A pantograph support insulator and a method for manufacturing the same

Abstract

The application discloses a pantograph support insulator and a preparation method thereof, relates to the technical field of insulator preparation, and obtains the electric field intensity of the insulator in the use state along the axial direction, divides the electric field sections according to the electric field intensity, determines the path extension parameters of each section, determines the corresponding local spiral parameters according to the path extension parameters, and continuously connects the local spiral paths of adjacent sections to form a variable-parameter spiral air channel forming track. Since the extension degree of the air channel at different axial positions can establish a corresponding relationship with the electric field state of the corresponding section, the method can more centrally configure the limited air channel bypass length to the section that needs to increase the internal path, reduces the dependence on the simultaneous increase of the bypass amount of all sections, and thus can consider the local internal insulation path and the overall air channel length under the condition that the size of the insulator is limited.

Description

Technical Field

[0001] This invention relates to the field of insulator manufacturing technology, specifically to a pantograph support insulator and its manufacturing method. Background Technology

[0002] The pantograph support insulator provides mechanical support and electrical insulation between the pantograph and the vehicle body. Some pantographs also require compressed air for raising and lowering via an air circuit. Placing the air circuit inside the insulator body reduces the need for external piping and concentrates the insulation support and gas transmission within the same component.

[0003] The axial electric field distribution of an insulator under operating voltage is affected by the end structure, body size, and surrounding conductive components, resulting in variations in local electric field strength. When uniform geometric parameters are used for the internal air passages, their path length is difficult to correspond to the electric field state at each axial position, and increasing the overall bypass length will simultaneously increase the gas flow path. Therefore, it is necessary to coordinate the local electric field state with the geometric path of the internal air passages. Summary of the Invention

[0004] The purpose of this invention is to provide a pantograph support insulator and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a pantograph support insulator.

[0006] The technical effects and advantages provided by the present invention in the above technical solution are as follows: 1. Compared to arranging air channels inside the insulator according to a uniform spiral geometry, this scheme first obtains the axial electric field strength of the insulator when it is in use, and then divides the electric field into sections and determines the path extension parameters of each section. Secondly, based on the path extension parameters, the corresponding local spiral parameters are determined, and then the local spiral paths of adjacent sections are continuously connected to form a variable-parameter spiral air channel forming trajectory. Since the extension degree of the air channel at different axial positions can establish a correspondence with the electric field state of the corresponding section, the limited air channel bypass length can be more concentrated on the sections that require increased internal paths, reducing the dependence on simultaneously increasing the bypass amount of all sections. This allows for a balance between local internal insulation paths and overall air channel length within the constraints of insulator size.

[0007] 2. In a further subordinate scheme, this scheme forms a local candidate parameter group based on helical radius, pitch, and effective number of turns. This group is then screened and corrected by considering parameter variations in adjacent sections, remaining resin thickness, resin isolation thickness between helices, and the degree of airway curvature. Subsequently, a transition section is used to continuously connect adjacent local helical paths in both position and tangential direction, forming the actual helical airway according to the obtained trajectory. This process ensures that local parameter adjustments are no longer performed in isolation. It allows for simultaneous consideration of the geometric continuity of adjacent sections and the spatial constraints of the insulator body when changing the extension degree of an airway in a certain section. This reduces the possibility of sharp local turns, insufficient resin isolation thickness, or ineffective increases in curvature paths, making the obtained airway trajectory suitable for continuous forming within the epoxy resin insulator body while maintaining the integrity of the airway. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0009] Figure 1 This is a schematic diagram of the process for preparing the pantograph support insulator in this invention.

[0010] Figure 2 This is a schematic diagram showing the correspondence between the electric field section and the variable parameter spiral air passage in this invention. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on this invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0012] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0013] In the following description, the terms "first, second, third" are used merely to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first, second, third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of the invention described herein can be implemented in an order other than that illustrated or described herein.

[0014] Unless otherwise defined, all technical and scientific terms used in the embodiments of this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in the embodiments of this invention is for descriptive purposes only and is not intended to limit the invention.

[0015] The following description, based on the actual installation state of the pantograph support insulator, further illustrates the fabrication process of this invention. The term "usage state" in this invention refers to the electrical state of the insulator after the high-voltage end metal parts, grounding end metal parts, and adjacent conductive components are installed according to the actual assembly relationship of the pantograph. For target insulators that have not yet been manufactured, test results from samples of the same specifications can be used, or an electric field calculation model can be established based on the installation dimensions, material parameters, and operating voltage of the target insulator to obtain the axial electric field strength. Therefore, it is not required to perform the fabrication process only after the target insulator has been put into operation.

[0016] For samples of the same specifications, the test data are mainly used to verify the electric field calculation model, and it is not required to place the electric field probe directly inside the cured epoxy resin. One or more measurable results, such as the end applied voltage, surface potential or surface field strength distribution, or partial discharge initiation state, can be used to correlate with the calculation results. When the model's geometry, material dielectric parameters, and boundary conditions are consistent with the target model, and the verification results are within the allowable deviation of the product design, the internal axial electric field strength output by the model is used as the input for subsequent partitioning.

[0017] The location for the axial electric field intensity is determined using a uniform aperture. First, the possible envelope region for the air duct is determined based on the insulator's shape, the position of the metal insert, and the reserved resin space. Then, several electric field sampling points are set within the cross-section corresponding to the j-th axial position. The magnitudes of the electric field vectors at each sampling point are compared, and the maximum value within that cross-section is taken as the electric field intensity E at that axial position. j If a single reference line is used for sampling, this reference line maintains the same radial and circumferential reference at all axial positions to avoid introducing additional differences due to variations in sampling position. The relative permittivity of the epoxy resin uses material data consistent with the actual molding resin grade or measured values ​​from the same batch of cured samples; the mesh is refined step by step, and the refined calculation result is used when the change in axial peak field strength obtained from two adjacent refinements meets the preset convergence condition. For example, a peak change of no more than 5% can be used as a modeling verification condition.

