Intake valve air tightness detection system

Abstract

The application relates to the technical field of intake valve sealing detection, in particular to an intake valve air tightness detection system which comprises an air source device, a sealing connection assembly, a micro-pressure sensor and a control processing unit; the control processing unit is used for acquiring a test pressure grade, controlling multi-stage pressure charging and pressure maintaining of the intake valve in a low-pressure test stage and a high-pressure test stage, and generating pressure maintaining time sequence data; the internal pressure of the intake valve is collected to generate a pressure decay curve corresponding to each test pressure grade; the pressure decay curve is subjected to exponential fitting to calculate each leakage rate and an initial decay rate; then, the leakage rates of all stages are compared with corresponding leakage judgment thresholds to output leakage grade judgment results and air tightness detection results; the application can realize continuous detection under multi-stage pressures and improve the micro-leakage identification capability.

Description

Technical Field

[0001] This invention relates to the field of intake valve sealing performance testing technology, specifically an intake valve airtightness testing system. Background Technology

[0002] Currently, the air tightness test of intake valves is usually based on a single test pressure and a fixed time pressure drop method. When the intake valve under test has a small leak or the leakage characteristics are different at different pressure stages, the existing detection method cannot stably identify and classify the leakage status, and it is also difficult to further locate the type of leakage fault, which reduces the accuracy and practicality of air tightness test. Summary of the Invention

[0003] The purpose of this invention is to provide an intake valve airtightness detection system to solve the following technical problems: Existing intake valve airtightness detection technologies have limited accuracy in identifying and classifying leakage states when there are minor leaks or differences in leakage characteristics at different pressure stages in the intake valve under test, and it is difficult to locate the type of leakage fault. This invention provides an intake valve airtightness detection system that can classify minor leaks and serious leaks by combining multi-stage pressurization and segmented pressure holding timing control with exponential decay fitting, and locate the fault type based on the staged trend characteristics of the initial decay rate. The purpose of this invention can be achieved through the following technical solutions:

[0004] An intake valve air tightness testing system includes: an intake valve to be tested, an air source device, a sealing connection assembly, a micro pressure sensor, and a control processing unit that is communicatively connected to the air source device, the sealing connection assembly, and the micro pressure sensor.

[0005] The control processing unit includes:

[0006] The pressurization control module is used to acquire test pressure levels including multiple levels, control the air source device and the sealing connection assembly to perform multi-stage pressurization and pressure holding control on the air intake valve under test, the multi-stage pressurization includes a low-pressure test stage and a high-pressure test stage, and outputs pressure holding timing data;

[0007] The data acquisition module is used to acquire the internal pressure of the intake valve under test through the micro-pressure sensor based on the pressure holding time sequence data, and generate pressure decay curves corresponding to each level of test pressure.

[0008] The leakage rate calculation module is used to perform exponential fitting on the pressure decay curves under each level of test pressure, extract decay parameters, and calculate the leakage rate under each level of test pressure; it also extracts the absolute value of the pressure derivative with respect to time at the initial moment under each level of test pressure as the initial decay rate under each level of test pressure.

[0009] The leakage level determination module is used to obtain the leakage determination threshold corresponding to the preset test pressure at each level, compare the leakage rate at each level with the corresponding leakage determination threshold, write the corresponding leakage level mark to the intake valve, and output the leakage level determination result.

[0010] The fault location module is used to extract the initial decay rate under each test pressure according to the leakage level determination result, analyze the changing trend of the initial decay rate according to the preset fault rules, determine the leakage fault type, and output the airtightness test result.

[0011] Optionally, the pressurization control module is specifically used for:

[0012] Multiple fixed test pressure levels are obtained, and the internal cavity volume parameters of the intake valve and the response time parameters of the micro-pressure sensor are extracted, as well as the preset charging rate and preset stabilization margin time are obtained.

[0013] The ratio of the internal cavity volume parameter to the preset pressurization rate, plus the response time parameter of the micro-pressure sensor and the preset stabilization margin time, is taken as the shortest pressure holding time required to reach a stable state.

[0014] The intake valve is pressurized and held at each stage according to the shortest holding time, thereby generating the holding time sequence data.

[0015] Optionally, the data acquisition module is specifically used for:

[0016] The pressure holding timing data is acquired, and the actual pressure value inside the intake valve is collected through the micro-pressure sensor.

[0017] Extract the absolute pressure value at the initial holding time under the current test pressure level;

[0018] The absolute pressure value and the actual pressure value are arranged in chronological order to generate a pressure decay curve corresponding to the test pressure level.

