A pneumatic bismuth alloy injection control system and method

Abstract

This invention discloses a pneumatic bismuth alloy injection control system and method, relating to the field of bismuth alloy injection technology. The system includes a pneumatic drive unit, an injection execution unit, and a control unit. The pneumatic drive unit comprises a high-pressure air source, a pressure regulating component, and a solenoid valve, connected to a bismuth alloy storage device via an air supply pipeline, and outputs a controllable pulsed air pressure. The injection execution unit includes an injection chamber, a built-in pressure detection component, and a nozzle component; the injection chamber is connected to the bismuth alloy storage device. The control unit is electrically connected to the pressure detection component and the solenoid valve. The control unit calculates the minimum driving air pressure P1 required for injection based on a bismuth alloy hydrodynamic model; it dynamically adjusts the pulse parameters using a PID algorithm; it synchronously calls a flow-pressure-temperature correlation model to correct the flow rate; and after injection, it detects the sealing leakage rate and stability. This method provides precise control, rapid response, maintains a stable injection rate, ensures injection quality, is suitable for industrial equipment sealing scenarios, and is safe and reliable.

Description

Technical Field

[0001] This invention belongs to the field of alloy sealing technology, specifically a pneumatic bismuth alloy injection control system and method. Background Technology

[0002] Bismuth alloys, due to their low melting point, good fluidity, and filling properties, are widely used in microelectronic packaging, precision casting, and power equipment leak sealing. Among these applications, precise injection control technology for bismuth alloys is one of the key technologies for achieving high-quality sealing, directly impacting the sealing effect.

[0003] Currently, in the field of bismuth alloy spraying technology, pneumatic spraying technology occupies an important position in the spraying applications of low-melting-point metals such as bismuth alloys due to its advantages such as simple structure and fast response speed. Pneumatic spraying technology achieves quantitative spraying of liquid metal by controlling gas pressure; spraying parameters are controlled by adjusting the on / off state of a solenoid valve. Existing pneumatic spraying technology has the following shortcomings: It lacks a pressure detection component, making it impossible to accurately monitor dynamic pressure changes inside the spraying chamber in real time, resulting in limited pressure control accuracy; it lacks a real-time closed-loop feedback adjustment mechanism for the pressure inside the spraying chamber, making it difficult to cope with pressure fluctuations caused by factors such as temperature changes and nozzle blockage during spraying. This leads to unstable sealing effects, making it difficult to meet the requirements of high-precision sealing.

[0004] Therefore, developing a pneumatic bismuth alloy injection control system and method that is precise, stable, reliable, and highly automated has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a pneumatic bismuth alloy injection control system. The system outputs controllable pulse air pressure through the air circuit drive unit, the injection execution unit monitors the injection chamber pressure in real time, and the control unit controls the on / off state of the solenoid valve in conjunction with the control unit. This achieves precise and real-time control of injection parameters, improves the stability and reliability of bismuth alloy injection, and meets the high precision requirements for parameter controllability and injection quality during the bismuth alloy injection process.

[0006] Another objective of this invention is to provide a pneumatic bismuth alloy injection control method. By collecting operating conditions and leakage parameters, the driving air pressure is accurately calculated, the air pressure pulse parameters are dynamically adjusted, and the injection flow rate is corrected in real time by calling the associated model. This achieves precise and controllable injection process with stable rate, ensuring that the sealing leakage rate and stability meet the standards, improving the accuracy and reliability of bismuth alloy injection control, and meeting the needs of efficient and high-quality bismuth alloy sealing and injection applications.

[0007] The technical solution of this invention is as follows: A pneumatic bismuth alloy injection control system, characterized in that it includes an air path drive unit, an injection execution unit, and a control unit; The pneumatic drive unit includes a high-pressure gas source, a pressure regulating component, and a solenoid valve. The high-pressure gas source is connected to the bismuth alloy storage device through a gas source pipeline. The pressure regulating component and the solenoid valve are located on the gas source pipeline and are used to output controllable pulse gas pressure. The injection execution unit includes an injection chamber, a pressure detection component, and a nozzle component; the nozzle component is mounted on the injection chamber; the injection chamber is connected to a bismuth alloy storage device, and the pressure detection component is built into the injection chamber to monitor the internal pressure of the injection chamber in real time; The control unit is electrically connected to the pressure detection component and the solenoid valve respectively. The control unit receives the pressure signal from the pressure detection component and controls the on / off state of the solenoid valve to adjust the injection parameters.

[0008] Furthermore, the nozzle has an axisymmetric structure, with an annular guide groove at the outlet and a polished inner wall.