[0018] The "path extension parameter" used in this invention describes the extent to which the actual path length of the spiral airway centerline extends relative to the axial length of a given axial segment. A larger parameter indicates a longer actual extension path of the airway within the same axial length. The path extension parameter corresponds to the spiral radius, pitch, and number of effective turns, thus serving as an intermediate parameter between the electric field segment and the local spiral geometry, allowing the electric field zoning results obtained in the previous stage to be continuously transferred to the subsequent process of determining the airway forming trajectory.

[0019] The "electric field strength along the insulator's axial direction" referred to in this invention refers to representative values ​​of local electric field strength obtained at different positions along the insulator's axial direction. This value describes the distribution of the electric field with respect to axial position, and does not represent only the axial component of the electric field vector. When using cross-sectional sampling, representative values ​​are obtained by comparing the electric field modulus values ​​within the envelope cross-section corresponding to the air passage at the same axial position. When using reference line sampling, the same radial and circumferential references are maintained at all axial positions. Therefore, the meaning of the data used for subsequent electric field segmentation remains consistent across all sampling positions.

[0020] The "optimized insulator" referred to in this invention is an insulator design model that has completed the generation of the variable-parameter spiral air channel forming trajectory, spatial constraint correction, and final electric field verification under the conditions of a given insulator shape, metal inserts, and air inlet / outlet interfaces. It does not refer to a physical insulator that has already been put into use and is being further processed. In actual manufacturing, the spiral core can be removed and epoxy resin casting can be completed based on this design model.

[0021] In this invention, the insulator body can be molded from epoxy resin insulating material, and the cross-section of the air duct is preferably circular or nearly circular with rounded corners. The air inlet and outlet ports can be respectively located at the metal inserts at both ends of the insulator and communicate with the internal spiral air duct. The insulator shape, metal insert structure, resin formulation, and interface form can be determined according to the pantograph model. The following implementation process focuses on describing the axial electric field zoning, path parameter allocation, local spiral parameter determination, trajectory continuity connection, spatial constraint correction, and the integrated molding process of the air duct. Example 1

[0022] like Figure 1As shown, the preparation process of this invention consists of obtaining the electric field under use, dividing the electric field segments and determining the path extension parameters, determining the local spiral parameters, continuously connecting adjacent segments, and sequentially connecting the spiral air channels formed according to the forming trajectory. This embodiment provides a basic implementation method for obtaining the variable parameter spiral air channel forming trajectory from the electric field distribution under use. First, the electric field strength along the axial direction of the insulator when it is in the actual assembly state is obtained. Specifically, a geometric model of the insulator body, upper metal insert, lower metal insert, pantograph connecting component, and vehicle grounding component can be established in three-dimensional electric field calculation software. The relative permittivity of epoxy resin, the conductivity properties of the metal parts, and the working voltage boundary are input into the model; the high-voltage side adopts the potential boundary corresponding to the actual power supply state of the pantograph, and the grounding side adopts the zero potential boundary. After the solution is completed, sampling positions arranged along the axial direction are set near the axial centerline of the insulator or within the predetermined air channel envelope area to obtain the electric field strength corresponding to each sampling position. For the pantograph insulation structure of 25 kV level, sampling points can be set at equal intervals according to the effective axial length of the insulator, with a sampling interval of, for example, 5 mm to 10 mm. When the field strength at the end changes rapidly, sampling points can be added in the end area to avoid local peak values ​​being ignored by excessively large sampling intervals.

[0023] After obtaining the axial electric field intensity sequence, the change in electric field intensity between adjacent sampling positions is calculated according to the sampling order. The segment boundaries can be determined by both the electric field change trend and the magnitude of the change. For example, first calculate the relative change rate of all adjacent sampling positions, and use positions with higher relative change rates as candidate boundaries. Simultaneously, use positions where the electric field intensity changes from increasing to decreasing or vice versa as supplementary candidate boundaries. Adjacent candidate boundaries with a distance less than the preset minimum segment length are merged to avoid forming excessively short segments. The minimum segment length can be determined by combining the air duct diameter, allowable pitch, and the required length of the transition section; for example, it can be no less than three times the air duct diameter. After the above processing, the insulator's axial direction is divided into several continuous electric field segments, each segment being connected end-to-end and covering the effective axial range where the air duct needs to be arranged.

[0024] To ensure that the "relative rate of change" and "higher quantile interval" have a clear calculation scope, the relative rate of change of electric field intensity δ is defined for the j-th and j+1-th adjacent sampling positions. j ; when E j With E j+1 When they are different, the ratio of the absolute value of their difference to the larger of the two values ​​is used for calculation; when both are 0, δ is... j Denote it as 0. For all δ j Sort by size from smallest to largest to obtain the quantile statistic Q. q q can be preset according to the number of segments and sampling density, for example, 0.75; satisfying δ j ≥Q qThe location is used as a candidate boundary for the magnitude of change. For locations where the direction of change in electric field intensity reverses, these locations are used as candidate boundaries for the trend, and then adjacent boundaries are merged based on the minimum segment length.

[0025] δ j =|E j+1 -E j | / max(E j E j+1 ); For each electric field segment, the average electric field strength, peak electric field strength, and segment length are calculated. To allow data with different dimensions to be used for segment comparison, the average electric field strength, peak electric field strength, and segment length are each divided by the maximum value of the corresponding item across all segments. The normalized results are then weighted and combined to obtain the segment's electric field characterization. In a feasible example, the average electric field strength and peak electric field strength are each assigned a weight of 0.45, and the segment length is assigned a weight of 0.10, with the sum of the three weights being 1. These weights do not necessarily need to be fixed values ​​and can be adjusted based on the prototype's withstand voltage verification results. However, the electric field strength-related items should maintain a dominant proportion so that the segment's electric field characterization reflects the degree of electric field influence at the corresponding axial position.

[0026] The segmental electric field characterization quantity is used to simultaneously reflect the electric field level within the segment and the axial range of the duration of this electric field state. Let M be the average electric field intensity of the i-th electric field segment. i The peak electric field intensity is P i The axial length of the section is H i The maximum values ​​corresponding to all segments are M. max P max and H max The characteristic quantity of the electric field in the section is denoted as F. i When using a weighted combination, each weight is a non-negative value and the sum of the weights is 1; in the example, w1=0.45, w2=0.45, w3=0.10, where the length term is only used to characterize the range of the corresponding electric field level in the axial direction, so its weight is lower than that of the electric field strength related terms.