[0019] Optionally, the leakage rate calculation module is specifically used for:

[0020] Obtain the pressure decay curves and read the discrete data points in each pressure decay curve;

[0021] Nonlinear fitting is performed on the discrete data points to calculate the decay parameters that conform to the exponential decay law under each level of test pressure;

[0022] The attenuation parameter is used as the leakage rate under this test pressure.

[0023] Optionally, the leakage level determination module is specifically used for:

[0024] Obtain multi-level calibration test data, extract the average leakage rate and standard deviation of qualified intake valves, and the average leakage rate and standard deviation of leaking intake valves; obtain the preset first multiple and preset second multiple;

[0025] The average leakage rate of the qualified intake valves is added to the standard deviation of the leakage rate of the qualified intake valves by the preset first multiple, and this is used as the qualified leakage rate threshold for the current test pressure level.

[0026] The average leakage rate of the leaking inlet valve is subtracted from the standard deviation of the leakage rate of the leaking inlet valve by the preset second multiple, and the severe leakage rate threshold of the current test pressure level is used as the leakage judgment threshold under each test pressure level.

[0027] The severe leakage rate threshold is greater than the acceptable leakage rate threshold.

[0028] Optionally, the leakage level determination module is further used for:

[0029] Compare the leakage rates at each level with the corresponding acceptable leakage rate threshold and the severe leakage rate threshold;

[0030] Write the qualified mark on the air intake valve whose leakage rate does not exceed the qualified leakage rate threshold under all test pressure levels.

[0031] For air intake valves with at least one level of leakage rate greater than the acceptable leakage rate threshold and less than the severe leakage rate threshold, and with all levels of leakage rate less than the severe leakage rate threshold, write a micro-leak mark.

[0032] An air intake valve with a leakage rate of at least one level not less than the severe leakage rate threshold is marked with a severe leakage mark to obtain the leakage level determination result.

[0033] Optionally, the fault location module is specifically used for:

[0034] Based on the leakage level determination results, the intake valves marked with micro-leakage and severe leakage are selected.

[0035] For the selected intake valves, their initial decay rates at various test pressures are called.

[0036] Optionally, the fault location module is further configured to:

[0037] Obtain the initial attenuation rate, and read the initial attenuation rates of the low-voltage test phase and the high-voltage test phase in sequence;

[0038] When the initial decay rate during the low-pressure test phase is greater than the preset initial decay rate threshold, and the difference between the initial decay rates corresponding to the two adjacent test pressures during the high-pressure test phase is less than the preset difference threshold, the intake valve is determined to have a valve seat scratch fault.

[0039] Optionally, the fault location module is further configured to:

[0040] When the initial decay rate during the low-pressure test phase is not greater than the preset initial decay rate threshold, and the difference between the initial decay rates corresponding to the two adjacent test pressures during the high-pressure test phase increases with the increase of the test pressure, it is determined that the intake valve has a sealing ring aging fault.

[0041] Optionally, the fault location module is further configured to:

[0042] When the initial decay rate at all test pressure levels is greater than the preset threshold for the initial decay rate of severe leakage, and the linear correlation coefficient between the initial decay rate at each level and the corresponding test pressure is greater than the preset correlation coefficient threshold, the intake valve is determined to have a valve body sand hole fault.

[0043] If any of the following criteria are not met: valve seat scratch fault, sealing ring aging fault, or valve body sand hole fault, then the intake valve is determined to have an unknown leakage fault.

[0044] The results of the assessments of the valve seat scratches, the sealing ring aging, the valve body pinholes, and the unknown leakage are summarized to generate the airtightness test results.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] 1. This system generates pressure holding time sequence data through multi-stage pressurization and pressure holding control, collects the internal pressure of the intake valve to generate a pressure decay curve and performs exponential fitting to extract the leakage rate and initial decay rate. This scheme overcomes the shortcomings of single pressure detection and fixed-time pressure drop being easily affected by single-point fluctuations, realizes stable quantification and identification of minute leakage states, and effectively improves the accuracy of airtightness detection.

[0047] 2. Based on the average value and standard deviation of multi-level calibration test data, this system establishes qualified leakage rate thresholds and severe leakage rate thresholds corresponding to each level of test pressure. By comparing the leakage rate at each level with the judgment thresholds, the system accurately writes qualified, minor leakage, or severe leakage marks to the intake valve. This mechanism solves the problem of distorted judgment criteria and realizes refined classification and judgment of leakage status.

