Efficient backpressure method leak detection parameter optimization method

Abstract

The invention provides an efficient backpressure method leak detection parameter optimization method, which comprises the following steps of: deducing a quantitative relationship among a measurement leak rate, inflation pressure, pressurization time, purification time and cavity volume by establishing a gas flow model for backpressure method leak detection; a leakage time constant is defined and used for representing the time characteristic of the gas pressure change in the closed device, and a computable leakage rate expression is formed on the basis of the time characteristic. Quantitative analysis and matching of key parameters such as helium filling pressure, pressurization time, purification time and detected piece volume are realized by establishing a theoretical model and a parameter optimization relational expression of back pressure method leakage detection, and when proper parameters cannot be determined in actual detection, the volume of the detected piece can be determined according to a formula system and an orthogonal test result of the method. According to the method, the optimal parameter combination meeting the sensitivity requirement is rapidly obtained, the setting process of back pressure method leakage detection is converted into theoretical calculation from experience judgment, the detection stability and sensitivity are improved, and high efficiency and standardization of the back pressure method leakage detection process are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of leak detection test, in particular to a high-efficiency back pressure method leak detection parameter optimization method. BACKGROUND

[0002] The back pressure method leak detection is mostly used for the sealing detection of electronic components. There are two leak detection methods for detecting electronic components, namely the fixed method and the flexible method. Generally, the volume of electronic components is small, and the material is mostly plastic. The leakage mode of the sealing structure is mostly the leakage of the material (plastic) itself, the leakage of the sealing glue between the combined parts of the plastic and plastic, and the air leakage phenomenon of the metal and plastic welding sealing part. Therefore, the leakage behavior of the sealing structure is mainly leakage. Common welding process defects of the metal welding part include shrinkage hole, air hole, slag inclusion, incomplete penetration, and incomplete fusion, etc.

[0003] Once these defects form a through defect, leakage will occur. The leakage behavior of this channel type leak hole is essentially different from the leakage. The main difference is that in the process of leakage, the gas molecules are first dissolved in the material, and then released from the material under the driving of the pressure difference and the concentration difference. For the channel leak hole, as long as there is a pressure difference or a concentration difference between the two ends of the leak hole, the gas molecules will migrate from one end to the other end without any obstacle. Compared with the leakage, the leakage rate is slower, and there is an adsorption phenomenon in the leakage process.

[0004] In this case, the back pressure method may be applied to the air tightness detection of the metal welding structure, and the setting of the leak detection parameters may be different.

[0005] Therefore, a high-efficiency back pressure method leak detection parameter optimization method is provided. SUMMARY

[0006] Therefore, the present application provides a high-efficiency back pressure method leak detection parameter optimization method to solve or alleviate the technical problems in the prior art, and at least provides a beneficial choice.

[0007] The technical solution of the present application is as follows: a high-efficiency back pressure method leak detection parameter optimization method, comprising the following steps:

[0008] S1, a flow model of gas passing through a leak hole is established according to the back pressure method leak detection principle, and a theoretical expression for measuring the leak rate is constructed. The steady-state and non-steady-state transmission process of the gas passing through the leak hole is described based on the gas diffusion equation and the pressure balance.

[0009] The theoretical calculation formula of the measured leak rate is as follows:

[0010] Wherein: ​is the equivalent standard leak rate; is the bombardment pressure of helium in the helium chamber; is the standard atmospheric pressure; is the molar mass of air; is the molar mass of helium; is the pressurization time; is the purging time; is the net volume of the internal cavity of the inspected part; is the equivalent standard leak rate;

[0011] The above calculation formula is a theoretical calculation expression of the back pressure method for measuring the leak rate , which establishes a direct calculation relationship between the leak rate and the gas parameters, pressure parameters and time parameters.