[0009] Furthermore, the annular guide groove has a depth of 0.1-0.3 mm; the nozzle material is alumina ceramic or silicon carbide, with a temperature resistance of ≥300°C, and the inner wall is polished to a roughness Ra≤0.5μm.

[0010] Furthermore, the control unit includes an embedded microprocessor and an analog-to-digital converter. The analog-to-digital converter acquires the analog signal from the pressure detection component in real time and converts it into a digital signal. The control unit calculates the optimal control parameters based on a preset injection model and dynamically adjusts the pulse width and operating frequency of the solenoid valve.

[0011] Furthermore, the gas path drive unit also includes a gas filter assembly, which is located in the gas source supply pipeline; the pressure regulating assembly is an electronic proportional pressure regulating valve, which is electrically connected to the control unit to achieve linkage control; the high-pressure gas source is filled with inert gas or dry clean air.

[0012] Furthermore, the system also includes a visual feedback unit, which includes an image acquisition component and an image processing module for real-time acquisition and analysis of the spray droplet morphology parameters; the visual feedback unit is electrically connected to the control unit and feeds back the droplet detection data to the control unit to optimize the spray uniformity.

[0013] A pneumatic bismuth alloy injection control method, characterized in that it includes: The equipment leakage parameters and operating parameters are collected, and the control unit calculates the minimum driving air pressure P1 required for injection based on the bismuth alloy hydrodynamic model. Molten bismuth alloy is injected into the injection chamber, the gas path drive unit is turned on, and the solenoid valve is turned on and off according to the pulse signal to generate a gas pressure pulse. The gas pressure pulse acts on the injection chamber and drives the molten bismuth alloy to form a jet through the nozzle. The pressure detection component provides real-time feedback on the injection chamber pressure, and the control unit runs a PID control algorithm to dynamically adjust the air pressure pulse width and air pressure pulse frequency. The control unit synchronously calls the flow-pressure-temperature correlation model to adjust the injection flow rate in real time based on the temperature of the molten bismuth alloy and the ambient temperature, maintains a stable injection rate, and ensures that the droplet diameter and beam straightness meet the standards. After spraying is completed, a post-approval process is performed to test the sealing leakage rate and stability.

[0014] Furthermore, the bismuth alloy hydrodynamic model satisfies the formula: P1≥[4σcos(π-α) / D]-ρgH, where σ is the surface tension coefficient of the bismuth alloy, preferably 0.5 N / m, α is the wetting angle (preferably 120°), D is the nozzle diameter, H is the liquid column height, and ρ is the bismuth alloy melt density (preferably 9000 kg / m³). 3 g is the acceleration due to gravity (9.8 m / s²). 2 ).

[0015] Furthermore, the flow-pressure-temperature correlation model is a mathematical relationship fitted by experiments: Q = k × P / T, where Q is the injection flow rate (unit: g / s), P is the driving gas pressure (unit: MPa), T is the temperature of the molten bismuth alloy (unit: K), and k is a calibration coefficient, with a value of 0.1-0.2, preferably 0.15. The calibration coefficient is adjusted based on the temperature of the molten bismuth alloy and the ambient temperature to correct the injection flow rate in real time.

[0016] Furthermore, the PID control algorithm uses the Ziegler-Nichols method to tune the parameters, with a proportional coefficient Kp=0.8, integral time Ti=0.1s, and derivative time Td=0.05s, ensuring that the system response delay is <0.1s.

[0017] Furthermore, the system performs temperature and pressure parameter constraint judgments: when the parameters exceed the preset constraint thresholds, the system automatically triggers adjustments or alarms. The temperature and pressure parameter constraint judgments include: melt temperature ≥ 100℃ and driving air pressure within 0.3-0.7MPa. If these conditions are not met, an alarm is triggered and spraying is prohibited. The pulse width adjustment range is 0.1-1s, and the pulse frequency adjustment range is 1-10Hz; the initial pulse width is preferably 0.5s, the initial frequency is preferably 2Hz, the injection rate is stable at 20-30g / s, the error is ≤5%, and the measured optimal injection rate is 25g / s; When the ambient temperature drops, the system automatically starts nozzle preheating compensation (e.g., when the ambient temperature is -10℃, the nozzle is preheated to 50℃).

[0018] In the pneumatic drive unit of this invention, after the high-pressure gas source is stabilized by the pressure regulating component, the control unit drives the solenoid valve to open and close at a set frequency and duration to form a controllable pulse pressure, which acts on the bismuth alloy storage device. Pulsed air pressure forces molten bismuth alloy into the injection chamber of the injection actuator, and the built-in pressure detection component collects the internal pressure of the chamber in real time and feeds it back to the control unit; The control unit dynamically adjusts the on / off sequence and on / off time of the solenoid valve based on the real-time pressure signal, and precisely controls parameters such as injection pressure and injection frequency, so that the bismuth alloy is stably and evenly sprayed out through the nozzle. The nozzle adopts an axisymmetric structure and an annular guide groove, combined with a high-gloss inner wall, to ensure smooth flow of bismuth alloy and stable spray pattern, avoiding material buildup, flow interruption or splashing.

