Molecular pump automatic purging pre-clean system and method

Abstract

The application belongs to the technical field of vacuum equipment maintenance, and specifically discloses a molecular pump automatic purging pre-cleaning system and method. The system comprises a detection module, a control module and an execution module. The detection module collects flow, pressure, temperature and vibration parameters in real time through various sensors, obtains a pollution index PI through normalization and weighted operation, and accurately determines the pollution grade. The control module combines PID and fuzzy control algorithms and dynamically generates cleaning instructions in combination with an adaptive learning strategy. The execution module uses high-purity inert gas to complete the purging operation. The application solves the problems of low efficiency, unstable effect, easy damage to equipment and poor universality of traditional manual cleaning, can automatically adjust the cleaning cycle according to the load of the molecular pump, and has good hardware and software compatibility. The scheme has high automation degree and good cleaning effect, can reduce operation and maintenance cost and prolong the service life of the equipment, and is suitable for high-vacuum scenes such as semiconductor manufacturing, vacuum coating and particle accelerators.

Description

Technical Field

[0001] This invention belongs to the field of vacuum equipment maintenance technology, and particularly relates to an automatic purging and pre-cleaning system and method for molecular pumps, which is applicable to the automated cleaning and maintenance of molecular pumps in high vacuum applications such as semiconductor manufacturing, vacuum coating, and particle accelerators. Background Technology

[0002] Molecular pumps are core vacuum-generating devices for high-vacuum operations, widely used in semiconductor manufacturing, vacuum coating, and scientific research—fields with stringent high-vacuum environment requirements. Their working principle is based on momentum transfer theory; high-speed rotating rotor blades guide gas molecules from the inlet to the outlet, thus achieving vacuum extraction. The core structure of a molecular pump typically consists of a rotor, stator, bearing system, and cooling device. The geometry and material properties of the rotor blades have a significant impact on the pump's performance.

[0003] Molecular pumps are susceptible to gas contamination and particulate matter deposition in complex operating environments, leading to performance degradation or even malfunction. Common molecular pump cleaning methods include:

[0004] (1) Manual disassembly and cleaning: Although it can thoroughly remove contaminants, the operation is cumbersome, time-consuming, and prone to damaging precision parts. It requires the participation of professional technicians, resulting in high maintenance costs.

[0005] (2) Chemical solvent cleaning: The residual solvent may corrode the pump body material, affecting its long service life.

[0006] (3) High temperature baking: Although it can effectively remove some organic pollutants, it may have an adverse effect on some seals or lubricating materials with poor high temperature resistance.

[0007] The aforementioned traditional cleaning methods share several common drawbacks: First, they are inefficient, relying entirely on manual operation, resulting in high labor costs. Second, the cleaning effect is unstable, with the quality entirely dependent on the operator's experience, making it impossible to guarantee consistent results across batches. Third, they lack real-time monitoring capabilities and cannot dynamically adjust cleaning parameters based on the actual contamination status of the molecular pump. Fourth, they have limited versatility, as existing cleaning equipment is mostly developed for specific molecular pump models and cannot be adapted to multiple brands and specifications of equipment, thus limiting their application scenarios. Summary of the Invention

[0008] This invention aims to solve the problems of low efficiency, unstable results, and high dependence on manual labor in traditional molecular pump cleaning methods. It provides a highly efficient, stable, and automated automatic purging and pre-cleaning system and method for molecular pumps. By integrating advanced sensor technology, intelligent control algorithms, and precise actuators, it achieves real-time monitoring and evaluation of the operating status and contamination level of the molecular pump, and automatically adjusts cleaning parameters based on the detection data, thereby significantly improving the performance and service life of the molecular pump while reducing maintenance costs.

[0009] To address the aforementioned technical problems, this invention provides an automatic purging and pre-cleaning system for molecular pumps, comprising the following modules:

[0010] The detection module is used to collect parameters of the molecular pump's operating status and contamination level in real time. The detection module includes a gas flow sensor, a pressure sensor, and a temperature sensor. The parameters include the molecular pump's inlet flow rate, the pump body's central pressure, the exhaust port pressure, the bearing's operating temperature, the pump body's outer casing temperature, and the effective value of the bearing housing's vibration acceleration.

[0011] The control module, connected to the detection module, is used to receive data collected by the detection module and generate cleaning strategy instructions based on the PID control algorithm and the fuzzy control algorithm.

[0012] An execution module, connected to the control module, is used to perform a purge pre-cleaning operation according to the cleaning strategy instructions. The execution module includes a solenoid valve for controlling the on / off of cleaning gas, a pneumatic valve for adjusting the flow rate of cleaning gas, and a gas supply system.