[0012] S2, define the leak time constant , which is used to characterize the time characteristics of the internal gas pressure change of the sealed device, and establish a quantitative relationship with the gas molecular weight, the geometric parameters of the leak hole and the internal cavity volume of the inspected part;

[0013] The leak time constant τ is determined according to the following formula:

[0014]

[0015] Among them: the leak time constant τ and the measured leak rate parameters , , are related to each other, which is used to determine the time characteristic quantity of the diffusion of the leak hole under the condition that the gas molecular weight is known.

[0016] S3, substitute the leak time constant into the leak rate equation, simplify and algebraically arrange the exponential term to form a solvable simplified leak rate calculation model;

[0017] The leak time constant is substituted into the measured leak rate expression, and the simplified expression of the back pressure method for measuring the leak rate is obtained:

[0018] Among them, is the internal gas pressure of the inspected part after the inflation is completed;

[0019] This formula uses as a unified time parameter to represent the calculation model of the back pressure method for measuring the leak rate , eliminates the coupling term in the denominator, so that the formula can be directly used for alternative calculation of time and pressure data;

[0020] When the leak detection medium is a mixture of air and helium, a helium leak time constant is defined. , and The relationship is:

[0021] Leakage rate measurement using back pressure method The formula for calculation is:

[0022]

[0023] By converting the air medium into an equivalent quantity form under the helium medium, To become a uniform variable in the formula, where As a method for measuring leakage rate using back pressure The calculation parameters are used in subsequent formula expansions;

[0024] Leakage rate measurement using back pressure method The exponential function term in the calculation formula:

[0025]

[0026] Expanding this into a power series, the expansion is as follows:

[0027]

[0028] Among them, variables The values ​​are respectively and The expansion process transforms the exponential function terms into a finite polynomial form, thereby enabling the back pressure method to measure the leakage rate. The computational expression is represented in polynomial form;

[0029] Expand the power series Substitute back pressure method to measure leakage rate The calculation formula is used to obtain the leakage rate measured by the back pressure method. The polynomial expansion expression:

[0030]

[0031] The polynomial expansion expression is mathematically related to the back pressure method for measuring the leak rate. The calculation formulas are equivalent, but the exponential function terms are expressed in polynomial expansion form for finite term truncation approximation. Their applicability is limited to the following conditions: and .

[0032] S4, with inflation pressure Pressurization time Purification time and the internal volume of the inspected part Design orthogonal experiments with variables as variables to obtain different results. , , and Under the conditions value;

[0033] Under the condition of satisfying the aforementioned finite term cutoff, the leak rate was measured using the back pressure method. After ignoring higher-order terms in the polynomial expansion, we obtain The first approximate calculation formula is as follows:

[0034]

[0035] This approximate calculation formula is used for back pressure method to measure leakage rate. The linearized expression, in Under the condition of being a fixed constant, and They exhibit a linear proportional relationship.

[0036] S5. Calculate the minimum detectable leak rate. and in Helium filling pressure under certain conditions With pressurization time The matching relationship is used to form an optimized calculation model for the back pressure method leak detection parameters;

[0037] The minimum detectable leak rate Determine using the following formula:

[0038]

[0039] in: Standard leakage rate; To stabilize the signal for the leak detector; This is the background signal; This is a noise signal;

[0040] This formula reflects the conversion relationship between the leak detector output signal and the standard leak rate, and its parameters... , , All samples were taken from the same leak detection circuit, and the units were kept consistent.

[0041] When measuring leak rate At that time, helium filling pressure With pressurization time Satisfy the following formula:

[0042] exist Established under the conditions, making and Become a set of mutually constraining variables to determine the given... and Parameter matching calculation relationship under the given conditions.

[0043] The key point of this invention is that, through orthogonal experimental design, it identifies pressurization time as the primary influencing factor and inflation pressure as the secondary influencing factor, thereby guiding parameter optimization.

