A coupling structure for a radio frequency matching device

Abstract

The utility model relates to radio frequency power tuning equipment technical field especially relates to a kind of joint structure for radio frequency matcher, including bottom shell, motor installed in bottom shell, D hole brass shaft sleeve, slit type four fluorine shaft coupling, air capacitor and angle detection component. The D shaft of motor is cooperated with sleeve hole shaft and is locked by tight screw, sleeve and four fluorine shaft coupling are connected by bolt, the other end of shaft coupling and air capacitor rotating shaft are connected by bolt;Elastic section is formed by circumferential slit of shaft coupling, and flexible compensation and high-frequency insulation are provided. Motor shaft end gear and potentiometer gear mesh, potentiometer real-time feedback capacitor shaft angle, realize closed-loop tuning. The structure reduces assembly coaxiality requirement, improves matcher tuning accuracy and reliability, and is convenient to assemble, disassemble and maintain.

Description

Technical Field

[0001] This utility model relates to the field of radio frequency power tuning equipment technology, and in particular to a coupling structure for radio frequency matching devices. Background Technology

[0002] Radio frequency (RF) matching devices are widely used in high-frequency power output applications such as plasma etching, sputtering coating, and induction heating. Their core function is to match the load impedance by adjusting reactive components (usually vacuum or air variable capacitors) in real time to achieve maximum power transmission and minimum reflected power. Existing devices generally use stepper motors or servo motors to directly drive the capacitor shaft, supplemented by potentiometers, inductive encoders, and other angle sensors to form a closed-loop control. To reliably transmit the torque generated by the motor to the capacitor shaft while ensuring electrical isolation and mechanical buffering, the coupling structure becomes a crucial mechanical component. Current RF matching devices mostly use rigid metal couplings to directly connect the motor shaft and the variable capacitor shaft, which lacks electrical insulation and flexible compensation capabilities and is highly dependent on the coaxiality of the two shafts, resulting in high manufacturing costs and difficult assembly and adjustment. Therefore, designing a coupling structure for RF matching devices is essential. Utility Model Content

[0003] The purpose of this invention is to provide a coupling structure for an RF matching unit to solve the problems mentioned in the background art.

[0004] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a coupling structure for an RF matching unit, including a base shell, a motor, an air capacitor, and a potentiometer. The D-shaped output shaft of the motor is fixedly connected to a PTFE coupling via a D-hole brass bushing. The other end of the PTFE coupling is fixedly connected to the capacitor shaft of the air capacitor. The D-hole brass bushing is locked to the D-shaped shaft of the motor by a set screw in a face-to-face fit. The PTFE coupling has a circumferential slit to form an elastic section, which is used to compensate for axial, radial, and angular installation errors and to electrically insulate the motor from the air capacitor. The motor gear at the motor shaft end meshes with the potentiometer gear, and the potentiometer provides real-time feedback on the rotation angle of the air capacitor. The air capacitor is fixed to the base shell by a capacitor bracket, and the motor and potentiometer are mounted on a potentiometer mounting plate and detachably connected to the base shell.

[0005] According to the above technical solution, the inner hole of the D-hole brass bushing is a D-shaped hole that matches the D-shaped shaft of the motor, and a radial set screw is provided on the outer circumference of the bushing to realize torque transmission and prevent axial slippage.

[0006] According to the above technical solution, the PTFE coupling is integrally cut from polytetrafluoroethylene, the radial depth of the cut is less than the radius of the PTFE coupling, and the cuts are equidistantly distributed along the axial direction and there are no fewer than three cuts.

[0007] According to the above technical solution, the potentiometer mounting plate is provided with an elongated adjustment hole for mounting parts between the motor shaft and the air capacitor shaft.

[0008] According to the above technical solution, the capacitor bracket is a bent metal part, with an opening at the upper end that is fixed to the two end faces of the air capacitor by screws, and the lower end is fixed to the bottom shell by bolts and nuts.

[0009] According to the above technical solution, the PTFE coupling maintains an axial electrical insulation gap of ≥8mm between the motor shaft end (after being fitted with a D-hole brass bushing) and the air capacitor shaft end.