[0013] The control module automatically determines whether the molecular pump is contaminated based on the parameters collected by the detection module. When contamination is detected, a cleaning program is triggered, and the optimal cleaning parameters are calculated based on the PID control algorithm and the fuzzy control algorithm.

[0014] Furthermore, in this invention, the gas flow sensor is a thermal mass flow meter, used to collect the inlet flow parameters of the molecular pump and monitor changes in the inlet flow; the pressure sensor is a piezoresistive pressure sensor, used to collect the pressure in the middle of the molecular pump body to monitor pressure changes and to collect the pressure in the exhaust pipe of the molecular pump to monitor changes in exhaust pressure; the temperature sensor is a thermocouple or a resistance temperature detector (RTD) sensor, used to collect the temperature of the molecular pump bearing housing to monitor changes in the bearing operating temperature and to collect the temperature of the outer casing of the molecular pump body to monitor the temperature of the outer casing of the pump body.

[0015] Furthermore, in this invention, the detection module also includes a piezoelectric acceleration sensor, which is installed on the surface of the molecular pump bearing housing to monitor the effective value of the vibration acceleration of the bearing housing in order to determine the change in rotor dynamic balance.

[0016] Furthermore, in this invention, the control module calculates the pollution index through a multi-parameter fusion algorithm. The multi-parameter fusion algorithm assigns weight coefficients to the intake flow rate, exhaust pressure, temperature and vibration data to calculate the pollution index, and classifies the pollution level according to the pollution index, and performs early warning, pre-cleaning or full cleaning operations according to different pollution levels.

[0017] Furthermore, in this invention, the weighting coefficients of intake flow rate, exhaust pressure, bearing operating temperature and vibration are determined using the analytic hierarchy process (AHP). The weighting coefficient for gas flow rate is 0.45, the weighting coefficient for exhaust pressure is 0.25, and the weighting coefficients for bearing operating temperature and vibration are 0.15. The control module performs a consistency check on the judgment matrix, and the weighting coefficients are valid when the consistency ratio CR is less than 0.1.

[0018] Furthermore, in this invention, the fuzzy control algorithm employs a dual-input single-output fuzzy controller, with flow deviation and deviation change rate as input variables and control increment as output variable; the universes of discourse for the flow deviation and deviation change rate are [-100%, +100%] and [-50%, +50%], respectively, and the universe of discourse for the output control increment is [-20%, +20%]; the fuzzy set includes seven levels: negative large, negative medium, negative small, zero, positive small, positive medium, and positive large, and the centroid method is used to complete the defuzzification operation.

[0019] Furthermore, in this invention, the control module calculates the cleaning gas flow rate based on Bernoulli's equation for compressible fluids:

[0020]

[0021]

[0022] in:

[0023] Volumetric flow rate; Flow coefficient, The flow area of ​​the valve orifice. This refers to the orifice diameter of the solenoid valve. The pressure difference across the valve. The density of the gas;

[0024] And based on the calculated valve port diameter of the solenoid valve The result determines the appropriate solenoid valve bore specification.

[0025] Furthermore, in this invention, the gas supply system includes a high-pressure gas cylinder, a pressure reducing valve, and a filter, and uses high-purity nitrogen or high-purity argon as the cleaning gas, and can switch the type of cleaning gas according to the type of contaminant.

[0026] This invention also provides an automatic purging and pre-cleaning method for molecular pumps, employing the aforementioned automatic purging and pre-cleaning system for molecular pumps, specifically including the following steps:

[0027] Step S1: Real-time acquisition of the flow rate, pressure, and temperature operating parameters of the molecular pump through the detection module;

[0028] Step S2: The control module analyzes the collected operating parameters. When the parameters exceed the preset threshold, it determines that the molecular pump is contaminated and triggers the cleaning program.

[0029] Step S3: The control module calculates the optimal cleaning parameters based on the PID control algorithm and the fuzzy control algorithm. The cleaning parameters include the cleaning gas flow rate, cleaning duration, and purging pressure.

[0030] Step S4: The execution module opens the solenoid valve to introduce cleaning gas according to the instruction of the control module, and adjusts the gas flow rate to the set value through the pneumatic valve to perform the purging pre-cleaning operation.

[0031] Step S5: During the cleaning process, the detection module continuously monitors various parameters, and the control module dynamically adjusts the cleaning parameters based on real-time data;

[0032] Step S6: After cleaning is completed, the execution module shuts off the air circuit, and the detection module verifies the cleaning effect.

