A high power radio frequency transmission slip ring

Abstract

The present application relates to the technical field of slip ring, especially to a high-power radio frequency transmission slip ring. The high-power radio frequency transmission slip ring comprises a shell, end covers arranged at both ends of the shell, a rotor assembly and a stator assembly arranged in the shell, the rotor assembly comprises a main shaft, an insulating sleeve and a conductive ring sleeved on the outer circle of the insulating sleeve, the stator assembly comprises a brush holder and a brush assembly in sliding contact with the conductive ring, a plurality of shielding rings are arranged on the main shaft at intervals, the shielding rings divide the space between the main shaft and the shell into a plurality of independent transmission zones, at least one set of conductive rings and corresponding brush assemblies are arranged in each transmission zone, the shielding rings, the main shaft, the shell and the end covers are configured as conductors, the inner circle of the shielding ring is sleeved on the main shaft to form an electrical connection, the outer circle of the shielding ring abuts against the inner wall of the shell to form an electrical connection, and a grounding connecting piece is arranged on the end cover. The present application has the beneficial effects of isolating each transmission zone independently and reducing the mutual interference of electric field and electromagnetic wave between different transmission zones.

Description

Technical Field

[0001] This invention relates to the field of slip ring technology, and in particular to a high-power radio frequency transmission slip ring. Background Technology

[0002] With the development of high-end manufacturing industries such as semiconductor chip manufacturing, industrial radio frequency induction heating, radio frequency drying, and plasma treatment, the requirements for high-power radio frequency transmission in key high-end manufacturing equipment are becoming increasingly stringent. Radio frequency transmission slip rings with 4000V high voltage, 30A high current, and 13MHz ultra-high power (120000W) are core components of high-end manufacturing equipment in semiconductor chip manufacturing, industrial radio frequency induction heating, radio frequency drying, and plasma treatment. The stability and reliability of their transmission directly affect the precision, yield, and reliability of semiconductor chip manufacturing, as well as the production efficiency of industrial radio frequency induction heating, radio frequency drying, and plasma treatment.

[0003] Currently, the transmission power range of ordinary RF transmission slip rings is typically 2W to 100W. The rotor and stator assemblies primarily achieve signal or power rotational transmission through the sliding contact of conductive rings and brushes. When transmitting ultra-high-power RF signals such as 4000V high voltage, 30A high current, and 13MHz, the high voltage and current (electric field and electromagnetic waves) generated during transmission can cause strong interference to adjacent transmission channels. Ordinary RF transmission slip rings lack internal isolation structures between different transmission channels, making it difficult to suppress this strong interference, thus affecting the stability and reliability of the transmission. Summary of the Invention

[0004] In order to solve at least some of the problems existing in the prior art, the present invention provides a high-power radio frequency transmission slip ring that can isolate each transmission zone individually, prevent mutual interference between electric fields and electromagnetic waves between different transmission zones, and improve overall reliability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A high-power radio frequency transmission slip ring includes a housing and end caps at both ends of the housing. The housing contains a rotor assembly and a stator assembly. The rotor assembly includes a main shaft, several insulating sleeves, and conductive rings respectively fitted around the outer rings of each insulating sleeve. A bearing is provided between the main shaft and the end caps. The stator assembly includes a brush holder and several sets of brush assemblies on the brush holder that slide in contact with the conductive rings. A rotor output assembly is fixed at one end of the main shaft. A stator input assembly connected to the brush assemblies is provided on the side of the housing. Several spaced shielding rings are provided on the main shaft, dividing the space between the main shaft and the housing into several independent transmission zones. Each transmission zone contains at least one set of conductive rings and a brush assembly corresponding to that conductive ring. The shielding rings, main shaft, housing, and end caps are all configured as conductors. The inner ring of the shielding ring is fitted onto the main shaft to form an electrical connection, and the outer ring of the shielding ring abuts against the inner wall of the housing to form an electrical connection. A grounding connector is provided on the end caps. By adopting the above technical solution: the shielding rings are arranged at intervals along the main shaft axis, dividing the annular space between the main shaft and the housing into multiple independent transmission zones; since the shielding rings, main shaft, housing, and end caps are all configured as conductors, the inner ring of the shielding ring forms an electrical connection with the main shaft, and the outer ring abuts against the inner wall of the housing to form an electrical connection, and is connected to the ground through the grounding connector on the end cap, so that each transmission zone is surrounded, isolated and grounded by the conductor structure, forming a Faraday cage; the Faraday cage guides the electric field and electromagnetic wave energy of adjacent transmission zones to the grounding end for discharge, effectively reducing the crosstalk between different transmission zones and improving the overall transmission reliability of the slip ring under unconventional high-power radio frequency conditions.