[0048] 3. This system further extracts the initial decay rate of the intake valve with leakage during the low-pressure and high-pressure testing phases. By analyzing the trend of the difference in the initial decay rate under adjacent test pressure levels and the correlation of linear fitting, it can accurately locate specific faults such as valve seat scratches, aging of the sealing ring, or sand holes in the valve body. This solution solves the problem that existing technologies cannot trace the cause of leakage and enhances the practicality of the system. Attached Figure Description

[0049] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0050] Figure 1 This is a schematic diagram of the air tightness detection system for an intake valve according to the present invention. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0052] like Figure 1 As shown, an intake valve airtightness testing system includes: an intake valve to be tested, an air source device, a sealing connection assembly, a micro-pressure sensor, and a control processing unit that is communicatively connected to the air source device, the sealing connection assembly, and the micro-pressure sensor.

[0053] The control processing unit includes:

[0054] The pressurization control module is used to acquire test pressure levels with multiple levels, control the air source device and sealing connection components to perform multi-stage pressurization and pressure holding control on the air intake valve under test. The multi-stage pressurization includes a low-pressure test stage and a high-pressure test stage, and outputs pressure holding timing data.

[0055] The data acquisition module is used to acquire the internal pressure of the intake valve under test through a micro-pressure sensor based on the pressure holding time sequence data, and generate pressure decay curves corresponding to each level of test pressure.

[0056] The leakage rate calculation module is used to perform exponential fitting on the pressure decay curves under each level of test pressure, extract decay parameters, and calculate the leakage rate under each level of test pressure; it also extracts the absolute value of the pressure derivative with respect to time at the initial moment under each level of test pressure as the initial decay rate under each level of test pressure.

[0057] The leakage level determination module is used to obtain the leakage determination threshold corresponding to the preset test pressure at each level, compare the leakage rate at each level with the corresponding leakage determination threshold, write the corresponding leakage level mark to the intake valve, and output the leakage level determination result.

[0058] The fault location module is used to extract the initial decay rate under each test pressure according to the leakage level determination result, analyze the changing trend of the initial decay rate according to the preset fault rules, determine the leakage fault type, and output the airtightness test result.

[0059] The pressurization control module is specifically used for:

[0060] Multiple fixed test pressure levels are obtained, and the internal cavity volume parameters of the intake valve and the response time parameters of the micro-pressure sensor are extracted, as well as the preset charging rate and preset stabilization margin time are obtained.

[0061] The ratio of the internal cavity volume parameter to the preset pressurization rate, plus the response time parameter of the micro-pressure sensor and the preset stabilization margin time, is used as the shortest pressure holding time required to reach a stable state.

[0062] The intake valve is pressurized and held at each stage according to the shortest holding time, generating holding time sequence data.

[0063] The data acquisition module is specifically used for:

[0064] Acquire pressure holding timing data and collect the actual pressure value inside the intake valve through a micro-pressure sensor;

[0065] Extract the absolute pressure value at the initial holding time under the current test pressure level;

[0066] The absolute pressure value and the actual pressure value are arranged in chronological order to generate a pressure decay curve for the corresponding test pressure level.

[0067] The leakage rate calculation module is specifically used for:

[0068] Obtain the pressure decay curves and read the discrete data points in each pressure decay curve;

[0069] Nonlinear fitting is performed on discrete data points to calculate decay parameters that conform to the exponential decay law under each level of test pressure;

[0070] The attenuation parameter is used as the leakage rate under this test pressure.

[0071] This embodiment provides an intake valve airtightness testing system. The system uses the intake valve as the test object. A gas source device fills the intake valve with test gas, which is then sealed via a sealing connection assembly. A micro-pressure sensor continuously collects pressure changes during the pressure holding process. A control processing unit generates the pressure holding sequence, constructs a pressure decay curve, calculates the leakage rate, determines the leakage level, and outputs the fault type. Through this continuous testing method under multi-level pressure, the system outputs the leakage rate, corresponding leakage level, and further fault type at each pressure level simultaneously.

[0072] In practical implementation, the gas source device can be connected to the main test circuit, the sealing connection assembly is sealed to the air inlet of the air inlet valve under test, and the micro-pressure sensor is installed at the detection position connected to the main test circuit to collect the internal pressure of the air inlet valve. As an optional example, an independent sensing channel is set up in parallel with the main test circuit, and a high-precision micro-pressure sensor group is installed in the channel. Its range can be 0-10 kPa and its accuracy can be ±0.1% of the full scale. This meets the pressure change detection resolution requirements of the test object in low-pressure micro-leakage scenarios.