[0033] Furthermore, in step S6 of this invention, verifying the cleaning effect includes: the detection module collects gas flow rate, pressure and temperature data again, compares them with the preset recovery threshold in the control module, and confirms that the molecular pump has returned to normal operation.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) High degree of automation, significantly improved cleaning efficiency, and reduced operation and maintenance costs: This invention realizes full automation of molecular pump cleaning process, eliminating the need for manual disassembly and manual operation, greatly reducing the investment of professional technicians and reducing labor costs; at the same time, the adaptive cleaning strategy can avoid over-cleaning and reduce the consumption of inert gas.

[0036] (2) Stable cleaning effect and improved equipment performance: Based on multi-parameter fusion and closed-loop control, relying on multi-parameter real-time monitoring + graded cleaning mechanism, the cleaning timing and cleaning parameters are dynamically adjustable, and the cleaning consistency is strong.

[0037] (3) High safety and extended equipment life: High-purity inert gas is used for purging and cleaning, which is free from chemical solvent corrosion and high-temperature baking damage. It can effectively protect the precision components such as molecular pump seals, bearings, and blades, reduce the frequency of equipment failure and downtime, and extend the overall service life of the equipment.

[0038] (4) Strong compatibility: The modular design and parameterized configuration make the system compatible with molecular pumps of different brands and specifications, and have wide applicability. Attached Figure Description

[0039] The specific embodiments of the present invention will be further explained below with reference to the accompanying drawings.

[0040] Figure 1 This is a system block diagram of the automatic purging and pre-cleaning system for molecular pumps according to the present invention.

[0041] Figure 2 This is a flowchart of the automatic purging and pre-cleaning method for molecular pumps according to the present invention. Detailed Implementation

[0042] Example 1

[0043] Combination Figure 1 As shown, the automatic purging and pre-cleaning system for molecular pumps in this embodiment includes the following modules:

[0044] The detection module is used to collect parameters of the molecular pump's operating status and contamination level in real time. The detection module includes a gas flow sensor, a pressure sensor, and a temperature sensor. The parameters include the molecular pump's inlet flow rate, the pump body's central pressure, the exhaust port pressure, the bearing's operating temperature, the pump body's outer casing temperature, and the effective value of the bearing housing's vibration acceleration.

[0045] The control module, connected to the detection module, is used to receive data collected by the detection module and generate cleaning strategy instructions based on the PID control algorithm and the fuzzy control algorithm.

[0046] An execution module, connected to the control module, is used to perform a purge pre-cleaning operation according to the cleaning strategy instructions. The execution module includes a solenoid valve for controlling the on / off of cleaning gas, a pneumatic valve for adjusting the flow rate of cleaning gas, and a gas supply system.

[0047] The control module automatically determines whether the molecular pump is contaminated based on the parameters collected by the detection module. When contamination is detected, a cleaning program is triggered, and the optimal cleaning parameters are calculated based on the PID control algorithm and the fuzzy control algorithm.

[0048] In this embodiment, preferably, the gas flow sensor is a thermal mass flow meter, used to collect the inlet flow parameters of the molecular pump and monitor changes in the inlet flow; the pressure sensor is a piezoresistive pressure sensor, used to collect the pressure in the middle of the molecular pump body to monitor pressure changes and to collect the pressure in the exhaust pipe of the molecular pump to monitor changes in exhaust pressure; the temperature sensor is a thermocouple or a resistance temperature detector (RTD) sensor, used to collect the temperature of the molecular pump bearing housing to monitor changes in the bearing operating temperature and to collect the temperature of the outer casing of the molecular pump body to monitor the temperature of the outer casing of the pump body.

[0049] In this embodiment, preferably, the detection module further includes a piezoelectric acceleration sensor, which is installed on the surface of the molecular pump bearing housing to monitor the effective value of the vibration acceleration of the bearing housing in order to determine the change in rotor dynamic balance.

[0050] In this embodiment, the detection module simultaneously collects multi-dimensional data such as temperature, pressure, and flow rate to construct molecular pump operating status data, improving the reliability of the detection results and providing more accurate data support for subsequent control decisions. The specific parameter acquisition method is as follows:

[0051] In this embodiment, the surface contamination of the rotor blades is assessed by monitoring changes in the intake airflow. Contaminants on the blade surface narrow the gas flow path, reducing the required intake airflow at the same pumping speed. Specifically, a thermal mass flow meter is installed at the inlet flange interface of the molecular pump to monitor the intake airflow in real time. The installation method is flange clamping, and the flow meter probe is inserted to a depth of 1 / 3 of the pipe diameter to ensure measurement accuracy.