[0044] The embodiments of the present invention have the following advantages due to the adoption of the above technical solutions:

[0045] This invention establishes a theoretical model and parameter optimization formula for back pressure leak detection, enabling quantitative analysis and matching of key parameters such as helium filling pressure, pressurization time, purification time, and the volume of the tested component. When suitable parameters cannot be determined in actual testing, the optimal parameter combination that meets sensitivity requirements can be quickly obtained based on the formula system and orthogonal experimental results of this invention. This method uses the leakage time constant as a unified variable, revealing the influence of each parameter on the leakage rate change, transforming the setting process of back pressure leak detection from empirical judgment to theoretical calculation. While ensuring detection accuracy, it shortens the leak detection cycle, improves detection stability and sensitivity, and achieves high efficiency and standardization of the back pressure leak detection process. This invention solves the problem of blind parameter setting by combining orthogonal experiments and theoretical models, significantly improving leak detection efficiency. Attached Figure Description

[0046] Figure 1 This is a diagram showing the composition of the pressure testing system of the present invention;

[0047] Figure 2 This is a diagram showing the experimental setup for the pressurization time of the present invention;

[0048] Figure 3 This is a graph showing the inflation pressure experimental data of the present invention.

[0049] Figure 4 This is a graph showing the experimental data of the pressurization time of the present invention;

[0050] Figure 5 This is a graph showing the experimental data on the relationship between volume and leakage rate in this invention.

[0051] Figure 6 This is a data fitting curve diagram of the leak hole 1 of the present invention;

[0052] Figure 7 This is a data fitting curve diagram of the leak hole 2 of the present invention;

[0053] Figure 8 This is a data fitting curve diagram of the leak hole 3 of the present invention;

[0054] Figure 9 This is a data fitting curve diagram of the leak hole 4 of the present invention;

[0055] Figure 10 This is a data processing curve diagram of the leak 1 of the present invention;

[0056] Figure 11 This is a data processing curve of the leak hole 2 in this invention;

[0057] Figure 12 This is a data processing curve of the leak hole 3 of the present invention;

[0058] Figure 13 This is a graph showing the changes in the data processing curve of the leak 1 according to the present invention;

[0059] Figure 14 This is a graph showing the changes in the data processing curve of the leak hole 2 according to the present invention;

[0060] Figure 15 This is a graph showing the changes in the data processing curve of the leak hole 3 according to the present invention. Detailed Implementation

[0061] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0062] like Figures 1-15 As shown, this embodiment of the invention provides an efficient method for optimizing back pressure leak detection parameters, comprising the following steps:

[0063] S1. Under the principle of back pressure leak detection, the tested component is sealed under vacuum and filled with gas at a certain pressure. The gas diffuses outward through tiny leak holes, forming a leakage flow from the high-pressure chamber to the low-pressure chamber. Based on the gas diffusion equation and pressure balance condition, a theoretical leakage rate model of the leaking gas through the leak holes is constructed, and the leakage rate is measured. The expression can be represented as

[0064]

[0065] In the formula:

[0066] To measure the leakage rate, Pa·m 3 / s;

[0067] The equivalent standard leakage rate is expressed in Pa·m. 3 / s;

[0068] The bombardment pressure of helium gas in the helium chamber, in Pa;

[0069] Standard atmospheric pressure, 1×10 5 Pa;

[0070] The molar mass of air is 2.9 × 10⁻⁶.-2 Kg / mol;

[0071] Here is the molar mass of helium, 4 × 10⁻⁶. -3 Kg / mol;

[0072] The pressurization time is in seconds.

[0073] The purification time is the time from the end of pressurization to the leak detection, expressed in seconds.

[0074] The net volume of the inner cavity of the inspected part is m. 3 ;

[0075] This equation reflects the relationship between the gas molecule diffusion rate and the characteristics of the leak channel, the molecular weight ratio, and the pressure and purification time under a set pressure difference.

[0076] S2, Define the leakage time constant To facilitate the standardized quantification of time parameters, a leakage time constant is defined. The leakage time constant represents the characteristic time of the change in gas pressure inside the sealed device over time. The leakage time constant is calculated according to the following formula:

[0077]

[0078] The leakage time constant, determined jointly by the gas physical properties and the structural parameters of the tested component, is a key parameter in helium pressure leak detection. The leakage time constant is defined as the time required for the internal pressure of a sealed device in a vacuum environment and filled with a certain gas to drop to 36.8% (i.e., 1 / e) of the original pressure, or the time required for the internal pressure of a sealed device in a certain gas environment and filled with a vacuum to rise to 63.2% (i.e., 1-1 / e) of the ambient pressure.