[0019] Advantages and effects of this invention: This invention discloses a pneumatic bismuth alloy injection control system. Through the coordinated arrangement of a high-pressure air source, pressure regulating component, and solenoid valve in the pneumatic drive unit, it can stably output controllable pulsed air pressure, effectively avoiding the adverse effects of air pressure fluctuations on bismuth alloy injection and providing stable power support for precise injection. The injection execution unit integrates a pressure detection component within the injection chamber, enabling real-time and accurate monitoring of the chamber's internal pressure, ensuring no lag in pressure data feedback and providing a reliable basis for parameter control. The control unit, in conjunction with the pressure detection component and the solenoid valve, can quickly adjust the solenoid valve's on / off state based on real-time pressure signals, achieving precise and real-time adjustment of injection parameters and significantly improving the stability and reliability of bismuth alloy injection. The overall system structure is rationally designed and highly efficient, effectively meeting the high-precision requirements for parameter controllability and injection quality during bismuth alloy injection, reducing injection errors, and broadening the system's practical application scenarios.

[0020] In embodiments of the present invention, the pneumatic drive unit is equipped with a gas filter component, which can effectively filter impurities in the gas source. Combined with an electronic proportional pressure regulating valve linked to the control unit, and in conjunction with inert gas or dry clean air filled with high-pressure gas source, it can output controllable pulse pressure more accurately and stably, avoiding the influence of impurities and gas source humidity and activity on bismuth alloy injection, and further improving the reliability of power support.

[0021] The nozzle adopts an axisymmetric structure, with an annular guide groove at the outlet and polished inner wall. It is equipped with alumina ceramic or silicon carbide material with a temperature resistance of ≥300°C, which can optimize the bismuth alloy jet morphology, reduce flow resistance, and ensure beam straightness and droplet uniformity.

[0022] The control unit uses an embedded microprocessor and analog-to-digital converter to achieve precise conversion of pressure signals and rapid calculation of optimal control parameters, dynamically adjusting the pulse width and frequency of the solenoid valve to improve the accuracy and response speed of parameter control.

[0023] The visual feedback unit collects and analyzes droplet morphology parameters in real time and feeds them back to the control unit, realizing closed-loop optimization of spray uniformity. The overall system structure is more efficient and fully meets the high-precision requirements of bismuth alloy spraying for parameter controllability, spray quality and long-term stability, reducing spraying errors and expanding application scenarios.

[0024] This invention discloses a pneumatic bismuth alloy injection control method. By collecting leakage parameters and operating parameters of the sealing equipment and combining them with a bismuth alloy hydrodynamic model, the minimum driving air pressure P1 required for injection can be calculated. This method can achieve precise matching of driving air pressure, avoiding resource waste and jet turbulence caused by excessively high air pressure, or insufficient injection power and inability to meet sealing requirements caused by excessively low air pressure.

[0025] After the air circuit drive unit is activated, the solenoid valve generates air pressure pulses by switching on and off according to the pulse signal. With the real-time feedback of the pressure detection component and the PID control algorithm of the control unit, the width and frequency of the air pressure pulses can be dynamically adjusted to achieve real-time and precise control of the injection parameters and improve the stability of the injection process.

[0026] The control unit synchronously invokes the flow-pressure-temperature correlation model to adjust the injection flow rate based on the temperature of the molten bismuth alloy and the ambient temperature. This effectively solves problems such as injection rate fluctuations and substandard droplet diameter and beam straightness caused by temperature changes, ensuring injection quality. The post-injection verification steps allow for direct monitoring of the sealing leakage rate and stability, ensuring the sealing effect meets standards and reducing the risk of sealing failure. The overall method significantly improves the reliability and practicality of bismuth alloy injection sealing, adapting to sealing requirements under different operating conditions. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the system structure of the present invention.

[0028] Figure 2 This is a schematic diagram of the nozzle structure of the present invention.

[0029] Figure 3 This is a flowchart of the method of the present invention.