[0010] Compared with the prior art, the beneficial effects achieved by this utility model are as follows: This utility model, through the flexible insulated transmission structure composed of a D-hole brass bushing and a slit-type PTFE coupling, and the motor gear-potentiometer gear feedback assembly, can compensate for axial, radial, and angular errors while maintaining reliable torque transmission, achieving electrical isolation between the motor shaft and the air capacitor shaft and significantly reducing coaxiality assembly requirements; the elastic slit of the coupling effectively absorbs start-stop shocks, improves tuning stability, and the closed-loop feedback improves the accuracy of capacitor angle adjustment; the overall structure is compact, easy to assemble, disassemble, and maintain, and has low manufacturing costs, which can significantly improve the working reliability and production efficiency of the RF matching device. Attached Figure Description

[0011] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0012] Fig. 1 This is a schematic diagram of the overall structure of a coupling structure for an RF matching unit proposed in this utility model;

[0013] Fig. 2 This is a schematic diagram of the component connections in a coupling structure for an RF matching unit proposed in this utility model;

[0014] Fig. 3 This is an exploded view of a coupling structure for an RF matching unit proposed in this utility model.

[0015] In the diagram: 1 Motor, 2 D-hole brass bushing, 3 PTFE coupling, 4 Air capacitor, 5 Capacitor bracket, 6 Potentiometer mounting plate, 7 Motor gear, 8 Potentiometer gear, 9 Potentiometer, 10 Bottom shell. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Example:

[0018] Reference Figs. 1-3 A coupling structure for an RF matching unit is disclosed. This structure uses the front panel of the base housing 10 as the mounting reference. The shaft axes of the motor 1 and the air capacitor 4 are arranged horizontally and aligned with each other. The potentiometer mounting plate 6 is vertically fixed inside the base housing 10 and is detachably connected to the mounting holes of the base housing 10 by screws. The air capacitor 4 is fixed to the base housing 10 by a capacitor bracket 5, which is a one-piece bent metal component. The bottom of the capacitor bracket 5 is fixed to the base housing 10 by bolts and nuts.

[0019] Motor 1 is fixed to potentiometer mounting plate 6 with screws via end face screw holes. The output shaft of motor 1 is a D-shaped shaft. D-hole brass bushing 2 is a cylindrical bushing with a D-shaped mating surface inside its inner hole. Its inner hole forms a hole-shaft fit with the D-shaft of motor 1. A set screw is installed at the mating point, which is radially tightened by the D-hole brass bushing 2 and pressed against the plane of the D-shaft to achieve reliable torque transmission. The other end face of the D-hole brass bushing 2 has a through hole, which is detachably connected to one end of the PTFE coupling 3 using a bolt and nut. Similarly, the other end of the PTFE coupling 3 is fixedly connected to the capacitor shaft through hole of air capacitor 4 using a bolt and nut. The PTFE coupling 3 is made of polytetrafluoroethylene (PTFE). Several slits are cut along the circumference of the coupling body to form an annular elastic section, providing micro-compensation capabilities in the axial, radial, and angular directions, while also providing electrical insulation and vibration isolation between motor 1 and air capacitor 4. All of the above connections are detachable. The rotational relationship between the motor 1 and the air capacitor 4 is a rotational motion around the axis. The PTFE coupling 3 allows for a small amount of coaxiality error and parallelism error while transmitting torque.

[0020] The potentiometer mounting plate 6 is provided with through holes and countersunk holes for positioning and fixing the motor 1, potentiometer 9, motor gear 7 and potentiometer gear 8 with screws; the signal line of potentiometer 9 is electrically connected to the matching unit control board.

[0021] The two core components of this coupling structure are the D-hole brass bushing 2 and the PTFE coupling 3. The D-hole brass bushing 2 forms a form-position fit with the D-shaft of the motor 1 through the D-hole. The mating surface is a combination of a plane and a circular arc, which can reliably transmit torque with a small radial dimension. It is supplemented by a set screw to prevent axial slippage. The PTFE coupling 3 adopts an elastic slit structure to form a circumferential flexibility similar to a spring. Without reducing the torque transmission capacity, it absorbs the small assembly deviations and working vibrations between the motor 1 shaft and the capacitor shaft, reduces the processing and assembly requirements for the coaxiality of the two shafts, and achieves electrical isolation of the high-frequency radio frequency circuit in terms of material.