[0073] Obtain the test pressure level, perform multi-stage pressurization and pressure holding control on the intake valve, and output pressure holding timing data;

[0074] Specifically, the test pressure level refers to the target pressure value applied to the inside of the intake valve in stages, such as 5 kPa, 10 kPa, 15 kPa, 20 kPa, and 25 kPa. The low-pressure test stage corresponds to the first and second test pressure levels, and the high-pressure test stage corresponds to the third to fifth test pressure levels, such as 15 kPa, 20 kPa, and 25 kPa. Unlike the traditional single test pressure detection method, this invention captures the leakage change pattern of the intake valve under different contact stress states by segmented pressure holding under multiple pressure levels. This transforms the deficiency of single pressure drop determination, which is easily affected by interference fluctuations, into the advantage of multi-level trend analysis.

[0075] In summary, the embodiments of the present invention can realize the detection input preparation of pressure levels based on multi-level pressurization and pressure holding timing control, avoid missing micro-leakage features at a single pressure point, and ultimately solve the technical problem that the lack of a graded detection mechanism in the prior art makes it difficult to identify micro-leakages.

[0076] Furthermore, based on the above embodiments, the pressurization control module of the embodiments will be described;

[0077] Multiple fixed test pressure levels are obtained, the internal cavity volume parameters of the intake valve and the response time parameters of the micro-pressure sensor are extracted, and the preset charging rate and preset stabilization margin time of the air source device are obtained; the ratio of the internal cavity volume parameters to the preset charging rate, plus the response time parameters and stabilization margin time, is taken as the shortest holding time required to reach a stable state; the intake valve is charged and held step by step according to the shortest holding time to generate holding time sequence data.

[0078] Specifically, the internal cavity volume parameter reflects the volume of test gas that the inlet valve under test can hold; the response time parameter reflects the time required for the micro-pressure sensor to reach a stable output after a pressure step change; the preset pressurization rate represents the rate at which the gas source device pressurizes the cavity under test; and the stabilization margin time is an additional time compensation amount reserved on the basis of theoretical stability, which can be obtained by calibration to reduce the impact of accidental fluctuations; the minimum holding time is essentially used to ensure that the pressure state in the system has entered the stable detection range when the acquisition begins, rather than in the transitional fluctuation range immediately after the pressurization ends.

[0079] The calculation logic for the shortest pressure holding time is as follows: the ratio of the internal cavity volume parameter of the intake valve to the preset pressurization rate, plus the response time parameter of the micro-pressure sensor and the preset stabilization margin time.

[0080] In specific calculations, the internal cavity volume parameter of the air inlet valve, which reflects the time required for the test cavity to fill and stabilize, is divided by the preset pressurization rate, which represents the ability of the gas source device to input test gas into the air inlet valve per unit time. Then, the lag time from the sensor sensing the pressure change to outputting a reliable detection value, and the safety buffer time to continue to retain pressure after theoretical stabilization to reduce the impact of small disturbances in the gas path and device response lag errors on subsequent fitting, together constitute the shortest holding time. If the aforementioned fixed test pressure level example is used, pressurization and holding pressure can be performed step by step in the order of 5 kPa, 10 kPa, 15 kPa, 20 kPa, and 25 kPa.

[0081] Unlike traditional methods that use a fixed waiting time, this invention combines the volume under test and the sensor response characteristics to perform targeted pressure holding calculations. By dynamically adapting the positive correlation between the volume under test and the pressure holding time, it prevents the loss of steady-state data or test redundancy caused by a fixed pressure holding time.

[0082] In summary, the embodiments of the present invention can determine the shortest holding time based on the internal volume, the charging rate, and the sensor response time, thereby achieving the reasonable generation of the step-by-step holding time sequence. This avoids data distortion or efficiency reduction caused by a fixed holding time setting, and ultimately solves the technical problem of the lack of an adaptive holding mechanism for different test devices in the prior art.

[0083] Furthermore, based on the above embodiments, the data acquisition module of the embodiments will be described;

[0084] Acquire pressure holding time sequence data and collect the actual pressure value inside the intake valve through a micro-pressure sensor; extract the absolute pressure value at the initial pressure holding moment under the current test pressure level; arrange the absolute pressure value and the actual pressure value in chronological order to generate the pressure decay curve corresponding to the test pressure level;

[0085] Specifically, under a certain test pressure, the pressure value at the start of the test at that level after the pressurization is completed and the minimum holding time requirement is met is the absolute pressure value at the initial holding time; the sequence of internal pressure values ​​continuously collected by the micro-pressure sensor during the holding stage is the actual pressure value; and the time-pressure relationship curve formed by the pressure changes from the initial pressure to the pressure changes at each subsequent moment is the pressure decay curve.