[0006] Preferably, a grounding area is formed between the shielding ring near the end cap and the corresponding end cap. A grounding ring is fitted on the main shaft at the location of the grounding area. A grounding base is fixed to the inner wall of the end cap, and a grounding brush is provided on the grounding base to make sliding electrical contact with the grounding ring. The grounding base and the grounding connector are disposed on the same end cap. By adopting the above technical solution, the grounding ring and the grounding brush maintain sliding electrical contact under rotational conditions, and together with the grounding base, they form a reliable low-resistance ground, thus improving the physical shielding effect of the Faraday cage.

[0007] Preferably, the inner wall of the housing has an annular stepped surface at the positions corresponding to the end cap and the shielding ring. A conductive bushing is provided between the end face of the end cap and the corresponding annular stepped surface, and a conductive bushing is also provided between the end face of the shielding ring and the corresponding annular stepped surface. By adopting the above technical solution, the conductive bushing fills the gap between the end cap, the shielding ring, and the annular stepped surface of the inner wall of the housing, increasing the contact area, reducing the contact resistance, and improving the physical shielding effect of the Faraday cage; at the same time, the annular stepped surface achieves physical positioning of the shielding ring and the end cap.

[0008] Preferably, the transmission area is configured with three zones: a high-power radio frequency transmission zone, a power transmission zone, and a signal transmission zone. The high-power radio frequency transmission zone has shielding rings at both ends. By adopting the above technical solution—arranging the high-power radio frequency, power, and signal transmission channels in separate zones, and providing shielding rings at both ends of the high-power radio frequency transmission zone—key isolation of the high-power radio frequency transmission zone is achieved.

[0009] Preferably, several support rods are provided between the two end caps, each support rod passing through all the shielding rings. The sides of the end caps are fastened to the support rods by countersunk bolts, and the sides of the shielding rings are fastened to the support rods by countersunk bolts. The brush holder is installed between adjacent shielding rings or between a shielding ring and an adjacent end cap. By adopting the above technical solution, where the support rods pass through all the shielding rings and are fastened to the end caps and shielding rings respectively by countersunk bolts, the end caps and shielding rings are connected as a whole, improving the overall rigidity and facilitating accurate axial positioning of the shielding rings.

[0010] Preferably, the conductive ring in the high-power radio frequency transmission region is configured as a silver-plated conductive ring, and the thickness of the silver plating layer on the silver-plated conductive ring is configured as: T≥1.5*δ, δ= =66 / In the formula: T is the thickness of the silver plating layer, in μm; δ is the skin depth of the silver material for high-frequency current, in μm; f is the electromagnetic wave frequency of the high-power radio frequency transmission region, in MHz; ρ is the resistivity of the conductor, in Ω·μm; μ0 is the permeability of free space, in H / m, and μ0 is a constant 4π*10 -7 μ r Given the relative permeability, silver has a relative permeability of 1; therefore, T ≥ 1.5 * 66 / =99 / By adopting the above technical solution, the silver plating layer has a low resistivity and its thickness is greater than 1.5 times the skin depth, allowing high-power radio frequency current to flow mainly within the silver layer, thus reducing high-frequency transmission loss.

[0011] Preferably, the shielding ring includes an inner ring body and an outer ring body. The outer edge of the inner ring body has several first annular grooves spaced radially apart, and the inner edge of the outer ring body has several second annular grooves spaced radially apart. The first and second annular grooves interlock to form multiple continuously bent shielding gaps. The cutoff frequency of the shielding gaps is higher than the electromagnetic wave frequency of the high-power radio frequency transmission region, causing the electromagnetic wave to attenuate when it passes through the shielding gaps. By adopting the above technical solution, the inner and outer ring bodies form multiple continuously bent shielding gaps through interlocking annular grooves. When the electromagnetic wave passes through these gaps, the path is lengthened and reflected, resulting in energy attenuation, which greatly improves safety.

[0012] Preferably, the cutoff frequency of the shielding gap is: f c =c / λ c , λ c =2πR / 1.841=πD / 1.841=1.706D; where: f c Let λ be the cutoff frequency of the shielding gap, c be the speed of light, and λ be the value of the shielding c Let λ be the critical wavelength in the Bessel function, and D be the maximum diameter of the cylindrical shielding gap; let λ c =1.706D Substitute into f c =c / λ c We get: f c =300 / (1.706D)≈175.8 / D; where f and f c Configured as: f / f c ≤0.5, where f is the electromagnetic wave frequency of the high-power radio frequency transmission region; the attenuation isolation of the shielding gap (53) is configured as: SE≈27.3*L / g, SE≥60dB; where SE is the attenuation isolation, L is the axial overlap depth of the shielding gap, and g is the radial gap value of the shielding gap. By adopting the above technical solution: by configuring the cutoff frequency to be much higher than the operating frequency and the attenuation isolation to be not less than 60dB, the shielding gap has good isolation capability for high-power radio frequency electromagnetic waves.