[0022] During assembly, first fix the capacitor bracket 5 using the base shell 10 as the base, then install the air capacitor 4 and lock it in place with the capacitor bracket 5; fix the potentiometer mounting plate 6 to the base shell 10, and then install the motor 1 and potentiometer 9 in sequence; install the motor gear 7 and potentiometer gear 8 onto the corresponding shaft ends to ensure proper meshing; press the D-hole brass bushing 2 into the D-shaft of the motor 1 and tighten the set screw; connect the PTFE coupling 3 to the D-hole brass bushing 2 with bolts, then connect the other end of the PTFE coupling 3 to the capacitor shaft through hole of the air capacitor 4; finally, check the perpendicularity of both end faces and tighten all fasteners. When parallel multi-channel matching is required, two identical structures can be installed side by side on the same mounting surface inside the base shell 10, with each set independently connected to the control board via its own potentiometer 9.

[0023] The workflow is as follows: The position signal output by potentiometer 9 is sent to the control board, which calculates the drive command for motor 1 based on the target capacitance. After motor 1 is powered on, it becomes the driving component, and the driving torque is continuously transmitted to the capacitor shaft of air capacitor 4 via the D-hole brass bushing 2 and the PTFE coupling 3, causing the moving plate to rotate around the axis, thus achieving continuous adjustment of the capacitance. Simultaneously, motor 1 drives the motor gear 7 on its shaft to rotate, and the motor gear 7 meshes with and drives the potentiometer gear 8 to rotate synchronously, thereby changing the output value of potentiometer 9 and providing real-time feedback on the angle of the capacitor shaft. The flexible compensation of the PTFE coupling 3 absorbs shocks during motor start-up, shutdown, and sudden load applications, maintaining smooth transmission and ensuring the stable and reliable tuning process of air capacitor 4 under RF power. The entire structure uses detachable fixing connections such as screws, bolts, and nuts, facilitating maintenance and replacement, and meeting the space and electrical isolation requirements of the RF matching unit.

[0024] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0025] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A coupling structure for an RF matching unit, comprising a base shell (10), a motor (1), an air capacitor (4), and a potentiometer (9), characterized in that: The D-shaped output shaft of the motor (1) is fixedly connected to the PTFE coupling (3) via the D-hole brass bushing (2), and the other end of the PTFE coupling (3) is fixedly connected to the capacitor shaft of the air capacitor (4). The D-hole brass bushing (2) is locked to the motor D-shaped shaft surface by a set screw; The PTFE coupling (3) has a circumferential slit to form an elastic section, which is used to compensate for axial, radial and angular installation errors and to electrically insulate the motor (1) from the air capacitor (4); The motor gear (7) at the shaft end of the motor (1) meshes with the potentiometer gear (8) of the potentiometer (9), and the potentiometer (9) provides real-time feedback on the rotation angle of the air capacitor (4). The air capacitor (4) is fixed to the bottom shell (10) by the capacitor bracket (5), and the motor (1) and potentiometer (9) are mounted on the potentiometer mounting plate (6) and detachably connected to the bottom shell (10).

2. A coupling structure for a radio frequency matching device according to claim 1, wherein The inner hole of the D-hole brass bushing (2) is a D-shaped hole that matches the D-shaped shaft of the motor (1). Radial set screws are provided on the outer circumference of the bushing to achieve torque transmission and prevent axial slippage.

3. The coupling structure for a radio frequency matching device according to claim 1, wherein The PTFE coupling (3) is integrally cut from polytetrafluoroethylene. The radial depth of the cut is less than the radius of the PTFE coupling (3). The cuts are equidistantly distributed along the axial direction and there are no fewer than three cuts.

4. The coupling structure for a radio frequency matching device according to claim 1, wherein The potentiometer mounting plate (6) is provided with an elongated adjustment hole for mounting parts between the motor shaft and the air capacitor shaft.

5. The coupling structure for a radio frequency matching device according to claim 1, wherein The capacitor support (5) is a bent metal part. The upper end is opened and fixed to the two end faces of the air capacitor (4) by screws, and the lower end is fixed to the bottom shell (10) by bolts and nuts.

6. The coupling structure for a radio frequency matching device of claim 1, wherein: The PTFE coupling (3) maintains an axial electrical insulation gap of ≥8mm between the shaft end of the motor (1) (after being fitted by the D-hole brass bushing (2)) and the shaft end of the air capacitor (4).

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