Leak detection structure and method for high voltage dc contactor ceramic assembly cavity

Abstract

This invention discloses a leak detection structure and method for the ceramic composite cavity of a high-voltage DC contactor, belonging to the field of contactor testing technology. The leak detection structure includes a base, an annular sealing ring, and an annular pressure plate. The base comprises a tubular body and an integrally formed disc. The disc has a stepped through-hole at its center, including first, second, and third hole sections with successively decreasing diameters. The annular pressure plate is located within the first hole section, and the annular sealing ring is located within the second hole section. Its free inner diameter is smaller than the outer diameter of the inflation tube and it fits snugly against the inner wall of the second hole section. Multiple quick-pressing mechanisms are provided on the top surface of the disc for pressing the annular pressure plate. During leak detection, the inflation tube passes through the annular pressure plate, the annular sealing ring, and the third hole section into the inner cavity of the tubular body. The quick-pressing mechanisms press the annular pressure plate, causing the annular sealing ring to deform inward and tightly grip the inflation tube. Then, it is connected to a helium mass spectrometer leak detector for quantitative leak detection. This invention achieves quantitative, rapid, and high-precision dry leak detection.

Description

Technical Field

[0001] This invention relates to the field of contactor testing technology, and in particular to a leak detection structure and method for a ceramic composite cavity of a high-voltage DC contactor. Background Technology

[0002] High-voltage DC contactors are core electrical components widely used in new energy vehicles, charging piles, energy storage systems, and rail transportation. Their function is to control the switching on and off of high-voltage DC circuits. In a high-voltage DC environment, when the contactor contacts break the circuit, a strong electric arc is generated between the contacts. This arc is characterized by high temperature and high energy; if it is not effectively suppressed and quickly extinguished, it will severely erode the contact material, leading to contactor failure and even safety accidents.

[0003] To improve the arc-extinguishing capability and electrical life of contactors, existing technologies typically employ the method of filling the cavity containing the contact system with a specific protective gas. These protective gases, such as hydrogen, nitrogen, or mixtures thereof, possess excellent thermal conductivity and arc-extinguishing properties, rapidly dissipating arc energy and promoting arc cooling and extinction, thereby significantly enhancing the contactor's withstand capability under high voltage and high current conditions. To achieve this, the contact system is encapsulated within a sealed cavity formed by a ceramic material assembly. Ceramic materials possess excellent insulation properties and mechanical strength, providing a stable operating environment and reliable electrical isolation for the contact system. During manufacturing, a protective gas at a specified pressure is injected into this ceramic assembly sealed cavity through a dedicated filling tube.

[0004] Clearly, the sealing performance of the ceramic assembly's enclosed cavity must be rigorously tested before filling with protective gas. This is a crucial step in ensuring the long-term reliable operation of the contactor. Even a minor leak in the cavity will cause the protective gas to gradually dissipate, leading to a drop in internal pressure, a weakening of the arc-extinguishing capability, and ultimately, deterioration or premature failure of the contactor. Therefore, accurate and efficient testing of the ceramic assembly's sealing performance is of paramount importance.

[0005] Currently, the industry commonly uses liquid leak detection for sealing tests. This method involves filling the cavity with gas at a certain pressure through an inflation tube, then immersing the ceramic assembly entirely in a leak detection liquid such as fluorocarbon oil. Leakage is determined by visually observing whether bubbles are generated. However, this method has significant drawbacks: First, it can only qualitatively determine the presence or absence of a leak, and cannot quantitatively measure the leakage rate, making it difficult to accurately assess the quality of the sealing performance. Second, the operation is cumbersome, requiring immersion, removal, cleaning, and drying, resulting in low detection efficiency, and the leak detection liquid can contaminate the product. Third, it relies on manual observation of bubbles, which can easily lead to misjudgments or missed detections due to visual fatigue or the inability to see visible bubbles in small leaks, resulting in insufficient detection accuracy and reliability.