[0013] Preferably, the spindle is equipped with a liquid cooling system, which includes a liquid cooling channel located inside the spindle and extending through both ends of the spindle, a rotary joint connected to one end of the liquid cooling channel, and a pipe connector on the rotor output assembly. The pipe connector is connected to the other end of the liquid cooling channel via a water pipe. By adopting the above technical solution, the coolant circulates through the rotary joint, liquid cooling channel, and water pipe, carrying away the conductive heat from the spindle and conductive ring, thus reducing the overall temperature rise.

[0014] Preferably, a throttling-assisted cooling system is provided on the main shaft corresponding to the high-power radio frequency transmission area. This system includes a cooling cavity on the surface of the main shaft and several circumferentially distributed guide cavities along the main shaft. The cooling cavity and the guide cavities are connected by guide grooves, and the guide cavities are connected to the ends of the main shaft by cooling holes. The housing is provided with a throttling valve for injecting liquid nitrogen into the high-power radio frequency transmission area, which is connected to the high-power radio frequency transmission area. The insulating sleeve within the high-power radio frequency transmission area has several guide holes connected to the cooling cavity. The side of the rotor output assembly has an exhaust channel connected to the cooling holes. By adopting the above technical solution, liquid nitrogen is injected into the high-power radio frequency transmission area through the throttling valve, flowing through the guide holes, cooling cavity, guide cavities, guide grooves, cooling holes, and exhaust channel, utilizing the heat absorption of liquid nitrogen vaporization to deeply cool the high-power radio frequency transmission area.

[0015] Therefore, the present invention has the following beneficial effects: (1) The shielding ring divides the space between the spindle and the housing into multiple independent transmission zones. The shielding ring, spindle, housing, and end cap are all configured as conductors and grounded to form a Faraday cage effect. Each transmission zone is shielded by the Faraday cage. The electric field and electromagnetic wave energy of adjacent transmission zones are guided to the grounding end for discharge by utilizing the Faraday cage effect, which effectively reduces the crosstalk between different transmission zones and improves the overall transmission reliability; (2) The inner ring and outer ring of the shielding ring form multiple continuous bending shielding gaps through interlocking annular grooves. When electromagnetic waves pass through the shielding gaps, they exhibit exponential growth. (2) The electromagnetic shielding isolation capability of the high-power radio frequency transmission area is significantly improved by using the parameters of the cutoff frequency and attenuation isolation. (3) The main shaft is equipped with a liquid cooling system and a throttling auxiliary cooling system is set at the corresponding location of the high-power radio frequency transmission area. By combining liquid cooling with liquid nitrogen throttling cooling, the temperature rise of the high-power radio frequency transmission area is effectively reduced, which helps to maintain stable contact between the conductive ring and the brush assembly. (4) Through the structure of grounding ring, grounding brush, grounding socket and conductive bushing, the conductive connection between the shielding ring, shell and end cover is made tighter and more reliable, which further improves the discharge effect of the grounding shielding circuit. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of one structure of the present invention.

[0017] Figure 2 yes Figure 1 A schematic diagram of the internal structure.

[0018] Figure 3 yes Figure 1 Axial sectional view.

[0019] Figure 4 for Figure 3 Sectional view at point AA.

[0020] Figure 5 for Figure 4 Sectional view at point BB.

[0021] Figure 6 for Figure 5 Enlarged view of a section at point C.

[0022] Figure 7 for Figure 5 Enlarged view of a section at point D.

[0023] Figure 8 This is a schematic diagram of a structure with a main axis.

[0024] Figure 9 This is an axial sectional view of the main axis.

[0025] Figure 10 This is a schematic diagram of the shielding ring.

[0026] Figure 11 This is a cross-sectional view of the shielding ring.

[0027] In the diagram: 1. Housing 1, Conductive Bushing 11, Throttling Valve 12, End Cap 2, Grounding Connector 21, Grounding Socket 22, Grounding Brush 221, Support Rod 23, Grounding Area 24, Rotor Assembly 3, Main Shaft 31, Bearing 311, Grounding Ring 312, Insulating Sleeve 32, Guide Hole 321, Conductive Ring 33, Silver-plated Conductive Ring 331, Rotor Output Assembly 34, Pipe Connector 341, Stator Assembly 4, Brush Holder 41, Brush Assembly 411, Stator Output... Component 42, shielding ring 5, inner ring body 51, first annular groove 511, outer ring body 52, second annular groove 521, shielding gap 53, transmission area 54, high-power radio frequency transmission area 541, power transmission area 542, signal transmission area 543, liquid cooling system 6, liquid cooling channel 61, rotary joint 62, water pipe 63, throttling auxiliary cooling system 7, cooling cavity 71, guide cavity 72, guide groove 73, cooling hole 74, exhaust channel 75. Detailed Implementation

[0028] To make the technical problems to be solved, the technical solutions and the beneficial technical effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and several exemplary embodiments.

[0029] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of the invention; the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance, nor should they be construed as implicitly specifying the number of indicated technical features. Features specified as "first" or "second" may explicitly or implicitly indicate the inclusion of at least one of those features.