[0052] In this embodiment, the blockage of the stator blade gap is assessed by monitoring pressure changes in the middle of the pump body (between the rotor and stator). Gaps blockage leads to increased flow resistance and higher intermediate pressure. Specifically, an M8×1 threaded hole is machined in the middle of the molecular pump body to install a piezoresistive pressure sensor and monitor the intermediate pressure. The installation method is a threaded connection + metal sealing ring (Viton fluororubber) to ensure high vacuum sealing performance.

[0053] In this embodiment, the clogging of the exhaust port filter is assessed by monitoring changes in exhaust port pressure. Filter clogging leads to increased back pressure, affecting the exhaust efficiency of the molecular pump. Specifically, a piezoresistive pressure sensor is installed on the molecular pump exhaust port pipeline to monitor the exhaust pressure. The installation method is a welded joint (VCR surface seal), which is suitable for high vacuum conditions.

[0054] In this embodiment, the deposition of contaminants in the bearing housing is assessed by monitoring changes in bearing operating temperature. Contaminants entering the bearing cavity can affect lubrication performance, leading to a faster temperature rise in the bearing. Specifically, a 3mm diameter hole (15mm deep) is drilled in the outer ring of the molecular pump bearing housing, and a type K thermocouple is embedded to monitor the bearing temperature. The installation method is to drill holes for embedding, fill with thermally conductive silicone grease, and fix with high-temperature resistant epoxy resin. The response time is <2s.

[0055] In this embodiment, the internal thermal equilibrium state is determined by monitoring the temperature of the pump body's outer casing. Specifically, a PT100 thermal resistor is attached to the surface of the molecular pump's outer casing to monitor the casing temperature. The installation method is surface mounting + magnetic fixation, which makes it easy to install and remove.

[0056] In this embodiment, the change in rotor dynamic balance is assessed by monitoring the effective value of vibration acceleration in the bearing housing. Uneven fouling on the rotor blades can lead to a disruption of dynamic balance, resulting in abnormal vibration. Specifically, a piezoelectric accelerometer is bolted to the surface of the molecular pump bearing housing to monitor the effective value of vibration acceleration. ,

[0057] In this embodiment, preferably, the control module calculates the pollution index through a multi-parameter fusion algorithm. The multi-parameter fusion algorithm assigns weight coefficients to the intake flow rate, exhaust pressure, temperature and vibration data to calculate the pollution index, and classifies the pollution level according to the pollution index, and performs early warning, pre-cleaning or full cleaning operations according to different pollution levels.

[0058] In this embodiment, the control module determines whether the molecular pump is contaminated based on data collected by the detection module. Specifically, the intake flow rate is the most sensitive to contamination, followed by the exhaust pressure, while temperature and vibration are mainly used as auxiliary criteria.

[0059] In this embodiment, preferably, the weighting coefficients for intake flow rate, exhaust pressure, bearing temperature, and vibration acceleration are determined using the analytic hierarchy process (AHP), wherein the weighting coefficient for gas flow rate is: The weighting factor for exhaust pressure is 0.45. The weighting factor for bearing temperature is 0.25. Weighting coefficients for vibration acceleration All are 0.15, and the control module performs a consistency check on the judgment matrix. The weight coefficients are valid when the consistency ratio CR is less than 0.1.

[0060] In this embodiment, the consistency check formula is specifically:

[0061]

[0062] in:

[0063]

[0064] CR is the consistency ratio, CI is the consistency index, and RI is the random consistency index. To determine the largest eigenvalue of the matrix, where n is the matrix order, a judgment matrix is ​​constructed for four monitoring parameters: intake flow rate, exhaust pressure, bearing temperature, and vibration value. Solving this matrix yields... n=4, the fourth-order matrix corresponds to RI=0.90. In this embodiment, CR=0.02<0.1, the judgment matrix meets the consistency requirement, and the weight coefficient is valid.

[0065] In this embodiment, the pollution index PI is specifically defined as:

[0066]

[0067] in:

[0068] Regarding intake airflow The collected real-time intake airflow rate For clean rated flow, The critical flow rate for severe pollution;

[0069] Regarding exhaust pressure For the real-time exhaust pressure, For clean pressure, The critical pressure for severe pollution;

[0070] Regarding bearing temperature, For the real-time bearing temperature collected. Normal operating temperature This is the critical temperature for high temperature alarm;

[0071] For vibration acceleration For real-time acquisition of vibration acceleration, This is the acceleration during normal vibration. This is the critical value for acceleration during abnormal vibration.