[0030] In the figure, the following labels are used: 1. Air path drive unit; 12. High-pressure air source; 13. Pressure regulating component; 14. Solenoid valve; 15. Filter component; 2. Injection execution unit; 21. Injection chamber; 22. Pressure detection component; 23. Nozzle component; 3. Control unit; 31. Embedded microprocessor; 32. Analog-to-digital conversion component; 4. Visual feedback unit; 41. Image acquisition component; 42. Image processing module; 5. Air source delivery pipeline; 6. Bismuth alloy storage device; 7. Annular guide groove. Detailed Implementation

[0031] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0032] Example 1 See Figure 1 , Figure 2 .

[0033] A pneumatic bismuth alloy injection control system includes an air drive unit 1, an injection execution unit 2, and a control unit 3; The pneumatic drive unit 1 includes a high-pressure gas source 12, a pressure regulating component 13, and a solenoid valve 14. The high-pressure gas source 12 is a high-pressure gas cylinder, and the pressure regulating component 13 is an electronic proportional pressure regulating valve. The high-pressure gas cylinder is connected to the bismuth alloy storage device 6 through the gas source supply pipeline 5. The pressure regulating valve and the solenoid valve 14 are installed on the gas source supply pipeline 5 and are used to output controllable pulse gas pressure. The injection execution unit 2 includes an injection chamber 21, a pressure detection component 22, and a nozzle 23. The pressure detection component 22 is a pressure sensor, and the nozzle component 23 is mounted on the injection chamber 21. The injection chamber 21 is connected to the bismuth alloy storage device 6. The pressure sensor is built into the injection chamber 21 to monitor the internal pressure of the injection chamber 21 in real time. The nozzle 23 has an axisymmetric structure and an annular guide groove 7 at the outlet with a groove depth of 0.1-0.3 mm. The nozzle 23 is made of alumina ceramic or silicon carbide, with a temperature resistance of ≥300°C, and the inner wall is polished to a roughness Ra≤0.5μm.

[0034] The control unit 3 is electrically connected to the pressure sensor and the solenoid valve 14 respectively. The control unit 3 receives the pressure signal from the pressure sensor and controls the on / off state of the solenoid valve 14 to adjust the injection parameters.

[0035] The control unit 3 includes an embedded microprocessor 31 and an analog-to-digital converter 32. The analog-to-digital converter 32 acquires the analog signal from the pressure detection component 22 in real time and converts it into a digital signal. The control unit 3 calculates the optimal control parameters based on a preset injection model and dynamically adjusts the pulse width and operating frequency of the solenoid valve 14.

[0036] The gas path drive unit 1 also includes a gas filter assembly 15, which is a gas filter and is located in the gas source pipeline 5; the electronic proportional pressure regulating valve is electrically connected to the control unit 3 to achieve linkage control; the high-pressure gas cylinder is filled with inert gas or dry clean air.

[0037] In another embodiment of the present invention, the system further includes a visual feedback unit 4, which includes an image acquisition component 41 and an image processing module 42. The image acquisition component 41 uses a high-definition camera, and the image processing module 42 integrates an image processing algorithm for real-time acquisition and analysis of the morphological parameters of the ejected droplets. The high-definition camera is electrically connected to the control unit 3 and feeds back the droplet detection data to the control unit 3 to optimize the uniformity of the ejection.

[0038] Example 2 See Figure 3 .

[0039] A pneumatic bismuth alloy injection control method based on the pneumatic bismuth alloy injection control system described in Example 1 includes: Collect leakage parameters and operating parameters of GIS equipment, and the control unit 3 calculates the minimum driving air pressure P1 required for injection based on the bismuth alloy hydrodynamic model; Molten bismuth alloy is injected into the injection chamber 21, the gas path drive unit 1 is turned on, and the solenoid valve 14 is turned on and off according to the pulse signal to generate a gas pressure pulse. The gas pressure pulse acts on the injection chamber 21, driving the molten bismuth alloy to form a jet through the nozzle 23. The pressure sensor provides real-time feedback on the pressure in the injection chamber 21, and the control unit 3 runs a PID control algorithm to dynamically adjust the air pressure pulse width and air pressure pulse frequency. Control unit 3 synchronously calls the flow-pressure-temperature correlation model, adjusts the injection flow rate in real time based on the temperature of the molten bismuth alloy and the ambient temperature, and performs temperature and pressure parameter constraint judgments. When the parameters exceed the preset constraint threshold, the system automatically triggers adjustment or alarm to maintain a stable injection rate and ensure that the droplet diameter and beam straightness meet the standards. After the injection is completed, the post-verification steps are performed to detect the sealing leakage rate and stability.

[0040] The hydrodynamic model of bismuth alloy satisfies the formula: P1≥[4σcos(π-α) / D]-ρgH, where σ is the surface tension coefficient of bismuth alloy, preferably 0.5 N / m, α is the wetting angle (preferably 120°), D is the nozzle diameter, H is the liquid column height, and ρ is the molten density of bismuth alloy (preferably 9000 kg / m³). 3 g is the acceleration due to gravity (9.8 m / s²). 2 ).