[0030] like Figures 1-5The high-power radio frequency transmission slip ring shown includes a housing 1 and end caps 2 at both ends of the housing 1. A rotor assembly 3 and a stator assembly 4 are housed inside the housing 1. The rotor assembly 3 includes a main shaft 31, several insulating sleeves 32, and conductive rings 33 respectively fitted around the outer rings of each insulating sleeve 32. A bearing 311 is provided between the main shaft 31 and the end caps 2. The stator assembly 4 includes a brush holder 41 and several sets of brush assemblies 411 on the brush holder 41 that slide in corresponding contact with the conductive rings 33. A rotor output assembly 34 is fixed to one end of the main shaft 31. A brush assembly 34 is provided on the side of the housing 1. The stator input assembly 42 connected to component 411 has a number of spaced shielding rings 5 ​​on the main shaft 31. The shielding rings 5 ​​divide the space between the main shaft 31 and the housing 1 into several independent transmission zones 54. Each transmission zone 54 has at least one set of conductive rings 33 and a brush assembly 411 corresponding to the conductive ring 33. The shielding rings 5, the main shaft 31, the housing 1, and the end cover 2 are all configured as conductors. The inner ring of the shielding ring 5 is fitted on the main shaft 31 to form an electrical connection, and the outer ring of the shielding ring 5 abuts against the inner wall of the housing 1 to form an electrical connection. The end cover 2 is provided with a grounding connector 21.

[0031] The main shaft 31 is supported by bearings 311 and rotates smoothly between the two end covers 2. An insulating sleeve 32 insulates the conductive ring 33 from the main shaft 31. The conductive ring 33 is fitted onto the outer ring of the insulating sleeve 32 and rotates synchronously with the main shaft 31 to carry and transmit radio frequency signals. The rotor output assembly 34 is fixed to one end of the main shaft 31, leading the radio frequency signal from the rotating side outwards. The brush assembly 411 slides in contact with the conductive ring 33, transmitting the signal or power input from the stator input assembly 42 to the rotating conductive ring 33, achieving a conductive connection between the stator and rotor sides. Shielding rings 5 ​​spaced apart on the main shaft 31 divide the annular space between the main shaft 31 and the housing 1 axially into multiple independent transmission zones 54, each... At least one set of conductive rings 33 and corresponding brush assemblies 411 are provided in the transmission zone 54, so that each transmission zone 54 independently carries the transmission of corresponding signals or power, reducing the crosstalk between electric fields and electromagnetic waves between different transmission zones 54; the inner ring of the shielding ring 5 is fitted on the main shaft 31, and the outer ring abuts against the inner wall of the housing 1. The shielding ring 5, the main shaft 31, the housing 1, and the end cover 2 are all configured as conductors and connected to the ground through the grounding connector 21 on the end cover 2, so that each transmission zone 54 is surrounded, isolated and grounded by the conductor structure, forming a Faraday cage. The Faraday cage is used to isolate the high-power electromagnetic waves of each transmission zone 54 inside and guide them to the grounding end for discharge, further reducing the crosstalk between adjacent transmission zones 54. In some embodiments, the insulating sleeve 32 is made of PEEK GF30 material; the brush assembly 411 is a bristle brush.

[0032] like Figure 2As shown, several support rods 23 are provided between the two end caps 2. Each support rod 23 passes through all the shielding rings 5. The side of the end cap 2 is fastened to the support rod 23 by countersunk bolts, and the side of the shielding ring 5 is fastened to the support rod 23 by countersunk bolts. The brush holder 41 is installed between adjacent shielding rings 5 ​​or between the shielding ring 5 and adjacent end caps 2. The support rods 23 pass through all the shielding rings 5 ​​and are fastened to the end caps 2 and shielding rings 5 ​​respectively by countersunk bolts, so that the end caps 2 and shielding rings 5 ​​are connected as a whole, which improves the overall rigidity and facilitates the accurate axial positioning of the shielding rings 5. At the same time, the shielding rings 5 ​​serve as the mounting brackets for the brush holder 41, improving the compactness of the structure.

[0033] like Figure 3 As shown, a shielding ring 5 near the end cover 2 forms a grounding area 24 with the corresponding end cover 2. A grounding ring 312 is fitted on the main shaft 31 at the grounding area 24. A grounding base 22 is fixed on the inner wall of the end cover 2. A grounding brush 221 is provided on the grounding base 22 and makes sliding electrical contact with the grounding ring 312. The grounding base 22 and the grounding connector 21 are set on the same end cover 2. An annular stepped surface is provided on the inner wall of the housing 1 at the position of the corresponding end cover 2 and shielding ring 5. A conductive bushing 11 is provided between the end face of the end cover 2 and the corresponding annular stepped surface. A conductive bushing 11 is provided between the end face of the shielding ring 5 and the corresponding annular stepped surface. The grounding ring 312 and the grounding brush 221 maintain sliding electrical contact under rotational conditions, forming a reliable low-resistance ground together with the grounding base 22, thus improving the physical shielding effect of the Faraday cage. The conductive bushing 11 fills the gap between the end cap 2, the shielding ring 5, and the annular stepped surface of the inner wall of the housing 1, increasing the contact area and reducing the contact resistance, thereby improving the physical shielding effect of the Faraday cage. At the same time, the annular stepped surface provides physical positioning for the shielding ring 5 and the end cap 2. In some embodiments, the conductive bushing 11 is made of silver-plated glass microspheres or conductive silicone rubber filled with pure silver.