[0006] Therefore, there is an urgent need for a detection solution that can achieve quantitative, rapid, high-precision, and non-destructive testing. Summary of the Invention

[0007] The main objective of this invention is to propose a leak detection structure and method for the ceramic assembly cavity of a high-voltage DC contactor. This aims to solve the technical problems existing in the prior art when using liquid leak detection to test the sealing performance of the ceramic assembly cavity of a high-voltage DC contactor. These problems include the inability to make qualitative judgments, the inability to measure the specific leakage rate, the cumbersome operation process that may contaminate the product, and the reliance on manual observation leading to low detection accuracy and reliability.

[0008] To achieve the above objectives, in a first aspect, the present invention proposes a leak detection structure for a ceramic assembly cavity of a high-voltage DC contactor. The ceramic assembly is provided with an inflation tube. The leak detection structure includes a base, an annular sealing ring, and an annular pressure plate. The base includes a tubular body and a disk integrally formed on the upper part of the tubular body. A stepped through-hole is provided at the center of the disk, communicating with the central hole of the tubular body. The stepped through-hole includes a first segment, a second segment, and a third segment with progressively decreasing diameters from top to bottom. The annular pressure plate is disposed at the first segment. The annular sealing ring is located within the second hole section; the inner diameter of the annular sealing ring is the outer diameter of the inflation tube in the free state, so that an interference fit can be formed to form a preliminary seal when the inflation tube is inserted; the annular sealing ring is in contact with the inner wall of the second hole section in the free state; so that when the annular pressure plate presses the annular sealing ring, the annular sealing ring undergoes elastic deformation in the direction of its inner diameter, thereby gripping the outer wall of the inflation tube inserted therein; multiple quick pressing mechanisms are provided on the top surface of the disc body for vertically pressing the annular pressure plate.

[0009] Preferably, the annular sealing ring is made of rubber and has a circular cross-section.

[0010] Preferably, the rapid clamping mechanism is a vertical elbow clamp.

[0011] Preferably, the bottom end of the tubular body is provided with an interface for connecting to a helium mass spectrometer leak detector.

[0012] Preferably, the inner diameter of the annular sealing ring in its free state is 0.5-1 mm smaller than the outer diameter of the inflation tube.

[0013] Preferably, the inner diameter of the third hole section is 0.1-0.2 mm larger than the outer diameter of the inflation tube, which facilitates the insertion of the inflation tube; a guide radius is provided at the opening position at the upper end of the third hole section to guide the inflation tube.

[0014] Preferably, it also includes a screw, which passes through a screw hole in the annular pressure plate and is screwed onto the bottom wall of the first hole section; the screw is not tightened, so that the annular pressure plate can float axially in the unpressurized state.

[0015] Preferably, the plurality of rapid pressing mechanisms are evenly distributed along the circumference of the disc, and the number is 2-4.

[0016] Secondly, the present invention also proposes a leak detection method for a ceramic composite cavity of a high-voltage DC contactor, employing the above-mentioned leak detection structure, comprising the following steps: Step 1: Adjust multiple quick-clamping mechanisms to the loosened state, so that the annular pressure plate moves upward to the initial position under the elastic force of the annular sealing ring; Step 2: Pass the inflation tube of the ceramic assembly to be tested through the central hole of the annular pressure plate, the inner hole of the annular sealing ring, and the third hole section of the base in sequence, and then extend it into the inner hole of the tubular body. At this time, the inflation tube and the annular sealing ring form an interference fit and a preliminary seal. Step 3: Operate multiple quick-pressing mechanisms to press the annular pressure plate downwards. The annular pressure plate moves downwards and presses the annular sealing ring. Since the outer wall of the annular sealing ring is in contact with the inner wall of the second hole section, the annular sealing ring undergoes elastic deformation in the direction of its inner diameter under axial pressure, thereby tightly gripping the outer wall of the air tube and forming a reliable sealing connection. Step 4: Connect the bottom of the tubular body to the helium mass spectrometer leak detector; Step 5: Start the helium mass spectrometer leak detector and purge helium gas from the outside of the ceramic assembly; Step 6: Read the leakage rate value displayed by the helium mass spectrometer leak detector to complete the quantitative leak detection.