[0027] F i =w1(M i / M max )+w2(P i / P max )+w3(H i / H max ); Subsequently, the path extension parameters are determined based on the relative relationships between the electric field characteristics of each section. The design range of the path extension parameters can be initially determined based on the available radial space inside the insulator, the diameter of the air passage, and the allowable air path length. Then, the electric field characteristics of each section are mapped to this design range from smallest to largest; sections with larger characteristics correspond to larger path extension parameters, and sections with smaller characteristics correspond to smaller path extension parameters. Thus, with the total axial length remaining constant, sections with higher electric field effects can obtain longer internal air passage paths, while sections with relatively lower electric field effects do not need to simultaneously increase the degree of detour.

[0028] The design range for path extension parameters is not arbitrarily given. First, within the possible envelope region of the air passage, a set of geometric candidates is generated based on selectable helical radius, pitch, and air passage diameter. Candidate combinations that do not meet the requirements for reserved resin thickness, adjacent ring spacing, core forming bending capability, and allowable total air passage length or allowable pressure drop are excluded. The minimum and maximum path extension achievable by the remaining candidate combinations are then defined as λ. min and λ max The permissible total length of the gas path or the permissible pressure drop can be determined by flow simulation or sample flow-pressure drop test based on the rated flow rate and interface pressure requirements of the pantograph gas path.

[0029] When different sections of F i When differences exist, F can be used. i Linearly mapped to [λ] according to its relative position in all segments. min , λ max The target path extension parameter λ is obtained. i tar When all segments of F i If the values ​​are the same, then the same target path extension parameters are used for each segment, such as the median value of the design range. This clarifies the data transfer relationship between the segment's electric field characterization parameters and subsequent geometric parameters.

[0030] λ i tar =λ min +[(F i -F min ) / (F max -F min )](λ max -λ min ); In the formula, F min and F max λ represents the minimum and maximum values ​​of the segmental electric field characterization quantity for the entire electric field region, respectively. min and λ max Let λ represent the lower and upper limits of the path extension parameters that can be used under the current available airway space and airway constraints, respectively, and λ min Not less than 1; λi tar This represents the target path extension parameter for the i-th electric field segment. When the aforementioned F... max With F min When they are equal, the mapping formula with a denominator of zero is not used, but the same target path extension parameters are applied to each segment in the manner described above.

[0031] For the i-th electric field segment, the path extension parameter can be defined as the ratio of the length of the spiral airway centerline to the axial length of the segment, i.e.: λ i =L i / H i ; In the formula, λ is the path extension parameter, L is the actual length of the spiral airway centerline within the corresponding electric field segment, H is the axial length of the corresponding electric field segment, and the subscript i indicates the i-th electric field segment. The path extension parameter is a dimensionless parameter. When an actual spiral path has not yet been generated for a certain electric field segment, L represents the target path length determined by the electric field characterization quantity of that segment; after the local spiral path is generated, the parameter is verified again using the actual centerline length.

[0032] Through the above process, the electric field intensity sequence is first converted into electric field segments with well-defined boundaries. Then, the average electric field intensity, peak electric field intensity, and segment length are used to form comparable segment electric field characterization quantities. Finally, the path extension parameters are obtained from the segment electric field characterization quantities. This avoids directly determining the spiral shape by the instantaneous field intensity of a single sampling point, ensuring that the determination of local spiral parameters has a stable foundation of preceding data, and providing a consistent parameter input for the continuous connection of adjacent segments. Example 2

[0033] like Figure 2 As shown, the variable-parameter spiral air passage connects the inlet and outlet ports along the insulator axis. Different electric field sections adopt local spiral radii and pitches corresponding to the path extension parameters, and adjacent electric field sections are continuously connected through transition sections. This embodiment, based on Embodiment 1, explains how to determine the local spiral parameters within each electric field section from the path extension parameters and how to continuously connect the spiral paths of adjacent sections. For each electric field section, the usable spiral radius range for that section is first determined based on the insulator outer diameter, the position of the internal metal insert, the air passage diameter, and the reserved resin thickness. Then, several candidate spiral radii are set within this radius range; simultaneously, candidate pitches are set based on the air passage diameter and the resin isolation thickness to be retained between adjacent turns. Each combination of candidate spiral radius and candidate pitch corresponds to a calculable unit axial length air passage extension, thus forming a candidate parameter group.

[0034] For a standard helical segment with unchanged local parameters, assuming a helical radius of r, a pitch of p, and an effective number of turns of n, a definite geometric relationship exists between the centerline length, axial length, and path extension of this segment. This relationship can be used to convert the path extension parameters obtained in Example 1 into candidate helical parameters and to exclude parameter combinations that cannot achieve the target path length. The specific relationship is as follows: L i =n i √((2πr i ) 2 +p i 2 ); H i =n i p i ; λ i =√(1+(2πr i / p i ) 2 ); In the formula, r is the local helical radius of the i-th electric field segment, p is the local helical pitch of the i-th electric field segment, n is the effective number of turns in the segment, and the meanings of the remaining parameters are the same as in Example 1. The effective number of turns is allowed to be a non-integer so that the local helical path can be intercepted according to the actual phase at the segment boundary. The path extension can be changed by changing the helical radius and the pitch; therefore, one path extension parameter usually corresponds to multiple candidate parameter sets.

[0035] Candidate parameter groups that meet the target path extension parameters are further spatially screened. First, the minimum distance from the outer edge of the spiral air passage to the outer surface of the insulator, the surface of the metal insert, and adjacent structures is calculated as the remaining resin thickness. Second, the minimum surface distance between adjacent spiral coils is calculated as the resin isolation thickness. For standard spiral segments of equal radius, the axial distance between the centerlines of adjacent complete spiral coils at the same circumferential position is equal to the pitch. Therefore, the resin isolation thickness can be initially judged by subtracting the air passage diameter from the pitch, and then verified by calculating the shortest distance using a three-dimensional geometric model. The allowable lower limits for the remaining resin thickness and the resin isolation thickness are determined by the target insulation class, mechanical load, and the withstand voltage and strength verification results of the resin material.