[0079] S3, the leakage time constant, is substituted into the leakage rate equation, and the above equation is... Substituting into the formula for measuring leakage rate using the back pressure method and simplifying algebraically, we get...

[0080] in, This simplified formula represents the instantaneous gas pressure inside the tested part after pressurization. Replace the original and The combination of terms makes the time term of the leakage rate equation independent, which facilitates subsequent sensitivity analysis and formula expansion.

[0081] S4. Introducing a helium leakage time constant. To standardize the testing medium, the testing will be conducted under air conditions. Equivalent time constant under helium conditions Its equivalent standard leakage rate The relationship is:

[0082]

[0083] After substitution, the leak rate is measured using the back pressure method. The expression is transformed into:

[0084]

[0085] at this time This becomes the only time parameter in helium medium. Through this formula, the calculation consistency can be maintained under different gas conditions, which facilitates parameter comparison in cross-medium leak detection experiments.

[0086] S5. Power Series Expansion and Approximation of the Exponential Term: Since the exponential function in the formula is not convenient to solve directly in engineering applications, a power series expansion method is adopted. and Expanding on this:

[0087]

[0088] Substituting the expansion into The equation yields:

[0089]

[0090] Under typical detection conditions, if and Neglecting squares and higher-order terms, we obtain an approximate linear equation:

[0091]

[0092] This formula achieves linear simplification of leak rate calculation, simplifying the calculation steps for leak detection parameters.

[0093] S6: System sensitivity calculation. The minimum detectable leak rate of the system refers to the leak rate of a sensor installed at a suitable location on the test piece. With the standard leak hole, leak detector, and leak detection system adjusted to leak detection mode, the valve of the standard leak hole closed, and the background noise level indicated by the leak detector output read. and background After opening the standard leak valve, read the stable signal value indicated by the leak detector output. The effective sensitivity of the system is... The calculation formula is as follows:

[0094]

[0095] When the measured leak rate of back pressure leak detection is exactly equal to the effective minimum detectable leak rate of the leak detection system ( When the value is 0, it represents the minimum detectable leak rate for back pressure leak detection. The corresponding helium filling pressure and filling time can be deduced from this formula.

[0096] S7. Parameter matching under the condition of minimum detectable leak rate, when measuring leak rate With the system's minimum detectable leak rate When they are equal, the helium filling pressure With pressurization time The following constraint must be satisfied between them:

[0097]

[0098] This formula is in It holds true under certain conditions, reflecting different cavity volumes. The matching law between pressurization time and helium filling pressure is used to determine the optimal range of helium filling parameters that meet the sensitivity requirements during the leak detection design stage, so that the test process remains consistent between the theoretical model and the actual measurement.

[0099] In this embodiment, Figure 3 , 4 Tables 5 and 6 show the experimental data curves relating inflation pressure, pressurization time, volume, and leakage rate, verifying the single-factor experimental results in Tables 5, 6, and 7.

[0100] Figure 6 , 7 Tables 8 and 9 are the fitted curves for the data of leaks 1, 2, 3, and 4 (the experimental data were processed and analyzed using univariate linear regression, quadratic polynomial regression, and analysis of variance), which verify the data analysis in Tables 8 and 9.

[0101] Figure 10 , 11 The fitting curves of data for leaks 1, 2, 3, and 4 in Table 12 (using univariate linear regression analysis) were used to verify the influence of Table 9 on the leak detection results.