[0017] Step 7: Loosen the multiple quick-clamping mechanisms to lift the annular pressure plate upwards, relieving the pressure on the annular sealing ring, and then pull out the ceramic assembly that has completed the test.

[0018] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows: (1) Achieve quantitative detection and more scientific and accurate evaluation: By adopting the leak detection structure and method provided by this invention, the qualitative method of observing bubbles with the naked eye is abandoned. By combining with a high-precision helium mass spectrometer leak detector, the leakage rate can be accurately measured, and the quantitative evaluation of the sealing performance of ceramic combination can be achieved. The judgment standard is objective and data-driven, providing a scientific basis for product quality grading and process improvement.

[0019] (2) Fast and efficient testing, suitable for mass production: The present invention adopts a vertical elbow clamp and other fast clamping mechanism, which makes the installation and disassembly of the inflation tube extremely fast. Operators only need to perform simple actions such as inserting, turning the handle, and pulling out to complete a testing cycle in a few seconds. The entire testing process does not require cumbersome procedures such as liquid immersion, cleaning, and drying, which significantly improves the testing efficiency and fully meets the needs of mass testing on the production line.

[0020] (3) Reliable sealing structure ensures accurate testing: The core sealing structure of this invention—the combination of stepped through holes (first, second, and third hole sections), an annular sealing ring, and an annular pressure plate—has extremely high sealing reliability. The key lies in the constraint of the inner wall of the second hole section on the outer diameter of the sealing ring and the precise guidance and positioning of the inflation tube by the third hole section, ensuring that the sealing ring deforms mainly in the inward direction when under pressure, forming a tight seal. Simultaneously, the minute gap fit (0.1-0.2 mm) between the third hole section and the inflation tube further improves the positioning accuracy of the inflation tube. This dual sealing mechanism effectively prevents interference from external air, ensuring the accuracy of the test results.

[0021] (4) Non-destructive and clean testing to avoid product contamination: The entire testing process of this invention is dry leak testing, which does not require the use of any leak testing liquid, completely avoiding the risk of product contamination and eliminating the need for subsequent cleaning processes. It is an ideal non-destructive testing method.

[0022] (5) Simple operation and reduced human error: The present invention realizes standardized operation through mechanical structure. The test results are directly read by the instrument, which greatly reduces the dependence on the operator's experience and the subjectivity of visual observation, and improves the consistency and reproducibility of the test results.

[0023] (6) Anti-drop and floating guide function: By adding screws, on the one hand, the annular pressure plate is prevented from accidentally falling out in the loose state; on the other hand, the loose screws allow the annular pressure plate to float axially. When the quick pressing mechanism is loosened, it can move upward under the action of the elastic force of the annular sealing ring, so as to facilitate the extraction of the ceramic assembly after the test. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the leak detection structure provided by the present invention.

[0026] Figure 2 for Figure 1 The enlarged view at point A shows the annular sealing ring in an uncompressed state.

[0027] Figure 3 This is a cross-sectional view of the base in this invention.

[0028] Explanation of reference numerals: 1. Ceramic assembly; 2. Inflation tube; 3. Annular sealing ring; 4. Annular pressure plate; 5. Base; 5a. Tubular body; 5b. Disc body; 5c. First hole section; 5d. Second hole section; 5e. Third hole section; 5f. Interface; 6. Quick clamping mechanism; 7. Screw. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0031] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0032] Example 1 Please combine Figures 1 to 3 As shown, this embodiment provides a leak detection structure for the ceramic combined cavity of a high-voltage DC contactor. This structure is a specific implementation of the technical solution of the present invention, and it is mainly composed of core components such as a base 5, an annular sealing ring 3, an annular pressure plate 4, multiple quick clamping mechanisms 6, and screws 7.