[0034] like Figure 5 As shown, the transmission area 54 is configured with three sections: a high-power radio frequency transmission area 541, a power transmission area 542, and a signal transmission area 543. Both ends of the high-power radio frequency transmission area 541 are equipped with shielding rings 5. The conductive ring 33 within the high-power radio frequency transmission area 541 is configured as a silver-plated conductive ring 331, with the silver plating thickness configured as: T≥1.5*δ, δ= =66 / In the formula: T is the thickness of the silver plating layer, in μm; δ is the skin depth of the silver material for high-frequency current, in μm; f is the electromagnetic wave frequency of the high-power radio frequency transmission region, in MHz; ρ is the resistivity of the conductor, in Ω·μm; μ0 is the permeability of free space, in H / m, and μ0 is a constant 4π*10 -7 μ r Given the relative permeability, silver has a relative permeability of 1; therefore, T ≥ 1.5 * 66 / =99 / The high-power radio frequency (RF), power, and signal transmission channels are arranged in separate zones. Shielding rings 5 ​​are installed at both ends of the high-power RF transmission zone 541, achieving key isolation of the high-power RF transmission zone 541. The silver-plated conductive ring 331 has a low resistivity and a thickness greater than 1.5 times the skin depth, causing the high-power RF current to mainly flow within the silver layer, reducing high-frequency transmission loss. The shielding rings 5 ​​at both ends of the high-power RF transmission zone 541 for key isolation, together with the silver-plated conductive ring 331 to reduce high-frequency loss, jointly improve the transmission reliability of the high-power RF transmission zone 541 under unconventional high-power RF conditions.

[0035] like Figure 3 , Figure 5 As shown, a liquid cooling system 6 is provided inside the spindle 31. The liquid cooling system 6 includes a liquid cooling channel 61 located inside the spindle 31 and passing through both ends of the spindle 31, a rotary joint 62 connected to one end of the liquid cooling channel 61, and a pipe joint 341 provided on the rotor output assembly 34. The pipe joint 341 is connected to the other end of the liquid cooling channel 61 via a water pipe 63. Figure 5 , Figure 8 and Figure 8 As shown, a throttling auxiliary cooling system 7 is provided on the main shaft 31 at a position corresponding to the high-power radio frequency transmission area 541. The throttling auxiliary cooling system 7 includes a cooling cavity 71 provided on the surface of the main shaft 31 and several guide cavities 72 distributed circumferentially along the main shaft 31. The cooling cavity 71 and the guide cavities 72 are connected by a guide groove 73. The guide cavities 72 are connected to the end of the main shaft 31 by a cooling hole 74. The housing 1 is provided with a throttling valve 12 for injecting liquid nitrogen into the high-power radio frequency transmission area 541, which is connected to the high-power radio frequency transmission area 541. The insulating sleeve 32 in the high-power radio frequency transmission area 541 is provided with several guide holes 321 that are connected to the cooling cavity 71. The side of the rotor output assembly 34 is provided with an exhaust channel 75 that is connected to the cooling hole 74.

[0036] The coolant circulates through the rotary joint 62, the liquid cooling channel 61, and the water pipe 63, carrying away the conductive heat from the spindle 31 and the conductive ring 33, thus reducing the overall temperature rise. Figure 5The arrows indicate the path of liquid nitrogen. Liquid nitrogen is injected into the high-power radio frequency transmission zone 541 through the throttle valve 12, and flows through the guide hole 321, cooling chamber 71, guide cavity 72, guide groove 73, cooling hole 74, and exhaust channel 75. The liquid nitrogen vaporization absorbs heat to deeply cool the high-power radio frequency transmission zone 541. The liquid cooling system 6 is responsible for the conventional heat dissipation of the entire spindle 31 and conductive ring 33, while the throttle-assisted cooling system 7 provides deep liquid nitrogen cooling for the high-power radio frequency transmission zone 541, where heat is most concentrated. The combination of the two achieves zoned and graded cooling, reducing the temperature rise of the high-power radio frequency transmission zone 541. In this structure, the cooling chamber 71, guide cavity 72, guide groove 73, and cooling hole 74 are directly set inside the spindle, and the annular cavity of the high-power radio frequency transmission zone 541 is used to disperse the liquid nitrogen. Without adding extra components or changing the overall structure of the slip ring, the entire throttle-assisted cooling system 7 is directly integrated into the existing structure of the slip ring, resulting in a compact overall structure.