[0086] The pressure decay curve is configured to output a complete time-series pressure sample instead of just comparing the pressure difference between two consecutive time points; taking a certain pressure level as an example, the initial holding time is denoted as... The corresponding absolute pressure is During the pressure holding period, the micro-pressure sensor continuously outputs the actual pressure at each moment. The data acquisition module will be provided by The beginning And subsequent moments Arrange them in chronological order to obtain the pressure decay curve for that pressure level;

[0087] In this scenario Characterizes the initial sealing pressure state at the current level, while This reflects the real-time pressure loss caused by leakage under pressure. As the test gas leaks into the external atmosphere, the gauge pressure inside the cavity relative to the environment will strictly decay toward 0. This provides the corresponding physical boundary basis for the subsequent use of a pure exponential model without an environmental base term, avoiding the problem that the physical principle deviation of the system model would occur if the absolute environmental pressure were substituted into the decay model.

[0088] Unlike traditional independent processing methods that only extract single-point pressure drop values, this invention retains continuous curve information throughout the entire pressure holding phase, enabling the acquisition of overall pressure decay characteristics. For minute leaks such as intake valves, single-point pressure differences are easily affected by instantaneous fluctuations, while time-series curves better reflect the true characteristics of stable leaks. In summary, the embodiments of this invention can construct pressure decay curves based on continuous pressure acquisition during the pressure holding period, avoiding excessive randomness in results caused by single-point sampling, and ultimately solving the technical problem of existing technologies where minute leaks are difficult to identify stably due to the lack of continuous curve information.

[0089] Furthermore, based on the above embodiments, the leakage rate calculation module of the embodiments will be described;

[0090] Obtain the pressure decay curves and read the discrete data points from each pressure decay curve; perform nonlinear fitting on the discrete data points to calculate the pressure at each test pressure level that conforms to the preset exponential decay model. attenuation parameters The decay parameter is used as the leakage rate under the test pressure level. Specifically, the discrete data points are time-pressure sample pairs recorded at the sampling time on the pressure decay curve. The decay parameter is used as an exponential parameter describing the rate of pressure drop under the pressure level, and the value of the exponential parameter is positively correlated with the leakage rate.

[0091] By constructing the following exponential decay model:

[0092]

[0093] In this model, the duration of the pressure holding test is... The remaining pressure inside the intake valve at this time The initial pressure reference when the analysis begins from the leak. Multiply by the base of the natural logarithm negative The power is used to calculate the attenuation parameter; among which, the attenuation parameter is calculated. The dimension of is the reciprocal of the unit of time; in the formula For equal signs, This is the multiplication operator. It is a negative sign;

[0094] As an exponential parameter that equivalently characterizes the leakage characteristics under this level of test pressure, it measures the relative rate of pressure decay per unit time; by performing nonlinear fitting on multiple discrete data points, the curve that best fits this parameter can be obtained. This allows for the conversion of dispersed pressure variation samples into quantifiable and comparable leakage rate results;

[0095] Based on this, the leakage rate calculation module also extracts the initial time under each test pressure level. pressure Regarding time absolute value of derivative , as the initial decay rate under various test pressures; where, in the formula It is the absolute value symbol. For time The derivative symbol, The equal sign indicates that, combined with the above exponential model, the pressure decay rate at any given time is used to characterize the instantaneous speed of pressure drop per unit time; while the initial decay rate at the initial time is equal to the product of the initial pressure reference and the decay parameter, used to characterize the most direct release intensity of leakage when entering the pressure holding analysis starting point; this parameter will serve as an important analytical basis in subsequent fault location.

[0096] In the field of airtightness testing, conventional evaluation benchmarks are usually fixed-time pressure drop values ​​or fixed-endpoint pressure differences. However, under complex operating conditions, such as when the valve seat has only minor scratches, the pressure drop over a short period may be very small, and relying solely on the end-point pressure difference is easily affected by environmental disturbances. This invention, however, extracts the common attenuation parameters throughout the entire time period by performing exponential fitting on the complete pressure attenuation curve. By combining the initial decay rate analysis with the front-end leakage intensity analysis, it is possible to distinguish between short-term random fluctuations and stable leakage processes; situations that are difficult to accurately identify and quantify using traditional single-point methods are transformed into comparable fitting parameters and rate characteristics in this invention.

[0097] In summary, the embodiments of the present invention can calculate the leakage rate and initial decay rate at each stage based on exponential decay fitting and initial derivative extraction, avoiding the single-point pressure difference method being too affected by instantaneous fluctuations, and ultimately solving the technical problem that the lack of a full-process fitting mechanism in the prior art makes it difficult to stably characterize small leaks.