[0041] The flow-pressure-temperature correlation model is the mathematical relationship fitted to the experiment: Q=k×P / T, where Q is the injection flow rate (unit: g / s), P is the driving air pressure (unit: MPa), T is the temperature of the bismuth alloy melt (unit: K), and k is the calibration coefficient, which takes a value of 0.1-0.2, preferably 0.15.

[0042] The PID control algorithm uses the Ziegler-Nichols method to tune the parameters, with a proportional coefficient Kp=0.8, integral time Ti=0.1s, and derivative time Td=0.05s, ensuring that the system response delay is <0.1s.

[0043] Temperature and pressure parameter constraints include: melt temperature ≥ 100℃ and driving air pressure within 0.3-0.7MPa. If these conditions are not met, an alarm will be triggered and spraying will be prohibited. The pulse width adjustment range is 0.1-1s, and the pulse frequency adjustment range is 1-10Hz; the initial pulse width is preferably 0.5s, the initial frequency is preferably 2Hz, the injection rate is stable at 20-30g / s, the error is ≤5%, and the measured optimal injection rate is 25g / s; When the ambient temperature drops, the system automatically starts nozzle preheating compensation (e.g., when the ambient temperature is -10℃, the nozzle is preheated to 50℃).

[0044] The pneumatic drive unit includes a 2L high-pressure gas cylinder (filled with dry air), an electronic proportional valve, a high-speed solenoid valve with a response time of <5ms, and a 5μm gas filter. The drive air pressure adjustment range is 0.3-0.7MPa, with a default adjustment to 0.5MPa.

[0045] When the ambient temperature decreases, the system automatically activates nozzle preheating compensation (e.g., preheating the nozzle to 50℃ when the ambient temperature is -10℃); the pulse width is negatively correlated with the melt temperature, and the pulse frequency increases with rising ambient temperature, ensuring consistent sealing and reducing sealing time to less than 8 minutes, with a measured leakage rate ≤0.8×10⁻⁶. -5 Pa·m 3 / s.

[0046] The control unit 3 uses an embedded microprocessor, preferably ARM Cortex-M4, with a sampling frequency of not less than 1kHz. It integrates a touch screen and a human-machine interaction unit, supports parameter setting and 4G wireless data upload, and is compatible with non-invasive leak sealing of GIS equipment.

[0047] Application examples This invention details a pneumatic bismuth alloy injection control system using application examples. Based on a typical GIS leakage scenario (leakage hole diameter 2mm, leakage gas pressure 0.5MPa), it demonstrates the system design, operation process, and test results.

[0048] The gas drive unit 1 includes a high-pressure gas cylinder and a pressure regulating valve and a solenoid valve 14 installed on the gas source pipeline 5, which are used to generate pulsed gas pressure with a pressure range of 0.3-0.7MPa, a pulse width of 0.1-1s, and a frequency of 1-10Hz; the injection chamber is connected to the bismuth alloy storage device 6, which has a built-in pressure sensor to monitor the pressure change in the chamber in real time; the gas source pipeline 5 is connected to the bismuth alloy storage device 6; a nozzle 23 is installed on the injection chamber 21. The control unit 3 receives the pressure sensor signal and dynamically adjusts the on / off state of the solenoid valve 14 through the PID algorithm to control the injection parameters; the nozzle 23 has an orifice diameter of 0.5-2mm and is made of alumina ceramic to ensure the directionality of the injection and the uniformity of the droplets. Furthermore, in another embodiment of the present invention, the nozzle 23 has an axisymmetric structure, and an annular guide groove 7 is provided at the outlet with a groove depth of 0.1-0.3mm; the nozzle 23 is made of alumina ceramic or silicon carbide, with a temperature resistance of ≥300°C, and the inner wall is polished to a roughness Ra≤0.5μm; the nozzle 23 and the spray chamber 21 are connected by threads.

[0049] Furthermore, in another embodiment of the present invention, the control unit 3 includes an embedded microprocessor 31 and an analog-to-digital converter 32. The analog-to-digital converter 32 employs an AD converter and a PID control algorithm. The embedded microprocessor 31 is an ARM Cortex-M series chip. The AD converter acquires pressure sensor signals in real time at a sampling frequency of 1kHz. The algorithm calculates the optimal pulse width and frequency based on a preset injection rate model and dynamically adjusts the opening and closing of the nozzle 23 to ensure that the injection stability deviation is ≤5%. In addition, the control unit 3 is equipped with a touch screen interface for parameter setting and status monitoring.