[0102] Test case

[0103] I. Pressure Experiment Design:

[0104] Based on the leak detection process of the back pressure method, the design is as follows: Figure 1 Experimental system;

[0105] The experimental procedure is as follows: ① Connect the leak detection point to the helium filling system, and apply the helium source to the leak detection point according to the preset helium filling pressure and pressurization time. ② Clean the helium source on the surface of the leak detection point with nitrogen. ③ Perform vacuum leak detection on the leak detection point. ④ Analyze the relationship between the filling pressure and the measured leak rate using a single-factor orthogonal experimental method (see Table 1).

[0106]

[0107] II. Experimental Design of Pressurization Time

[0108] Experimental design for the relationship between pressurization time and leakage rate, as shown in the figure. Figure 2 As shown. The above standard leak holes were placed in a leak detection box and filled with pure helium at a certain pressure. Within a specified time period, the standard leak holes were removed, and nitrogen gas was used to remove the helium gas adhering to the surface of the leak holes. The standard leak holes were then connected to the leak detection system to measure their leakage rate. The experimental results were analyzed using a single-factor orthogonal experimental method (see Table 2) to analyze the relationship between pressurization time and measured leakage rate.

[0109]

[0110] III. Cavity Volume Experimental Design

[0111] Different volume gas collection chambers were set at the gas inlet end of the leak. The aforementioned quasi-leak was placed in a leak detection box and filled with pure helium at a certain pressure. Within a specified time period, the standard leak was removed, and nitrogen was used to remove the helium adhering to the surface of the leak. Then, the standard leak was connected to the leak detection system to measure its leakage rate. The experimental results were analyzed using a single-factor orthogonal experimental method (see Table 3) to analyze the relationship between volume and measured leakage rate.

[0112]

[0113] IV. Multi-factor orthogonal experimental design

[0114] An orthogonal experimental design with three levels was used to investigate the effects of inflation pressure and pressurization time on the leak detection rate. The effect of volume was not considered here (the container at the tested site was quantitative). A 9-level L-type orthogonal experiment was designed. 9 (3) 4 An orthogonal experiment was conducted (see Table 4), and the main and secondary influencing factors were analyzed.

[0115]

[0116] V. Discussion of Single-Factor Experiment Results

[0117] The raw data of the single-factor experiments affecting the back pressure method for leak detection are shown in Tables 5, 6, and 7. Figures 3-5 , Figures 6-9 , Figures 10-12This is the original experimental data curve;

[0118]

[0119]

[0120]

[0121] (1) Effect of helium filling pressure

[0122] The relationship between pressure and leakage rate shows that under molecular flow conditions, leakage rate and pressure have a linear relationship, while under viscous flow conditions, leakage rate and pressure have a squared difference relationship. The leak length used in this experiment was approximately 10 mm, similar to the wall thickness of the inspected area. The leak length used in the experiment was 10 mm. -5 Pa·m 3 / s, 10 -6 Pa·m 3 / s、10 -7 Pa·m 3 / s、10 -8 Pa·m 3 Will there be a large error in calculating leaks on the order of / s using the molecular flow formula?

[0123] Therefore, this experiment used univariate linear regression, quadratic polynomial regression, and analysis of variance to process and analyze the experimental data for the same leak. The experimental fitting curves are shown in [the figure]. Figures 6-9 As shown, the fitted curve equation and analysis of variance are shown in Tables 8 and 9. Data analysis shows that:

[0124]

[0125]

[0126] For the four leaks mentioned above, when the inflation pressure is between 0.2 MPa and 1.0 MPa, the correlation index R²² < R¹², indicating that the experimental results curve is closer to a linear relationship. This suggests that considering the molecular flow state when estimating the transition flow leaks (length 10⁻² m) will not produce significant errors. Furthermore, an analysis of variance was performed on the linear regression equation using the F-test, and F₀.₀¹(1, 7) = 12.25 < F, similarly indicating a close linear relationship between the leak rate and pressure. Table 9 shows the error range for the leaks used in the experiment when considering molecular flow leaks. When using the helium-pressure method for leak detection, the inflation pressure should be increased as much as possible, within the allowable pressure range of the leak detection location, to improve the system's leak detection sensitivity.