[0072] Specifically, in this embodiment, the pollution index PI is calculated based on multi-parameter fusion, and the pollution level is divided according to the weight of each parameter. Corresponding treatment actions are then executed according to the level. The specific judgment criteria are as follows:

[0073] Pollution Index (PI) Pollution level Handling method PI≤0.2 clean No cleaning required, the molecular pump operates normally. 0.2 < PI ≤ 0.3 Slight pollution An early warning notice was issued, recommending planned cleaning. 0.3 < PI ≤ 0.5 Moderate pollution Automatically start the pre-cleaning program PI > 0.5 Severe pollution Initiate a full cleaning procedure immediately and notify on-site personnel.

[0074] Furthermore, when the detection module detects abnormal fluctuations in the gas flow rate, pressure, or temperature inside the molecular pump, it determines whether to initiate a cleaning program based on preset thresholds. For example, when the gas flow rate is lower than a set value, the system automatically triggers a purging operation to remove any potential blockages.

[0075] In this embodiment, the control module further includes an adaptive learning unit, which is used to establish a molecular pump health record and identify contamination patterns through K-means clustering algorithm, and dynamically adjust the cleaning strategy.

[0076] In this embodiment, preferably, the control module calculates the cleaning gas flow rate according to Bernoulli's equation for compressible fluids:

[0077]

[0078]

[0079] in:

[0080] This is the volumetric flow rate, expressed in L / min.

[0081] Flow coefficient, in this embodiment, takes into account valve orifice throttling losses. Take 0.65;

[0082] The flow area of ​​the valve orifice is in mm. 2 , This refers to the orifice diameter of the solenoid valve, in mm.

[0083] The pressure difference across the valve is expressed in Pa.

[0084] This refers to the density of a gas, expressed in kg / m³. 3 At room temperature (25 ℃) and under standard conditions of 1 atm, the density of nitrogen gas is ρ = 1.145 kg / m³. 3 .

[0085] In this embodiment, the valve port diameter of the solenoid valve is calculated. The result is the selection of the solenoid valve's diameter specification to meet the cleaning flow requirements. Cleaning pressure For example, by substituting into the above formula, the orifice diameter of the solenoid valve can be obtained. Based on a safety margin, the solenoid valve diameter is selected as 3 mm. The ASCO 8262G022 solenoid valve is chosen, with a pressure rating of 2×10⁻⁶. 5 Pa, response time <30 ms, valve body material is 316L stainless steel (corrosion resistant), and the seal is made of Viton fluororubber (suitable for most inert gases).

[0086] In this embodiment, preferably, to adapt to the complex nonlinear operating conditions of the molecular pump, the fuzzy control algorithm adopts a dual-input single-output fuzzy controller, with flow deviation and deviation change rate as input variables and control increment as output variable; the universes of discourse of the flow deviation and deviation change rate are [-100%, +100%] and [-50%, +50%], respectively, and the universe of discourse of the output control increment is [-20%, +20%]; the fuzzy set includes 7 levels: negative large, negative medium, negative small, zero, positive small, positive medium, and positive large, and the centroid method is used to complete the defuzzification operation.

[0087] In this embodiment, specifically, the two input variables and one output variable are as follows:

[0088] Input variable 1: Flow deviation The domain of discourse is [-100%, +100%];

[0089] Input variable 2: Rate of change of deviation The domain of discourse is [-50%, +50%];

[0090] Output variable: controls the increment The domain of discourse is [-20%, +20%].

[0091] The fuzzification stage transforms precise input quantities into fuzzy linguistic variables, defining seven fuzzy sets: Negative Large (NB), Negative Medium (NM), Negative Small (NS), Zero (ZO), Positive Small (PS), Positive Medium (PM), and Positive Large (PB).

[0092] Fuzzy set identifier meaning Membership function Domain of discourse NB (Negative Big) Large burden Left half trapezoid [−100%，−60%] NM (Negative Medium) Negative triangle [−80%，−40%] NS (Negative Small) Negative small triangle [−60%，−10%] ZO (Zero) zero triangle [−20%，+20%] PS (Positive Small) Just small triangle [+10%，+60%] PM (Positive Medium) middle triangle [+40%，+80%] PB (Positive Big) Zhengda Right half trapezoid [+60%，+100%]

[0093] The fuzzy control rule base contains 49 rules (7×7), forming fuzzy control rules that cover the entire operating condition adjustment logic. As shown in the table below, the columns represent input variable 1 (flow deviation), and the rows represent input variable 2 (deviation change rate). The cell in row i and column j represents the output result under the conditions of the flow deviation indicated in row i and the deviation change rate indicated in column j (i, j=1, 2, 3, 4, 5, 6, 7). In this embodiment, the rules are sorted from left to right and top to bottom, from 1 to 49, meaning the rule number corresponding to the cell in row i and column j is (i-1)×7+j.