[0050] Furthermore, in another embodiment of the present invention, the gas path drive unit 1 further includes a gas filter installed on the gas source pipeline 5, with a filter accuracy of 5μm to ensure gas purity; the pressure regulating component is an electronic proportional valve, which is connected to the control unit 3 for linkage to achieve precise gas pressure control (accuracy ±0.01MPa); the high-pressure gas cylinder has a capacity of 1-5L and is filled with nitrogen or dry air to avoid reaction with bismuth alloy.

[0051] Furthermore, in another embodiment of the present invention, the system further includes a visual feedback unit 4, which includes a high-definition camera and an image processing algorithm to monitor the shape of the sprayed droplets in real time and feed back to the control unit 3 to adjust the parameters; the visual unit has a resolution of 1080p and a frame rate of 60fps, and is used to identify the droplet diameter and speed to optimize the spray uniformity.

[0052] Furthermore, in another embodiment of the present invention, the control unit 3 is the brain of the system, employing an embedded microprocessor (such as an ARM Cortex-M4) to run a PID control algorithm. The algorithm is based on a bismuth alloy hydrodynamic model, calculates the minimum driving air pressure P1 required for injection, and dynamically adjusts the air pressure pulse width (0.1-1s) and air pressure pulse frequency (1-10Hz) in conjunction with real-time pressure feedback. For example, according to the formula P1≥[4σcos(π-α) / D]-ρgH, where σ is the surface tension coefficient of the bismuth alloy, α is the wetting angle, D is the nozzle diameter, and H is the liquid column height, the control unit automatically calculates the optimal driving conditions using preset parameters (such as σ=0.5N / m, α=120°) to ensure the injection rate remains stable at 20-30g / s.

[0053] Furthermore, in another embodiment of the present invention, the control unit 3 integrates a flow-pressure-temperature correlation model. This model establishes a mathematical relationship between the injection flow rate Q, the driving gas pressure P, and the bismuth alloy melt temperature T through experimental data fitting. The expression is Q=k×P / T, where k is a calibration coefficient (usually set to 0.1-0.2 through calibration). The flow-pressure-temperature correlation model receives real-time data from temperature sensors (such as thermocouples monitoring the melt temperature) and ambient temperature sensors, dynamically adjusts calibration parameters, and introduces conditional constraints (such as temperature thresholds and pressure ranges) to enhance the robustness of the system under varying operating conditions. The control unit 3 also integrates a touchscreen to support parameter settings.

[0054] Nozzle 3 is optimized for the properties of bismuth alloys, with an orifice diameter of 0.5-2mm. It is made of alumina ceramic, resistant to temperatures above 300°C, and its inner wall is polished to Ra≤0.5μm to reduce flow loss. An annular guide groove 7, 0.2mm deep, is designed at the outlet to guide and concentrate the liquid flow, preventing splashing. This invention is based on the principle of pneumatic jetting, where pulsed air pressure breaks the force balance of the molten liquid, forming a jet. Furthermore, through control optimization, the droplet diameter deviation is ≤10%, and the jet straightness deviation is ≤5°.

[0055] Furthermore, the system workflow of the present invention is as follows: After initialization, the user sets the leakage parameters of the GIS equipment (such as the size of the leak hole and the ambient temperature) through the touch screen; the control unit 3 calculates the initial injection parameters according to the built-in model; the gas path drive unit 1 is started, and the solenoid valve 14 opens and closes according to the pulse signal to generate a gas pressure pulse; the pressure sensor provides real-time feedback data, and the PID algorithm dynamically adjusts the pulse width and frequency to adapt to changes in operating conditions; at the same time, the flow-pressure-temperature correlation model corrects the injection flow rate according to the real-time temperature data and checks whether the parameters meet the constraints (such as T≥100°C, P within 0.3-0.7MPa), otherwise, adjustment or alarm is triggered; the nozzle injects molten bismuth alloy, and the visual feedback unit 4 (optional) monitors the droplet morphology to further optimize the control.

[0056] The technical problems solved by this invention include: first, the problem of uneven droplet distribution, which is addressed by ensuring stable droplet breakage through precise air pressure control; second, the problem of response lag, where solenoid valves and real-time algorithms reduce the delay to <0.1s; and third, the problem of adaptability, where the model adaptively adjusts parameters to accommodate different leakage modes (such as orifice leaks or flange leaks). Furthermore, the model extends the constraints on injection parameters, such as the negative correlation between pulse width and temperature, and the increase in frequency with rising ambient temperature, ensuring consistent sealing. The system of this invention has achieved a measured injection rate of 25g / s, and the sealing time can be shortened to less than 8 minutes, achieving the required leakage rate.