[0033] The base 5 serves as the foundation and support for the entire leak detection structure. It is integrally machined from stainless steel, possessing excellent mechanical strength and corrosion resistance. The base 5 comprises a tubular body 5a and a disc body 5b integrally formed on top of the tubular body 5a. The tubular body 5a is a vertical cylindrical structure with a central hole serving as the main channel for gas flow. The disc body 5b, with a diameter larger than that of the tubular body 5a, is located at the top of the tubular body 5a, and the two transition smoothly.

[0034] A stepped through-hole is provided at the center of the disc 5b, which communicates with the central hole of the tubular body 5a. The stepped through-hole includes, from top to bottom, a first section 5c, a second section 5d, and a third section 5e, with diameters decreasing sequentially. The first section 5c is a cylindrical hole with the largest diameter, used to accommodate the annular pressure plate 4. Its inner wall is machined with a smooth surface to ensure that the annular pressure plate 4 can slide smoothly up and down inside it. The second section 5d is a cylindrical hole with a medium diameter, used to accommodate the annular sealing ring 3. Its inner wall fits snugly against the annular sealing ring 3. The third section 5e is a cylindrical hole with the smallest diameter. Its inner diameter is precisely designed to be 0.1-0.2 mm larger than the outer diameter of the inflation tube 2. This dimensional design creates a clearance fit when the inflation tube 2 is inserted, providing good guidance and positioning without generating excessive frictional resistance, ensuring smooth insertion. At the opening position at the upper end of the third hole section 5e, a guide rounded corner is machined. This guide rounded corner can smoothly guide the insertion of the air tube 2 and prevent the end of the air tube from being scratched or stuck.

[0035] The bottom end of the tubular body 5a is provided with an interface 5f, which is a KF16 standard vacuum flange for quick and sealed connection to the test port of the helium mass spectrometer leak detector.

[0036] The annular sealing ring 3 is a standard O-ring made of fluororubber with a circular cross-section. Fluororubber has excellent high-temperature resistance, corrosion resistance, and aging resistance, making it suitable for long-term use. The annular sealing ring 3 is precisely positioned within the second hole section 5d. Its outer diameter in its free state is equal to the inner diameter of the second hole section 5d, achieving a tight fit. Its inner diameter in its free state is designed to be 0.5-1mm smaller than the outer diameter of the inflation tube 2. In this embodiment, the outer diameter of the inflation tube 2 is 6mm, therefore the free inner diameter of the annular sealing ring 3 is 5.0mm to 5.5mm. This dimensional difference ensures a proper interference fit when the inflation tube 2 is inserted, forming an initial seal.

[0037] The annular pressure plate 4 is a ring-shaped part made of aluminum alloy and is set inside the first hole section 5c. A gap of approximately 0.1mm is maintained between the outer diameter of the annular pressure plate 4 and the inner diameter of the first hole section 5c to ensure smooth up-and-down sliding. A through hole is formed in the center of the annular pressure plate 4, the diameter of which is approximately 1mm larger than the outer diameter of the inflation tube 2, allowing the inflation tube 2 to pass through unobstructed. The lower end face of the annular pressure plate 4 is precision-machined into a flat annular plane to ensure that pressure is evenly transmitted to the upper end face of the annular sealing ring 3 below when subjected to downward pressure. The upper end face of the annular pressure plate 4 contacts the clamping ends of multiple quick-clamping mechanisms 6, receiving the clamping force. Screw holes are also provided on the annular pressure plate 4 for mounting screws 7.

[0038] Multiple quick-clamping mechanisms 6 are provided on the top surface of the disc 5b. In this embodiment, there are two quick-clamping mechanisms 6, which are symmetrically distributed at 180° along the circumference of the disc 5b. Each quick-clamping mechanism 6 is a vertical elbow clamp. The vertical elbow clamp is a standardized quick-clamping device, the structure of which includes: a fixed base, which is installed on the top surface of the disc 5b by screws or welding; an operating handle, which is connected to a linkage mechanism; and a clamping rod, the lower end of which is equipped with a rubber pressure head or a metal pressure head for contacting and clamping the upper surface of the annular pressure plate 4.