[0037] like Figure 6 , Figure 10 , Figure 11 As shown, the shielding ring 5 includes an inner ring body 51 and an outer ring body 52. ​​The outer edge of the inner ring body 51 is provided with a plurality of first annular grooves 511 distributed radially at intervals, and the inner edge of the outer ring body 52 is provided with a plurality of second annular grooves 521 distributed radially at intervals. The first annular grooves 511 and the second annular grooves 521 interlock with each other to form a plurality of continuously bent shielding gaps 53. The cutoff frequency of the shielding gaps 53 is greater than the electromagnetic wave frequency of the high-power radio frequency transmission area 541, so that when the electromagnetic wave passes through the shielding gaps 53, the electromagnetic wave is attenuated. In some embodiments, the inner ring body 51 and the outer ring body 52 are made of aluminum alloy.

[0038] The cutoff frequency of the shielding gap 53 is: f c =c / λ c , λ c =2πR / 1.841=πD / 1.841=1.706D; where: f c Let λ be the cutoff frequency of the shielding gap, c be the speed of light, and λ be the value of the shielding gap. c Let λ be the critical wavelength in the Bessel function, and D be the maximum diameter of the cylindrical shielding gap; let λ c =1.706D Substitute into f c =c / λ c We get: f c =300 / (1.706D)≈175.8 / D; where f and f c Configured as: f / f c ≤0.5, where f is the electromagnetic wave frequency of the high-power radio frequency transmission region; the attenuation isolation of the shielding gap 53 is configured as: SE≈27.3*L / g, SE≥60dB; where SE is the attenuation isolation, L is the axial overlap depth of the shielding gap, and g is the radial gap value of the shielding gap.

[0039] The inner ring 51 and the outer ring 52 form a series of continuously bent shielding gaps 53 through the interlocking first annular groove 511 and second annular groove 521. When electromagnetic waves pass through the shielding gaps 53, the path is lengthened and reflected, and the energy is attenuated exponentially. By configuring the cutoff frequency of the shielding gaps 53 to be much higher than the operating frequency and the attenuation isolation to be no less than 60dB, the shielding gaps 53 have good isolation capability for high-power radio frequency electromagnetic waves. The series of continuously bent shielding gaps 53 provide a pressure relief port for electromagnetic waves in the transmission area 54. With the parameter configuration of cutoff frequency and attenuation isolation, the electromagnetic waves are fully attenuated in the shielding gaps 53, achieving high-isolation electromagnetic shielding. This reduces the risk of electromagnetic waves reflecting back and forth in the closed transmission area 54 to form standing waves, which in turn leads to a surge in field strength and heat, and the risk of arcing due to air breakdown. This reduces the risk of the slip ring being burned out.

[0040] Regarding the electromagnetic shielding principle of the shielding gap 53, when electromagnetic waves propagate in the metal shielding gap, they must satisfy Maxwell's equations and the boundary conditions of the metal wall. The transverse field distribution is constrained. The condition for electromagnetic waves to pass through the metal shielding gap is that the transverse width of the gap is greater than or equal to half a wavelength. Since frequency equals velocity divided by wavelength, the cutoff frequency is used to describe the attenuation isolation of the metal shielding gap. That is, when the electromagnetic wave frequency of the high-power RF transmission region 541 is less than the cutoff frequency of the shielding gap 53, the electromagnetic wave begins to attenuate. When the electromagnetic wave frequency of the high-power RF transmission region 541 is much lower than the cutoff frequency of the shielding gap, the electromagnetic wave attenuates exponentially. The cutoff frequency of the waveguide is: f c =c / λ c In the formula: f c is the cutoff frequency, in Hz; c is the speed of light, taken as 3 × 10⁻⁶. 8 meters per second; λ c The critical wavelength is given in meters; in a cylindrical waveguide, according to the Bessel function, the critical wavelength λ is... c The relationship between λc and the radius R or diameter D of the circular tube is: λc = 2πR / 1.841 = πD / 1.841 = 1.706D. c Substituting 1.706D, the cutoff frequency of the cylindrical gap (i.e., shielding gap 53) is: f c =c / λ c =3×10 8 / (1.706D), converting the speed of light to 3 × 10 11 mm, frequency unit converted to GHz, then f c =300 / (1.706D)≈175.8 / D. For example, in this embodiment, the maximum diameter of the cylindrical shielding gap is 61.5mm, then the cutoff frequency of the shielding gap is: f c=300 / (1.706D)≈175.8 / D=175.8 / 61.5≈2.86GHz; The radio frequency operating frequency f in this embodiment is 13MHz, f / f c =0.0045≤0.5, 0.0045 is much less than 0.5, that is, the electromagnetic wave frequency in the high-power radio frequency transmission area is much less than the cutoff frequency of the shielding gap, and the electromagnetic wave attenuates exponentially. When the electromagnetic wave frequency in the high-power radio frequency transmission area is less than the cutoff frequency of the shielding gap, the effect of the shielding gap is related to the axial overlap depth L and the radial gap g of the shielding gap. The number of layers of the first annular groove and the second annular groove can be configured as 2-3 layers. The shielding effect of the shielding gap is nominally expressed as isolation SE: SE≈27.3×L / g, where: SE is the attenuation isolation, in dB; L is the axial overlap depth of the shielding gap, in mm; g is the radial gap of the shielding gap, in mm; in some embodiments, SE is configured as 60dB, then the ratio of L / g should be 60 / 27.3≈2.2, that is, if the radial gap g=0.5mm, then the axial overlap depth L of the shielding gap should be greater than 2.2×0.5≈1.1mm.