[0057] The gas drive unit 1 uses a 2L high-pressure gas cylinder filled with dry air, and the gas pressure is precisely adjusted to 0.5MPa by an electronic proportional valve. The solenoid valve 14 is a high-speed type (response time <5ms), connected to the electronic proportional valve and a 5μm filter to ensure gas purity. The injection chamber 21 is made of stainless steel, with a volume of 50ml, and has a built-in piezoresistive pressure sensor (range 0-1MPa, accuracy ±0.5%) to monitor pressure in real time. The injection chamber 21 is connected to the bismuth alloy storage device 6 (capacity 100g) via a quick-connect coupling for easy disassembly. Constraints are set: the system automatically alarms when T is below 100°C or P exceeds 0.3-0.7MPa. The 5-inch touchscreen is used to set parameters such as the injection rate of 25g / s; the wireless module supports 4G communication, and data is uploaded to the cloud. The nozzle 23 has a 1mm orifice diameter, is made of alumina ceramic, and its inner wall is polished to Ra=0.3μm. An annular guide groove 7 (0.2mm deep) is provided at the outlet to reduce turbulence. The system integrates a visual feedback unit, including a 5-megapixel camera with a frame rate of 60fps, for real-time monitoring of droplets.

[0058] The operation process consists of five steps: initialization, parameter setting, injection execution, real-time adjustment, and post-implementation verification. Step 1: Initialization: Check system sealing, connect the gas and electrical circuits, and initiate a self-test for the control unit. The self-test includes temperature sensor calibration and correlation model coefficient verification to ensure effective parameter constraints. Step 2: Parameter setting: Input leakage parameters via the touchscreen: leak size 2mm, ambient temperature 25°C, leakage pressure 0.5MPa; the control unit automatically calculates initial injection parameters (pulse width 0.5s, frequency 2Hz), based on the fluid model (P1≥[4×0.5×cos(180-120) / 0.001]-9000×9.8×0.02, calculated as P1≥0.4MPa). Step 3: Injection execution: Open the drive gas circuit; the solenoid valve switches on and off according to the pulse signal, generating a pressure pulse; the pressure sensor provides real-time feedback data (e.g., internal pressure 0.45MPa); the PID algorithm dynamically adjusts the pulse width to 0.55s and the frequency to 2.2Hz, stabilizing the injection rate at 25g / s. The spraying time lasted 3 seconds, with a total bismuth alloy usage of 75g. The fourth step involved real-time adjustment: a vision unit monitored the droplets, and an image processing algorithm identified the diameter (average 1.5mm, deviation ≤8%), feeding back to the control unit for parameter fine-tuning. The fifth step was post-implantation verification: after sealing, the leakage rate was measured using a wrapping method, yielding a result of 0.8 × 10⁻⁶. -5 Pa·m 3 / s, below the threshold; no change in leakage rate after vibration test (20Hz, 24 hours).

[0059] The key innovation of this embodiment lies in its control accuracy and adaptability. The PID algorithm is tuned using the Ziegler-Nichols method, with a proportional gain Kp=0.8, integral time Ti=0.1s, and derivative time Td=0.05s, ensuring fast response and minimal overshoot. The introduction of a flow-pressure-temperature correlation model, through parameter constraints and temperature compensation, significantly improves the system's robustness under varying temperature conditions. Actual measurements show that the injection rate deviation is ≤3% under different temperature conditions. The system was also tested under different operating conditions: for example, when the leakage pressure is 0.3MPa, the algorithm automatically reduces the pulse width to 0.3s; when the ambient temperature is -10°C, temperature compensation is activated, preheating the nozzle to 50°C. Results consistently show an injection rate deviation ≤5% and a sealing time ≤9 minutes. This invention achieves non-invasive sealing, promoting the development of GIS leak control technology.

Claims

1. A pneumatic bismuth alloy injection control system, characterized in that, It includes a pneumatic drive unit, an injection execution unit, and a control unit; the pneumatic drive unit includes a high-pressure gas source, a pressure regulating component, and a solenoid valve. The high-pressure gas source is connected to a bismuth alloy storage device through a gas source supply pipeline. The pressure regulating component and the solenoid valve are located on the gas source supply pipeline and are used to output controllable pulsed gas pressure. The injection actuator includes an injection chamber, a pressure detection assembly, and a nozzle component; the nozzle component is mounted on the injection chamber. The injection chamber is connected to the bismuth alloy storage device, and the pressure detection component is built into the injection chamber to monitor the internal pressure of the injection chamber in real time. The control unit is electrically connected to the pressure detection component and the solenoid valve respectively. The control unit receives the pressure signal from the pressure detection component and controls the on / off state of the solenoid valve to adjust the injection parameters.