[0036] After spatial screening, candidate parameter groups are compared with the radius and pitch changes of their respective end parameters in adjacent electric field sections. Priority is given to parameter groups that achieve the target path extension while exhibiting minimal parameter differences from adjacent sections, thus reducing parameter abrupt changes in transition sections. When multiple candidate groups satisfying the conditions exist for a section, they can be sorted sequentially according to remaining resin thickness margin, resin isolation thickness margin, and parameter differences from adjacent sections, with the highest-ranked candidate group selected as the local helical parameter.

[0037] To avoid a lack of criteria for determining "the extent to which the target path extension has been achieved", for the k-th group of candidate parameters in the i-th segment, the candidate path extension parameter λ is first calculated according to the spiral geometric relationship. i,k Then calculate its extension parameter λ relative to the target path. i tar relative deviation e i,k Permissible deviation ε λ The tolerances are preset based on the core machining accuracy and air passage dimensions, for example, 5%. When e exists... i,k ≤ε λ When selecting candidate groups, first sort them by path extension deviation from smallest to largest. Then, among candidate groups with similar deviations, prioritize the combination with larger remaining resin thickness margin and resin isolation thickness margin, and smaller changes in end radius and pitch with adjacent sections. If there is no candidate group that meets the allowable deviation, select the candidate group with the smallest deviation for subsequent constraint correction, instead of directly acknowledging that it meets the design requirements.

[0038] e i,k =|λ i,k -λ i tar | / λ i tar ; After determining the local helical parameters of two adjacent electric field sections, a transition section is set between them. The length of the transition section can be determined based on the difference in helical radius and pitch at both ends, ensuring that at least three positions with continuous parameter changes can be arranged. The helical radius, pitch, spatial position, and tangential direction at the end of the previous electric field section are used as the transition initiation conditions, and the corresponding parameters at the beginning of the next electric field section are used as the transition termination conditions. The helical radius and pitch are changed step by step along the axial direction, while the circumferential phase is adjusted so that the starting point of the transition path is in the same position and tangential direction as the previous local helical path, and the ending point of the transition path is in the same position and tangential direction as the next local helical path. If necessary, a cubic curve can be used to fit the transition centerline to obtain a first-order continuous centerline.

[0039] When using continuous parameter interpolation for the transition section, the axial position of the transition section can be normalized to t∈[0,1]. Cubic Hermite interpolation is then applied to the helical radius and pitch. The interpolation takes the radius and pitch at the end of the previous electric field segment at t=0, and the radius and pitch at the beginning of the next electric field segment at t=1. The first derivatives at both ends are determined by the rate of change of the parameters of the corresponding local helical segments at the connection point. Then, the transition centerline is generated point-by-point based on the interpolated radius, pitch, and continuously changing circumferential phase. After generation, the endpoint positions and tangential directions of the transition centerline and the local helical paths on both sides are checked. If both are continuous, the connection is considered complete, thus providing executable boundary conditions for "cubic curve fitting" and "first-order continuity."

[0040] The axial length of the transition section can be initially set based on the airway diameter and the available section length. For example, the initial transition length can be set to be no less than three times the airway diameter, ensuring that at least three parameter control positions can be arranged. After generating the transition centerline based on this initial value, the maximum local curvature is calculated. If the maximum local curvature exceeds the maximum allowable curvature, the transition section is gradually extended and re-interpolated, provided that there is still axial margin in the adjacent electric field section, until the curvature constraint is met. If extending to the available boundary still cannot meet the constraint, the local spiral parameters on both sides are reselected instead of using a transition trajectory with a sharp turn.

[0041] After completing all transition sections, the local helical paths and transition paths are connected sequentially according to the insulator's axial order. The end position and tangential direction of the previous transition path are directly used as the starting conditions for the next local helical path, avoiding the need to independently set the starting point at the section connection. The foremost path is connected to the center position of the air inlet, and the last path is connected to the center position of the air outlet, thus obtaining a variable-parameter helical air channel forming trajectory that runs through the insulator body. This trajectory simultaneously preserves the path extension relationship between each axial section and the corresponding electric field state, and ensures geometric continuity between adjacent sections. Example 3

[0042] This embodiment illustrates the spatial constraint check and local correction process of the variable-parameter spiral air channel forming trajectory before actual forming. Since the insulator's shape, metal inserts, and interface positions all limit the usable space of the internal air channel, local spiral parameters generated solely based on the target path extension parameters may result in insufficient remaining resin thickness, excessively small distances between adjacent spiral coils, or excessive local bending at certain locations. Therefore, after forming the initial forming trajectory, the centerline is discretely sampled along its length, and a section perpendicular to the tangential direction of the centerline is established at each sampling position to calculate the minimum distance from the outer edge of the air channel to the outer surface of the insulator and the internal metal structure; for adjacent spiral coils, the minimum distance between the outer surfaces of the two air channel segments is calculated.

[0043] The degree of airway curvature can be represented by the centerline curvature or the minimum curvature radius. For helical segments with approximately constant local parameters, the degree of curvature can be quantified using the helical curvature. Lower limit of remaining resin thickness t min The minimum allowable resin isolation thickness between adjacent spirals is s. minThe thickness is determined according to the insulation and mechanical design conditions of the target model. Specifically, the above thickness can be parameter-scanned in a 3D model, the maximum electric field strength within the resin body is calculated under the corresponding design voltage or detection voltage, and the stress in the resin body and adjacent areas of the insert is calculated under the specified mechanical load of the pantograph. The allowable electrical and mechanical values ​​of the material adopt material data consistent with the actual resin system or the results of the same batch of samples and are included in the design margin. The minimum thickness that simultaneously meets the allowable electrical and mechanical values ​​is selected as the corresponding lower limit, and this lower limit is used as a spatial constraint for all subsequent candidate trajectories.