[0039] When the operating handle is pulled upwards to the vertical position, the linkage mechanism straightens and generates a strong downward clamping force. Simultaneously, the mechanism enters a self-locking state and will not release on its own. When the operating handle is pulled downwards to the horizontal position or past the dead center, the linkage mechanism bends, and the clamping rod quickly rises upwards, releasing the pressure on the annular pressure plate 4. The vertical elbow clamp has advantages such as quick operation, large clamping force, reliable self-locking, and long service life, making it ideal for frequent operations on production lines.

[0040] The number of screws 7 corresponds to the number of screw holes on the annular pressure plate 4, which is four in this embodiment, evenly distributed circumferentially. The shank of the screw 7 passes through the screw hole of the annular pressure plate 4, and its threaded portion engages in a pre-machined threaded hole on the bottom wall of the first hole section 5c. During installation, the screw 7 is not fully tightened, but a certain gap is left, so that the distance between the lower end face of the screw head and the upper end face of the annular pressure plate 4 is about 2-3 mm. In this way, when the annular pressure plate 4 is not pressed by the quick-clamping mechanism 6, it can float freely up and down along the axial direction of the screw 7, but cannot be dislodged from the first hole section 5c, because the head of the screw 7 acts as a limit. At the same time, the clearance fit between the screw 7 and the screw hole also allows for a small radial adjustment of the annular pressure plate 4, thereby achieving automatic centering.

[0041] Working principle and dynamic sealing process: During leak detection, first pull the handles of the two vertical elbow clamps downwards to a horizontal position, thus releasing the annular pressure plate 4. At this time, the annular pressure plate 4 remains within the first hole section 5c under the limiting action of the screw 7, but can float axially.

[0042] Then, the inflation tube 2 of the ceramic assembly 1 to be tested is inserted vertically downwards, passing sequentially through the central hole of the annular pressure plate 4 and the inner hole of the annular sealing ring 3. When the end of the inflation tube 2 contacts the guide rounded corner at the upper end of the third hole section 5e, the guide rounded corner will automatically guide the inflation tube 2 to the center position of the third hole section 5e. Continuing downwards, the inflation tube 2 enters the third hole section 5e. Since the inner diameter of the third hole section 5e is 0.1-0.2 mm larger than the outer diameter of the inflation tube 2, a clearance fit is formed, making the insertion process easy and smooth. At the same time, the inner wall of the third hole section 5e provides precise radial positioning for the inflation tube 2, ensuring the coaxiality of the inflation tube 2 and the annular sealing ring 3. At this point, because the free inner diameter of the annular sealing ring 3 is smaller than the outer diameter of the inflation tube 2, the inflation tube 2 is subjected to the elastic clamping force of the annular sealing ring 3, forming a preliminary, low-pressure seal. The inflation tube 2 is then inserted downwards into the inner hole of the tubular body 5a.

[0043] Next, simultaneously pull up the operating handles of both vertical elbow clamps to bring them to a vertical position. The clamping heads of the vertical elbow clamps press against the upper end face of the annular pressure plate 4, driving the annular pressure plate 4 to move downward along the axis of the screw 7. Since the screw 7 is not tightened, the annular pressure plate 4 can slide down smoothly. The lower end face of the annular pressure plate 4 begins to press against the upper end face of the annular sealing ring 3 below. The annular sealing ring 3 is subjected to axial compressive force. Since the outer diameter of the annular sealing ring 3 is restricted by the inner wall of the second hole section 5d and cannot expand outward radially, this axial compressive force forces the rubber material to elastically deform in its only direction of free deformation—that is, inward radially. As the annular pressure plate 4 continues to press down, the inner diameter portion of the annular sealing ring 3 will bulge significantly inward, thereby gripping the outer wall of the inflation tube 2 with greater pressure and a tighter fit.