[0098] In this embodiment, the leakage level determination module is specifically used for:

[0099] Obtain multi-level calibration test data, extract the average leakage rate and standard deviation of qualified intake valves, and the average leakage rate and standard deviation of leaking intake valves; obtain the preset first multiple and preset second multiple;

[0100] The average leakage rate of qualified intake valves is added to the standard deviation of the leakage rate of qualified intake valves by a preset first multiple, which is used as the qualified leakage rate threshold for the current test pressure level.

[0101] The average leakage rate of the leaking inlet valve is subtracted from the standard deviation of the leakage rate of the leaking inlet valve by a preset second multiple, which is used as the severe leakage rate threshold of the current test pressure level, thus obtaining the leakage judgment threshold under each test pressure level.

[0102] Among them, the threshold for severe gas leakage rate is greater than the threshold for qualified leakage rate.

[0103] The leakage level determination module is also used for:

[0104] Compare the leakage rates at each level with the corresponding acceptable leakage rate threshold and the severe leakage rate threshold;

[0105] Write the qualified mark on the air intake valve whose leakage rate does not exceed the qualified leakage rate threshold under all test pressure levels.

[0106] For air intake valves with at least one level of leakage rate greater than the acceptable leakage rate threshold and less than the severe leakage rate threshold, and with all levels of leakage rate less than the severe leakage rate threshold, write a micro-leak mark.

[0107] For air intake valves with at least one level of leakage rate not less than the severe leakage rate threshold, write a severe leakage mark to obtain the leakage level determination result.

[0108] Furthermore, based on the above embodiments, the leakage level determination module of the embodiments will be described;

[0109] Obtain multi-level calibration test data, extract the average leakage rate and standard deviation of qualified intake valves, and the average leakage rate and standard deviation of leaking intake valves; obtain the preset first multiple k1 and preset second multiple k2; add the product of the preset first multiple k1 and the standard deviation of the qualified intake valves to the average leakage rate of qualified intake valves, and use it as the qualified leakage rate threshold for the current test pressure level; subtract the product of the preset second multiple k2 and the standard deviation of the leaking intake valves from the average leakage rate of leaking intake valves, and use it as the severe leakage rate threshold for the current test pressure level, thus obtaining the leakage judgment threshold for each test pressure level;

[0110] Specifically, the multi-level calibration test data consists of sample data collected in advance for multiple pressure levels before the system is put into formal testing. Among them, the average and standard deviation of the leakage rate of qualified intake valves reflect the leakage level and sample dispersion of normal products at that pressure level, respectively, while the average and standard deviation of the leakage rate of leaking intake valves reflect the leakage distribution range of products with obvious defects. An example is to select 50 intake valves that have passed cross-validation and 50 intake valves with obvious leakage defects for multi-level pressure calibration testing.

[0111] Regarding the first The level test stress establishes the following relationship, where A positive integer representing the test pressure level number:

[0112]

[0113]

[0114] In specific calculations, the qualified intake valve, which characterizes the center value of the normal sealing level, will be used in the first... Average leakage rate under test pressure Add the preset first multiplier The standard deviation of the qualified intake valve leakage rate, which characterizes the dispersion of normal products. The product of , we get the first Acceptable leakage rate threshold under test pressure This serves as the upper limit boundary set after ensuring the fluctuation range of the qualified product group; where + in the formula is the addition operator and ⋅ is the multiplication operator;

[0115] Similarly, the leaking air intake valve is placed at the first... Average leakage rate under test pressure Subtract the preset second multiple Standard deviation of leakage rate of air intake valve The product of , we get the first Severe leakage rate threshold under test pressure This serves as the lower limit boundary for products with obvious air leakage; and requires... Greater than This preserves an intermediate judgment range between acceptable and serious leaks; where − in the formula is the subtraction operator;

[0116] In actual calibration, if the severe leakage rate threshold calculated based on a fixed multiple is not greater than the acceptable leakage rate threshold due to differences in sample batches or insufficient leakage discrimination at the lowest test pressure level, the system will trigger an adaptive correction mechanism to obtain a preset multiple adjustment step size and synchronously reduce the preset first multiple according to the multiple adjustment step size. With the preset second multiple Recalculate until the critical leak rate threshold is met. Leakage rate greater than the acceptable threshold The boundary conditions; this mechanism ensures that the mathematical consistency and physical validity of the decision interval will not fail even under non-ideal working conditions with high sample overlap;

[0117] Unlike traditional methods that only set a single, uniform threshold, this invention does not apply the same judgment standard to all pressure levels and all product states. Instead, it establishes thresholds for each level of test pressure. This can adapt to the different characteristics of leakage rate distribution under low-pressure and high-pressure levels, and avoid the problem of inaccurate judgment caused by a uniform threshold, where the low-pressure judgment range is too large and the high-pressure judgment range is too small.