[0044] Maximum allowable curvature κ max Simultaneously constrained by the moldability of the core and the flow properties of the air passage. Let R be the minimum bending radius that the selected core can maintain dimensional stability under the curing temperature and positioning method. c The minimum airway bend radius that satisfies the allowable pressure drop under the pantograph's rated flow conditions is R. f Then the smaller of the two corresponding upper limits of curvature is used as κ. max ;R c The results can be obtained through a core strip bending / curing retention test, R f It can be obtained through flow simulation or flow-pressure drop tests on bent pipe samples.

[0045] κ max =min(1 / R c ,1 / R f ); κ i =r i / [r i 2 +(p i / 2π) 2 ]; In the formula, κ represents the curvature of the local spiral path in the i-th electric field segment, and r and p represent the spiral radius and pitch of that segment, respectively. A larger curvature indicates a tighter bend in the air passage. For transition sections, the local curvature can be directly obtained using the tangential variation between adjacent sampling points on the three-dimensional centerline. The maximum allowable curvature can be determined based on the core forming capability, air passage diameter, and target air passage pressure drop; therefore, different upper limits of curvature can be used for pantograph support insulators of different sizes.

[0046] When a certain electric field section has any of the following conditions: the remaining resin thickness is below the allowable lower limit, the resin isolation thickness is below the allowable lower limit, or the local curvature exceeds the allowable upper limit, that electric field section is identified as the section to be adjusted. First, calculate the adjustable distances of this section radially inward and outward, excluding directions that would approach the metal insert or the outer surface of the insulator. Second, determine the impact of three adjustment actions: increasing the pitch, decreasing the helix radius, and changing the transition length on the current problem. For insufficient resin isolation thickness, prioritize increasing the pitch; for cases approaching the outer surface of the insulator or metal parts, prioritize decreasing the helix radius or changing the helix center position; for excessive local curvature, prioritize increasing the pitch and extending the transition section.

[0047] Local parameter corrections will change the actual airway path length of the original electric field section. To avoid disrupting the established path extension relationships between sections after correction, the difference in path length before and after correction for the section to be adjusted is first calculated. When correction results in a reduction in the actual path length of this section, a compensation section is selected from the adjacent electric field sections that have remaining radial space; if compensation is possible on both sides, the path length to be compensated is allocated according to the remaining space margin on both sides. The compensation section increases the path length by appropriately increasing the helical radius or decreasing the pitch, while continuing to meet its own remaining resin thickness, resin isolation thickness, and curvature limitations.

[0048] Let the original target centerline length of the section to be adjusted be the target length, and the corrected centerline length be the corrected length. Then, the difference in path length that needs to be reallocated is determined by the difference between the two: When both adjacent segments have compensation conditions, first calculate the maximum centerline path length that each adjacent segment can increase without exceeding the remaining resin thickness, resin isolation thickness, curvature, and its own path extension allowable deviation, and record it as the compensable capacity C of that adjacent segment. j Compensable capacity can be obtained by scanning parameters step-by-step within the allowable radius and pitch range. If the sum of all compensable capacities is not less than the path length difference ΔL to be assigned... i Then, according to each adjacent segment C j The compensation is allocated proportionally to the total compensable capacity; if the total capacity is insufficient, forced compensation will not continue, and the system will return to adjusting the design range of the path extension parameters or the available space for airway arrangement.

[0049] ΔL i→j =ΔL i C j / ΣC m ; In the formula, ΔL i→j C represents the path length allocated from the i-th electric field segment to be adjusted to the j-th adjacent compensation segment; jThis represents the compensable capacity of the j-th adjacent compensation segment; the subscript m in the summation term traverses all adjacent segments on both sides of the current segment to be adjusted that meet the compensation conditions. If there are no adjacent segments that meet the compensation conditions, the allocation formula is not executed, and the design range of local parameters or path extension parameters for adjusting the current segment is returned.

[0050] ΔL i =λ i H i -L′ i ; In the formula, ΔL represents the path length difference caused by constraint correction in the i-th electric field segment, λ and H represent the original path extension parameter and axial length of the segment, respectively, and L′ represents the corrected centerline length. When the path length difference is greater than zero, the adjacent segment with spatial margin needs to bear the compensation; when the path length difference is not greater than zero, the path length of the adjacent segment is not increased. After the compensation is completed, the actual path extension degree of each segment is reordered and checked to ensure that the segment with a larger original electric field characterization value does not become significantly lower than the path extension degree of the segment with a smaller electric field characterization value due to the compensation operation.

[0051] The aforementioned "keeping the relative relationship of path extension parameters unchanged for each electric field segment" is checked according to the segment order. Specifically, for any two electric field segments a and b, when F a Greater than F b At that time, the corrected actual path extension parameter λ a act It should be no less than λ b act The actual path extension parameters are recalculated based on the ratio of the corrected centerline actual length to the axial length of the corresponding segment. When the electric field characteristics of two segments are equal, no order is specified between them. If a situation arises after compensation that deviates from the above ordering, the compensation amount causing the order reversal is reduced, and the remaining path length is redistributed among other segments with compensable capacity.

[0052] For sections where new spatial constraint conflicts arise after compensation, the above checks and corrections are repeated until all sections meet the requirements for remaining resin thickness, resin isolation thickness, and curvature, or until the preset number of iterations is reached. If conflicts still exist after reaching the preset number of iterations, the available radial space of the insulator body is expanded, the air duct diameter is reduced, or the design range of the path extension parameters is adjusted to regenerate the trajectory, instead of directly using the trajectory with geometric conflicts for casting. This ensures that the path allocation driven by the electric field is coordinated with the actual manufacturable space of the insulator, avoiding insufficient local resin solidity caused by only pursuing path extension.

