reactance, and capacitive reactance) of the entire loop antenna will be optimized. At this point, the antenna is in a tuned state and has the best transmission and reception performance for electromagnetic waves. During the capacitor adjustment process, the operator can observe this tuning state using the standing wave meter or antenna analyzer of the communication radio connected to the loop antenna. When in this state, the communication radio can perform transmission and reception operations, and this capacitor completes the loop antenna tuning function. 3) During radio transmission and reception. The electrode assembly of this capacitor will generate a small amount of heat due to the slight resistance of the metal components. However, because these metal components (especially the electrode assembly) have a large heat dissipation area, heat dissipation is facilitated. Moreover, these heat-generating components are immersed in a liquid (a typical and primary material type for the fluid dielectric of this capacitor). These liquids have good thermal conductivity, and the heat generated during the operation of this capacitor is easily absorbed by the liquid and conducted to the housing assembly before being dissipated into the external space. Therefore, this capacitor can operate at a relatively high power.

[0071] The above outlines the specific implementation steps for using this capacitor in loop antenna tuning. In other applications, users can replace the dielectric material with different dielectric constants to suit the required capacitance adjustment range. This changes the adjustment range of the capacitor accordingly, which is one of the main differences between this capacitor and traditional variable capacitors.

[0072] This invention provides a high-voltage variable capacitor with replaceable fluid medium and its operating method, relating to the electrical and electronic fields. To address the difficulty of balancing high voltage resistance, size, power, and application flexibility in existing variable capacitors, the capacitor of this invention comprises: a sealable housing assembly with ports; an electrode assembly mounted within the cavity of the housing assembly, whose capacitance value is adjusted by changing the effective overlap area between the electrodes; and an insulating fluid medium filling the cavity to immerse the electrode assembly. This invention also provides a method for operating the capacitor, including draining the original first fluid medium from the cavity and injecting a second fluid medium with a different dielectric constant. Through this structure and method, users can replace different types of fluid media, thereby changing the overall capacitance adjustment range and voltage rating of the capacitor. The capacitor of this invention has the advantages of high voltage resistance, small size, high power carrying capacity, flexible application, and relatively low cost.

[0073] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0074] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A high-voltage resistant variable capacitor, characterized in that, include: The housing assembly is configured as a sealable cavity, and the housing assembly includes at least one medium port for discharging and injecting a fluid dielectric. An electrode assembly is installed in the cavity of the housing assembly. The electrode assembly includes a first electrode assembly and a second electrode assembly that are insulated from each other. At least one electrode assembly is a movable electrode assembly, which is used to adjust the capacitance value by changing the effective overlap area between the first electrode assembly and the second electrode assembly. as well as A fluid dielectric, an insulating fluid, is filled into the cavity of the housing assembly to immerse the electrode assembly; the fluid dielectric is a liquid dielectric.

2. The high-voltage resistant variable capacitor according to claim 1, characterized in that, The medium port includes a threaded opening and a removable sealing plug.

3. The high-voltage resistant variable capacitor according to claim 1, characterized in that, The relative permittivity of the liquid dielectric is greater than 2.

4. The high-voltage resistant variable capacitor according to claim 3, characterized in that, The liquid dielectric is mineral oil or castor oil.

5. The high-voltage resistant variable capacitor according to claim 1, characterized in that, The first electrode assembly is a fixed electrode assembly, and the second electrode assembly is a rotatable electrode assembly; The fixed electrode assembly is fixedly mounted inside the housing assembly via a fixed shaft; The rotatable electrode assembly is rotatably disposed within the housing assembly via a rotating shaft, thereby changing its overlap area with the fixed electrode assembly.

6. The high-voltage resistant variable capacitor according to claim 5, characterized in that, It also includes a spring-loaded conductive sheet, which is used to maintain an electrical connection with the rotatable electrode assembly as it rotates.

7. The high-voltage resistant variable capacitor according to claim 5, characterized in that, The housing assembly includes a lower housing, a cover, and a sealing ring disposed between the lower housing and the cover; A shaft sealing plug is provided at the point where the shaft protrudes from the housing assembly.

8. The high-voltage resistant variable capacitor according to claim 5, characterized in that, One end of the fixed shaft is inserted into the fixed shaft blind hole on the lower housing; the other end of the fixed shaft passes through the lower housing and extends to the outside of the housing assembly, and a fixed shaft sealing plug is provided at the through position; One end of the rotating shaft is inserted into the blind hole on the lower housing; the other end of the rotating shaft passes through the lower housing and extends to the outside of the housing assembly for connecting to an external drive mechanism, and a rotating shaft sealing plug is provided at the through position; A spring conductive sheet is provided on the lower housing. The spring conductive sheet is fixed to the lower housing by a rotatable electrode assembly wiring screw. The spring conductive sheet is electrically connected to the rotatable electrode assembly wiring screw, which is used to electrically connect to an external wire. The spring conductive sheet includes a spring sheet portion and a planar contact portion. The planar contact portion contacts the shoulder portion of the rotating shaft through the spring sheet portion, allowing the rotating shaft to rotate. The planar contact portion is electrically connected to the shoulder portion.

9. A method of using a high-voltage resistant variable capacitor, characterized in that, The application of the high-voltage resistant variable capacitor according to any one of claims 1 to 8, wherein the cavity of the high-voltage resistant variable capacitor is pre-filled with a first fluid dielectric, includes the following steps: The first fluid dielectric is discharged from the cavity of the housing assembly through the medium port; and A second fluid dielectric with a different dielectric constant than the first fluid dielectric is injected into the cavity through the dielectric port.

10. The method of using the high-voltage resistant variable capacitor according to claim 9, characterized in that, The first fluid dielectric and the second fluid dielectric are two liquid dielectrics with different dielectric constants.

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