[0118] In summary, the embodiments of the present invention can determine the qualified leakage rate threshold and the severe leakage rate threshold corresponding to each level of test pressure based on multi-level calibration data, avoiding misjudgment caused by a single threshold determination, and ultimately solving the technical problem of the lack of a graded threshold mechanism in the prior art, which leads to the distortion of the judgment standard.

[0119] Furthermore, in specific implementation, the leakage level determination module performs level writing according to the embodiment;

[0120] Compare the leakage rates at all levels with the corresponding qualified leakage rate thresholds and serious air leakage rate thresholds; write the intake valves with leakage rates not greater than the qualified leakage rate thresholds under all test pressure levels into the qualified mark; write the intake valves with at least one level of leakage rate greater than the qualified leakage rate threshold and less than the serious air leakage rate threshold, and all levels of leakage rates less than the serious air leakage rate threshold into the micro-leak mark; write the intake valves with at least one level of leakage rate not less than the serious air leakage rate threshold into the serious air leakage mark to obtain the leakage level determination result.

[0121] Specifically, the operation of saving the determination result as a part of the corresponding detection record of the intake valve for subsequent call is writing the mark; among them, the micro-leak mark is used to characterize the intermediate state where the leakage degree exceeds the qualified range but does not reach the serious air leakage range.

[0122] Combined with the five-level pressure example, if the leakage rates at the five levels of 5 kPa, 10 kPa, 15 kPa, 20 kPa, and 25 kPa are all less than or equal to their respective , then the intake valve is determined to be qualified; if at least one of the levels is between and , and none of the levels reaches or exceeds , then it is determined to be a micro-leak; if any one level reaches or exceeds , then it is determined to be seriously leaking; this three-level classification method enables the detection result to directly serve production diversion, for example, outputting a compliance signal for qualified parts, a re-inspection prompt signal for micro-leak parts, and a defective product alarm signal for seriously leaking parts.

[0123] In the field of pneumatic component detection, conventional benchmarks mostly adopt a single setting method. When facing objects such as intake valves that have both micro-leaks and obvious air leaks, it is impossible to quantitatively distinguish the differences in leakage defect degrees; through the dual-threshold structure, this invention establishes an intermediate interval at each pressure level, so that products near the boundary are no longer forced to be classified into a single category, thus making the detection result closer to the actual leakage level.

[0124] In summary, the embodiments of this invention can achieve hierarchical determination of qualified, micro-leak, and serious air leakage based on multi-level threshold comparison, avoiding the insufficient resolution of traditional single-threshold results, and finally solving the technical problem that it is difficult to distinguish micro-leaks and serious air leaks due to the lack of a hierarchical determination mechanism in the prior art.

[0125] In this embodiment, the fault location module is specifically used for:

[0126] According to the leakage level determination result, screen out the intake valves written with the micro-leak mark and the serious air leakage mark.

[0127] For the screened intake valves, call their initial decay rates at each test pressure.

[0128] The fault location module is also used for:

[0129] Obtain the initial attenuation rate, and read the initial attenuation rates of the low-voltage test phase and the high-voltage test phase in sequence;

[0130] When the initial decay rate during the low-pressure test phase is greater than the preset initial decay rate threshold, and the difference between the initial decay rates corresponding to the two adjacent test pressures during the high-pressure test phase is less than the preset difference threshold, the intake valve is determined to have a valve seat scratch fault.

[0131] The fault location module is also used for:

[0132] When the initial decay rate during the low-pressure test phase is not greater than the preset initial decay rate threshold, and the difference between the initial decay rates corresponding to the two adjacent test pressures during the high-pressure test phase increases with the increase of the test pressure, it is determined that the intake valve has a sealing ring aging fault.

[0133] The fault location module is also used for:

[0134] When the initial decay rate at all test pressure levels is greater than the preset threshold for the initial decay rate of severe leakage, and the linear correlation coefficient between the initial decay rate at each level and the corresponding test pressure is greater than the preset correlation coefficient threshold, the intake valve is determined to have a valve body sand hole fault.

[0135] If any of the criteria for valve seat scratch failure, sealing ring aging failure, and valve body sand hole failure is not met, then the intake valve is determined to have an unknown leakage failure.

[0136] The results of the judgments on valve seat scratches, sealing ring aging, valve body sand holes, and unknown leakage are summarized to generate airtightness test results.