[0094] For example, the first row and first column is Rule 1: If the deviation is negative (flow rate is much lower than the set value) and the deviation continues to worsen (the rate of change of deviation is negative), then the control output is increased significantly (the opening of the solenoid valve is increased significantly).

[0095] For example, the fourth row and fourth column is rule 25: if the deviation is zero and the rate of change of the deviation is zero (the system has reached steady state), then the control output remains unchanged.

[0096] NB NM NS ZO PS PM PB NB NB NB NB NM NS ZO ZO NM NB NB NM NS ZO PS PS NS NM NM NS ZO PS PM PM ZO NS NS ZO ZO ZO PS PM PS ZO ZO PS PM PM PB PB PM ZO PS PM PM PB PB PB PB ZO PS PM PM PB PB PB

[0097] The output obtained from fuzzy inference is a fuzzy set, which needs to be converted into precise control quantities to drive the actuator. After fuzzy inference is completed, the center of gravity (COG) method is used for defuzzification, converting the fuzzy output into precise control quantities. The calculation formula is as follows:

[0098]

[0099] in:

[0100] The activation strength of the i-th rule (values ​​from 0 to 1);

[0101] Let the center value of the output fuzzy set of the i-th rule be _____.

[0102] N is the total number of fuzzy rules; in this embodiment, N=49.

[0103] The clear output value obtained by the center of gravity method can make full use of all the information of fuzzy inference, has good control smoothness, and is suitable for occasions such as molecular pump cleaning that require stable adjustment.

[0104] The system employs a PID (Proportional-Integral-Derivative) algorithm as its core control algorithm. It calculates the deviation between the detected value and the setpoint by weighting the proportional, integral, and derivative terms to generate a control signal that adjusts the operation of the execution module. The system also introduces a fuzzy control algorithm to enhance its adaptability to complex operating conditions. By establishing a fuzzy rule base, expert experience is transformed into control logic, further improving the system's intelligence level. The fuzzy control algorithm works in conjunction with the PID algorithm; the PID algorithm handles steady-state accuracy, while the fuzzy control algorithm addresses complex operating conditions such as nonlinearity and time-varying conditions. Together, they enhance the system's adaptive capability.

[0105] In this embodiment, preferably, the gas supply system includes a high-pressure gas cylinder, a pressure reducing valve, and a filter. High-purity nitrogen or high-purity argon is used as the cleaning gas, and the type of cleaning gas can be switched according to the type of contaminant. This is achieved through a high-pressure gas cylinder equipped with a pressure gauge and a safety valve to ensure safety during storage. After being depressurized by the pressure reducing valve, the gas enters the pipeline and, under the control of a solenoid valve and a pneumatic valve, enters the molecular pump for cleaning. The system is equipped with a filter to further purify the gas, preventing trace impurities from affecting the cleaning effect and ensuring the purity and consistency of the cleaning process.

[0106] In this embodiment, high-purity nitrogen (N2, 99.999% purity) is preferred as the standard cleaning gas. For vacuum coating processes (where contaminants may be metal vapors), high-purity argon (Ar, 99.999% purity) can be used to avoid the reaction of nitrogen with the coating material (such as aluminum) to form aluminum nitride contamination. After the cleaning gas flows out of the gas cylinder, it needs to undergo processes such as pressure reduction, filtration, and flow regulation before entering the molecular pump.

[0107] In this embodiment, compatibility design was specifically implemented. On the hardware side, the execution module uses universal solenoid valves and pneumatic valves, allowing seamless interface integration with most molecular pumps; the gas supply system supports the selection and switching of various cleaning gases. On the software side, parameterized design is achieved through the introduction of configuration files. Users input the corresponding configuration parameters according to the actual molecular pump model used, and the system automatically adjusts the cleaning strategy and control logic. For example, for high-end molecular pumps requiring high cleaning gas purity, the system automatically switches to a high-purity gas supply mode and optimizes the cleaning process to avoid secondary contamination.

[0108] The automatic purging and pre-cleaning system for molecular pumps in this embodiment is applied to the cleaning of molecular pumps used in semiconductor manufacturing. Molecular pumps in semiconductor manufacturing lines operate for extended periods in environments containing corrosive gases. The system configuration is as follows:

[0109] Detection modules: Thermal mass flow meter (range 0~10 L / min, accuracy ±1%), piezoresistive pressure sensor (range 0~10 L / min). 5 Pa (accuracy ±0.5%), K-type thermocouple (range 200 °C ~ 1300 °C)

[0110] Control module: Embedded processor, running PID + fuzzy control algorithm.