[0044] This "controlled inward deformation" mechanism is the core technical feature of this invention. It ensures that almost all of the applied clamping force is converted into effective sealing and clamping force. Ultimately, a dense, uniform, and high-quality sealing interface capable of withstanding a certain pressure difference is formed between the outer wall of the inflation tube 2 and the annular sealing ring 3. This interface reliably isolates the atmosphere, allowing the enclosed cavity of the ceramic assembly 1 to be connected to the helium mass spectrometer leak detector only through the inflation tube 2, the central hole of the tubular body 5a, and the interface 5f.

[0045] Leak detection method based on the above structure: This embodiment also provides a method for sealing performance testing using the above-mentioned leak detection structure, the specific steps of which are as follows: Step 1: Adjust the multiple quick-clamping mechanisms 6 to the loosened state, so that the annular pressure plate 4 moves upward to its initial position under the elastic force of the annular sealing ring 3. That is, the annular pressure plate 4 is in a floating state under the limit of the screw 7.

[0046] Step Two: The operator holds the ceramic assembly 1 to be tested and inserts the end of its inflation tube 2 vertically downwards through the central hole of the annular pressure plate 4, the inner hole of the annular sealing ring 3, and the third hole section 5e of the base 5, before finally inserting it into the inner hole of the tubular body 5a. At this point, the inflation tube 2 and the annular sealing ring 3 form a preliminary seal with an interference fit. During insertion, the guide radius at the upper end of the third hole section 5e guides the inflation tube 2 smoothly into the third hole section 5e.

[0047] Step 3: The operator simultaneously pulls the operating handles of both vertical elbow clamps upwards to the vertical self-locking position. The clamping head of the vertical elbow clamp presses down on the annular pressure plate 4. The annular pressure plate 4 moves downwards and presses down on the annular sealing ring 3. Since the outer wall of the annular sealing ring 3 is in contact with the inner wall of the second hole section 5d, the annular sealing ring 3 undergoes elastic deformation in the direction of its inner diameter under axial pressure, thereby tightly gripping the outer wall of the air inflator 2 and forming a reliable sealing connection.

[0048] Step 4: Connect the leak detection structure to the test port of a preheated, stable, and calibrated helium mass spectrometer leak detector (not shown in the figure) via its interface 5f.

[0049] Step 5: Start the helium mass spectrometer leak detector and put it into "leak detection" mode. The vacuum pump inside the leak detector will start working to evacuate the sealed cavity of ceramic assembly 1 and establish a stable vacuum level. Once the "background" signal of the leak detector stabilizes, the detection can begin. The operator uses a spray gun connected to a helium cylinder to evenly spray helium gas with a purity of 99.99% or higher at a moderate flow rate onto the outer surface of ceramic assembly 1, paying particular attention to key areas such as the seal between the ceramic and the metal end cap, and the connection root between the filling tube 2 and the ceramic body—areas with a high risk of potential leaks. During spraying, ensure that the entire outer surface of the cavity is covered, with each area sprayed for approximately 1-3 seconds.

[0050] Step Six: Read the leakage rate value displayed by the helium mass spectrometer leak detector to complete the quantitative leak detection. Specifically, while injecting helium gas, closely observe the display screen of the helium mass spectrometer leak detector. If there is any penetrating leak channel in the sealed cavity of ceramic assembly 1, helium molecules will enter the cavity through this channel and be immediately carried into the mass spectrometer chamber of the leak detector by the pumping gas flow. The leak detector will detect a sharp increase in the helium partial pressure and calculate the corresponding leakage rate. The operator records the maximum leakage rate value displayed by the instrument and compares it with the preset quality judgment standard. If the measured value is less than or equal to the standard value, the product is judged to be qualified; otherwise, it is judged to be unqualified.