2. The pneumatic bismuth alloy injection control system according to claim 1, characterized in that, The nozzle has an axisymmetric structure, with an annular guide groove at the outlet and a polished inner wall.

3. The pneumatic bismuth alloy injection control system according to claim 2, characterized in that, The annular guide groove has a depth of 0.1-0.3 mm; the nozzle is made of alumina ceramic or silicon carbide, with a temperature resistance of ≥300°C, and the inner wall is polished to a roughness Ra≤0.5μm.

4. The pneumatic bismuth alloy injection control system according to claim 1, characterized in that, The control unit includes an embedded microprocessor and an analog-to-digital converter. The analog-to-digital converter acquires the analog signals from the pressure detection component in real time and converts them into digital signals. The control unit calculates the optimal control parameters based on a preset injection model and dynamically adjusts the pulse width and operating frequency of the solenoid valve.

5. The pneumatic bismuth alloy injection control system according to claim 1, characterized in that, The gas path drive unit also includes a gas filter assembly, which is located in the gas source pipeline; the pressure regulating assembly is an electronic proportional pressure regulating valve, which is electrically connected to the control unit to achieve linkage control; the high-pressure gas source is filled with inert gas or dry clean air.

6. The pneumatic bismuth alloy injection control system according to claim 1, characterized in that, The system also includes a visual feedback unit, which includes an image acquisition component and an image processing module, for real-time acquisition and analysis of the spray droplet morphology parameters; the visual feedback unit is electrically connected to the control unit and feeds back the droplet detection data to the control unit to optimize the spray uniformity.

7. A pneumatic bismuth alloy injection control method based on any one of the pneumatic bismuth alloy injection control systems according to claims 1-6, characterized in that, include: Collect leakage parameters and operating parameters of the sealing equipment, and the control unit calculates the minimum driving air pressure P1 required for injection based on the bismuth alloy hydrodynamic model; Molten bismuth alloy is injected into the injection chamber, the gas path drive unit is turned on, and the solenoid valve is turned on and off according to the pulse signal to generate a gas pressure pulse. The gas pressure pulse acts on the injection chamber and drives the molten bismuth alloy to form a jet through the nozzle. The pressure detection component provides real-time feedback on the injection chamber pressure, and the control unit runs a PID control algorithm to dynamically adjust the air pressure pulse width and air pressure pulse frequency. The control unit synchronously calls the flow-pressure-temperature correlation model to adjust the injection flow rate in real time according to the temperature of the molten bismuth alloy and the ambient temperature, maintains a stable injection rate, and ensures that the droplet diameter and beam straightness meet the standards. After spraying is completed, a post-approval process is performed to test the sealing leakage rate and stability.

8. The pneumatic bismuth alloy injection control method according to claim 7, characterized in that, The bismuth alloy hydrodynamic model satisfies the formula: P1≥[4σcos(π-α) / D]-ρgH, where σ is the surface tension coefficient of the bismuth alloy, α is the wetting angle, D is the nozzle diameter, H is the height of the liquid column, ρ is the density of the bismuth alloy melt, and g is the acceleration due to gravity.

9. The pneumatic bismuth alloy injection control method according to claim 7, characterized in that, The flow-pressure-temperature correlation model is a mathematical relationship fitted by the experiment: Q=k×P / T, where Q is the injection flow rate, P is the driving air pressure, T is the temperature of the molten bismuth alloy, and k is the calibration coefficient. The calibration coefficient is adjusted according to the temperature of the molten bismuth alloy and the ambient temperature, thereby correcting the injection flow rate in real time.

10. The pneumatic bismuth alloy injection control method according to claim 7, characterized in that, The PID control algorithm uses the Ziegler-Nichols method to tune the parameters, with a proportional coefficient Kp=0.8, integral time Ti=0.1s, and derivative time Td=0.05s, ensuring that the system response delay is <0.1s.

11. The pneumatic bismuth alloy injection control method according to claim 7, characterized in that, It also includes the determination of temperature and air pressure parameters: when the parameters of the solenoid valve exceed the preset constraint threshold, the system automatically triggers adjustment or alarm. The determination of temperature and air pressure parameters includes: melt temperature ≥ 100℃ and driving air pressure within 0.3-0.7MPa. If the conditions are not met, an alarm is triggered and spraying is prohibited. The pulse width adjustment range is 0.1-1s, and the pulse frequency adjustment range is 1-10Hz; the initial pulse width is preferably 0.5s, the initial frequency is preferably 2Hz, and the injection rate is stabilized at 20-30g / s with an error ≤5%. When the ambient temperature drops, the system automatically activates nozzle preheating compensation.

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