[0053] After each round of correction, the actual path extension parameters of each segment and their deviations relative to the target value are recalculated, and t is rechecked. mins min and κ max Three constraints. All segments satisfy the spatial constraints and the path extension deviation is no greater than ε. λ The iteration stops when the maximum number of iterations is reached. The preset maximum number of iterations is only used as a termination condition to prevent non-convergent loops; for example, it can be set to 20 iterations. If the above condition is not met even after reaching the maximum number of iterations, the trajectory is determined to be unusable and the design range is reset, instead of entering core manufacturing with a non-convergent result.

[0054] It should be noted that the path extension parameter is used to allocate the internal gas channel geometry according to the electric field distribution in the initial use state, and does not directly equate "longer path" with the final insulation strength. After the spiral gas channel is formed, the difference in dielectric parameters between the gas region and the epoxy resin will change the local electric field distribution. Therefore, after the trajectory passes through the remaining resin thickness, resin isolation thickness, and curvature checks, an electric field verification should also be performed on the insulator model containing the final spiral gas channel.

[0055] During electric field verification, a gas domain is established in the 3D model according to the final centerline and gas duct diameter. The gas domain and epoxy resin domain are assigned dielectric parameters consistent with the actual working medium and resin system, respectively. Boundary conditions for the high-voltage end, grounding end, and adjacent conductive components, consistent with the usage conditions, are continued. The maximum electric field strength within the epoxy resin entity, the maximum electric field strength within the gas duct domain, and the maximum tangential electric field strength along the epoxy resin-gas interface are obtained. The corresponding allowable values ​​are determined using design data for the target insulation class, electric field resistance data of the selected material samples, and the results of withstand voltage or partial discharge initiation tests on gas duct samples under actual gas pressure conditions, and are included in the product design margin.

[0056] When any of the aforementioned verification field strengths exceeds the corresponding allowable value, the out-of-limit location is mapped back to its corresponding electric field segment. The trajectory is corrected primarily by increasing the remaining resin thickness at that location, adjusting the helical radius or pitch, moving the local helical center position, and extending the transition segment, among one or more other methods. Subsequently, the spatial constraint check and electric field solution including the air passage are re-executed. Only when the final trajectory simultaneously satisfies the geometric spatial constraints and electric field verification conditions is it used as the core manufacturing input. This avoids determining the helical trajectory solely based on the initial electric field distribution that does not include the final air passage structure, while ignoring the reaction of the air passage itself to the local electric field. Example 4

[0057] This embodiment illustrates the process of forming an actual spiral air channel within an epoxy resin insulator body according to a modified variable-parameter spiral air channel forming trajectory. The final forming trajectory is imported into core processing or additive manufacturing equipment to generate a continuous, removable spiral core according to a predetermined air channel diameter. The removable spiral core can be made of water-soluble inorganic salt composite material, water-soluble resin material, or a composite core that can be extracted in segments after curing. For trajectories where the spiral radius and pitch vary significantly along the axial direction, a core that can be integrally formed according to a three-dimensional trajectory and can be dissolved and removed after curing is preferred to avoid situations where a rigid integral core cannot be extracted along a curved path.

[0058] The selection of core materials should also meet the compatibility requirements with the epoxy resin curing process. Specifically, under the resin pouring pressure and maximum curing temperature, softening, shrinkage, or cracking that would cause the air passages to exceed dimensional tolerances should not occur. Furthermore, the removal medium used should not cause significant swelling of the cured epoxy resin that would affect its airtightness or insulation performance. Before actual production, a short core sample with the same diameter as the air passage can be used to conduct a pouring-curing-removal compatibility test, measuring the pore size and resin surface condition after removal. Once the target air passage dimensional tolerances are met and there is no visible damage to the resin surface, the corresponding core material and removal conditions can then be used for complete insulators.

[0059] In one specific implementation, a water-soluble inorganic salt composite core is used. The outer diameter of the core is consistent with the diameter of the target air passage, and straight positioning sections are formed at both ends. These straight positioning sections are inserted into the mold positioning holes corresponding to the air inlet and outlet ports, respectively, so that the center of the first end of the core coincides with the center of the air inlet port, and the center of the last end coincides with the center of the air outlet port. A small number of auxiliary positioning points are set in the middle of the core, which can be dissolved and removed together after curing, to limit core drift during casting. These auxiliary positioning points should be arranged in locations with relatively low electric field and sufficient resin space, with a cross-sectional area smaller than the cross-sectional area of ​​the air passage. After core removal and cleaning, when tiny pores connecting to the main air passage are formed, epoxy sealing is performed to maintain the continuity of the inner wall of the main spiral air passage.

[0060] After positioning the core and metal inserts, the epoxy resin system is mixed and degassed before being poured into the insulator molding mold. During pouring, the resin is slowly fed from the lower part of the mold, allowing it to gradually coat the core and expel air towards the higher part. For longer variable-parameter spiral cores, the mold can be preheated before pouring, and resin degassed under negative pressure to reduce air bubbles and voids near the outer edge of the spiral air channels. The curing temperature and time of the epoxy resin are determined according to the selected resin system, ensuring that the core does not deform beyond the allowable tolerance of the air channel dimensions during curing. After curing and demolding, an insulator body is formed with an internal coating of a removable spiral core.

[0061] Subsequently, the corresponding removal medium is introduced into the core through the air inlet or outlet. When using a water-soluble core, warm water can be circulated to gradually dissolve the core, and the dissolved material can be discharged from another outlet. After the core body is removed, continue rinsing with clean water until there is no obvious solid residue in the discharged liquid, and then introduce dry gas to remove internal moisture. When using other removable cores, melting, chemical dissolution, or segmented extraction methods can be used depending on the material properties, but the removal process should not damage the epoxy resin air passage walls. After the core is completely removed, the space occupied by the original core forms an internal air passage extending along the variable-parameter spiral air passage forming trajectory, and the air passage walls are directly composed of the cured epoxy resin body.

[0062] For cases where auxiliary positioning points are used and holes connecting to the main air duct are formed after core removal, the holes should be cleaned and dried first, then potted with a low-viscosity epoxy material compatible with the epoxy system of the insulator body, and cured according to the corresponding curing regime; after potting, an airtightness test should be performed. The completion of core removal can be comprehensively judged by the absence of visible solid particles in the drained liquid for a continuous period, the air duct diameter meeting the design diameter, and the normal connection between the inlet and outlet air ends. After cleaning, dry gas should be continuously introduced until the outlet humidity or the quality of the part tends to stabilize, and then the air pressure and insulation condition should be tested to avoid residual moisture affecting subsequent test results.