[0127] (2) Effect of pressurization time

[0128] Theoretically, the relationship between the pressurization time and the leakage rate of a leak should be exponential, as shown by the original experimental data curve.Figure 3 It can be seen that the leakage rate exhibits an approximately linear relationship with the increase of pressurization time. A univariate linear regression analysis was performed on the experimental data (see...). Figures 6-9 (and Table 10), data analysis shows that:

[0129]

[0130] ① When the pressurization time is between 3 and 20 hours, which is much less than the time constant τ, the R value is approximately 1 according to the univariate linear regression analysis. The leakage rate increases linearly with the pressurization time, which is a linear relationship. Moreover, the leakage rate changes rapidly with the pressurization time.

[0131] ② When using the back pressure method for leak detection, if the pressurization time is much shorter than the time constant, increasing the pressurization time can increase the measured leak rate, which is beneficial to improving the leak detection sensitivity of the system.

[0132] (3) The effect of volume

[0133] Exponential regression fitting was performed on the experimental data curves of leaks 1, 2, and 3. Data analysis showed that:

[0134] ① When the volume is 10-50 mL, the leakage rate changes exponentially with the volume, and the correlation coefficient R is approximately equal to 1. As the volume increases, the increase in leakage rate slows down.

[0135] ② The data curves for leaks 1, 2, and 3 show that a volume difference of 40 mL results in a leak rate difference of nearly an order of magnitude under the conditions of an inflation pressure of 0.5 MPa and a pressurization time of 10 h. Therefore, when the volume of the cavity being tested is small, the volume has a significant impact on the leak rate. The parameters for leak detection sites of different volumes cannot be set to the same value, otherwise the reliability of the leak detection results will be affected.

[0136]

[0137] VI. Results and Discussion of Multifactor Experiments

[0138] Based on the results of single-factor experimental studies and the allowable setting range of each factor in practical applications, an orthogonal experimental table as shown in Table 12 was designed. The intuitive analysis method was used to identify the primary and secondary influencing factors affecting the leakage rate and to analyze the parameter combinations that meet the leakage detection requirements.

[0139]

[0140]

[0141] Table 13 shows that the range of pressurization time is greater than the range of inflation pressure, indicating that pressurization time is the main influencing factor. Based on the leak detection point's sealing performance being better than 1.0 × 10⁻⁶, -7 Pa·m 3 / s, the actual detection capacity should be 10 -8 ~10 -9 Pa·m 3 / s, take its upper limit, and estimate according to formula (9). =5.1×10 -9 Pa·m 3 / s, meaning the measured leak rate in the table above should be better than 5.1 × 10⁻⁶. -9 Pa·m 3 The table shows that the following conditions are met for leak detection: a pressure of 0.4 MPa with a pressurization time greater than 3 hours; a pressure of 0.3 MPa with a pressurization time greater than 5 hours; and a pressure of 0.2 MPa with a pressurization time greater than 7 hours. Therefore, it can be concluded that when using the back pressure method for leak detection, improving the settings of the key parameters can shorten the leak detection time and increase the leak detection efficiency.

[0142] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in the present invention, and these should all be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A highly efficient method for optimizing back pressure leak detection parameters, characterized in that: Includes the following steps: S1. Based on the back pressure leak detection principle, establish a gas flow model through the leak and construct a model for measuring the leak rate. The theoretical expression, based on the gas diffusion equation and pressure balance, describes the steady-state and unsteady-state transmission process of gas through the leak. S2, Define the leakage time constant This is used to characterize the time-dependent changes in gas pressure inside a sealed device, and to establish... Quantitative relationship with gas molecular weight, leak geometry parameters and internal cavity volume of the tested part; S3. Substitute the leakage time constant into the leakage rate equation, and... The exponential term is simplified and algebraically rearranged to form a solvable simplified leakage rate calculation model; S4, with inflation pressure Pressurization time Purification time and the internal volume of the inspected part Design orthogonal experiments with variables as variables to obtain different results. , , and Under the conditions value; S5. Calculate the minimum detectable leak rate. and in Helium filling pressure under certain conditions With pressurization time The matching relationship is used to form an optimized calculation model for the back pressure method leak detection parameters.