[0051] Step 7: Loosen the multiple quick-clamping mechanisms 6, causing the annular pressure plate 4 to lift upwards, relieving the pressure on the annular sealing ring 3, and then pull out the ceramic assembly 1 that has completed the test. Specifically, after the test is completed, turn the operating handles of the two vertical elbow clamps to a horizontal position to release the annular pressure plate, causing the annular pressure plate 4 to lift upwards under the elastic force of the annular sealing ring 3, relieving the pressure on the annular sealing ring 3. At this time, the elastic deformation of the annular sealing ring 3 is restored, and the clamping force on the inflation tube 2 disappears. The operator can easily pull the inflation tube 2 of the ceramic assembly 1 out of the leak detection structure. Due to the limiting effect of the screw 7, the annular pressure plate 4 will not fall off the base 5 and remains in a ready state. At this point, a complete test cycle is completed. The test of the next product can begin immediately.

[0052] Example 2 This embodiment has the same basic structure and working principle as Embodiment 1. The main difference lies in the number and arrangement of the rapid pressing mechanism 6.

[0053] In this embodiment, to provide a more uniform and powerful clamping force, the number of rapid clamping mechanisms 6 is set to three, evenly distributed at 120° along the circumference of the disc 5b. Correspondingly, the number of screws 7 is also three, arranged alternately with the rapid clamping mechanisms 6. The three vertical elbow clamps operate simultaneously to form a three-point clamping structure, applying downward pressure symmetrically to the annular pressure plate 4 from three positions. This ensures that the annular pressure plate 4 remains horizontal during the clamping process and does not tilt, thereby making the force on the annular sealing ring 3 more uniform and the sealing effect more reliable.

[0054] The leak detection method is the same as in Example 1, and will not be described again here.

[0055] In summary, this invention provides a leak detection structure and method for ceramic composite cavities in high-voltage DC contactors. Through the design of a base 5 with stepped through-holes, an annular sealing ring 3, an annular pressure plate 4, a vertical elbow clamp, and an anti-detachment floating screw 7, it achieves an efficient and reliable sealed connection with a helium mass spectrometer leak detector. Its core lies in the constraint of the inner wall of the second hole section 5d on the outer diameter of the annular sealing ring 3 and the precise guidance and positioning of the third hole section 5e on the inflation tube 2 (with a clearance fit where the inner diameter of the third hole section 5e is 0.1-0.2 mm larger than the outer diameter of the inflation tube). This ensures that the annular sealing ring 3 deforms primarily inwards under pressure, forming a tight seal. The addition of the screw 7 further improves operational convenience. This invention completely solves the problems of existing liquid leak detection methods, such as qualitative detection only, cumbersome operation, easy contamination, low accuracy, and poor reliability. It achieves quantitative, rapid, high-precision, and non-destructive testing of the sealing performance of ceramic composite sealed cavities, which has significant practical value and broad application prospects for improving the product quality and production efficiency of high-voltage DC contactors.

[0056] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A leak detection structure for a ceramic assembly cavity of a high-voltage DC contactor, wherein an air filling pipe (2) is provided on the ceramic assembly (1), characterized in that, The leak detection structure includes a base (5), an annular sealing ring (3), and an annular pressure plate (4); The base (5) includes a tubular body (5a) and a disk body (5b) integrally formed on the upper part of the tubular body (5a). A stepped through hole is provided in the center of the disk body (5b) and communicates with the central hole of the tubular body (5a). The stepped through hole includes a first hole segment (5c), a second hole segment (5d) and a third hole segment (5e) with decreasing diameters from top to bottom. The annular pressure plate (4) is disposed within the first hole section (5c); The annular sealing ring (3) is disposed within the second hole section (5d); The inner diameter of the annular sealing ring (3) is the outer diameter of the air tube (2) in the free state, so that an interference fit can be formed when the air tube (2) is inserted to form a preliminary seal; the annular sealing ring (3) is in contact with the inner wall of the second hole section (5d) in the free state; so that when the annular pressure plate (4) presses the annular sealing ring (3), the annular sealing ring (3) undergoes elastic deformation in the direction of its inner diameter, thereby holding the outer wall of the air tube (2) inserted therein; Multiple quick-pressing mechanisms (6) are provided on the top surface of the disc (5b) for vertically pressing the annular pressure plate (4).