[0063] After the air passage is formed, an air passage integrity check is performed. The outlet port can be sealed, and dry air can be introduced through the inlet port to raise the internal pressure of the air passage to the product's designed test pressure and maintain it for a predetermined time, recording the pressure changes. Simultaneously, leak checks are performed at the inlet port, outlet port, and the outer surface of the insulator at potential leakage locations. The test pressure can be determined based on the rated operating pressure of the pantograph air passage, for example, set at 1.20 to 1.30 times the rated operating pressure. The allowable pressure holding value is determined according to product design requirements and is not limited to a single fixed value for different insulator models.

[0064] After completing the gas path inspection, the insulation condition of the insulator body is checked. The high-voltage end and grounding end are connected according to the usage condition. A test voltage corresponding to the product's insulation class is applied to the insulator to observe for breakdown or abnormal discharge. Partial discharge testing can also be used to inspect the area containing the spiral gas path. Only when the gas path pressure maintenance, interface leakage, and insulation condition all meet the corresponding product acceptance conditions is the insulator identified as a completed pantograph support insulator. Thus, the geometric design results of the variable-parameter spiral gas path can be continuously transferred to the actual product through core positioning, resin casting, core removal, and finished product inspection.

[0065] The pantograph support insulator formed using the above method includes an epoxy resin insulator body, an air inlet, an air outlet, and a variable-parameter spiral air duct located inside the epoxy resin insulator body. Different axial sections of the variable-parameter spiral air duct have different local spiral parameters, and adjacent sections are connected by a continuous transition path; both ends of the air duct are connected to the air inlet and air outlet, respectively. Since the air duct wall is directly formed from the epoxy resin body, there is no need to retain a separate flexible hose as a permanent air duct carrier inside. Example 5

[0066] This embodiment uses an epoxy resin support insulator for 25 kV pantograph pneumatic transmission as an example to illustrate the aforementioned method. This example is only used to illustrate the transmission relationship between various data and does not limit the size of other types of pantograph support insulators. Assume the effective axial length of the insulator requiring pneumatic channels is 300 mm, and the target pneumatic channel diameter is 6 mm. A three-dimensional electric field model is established according to the actual installation relationship. A basic sampling position is set every 10 mm within the effective axial length, and the sampling interval is reduced to 5 mm near the metal inserts at both ends. After solving the electric field, based on the field strength changes and trends between adjacent sampling positions, the effective axial range is divided into a first electric field segment, a second electric field segment, and a third electric field segment, with axial lengths of approximately 70 mm, 150 mm, and 80 mm, respectively.

[0067] After statistically analyzing the average electric field strength, peak electric field strength, and segment length for each of the three sections and normalizing the results, the electric field characteristics of the segments, from largest to smallest, are designated as the first electric field segment, the third electric field segment, and the second electric field segment. Based on the internal radial space of the insulator and the allowable total length of the air passage, the path extension parameter is designed to range from 1.50 to 2.80, and mapped according to the relative magnitudes of the electric field characteristics of the three segments; the path extension parameter for the first electric field segment is 2.80, for the second electric field segment it is 1.65, and for the third electric field segment it is 2.40. Thus, the first electric field segment, where the field strength effect is more pronounced, is allocated more air passage paths for the same axial length, while the second electric field segment maintains a relatively extended spiral path.

[0068] Candidate parameter groups were established based on the geometric relationships described in Example 2. Under the premise of satisfying the remaining resin thickness on the outer side and the resin isolation thickness between adjacent turns, the candidate group with a helix radius of approximately 12 mm and a pitch of approximately 29 mm was selected for the first electric field section; the candidate group with a helix radius of approximately 10 mm and a pitch of approximately 48 mm was selected for the second electric field section; and the candidate group with a helix radius of approximately 12 mm and a pitch of approximately 35 mm was selected for the third electric field section. The path extension degree corresponding to the above parameters is close to the target values ​​of the three sections. Since the axial length of each section is not necessarily an integer multiple of the pitch, the end of the section is cut off according to the actual spatial position, and a non-integer number of effective turns is completed by a transition section.

[0069] The above three sets of local helical parameters are calculated according to λ. i =√(1+(2πr i / p i ) 2 Upon review, the path extensions corresponding to the first, second, and third electric field sections are approximately 2.79, 1.65, and 2.38, respectively. These values ​​maintain a consistent magnitude with the target values ​​of 2.80, 1.65, and 2.40, with minimal deviation. Therefore, these values ​​can serve as an feasible example of the aforementioned parameter transfer process. However, if actual manufacturing tolerances cause the review deviation to exceed the preset ε... λ If the constraint correction method of Example 3 is not used, the parameters will be readjusted instead of directly using the same set of parameters.

[0070] A transition range of approximately 20 mm is set between the first and second electric field sections, within which the helical radius is gradually reduced and the pitch is increased. A similar transition range is set between the second and third electric field sections, with the helical radius gradually increasing and the pitch decreasing. Each transition range has at least three parameter control positions, and the circumferential phase is adjusted according to the tangential direction of the centerlines of the preceding and following sections. After connection, a three-dimensional minimum distance check is performed on the entire centerline. If the remaining resin thickness from the air passage to the outer surface is found to be less than the design allowable value within the first transition range, the helical radius at that location is first reduced, and the reduced path length is preferentially allocated to a position in the first electric field section near the transition range that still has radial space margin. If this section cannot continue to be compensated, it is then allocated to adjacent sections according to the method in Example 3.