[0111] Execution modules: DN15 solenoid valve (response time <50 ms), DN20 pneumatic control valve, high-purity nitrogen supply system.

[0112] The specific workflow is as follows:

[0113] (1) The detection module collects gas flow rate, pressure and temperature data of the molecular pump in real time;

[0114] (2) When the gas flow rate drops below 1.2 L / min (set threshold 1.5 L / min), the control module determines that there is pollution;

[0115] (3) The control module calculates the optimal cleaning parameters based on the PID algorithm: cleaning gas flow rate 1.5 L / min, cleaning time 30 minutes, and purging pressure 1×10⁻⁶. 5 Pa;

[0116] (4) The execution module opens the solenoid valve to introduce high-purity nitrogen gas, and the pneumatic valve adjusts the flow rate to the set value;

[0117] (5) During the cleaning process, the detection module continuously monitors various parameters, and the control module dynamically adjusts the cleaning parameters based on real-time data;

[0118] (6) After cleaning is completed, the execution module shuts off the gas path, the detection module verifies the cleaning effect, and confirms that the molecular pump has returned to normal operation.

[0119] The total nitrogen consumption for a single cleaning cycle is 45 L. All performance indicators of the molecular pump are restored to the factory standard range, and the equipment is not damaged twice. The system automatically shortens the regular cleaning interval based on the high load condition of the molecular pump, ensuring long-term stable operation.

[0120] Example 2

[0121] Combination Figure 2 As shown, the automatic purging and pre-cleaning method for the molecular pump in this embodiment uses the automatic purging and pre-cleaning system for the molecular pump in Example 1, and specifically includes the following steps:

[0122] Step S1: Real-time acquisition of the flow rate, pressure, and temperature operating parameters of the molecular pump through the detection module;

[0123] Step S2: The control module analyzes the collected operating parameters. When the parameters exceed the preset threshold, it determines that the molecular pump is contaminated and triggers the cleaning program.

[0124] Step S3: The control module calculates the optimal cleaning parameters based on the PID control algorithm and the fuzzy control algorithm. The cleaning parameters include the cleaning gas flow rate, cleaning duration, and purging pressure.

[0125] Step S4: The execution module opens the solenoid valve to introduce cleaning gas according to the instruction of the control module, and adjusts the gas flow rate to the set value through the pneumatic valve to perform the purging pre-cleaning operation.

[0126] Step S5: During the cleaning process, the detection module continuously monitors various parameters, and the control module dynamically adjusts the cleaning parameters based on real-time data;

[0127] Step S6: After cleaning is completed, the execution module shuts off the air circuit, and the detection module verifies the cleaning effect.

[0128] In this embodiment, preferably, step S6, verifying the cleaning effect includes: the detection module collects gas flow rate, pressure and temperature data again, compares them with the preset recovery threshold in the control module, and confirms that the molecular pump has returned to normal operation.

[0129] Many specific details have been set forth in the foregoing description to provide a thorough understanding of the present invention. However, the above description is merely a preferred embodiment of the present invention, and the present invention can be implemented in many other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed above. Furthermore, any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, using the methods and techniques disclosed above, without departing from the scope of the present invention. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. An automatic purging and pre-cleaning system for a molecular pump, characterized in that: Includes the following modules: The detection module is used to collect parameters of the molecular pump's operating status and contamination level in real time. The detection module includes a gas flow sensor, a pressure sensor, and a temperature sensor. The control module, connected to the detection module, is used to receive data collected by the detection module and generate cleaning strategy instructions based on the PID control algorithm and the fuzzy control algorithm. An execution module, connected to the control module, is used to perform a purge pre-cleaning operation according to the cleaning strategy instructions. The execution module includes a solenoid valve for controlling the on / off of cleaning gas, a pneumatic valve for adjusting the flow rate of cleaning gas, and a gas supply system. The control module automatically determines whether the molecular pump is contaminated based on the parameters collected by the detection module. When contamination is detected, a cleaning program is triggered, and the optimal cleaning parameters are calculated based on the PID control algorithm and the fuzzy control algorithm.