2. The leak detection structure for a ceramic composite cavity of a high-voltage DC contactor according to claim 1, characterized in that, The annular sealing ring (3) is made of rubber and has a circular cross-section.

3. The leak detection structure for a ceramic composite cavity of a high-voltage DC contactor according to claim 1, characterized in that, The rapid clamping mechanism (6) is a vertical elbow clamp.

4. The leak detection structure for a ceramic composite cavity of a high-voltage DC contactor according to claim 1, characterized in that, The bottom end of the tubular body (5a) is provided with an interface (5f) for connecting to a helium mass spectrometer leak detector.

5. A leak detection structure for a ceramic composite cavity of a high-voltage DC contactor according to claim 1, characterized in that, The inner diameter of the annular sealing ring (3) in its free state is 0.5-1 mm smaller than the outer diameter of the air inflator (2).

6. A leak detection structure for a ceramic composite cavity of a high-voltage DC contactor according to claim 1, characterized in that, The inner diameter of the third hole section (5e) is 0.1-0.2 mm larger than the outer diameter of the inflation tube (2), which facilitates the insertion of the inflation tube (2); a guide radius is provided at the opening position at the upper end of the third hole section (5e) to guide the inflation tube (2).

7. A leak detection structure for a ceramic composite cavity of a high-voltage DC contactor according to claim 1, characterized in that, It also includes a screw (7), which passes through the screw hole of the annular pressure plate (4) and is screwed onto the bottom wall of the first hole section (5c); the screw (7) is not tightened, so that the annular pressure plate (4) can float axially in the unpressurized state.

8. A leak detection structure for a ceramic composite cavity of a high-voltage DC contactor according to claim 1, characterized in that, The plurality of rapid pressing mechanisms (6) are evenly distributed along the circumference of the disc (5b), and the number is 2-4.

9. A leak detection method for a ceramic composite cavity of a high-voltage DC contactor, characterized in that, The leak detection structure according to any one of claims 1 to 8 includes the following steps: Step 1: Adjust multiple quick-pressing mechanisms (6) to the loosened state, so that the annular pressure plate (4) moves upward to the initial position under the elastic force of the annular sealing ring (3); Step 2: Pass the inflation tube (2) of the ceramic assembly (1) to be tested through the center hole of the annular pressure plate (4), the inner hole of the annular sealing ring (3), and the third hole section (5e) of the base (5) in sequence, and then extend it into the inner hole of the tubular body (5a). At this time, the inflation tube (2) and the annular sealing ring (3) form an interference fit preliminary seal. Step 3: Operate multiple quick pressing mechanisms (6) to press down the annular pressure plate (4). The annular pressure plate (4) moves down and presses down the annular sealing ring (3). Since the outer wall of the annular sealing ring (3) is in contact with the inner wall of the second hole section (5d), the annular sealing ring (3) undergoes elastic deformation in the direction of its inner diameter under axial pressure, thereby tightly gripping the outer wall of the air tube (2) and forming a reliable sealing connection. Step 4: Connect the bottom end of the tubular body (5a) to the helium mass spectrometer leak detector; Step 5: Start the helium mass spectrometer leak detector and spray helium gas outside the ceramic assembly (1); Step 6: Read the leakage rate value displayed by the helium mass spectrometer leak detector to complete the quantitative leak detection.

10. The leak detection method according to claim 9, characterized in that, Step six is ​​followed by step seven: loosen multiple quick-pressing mechanisms (6) to lift the annular pressure plate (4) upward, relieve the pressure on the annular sealing ring (3), and then pull out the ceramic assembly (1) that has completed the test.

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