[0041] Referring to the accompanying drawings, the working principle of this invention is as follows: During operation, the grounding connector is grounded through a wire. The stator input assembly 42 sends the radio frequency signal or power into the stator assembly 4, which is then transmitted to the conductive ring 33 rotating with the main shaft 31 through the sliding contact between the brush assembly 411 and the conductive ring 33. The signal is then led outward by the rotor output assembly 34, realizing the rotational conductive transmission between the stator side and the rotor side. During the transmission process, the conductor structure formed by the shielding ring 5, the main shaft 31, the housing 1, and the end cover 2 surrounds, isolates, and grounds each transmission area 54, forming a Faraday cage. This guides the electric field and electromagnetic wave energy between adjacent transmission areas 54 to the grounding end for discharge. The shielding gap 53 provides a pressure relief port for the electromagnetic waves in the transmission area 54, allowing the electromagnetic waves to be fully attenuated within the shielding gap 53, reducing the risk of standing waves and arcing. At the same time, the liquid cooling system 6 and the throttling auxiliary cooling system 7 cool the main shaft 31 and the high-power radio frequency transmission area 541, reducing the temperature rise. Therefore, the present invention achieves the purpose of isolating each transmission zone 54 individually through the Faraday cage structure composed of shielding ring 5, main shaft 31, housing 1, and end cap 2, effectively alleviating the problem of mutual interference between electric fields and electromagnetic waves between different transmission zones 54 during high-power radio frequency transmission; at the same time, the use of shielding gaps makes electromagnetic waves attenuate exponentially when passing through the shielding gaps, improving the safety of use.

[0042] In the description of this invention, it should be understood that the directions or positional relationships indicated by up, down, left, right, inner end, outer end, one end, and the other end are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the purpose of more clearly describing the technical solutions of this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as limiting this invention.

[0043] Although specific embodiments of the invention have been described in detail herein, they are given for illustrative purposes only and should not be construed as limiting the scope of the invention. Various substitutions, alterations, and modifications can be conceived without departing from the spirit and scope of the invention.

Claims

1. A high-power radio frequency transmission slip ring, comprising a housing (1) and end caps (2) disposed at both ends of the housing (1), wherein a rotor assembly (3) and a stator assembly (4) are disposed inside the housing (1), the rotor assembly (3) comprising a main shaft (31), a plurality of insulating sleeves (32), and conductive rings (33) respectively sleeved on the outer ring of each insulating sleeve (32), a bearing (311) is provided between the main shaft (31) and the end caps (2), the stator assembly (4) comprising a brush holder (41) and a plurality of brush assemblies (411) disposed on the brush holder (41) and correspondingly slidingly contacting the conductive rings (33), a rotor output assembly (34) is fixedly disposed at one end of the main shaft (31), and a stator input assembly (42) connected to the brush assembly (411) is provided on the side of the housing (1), characterized in that, The main shaft (31) is provided with a plurality of spaced shielding rings (5), which divide the space between the main shaft (31) and the housing (1) into a plurality of independent transmission zones (54). Each transmission zone (54) is provided with at least one set of conductive rings (33) and a brush assembly (411) corresponding to the conductive ring (33). The shielding ring (5), main shaft (31), housing (1), and end cap (2) are all configured as conductors. The inner ring of the shielding ring (5) is fitted onto the main shaft (31) to form an electrical connection. The outer ring of the shielding ring (5) abuts against the inner wall of the housing (1) to form an electrical connection. The end cap (2) is provided with a grounding connector (21). One of the transmission areas (54) is configured as a high-power radio frequency transmission area (541), and both ends of the high-power radio frequency transmission area (541) are provided with the shielding ring (5); the shielding ring (5) includes an inner ring body (51) and an outer ring body (52). The outer edge of the inner ring body (51) is provided with a number of first annular grooves (511) distributed radially at intervals, and the inner edge of the outer ring body (52) is provided with a number of second annular grooves (521) distributed radially at intervals. The first annular grooves (511) and the second annular grooves (521) interlock to form multiple continuously bent shielding gaps (53); the cutoff frequency of the shielding gap (53) is greater than the electromagnetic wave frequency of the high-power radio frequency transmission area (541), so that when the electromagnetic wave passes through the shielding gap (53), the electromagnetic wave is attenuated.