2. The automatic purging and pre-cleaning system for molecular pumps according to claim 1, characterized in that: The gas flow sensor is a thermal mass flow meter, used to collect the inlet flow parameters of the molecular pump and monitor changes in the inlet flow rate; the pressure sensor is a piezoresistive pressure sensor, used to collect the pressure in the middle of the molecular pump body to monitor pressure changes and to collect the pressure in the exhaust pipe of the molecular pump to monitor changes in exhaust pressure; the temperature sensor is a thermocouple or resistance temperature detector, used to collect the temperature of the molecular pump bearing housing to monitor changes in bearing operating temperature and to collect the temperature of the outer casing of the molecular pump body to monitor the temperature of the outer casing of the pump body.

3. The automatic purging and pre-cleaning system for molecular pumps according to claim 1, characterized in that: The detection module also includes a piezoelectric accelerometer, which is installed on the surface of the molecular pump bearing housing to monitor the effective value of the vibration acceleration of the bearing housing in order to determine the change in rotor dynamic balance.

4. The automatic purging and pre-cleaning system for molecular pumps according to claim 1, characterized in that: The control module calculates the pollution index through a multi-parameter fusion algorithm. The multi-parameter fusion algorithm assigns weight coefficients to intake flow rate, exhaust pressure, bearing operating temperature and vibration data to calculate the pollution index. Based on the pollution index, the module classifies the pollution level and performs early warning, pre-cleaning or full cleaning operations according to different pollution levels.

5. The automatic purging and pre-cleaning system for molecular pumps according to claim 4, characterized in that: The weighting coefficients for intake flow rate, exhaust pressure, bearing operating temperature, and vibration are determined using the analytic hierarchy process (AHP). The weighting coefficient for gas flow rate is 0.45, the weighting coefficient for exhaust pressure is 0.25, and the weighting coefficients for bearing operating temperature and vibration are 0.

15. The control module performs a consistency check on the judgment matrix, and the weighting coefficients are valid when the consistency ratio (CR) is less than 0.

1.

6. The automatic purging and pre-cleaning system for molecular pumps according to claim 1, characterized in that: The fuzzy control algorithm employs a dual-input single-output fuzzy controller, with flow deviation and deviation change rate as input variables and control increment as output variable. The universes of discourse for the flow deviation and deviation change rate are [-100%, +100%] and [-50%, +50%], respectively, while the universe of discourse for the output control increment is [-20%, +20%]. The fuzzy set includes seven levels: negative large, negative medium, negative small, zero, positive small, positive medium, and positive large. The centroid method is used to complete the defuzzification operation.

7. The automatic purging and pre-cleaning system for molecular pumps according to claim 1, characterized in that: The control module calculates the cleaning gas flow rate based on Bernoulli's equation for compressible fluids: in: Volumetric flow rate; Flow coefficient, The flow area of ​​the valve orifice. This refers to the orifice diameter of the solenoid valve. The pressure difference across the valve. The density of the gas; And based on the calculated valve port diameter of the solenoid valve The result determines the appropriate solenoid valve bore specification.

8. The automatic purging and pre-cleaning system for molecular pumps according to claim 1, characterized in that: The gas supply system includes a high-pressure gas cylinder, a pressure reducing valve, and a filter. It uses high-purity nitrogen or high-purity argon as the cleaning gas and can switch the type of cleaning gas according to the type of contaminant.

9. An automatic purging and pre-cleaning method for a molecular pump, characterized in that: The automatic purging and pre-cleaning system for molecular pumps according to any one of claims 1-8 includes the following steps: Step S1: Real-time acquisition of the flow rate, pressure, and temperature operating parameters of the molecular pump through the detection module; Step S2: The control module analyzes the collected operating parameters. When the parameters exceed the preset threshold, it determines that the molecular pump is contaminated and triggers the cleaning program. Step S3: The control module calculates the optimal cleaning parameters based on the PID control algorithm and the fuzzy control algorithm. The cleaning parameters include the cleaning gas flow rate, cleaning duration, and purging pressure. Step S4: The execution module opens the solenoid valve to introduce cleaning gas according to the instruction of the control module, and adjusts the gas flow rate to the set value through the pneumatic valve to perform the purging pre-cleaning operation. Step S5: During the cleaning process, the detection module continuously monitors various parameters, and the control module dynamically adjusts the cleaning parameters based on real-time data; Step S6: After cleaning is completed, the execution module shuts off the air circuit, and the detection module verifies the cleaning effect.

10. The automatic purging and pre-cleaning method for a molecular pump according to claim 9, characterized in that: Step S6 verifies the cleaning effect by having the detection module collect gas flow, pressure, and temperature data again, compare them with the preset recovery threshold in the control module, and confirm that the molecular pump has returned to normal operation.

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