[0071] After the trajectory passes the spatial constraint check, a 6 mm diameter water-soluble inorganic salt composite core is manufactured according to the trajectory. The two ends of the core are fixed to the positioning positions of the air inlet and outlet ports, respectively. After installing the insulator metal inserts, epoxy resin is poured and cured. After curing and demolding, warm water is circulated from one end to dissolve and remove the core, and the dissolved material is discharged from the other end. Then, the core is rinsed with clean water and dried to obtain a continuous, variable-parameter spiral air channel inside. Pressure maintenance and leakage checks are performed on the air channel, and withstand voltage and partial discharge checks corresponding to its insulation class are performed on the insulator. After passing the checks, a support insulator suitable for pantograph mechanical support, electrical insulation, and compressed air transmission is obtained.

[0072] In this embodiment, the electric field strength does not directly determine a single helical radius or pitch. Instead, an intermediate correspondence is first established through electric field segments and path extension parameters, and then local helical parameters are selected within the allowable range of geometric space and insulation thickness. In this way, even if the insulator size, end metal structure, or operating voltage changes, the axial electric field distribution under the corresponding operating conditions can be re-acquired, and the air passage morphology of each segment can be re-determined according to the same data transmission process, without having to use a fixed set of helical dimensions.

[0073] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and scope of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for manufacturing a pantograph support insulator, characterized in that, The method includes: The electric field strength along the axis of the insulator in use is obtained, and the insulator is divided into electric field segments based on the electric field strength, and the path extension parameters of each electric field segment are determined. The local spiral parameters of the spiral airway in each electric field section are determined based on the path extension parameters, and the spiral paths of adjacent electric field sections are continuously connected according to the local spiral parameters to form a variable parameter spiral airway forming trajectory. A spiral air channel is formed within the optimized insulator according to the variable parameter spiral air channel forming trajectory, resulting in a pantograph support insulator.

2. The method as described in claim 1, characterized in that, The process of dividing the insulator into electric field segments based on the electric field strength and determining the path extension parameters of each electric field segment includes: The electric field intensities corresponding to each sampling position are arranged along the insulator axis, and the section boundary is determined based on the change in electric field intensity between adjacent sampling positions. The average electric field intensity, peak electric field intensity, and segment length of each electric field segment are extracted to form segment electric field characterization quantities. Based on the relative relationship between the electric field characterization quantities of each section, path extension parameters are assigned to each electric field section to characterize the airway path length corresponding to a unit axial length.

3. The method as described in claim 2, characterized in that, The determination of the local spiral parameters of the spiral air passage in each electric field segment based on the path extension parameters includes: For each electric field section, a candidate parameter group consisting of helical radius, pitch and effective number of turns is established, and the candidate parameter group that can form the target airway path length is selected according to the corresponding path extension parameters. The radius and pitch changes between the selected candidate parameter group and the end helical parameters of adjacent electric field sections are obtained. Combined with the radial space of the insulator and the resin isolation thickness between adjacent helices, the local helical parameters are determined from the candidate parameter group.

4. The method as described in claim 3, characterized in that, The continuous connection of spiral paths between adjacent electric field sections according to the local spiral parameters includes: A transition section is set between adjacent electric field sections to obtain the helical radius, pitch and tangential direction at the end of the previous electric field section and the beginning of the next electric field section; The sequence of parameter changes in the transition section is determined based on the differences in local helical parameters at both ends, so that the helical radius and pitch gradually transition along the axial direction. The helical phase of the transition section is corrected according to the tangential direction at both ends to form a continuous segment connection path.

5. The method as described in claim 4, characterized in that, The formation of the variable-parameter spiral airway shaping trajectory includes: According to the arrangement order of each electric field section along the insulator axis, each local spiral path and the transition path between adjacent local spiral paths are generated sequentially. The end position and tangential direction of the previous transition path are used as the starting constraints of the next local spiral path, and the positions of each local spiral path are aligned. By connecting the first end to the air inlet and the last end to the air outlet, a variable-parameter spiral air channel forming trajectory that runs through the insulator body is obtained.

6. The method according to any one of claims 1 to 5, characterized in that, After forming the variable-parameter spiral airway shaping trajectory, the process further includes: Based on the molding trajectory, the remaining resin thickness from the spiral air channel to the outer surface of the insulator in each electric field section, the resin isolation thickness between adjacent spirals, and the degree of air channel curvature in the corresponding section are obtained. The remaining resin thickness and resin isolation thickness are compared with the allowable range of the insulation structure, and the electric field section to be adjusted is determined in combination with the degree of air channel curvature, so as to constrain and correct the local spiral parameters of the electric field section to be adjusted.

7. The method as described in claim 6, characterized in that, The constraint correction of the local helical parameters of the electric field section to be adjusted includes: Determine the adjustable space of the electric field segment to be adjusted in the radial direction, and obtain the path extension parameters of its adjacent electric field segments; While keeping the relative relationship of the path extension parameters of each electric field segment unchanged, the spiral radius and pitch are adjusted first, and the path length difference generated by the local adjustment is distributed to the adjacent electric field segments with remaining radial space. The adjusted local spiral path is then reconnected to obtain the corrected variable parameter spiral air passage forming trajectory.

8. The method as described in claim 7, characterized in that, The process of forming a spiral air channel within an optimized insulator according to the variable-parameter spiral air channel forming trajectory includes: A continuous removable spiral core is prepared according to the variable parameter spiral air passage forming trajectory, and the two ends of the removable spiral core are respectively positioned at the mold positions corresponding to the air inlet and air outlet. Epoxy resin is poured around the removable spiral core and cured to form an insulator body covering the removable spiral core; The removable helical core is removed from the insulator body to form a helical air passage.

9. The method as described in claim 8, characterized in that, After forming the spiral airway, the process also includes: Test gas is introduced into the spiral air passage to obtain the pressure maintenance status between the air inlet and the air outlet, as well as the leakage status at each connection point. An insulation detection voltage corresponding to the usage state is applied to the insulator body to obtain the insulation state of the area where the spiral air passage is located; Corresponding the pressure holding status, leakage status, and insulation status to the preparation and acceptance conditions.

10. A pantograph support insulator, comprising an epoxy resin insulator body, an air inlet, and an air outlet, characterized in that, Also includes: A variable-parameter spiral air passage is formed inside the epoxy resin insulator body and connects the air inlet and air outlet.

Images