2. The high-power radio frequency transmission slip ring according to claim 1, characterized in that, Among them, near A grounding area (24) is formed between the shielding ring (5) of the end cover (2) and the corresponding end cover (2). A grounding ring (312) is sleeved on the part of the main shaft (31) located in the grounding area (24). A grounding base (22) is fixed on the inner wall of the end cover (2). A grounding brush (221) is provided on the grounding base (22) and makes sliding electrical contact with the grounding ring (312). The grounding base (22) and the grounding connector (21) are arranged on the same end cover (2).

3. A high-power radio frequency transmission slip ring according to claim 1 or 2, characterized in that, The inner wall of the housing (1) is provided with an annular stepped surface at the positions of the corresponding end cap (2) and shielding ring (5). A conductive bushing (11) is provided between the end face of the end cap (2) and the corresponding annular stepped surface. A conductive bushing (11) is provided between the end face of the shielding ring (5) and the corresponding annular stepped surface.

4. A high-power radio frequency transmission slip ring according to claim 1, characterized in that, The transmission area (54) is configured as three, namely a high-power radio frequency transmission area (541), a power transmission area (542), and a signal transmission area (543).

5. A high-power radio frequency transmission slip ring according to claim 1, characterized in that, Several support rods (23) are provided between the two end caps (2), and each support rod (23) passes through all the shielding rings (5). The side of the end cap (2) is fastened to the support rod (23) by countersunk bolts, and the side of the shielding ring (5) is fastened to the support rod (23) by countersunk bolts. The brush holder (41) is installed between adjacent shielding rings (5) or between shielding rings (5) and adjacent end caps (2).

6. A high-power radio frequency transmission slip ring according to claim 4, characterized in that, The conductive ring (33) within the high-power radio frequency transmission region (541) is configured as a silver-plated conductive ring (331), and the thickness of the silver plating layer on the silver-plated conductive ring (331) is configured as: T≥1.5*δ, δ= =66 / ; In the formula: T is the thickness of the silver plating layer, in μm; δ represents the skin depth of the silver material under high-frequency current, in μm; f is the electromagnetic wave frequency in the high-power radio frequency transmission region, in MHz; ρ is the resistivity of the conductor, in Ω·μm; μ0 is the free magnetic permeability in H / m, and μ0 is a constant of 4π × 10⁻⁴. -7 ; μ r The relative permeability is 1; Therefore, T≥1.5*66 / =99 / .

7. A high-power radio frequency transmission slip ring according to claim 1, characterized in that, The cutoff frequency of the shielding gap (53) is: f c =c / λ c , λ c =2πR / 1.841=πD / 1.841=1.706D; In the formula: f c Let λ be the cutoff frequency of the shielding gap, c be the speed of light, and λ be the value of the shielding c Where λ is the critical wavelength in the Bessel function, and D is the maximum diameter of the cylindrical shielding gap. λ c =1.706D Substitute into f c =c / λ c We get: f c =300 / (1.706D)≈175.8 / D; Where f and f c Configured as: f / f c ≤0.5, where f is the electromagnetic wave frequency in the high-power radio frequency transmission region; The attenuation isolation of the shielding gap (53) is configured as follows: SE≈27.3*L / g, SE≥60dB; where SE is the attenuation isolation, L is the axial overlap depth of the shielding gap, and g is the radial gap value of the shielding gap.

8. A high-power radio frequency transmission slip ring according to claim 1, 2, or 4, characterized in that, The main shaft (31) is provided with a liquid cooling system (6). The liquid cooling system (6) includes a liquid cooling channel (61) located inside the main shaft (31) and passing through both ends of the main shaft (31), and a rotary joint (62) connected to one end of the liquid cooling channel (61). The rotor output assembly (34) is provided with a pipe joint (341). The pipe joint (341) is connected to the other end of the liquid cooling channel (61) through a water pipe (63).

9. A high-power radio frequency transmission slip ring according to claim 1, characterized in that, A throttling auxiliary cooling system (7) is provided on the main shaft (31) corresponding to the high-power radio frequency transmission area (541). The throttling auxiliary cooling system (7) includes a cooling cavity (71) on the surface of the main shaft (31) and several guide cavities (72) distributed circumferentially along the main shaft (31). The cooling cavity (71) and the guide cavity (72) are connected by a guide groove (73). The guide cavity (72) is connected to the end of the main shaft (31) by a cooling hole (74). A throttling valve (12) for injecting liquid nitrogen into the high-power radio frequency transmission area (541) is provided on the housing (1). Several guide holes (321) connected to the cooling cavity (71) are provided on the insulating sleeve (32) in the high-power radio frequency transmission area (541). An exhaust channel (75) connected to the cooling hole (74) is provided on the side of the rotor output assembly (34).

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