2. The efficient back pressure leak detection parameter optimization method according to claim 1, characterized in that: The measured leak rate The theoretical calculation formula is: in: Equivalent standard leakage rate; The bombardment pressure of helium gas in the helium chamber; Standard atmospheric pressure; The molar mass of air; is the molar mass of helium; For pressurization time; Purification time; The net volume of the inner cavity of the inspected part; Equivalent standard leakage rate; The above formula is for measuring leakage rate using the back pressure method. The theoretical calculation expression is used to establish the direct calculation relationship between leakage rate and gas parameters, pressure parameters, and time parameters.

3. The efficient back pressure leak detection parameter optimization method according to claim 1, characterized in that: The leakage time constant τ is determined by the following formula: Where: leakage time constant τ and measured leakage rate parameter , , These are interconnected and used to determine the time-dependent characteristics of pore diffusion when the molecular weight of the gas is known.

4. The efficient back pressure leak detection parameter optimization method according to claim 3, characterized in that: The leakage time constant Substitute into the measured leak rate The expression yields a simplified expression for the leakage rate measured by the back pressure method: in, The internal gas pressure of the inspected part after inflation is complete; This formula is based on To standardize the time parameter representation of back pressure method leakage rate The computational model eliminates The coupling terms in the denominator allow the formula to be used directly for substitution calculations of time and pressure data.

5. The efficient back pressure leak detection parameter optimization method according to claim 4, characterized in that: When the leak detection medium is a mixture of air and helium, a helium leak time constant is defined. , and The relationship is: Leakage rate measurement using back pressure method The formula for calculation is: By converting the air medium into an equivalent quantity form under the helium medium, To become a uniform variable in the formula, where As a method for measuring leakage rate using back pressure The calculation parameters are used in subsequent formula expansions.

6. The efficient back pressure leak detection parameter optimization method according to claim 5, characterized in that: Leakage rate measurement using back pressure method The exponential function term in the calculation formula: Expanding this into a power series, the expansion is as follows: Among them, variables The values ​​are respectively and The expansion process transforms the exponential function terms into a finite polynomial form, thereby enabling the back pressure method to measure the leakage rate. The computational expression is represented in polynomial form.

7. The efficient back pressure leak detection parameter optimization method according to claim 6, characterized in that: Expand the power series Substitute back pressure method to measure leakage rate The calculation formula is used to obtain the leakage rate measured by the back pressure method. The polynomial expansion expression: The polynomial expansion expression is mathematically related to the back pressure method for measuring the leak rate. The calculation formulas are equivalent, but the exponential function terms are expressed in polynomial expansion form for finite term truncation approximation. Their applicability is limited to the following conditions: and .

8. The efficient back pressure leak detection parameter optimization method according to claim 7, characterized in that: Leakage rate was measured using the back pressure method under the condition of satisfying the finite term cutoff. After ignoring higher-order terms in the polynomial expansion, we obtain The first approximate calculation formula is as follows: This approximate calculation formula is used for back pressure method to measure leakage rate. The linearized expression, in Under the condition of being a fixed constant, and They exhibit a linear proportional relationship.

9. The efficient back pressure leak detection parameter optimization method according to claim 8, characterized in that: The minimum detectable leak rate Determine using the following formula: in: Standard leakage rate; To stabilize the signal for the leak detector; This is the background signal; This is a noise signal; This formula reflects the conversion relationship between the leak detector output signal and the standard leak rate, and its parameters... , , All samples were taken from the same leak detection circuit, and the units were kept consistent.

10. The efficient back pressure leak detection parameter optimization method according to claim 9, characterized in that: When measuring leak rate At that time, helium filling pressure With pressurization time Satisfy the following formula: exist Established under the conditions, making and Become a set of mutually constraining variables to determine the given... and Parameter matching calculation relationship under the given conditions.

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