[0137] Furthermore, based on the above embodiments, the fault location module of the embodiments will be described;

[0138] Based on the leakage level assessment results, intake valves marked with micro-leakage and severe leakage were selected. For the selected intake valves, their initial decay rates at various test pressures were retrieved. Specifically, the selected intake valves are those confirmed to have leakage risk and require further analysis of the leakage type. The initial decay rate corresponds to the initial decay rate at each test pressure. The absolute value of the pressure derivative with respect to time at any given moment; unlike traditional testing which ends processing after a non-compliance conclusion is reached, this invention further extracts rate information at each pressure level for analysis, and subdivides non-compliant products into failure types with different causes.

[0139] In summary, the embodiments of the present invention can continue to retrieve the initial decay rate data for suspected intake valves based on the leakage level determination results, avoiding the detection results from only remaining at a general level of non-compliance, and ultimately solving the technical problem that the cause of failure is difficult to trace due to the lack of a follow-up positioning mechanism in the prior art;

[0140] Furthermore, in the specific implementation, the initial decay rate is obtained, and the initial decay rates of the low-pressure test stage and the high-pressure test stage are read sequentially; when the initial decay rate of the low-pressure test stage is greater than the preset initial decay rate threshold, and the difference between the initial decay rates corresponding to the two adjacent test pressures in the high-pressure test stage is less than the preset difference threshold, it is determined that the intake valve has a valve seat scratch fault.

[0141] Specifically, the low-pressure test phase and the high-pressure test phase can be divided using a five-level pressure example; the initial decay rate threshold is used to identify whether there is a significant leakage trend under low-pressure conditions, while the difference threshold is used to determine whether the change in the initial decay rate between adjacent stages in the high-pressure phase tends to be gradual.

[0142] During the low-pressure test phase, because the valve seat did not reach the preset contact stress, the scratched channel formed airflow conduction, and the initial attenuation rate of the output was greater than the initial attenuation rate threshold. However, after entering the high-pressure phase, the valve core was further pressed against the valve seat under the action of air pressure, and the original small gap was filled to a certain extent. The change in the initial attenuation rate between the two adjacent high-pressure stages was no longer obvious.

[0143] Taking the fifth pressure level as an example, first check whether the initial decay rate at 5 kPa or 10 kPa is greater than the preset initial decay rate threshold. Then compare the difference between the initial decay rates corresponding to 15 kPa and 20 kPa, and whether the difference between the initial decay rates corresponding to 20 kPa and 25 kPa is less than the preset difference threshold. If the conditions are met, it is determined to be a valve seat scratch fault.

[0144] Unlike traditional independent processing methods that only analyze the total leakage, this invention extracts the characteristics of significant leakage in the low-pressure stage and slowed rate increase in the high-pressure stage by combining the rate change rules of the low-pressure and high-pressure stages, thus distinguishing faults that are easily confused with general sealing problems.

[0145] In summary, the embodiments of the present invention can determine valve seat scratch faults based on the phased initial decay rate changes, avoiding confusion of fault types caused by relying solely on the total leakage amount, and ultimately solving the technical problem that the lack of a phased pressure analysis mechanism in the prior art makes it difficult to identify valve seat defects.

[0146] Furthermore, in specific implementation, when the initial decay rate in the low-pressure test stage is not greater than the preset initial decay rate threshold, and the difference between the initial decay rates corresponding to the two adjacent test pressures in the high-pressure test stage increases with the increase of the test pressure, it is determined that the intake valve has a sealing ring aging fault.

[0147] During this process, the initial decay rate in the low-pressure test stage is not greater than the preset threshold, indicating that the sealing ring can still maintain a basic seal under low pressure; while the rate difference between adjacent stages in the high-pressure test stage increases with the increase of test pressure, indicating that as the pressure increases, the leakage growth exhibits a nonlinear change characteristic of accelerated expansion.

[0148] The aging of a sealing ring is characterized by a decrease in its elastic modulus, which falls below the deformation threshold during the low-pressure test stage. Under high pressure, it undergoes nonlinear deformation, causing the cross-sectional area of ​​the leakage channel to expand exponentially. This invention analyzes the second-order nonlinear increasing trend of the difference in the initial decay rate between adjacent levels during the high-pressure stage. To support this calculation, the system's high-pressure test stage is configured with multiple pressure levels. When the initial decay rate under the low-pressure level is not greater than the preset initial decay rate threshold, and the rate difference of the next level in the high-pressure stage is greater than the rate difference of the previous level, it can be confirmed that the leakage rate accelerates with increasing pressure, thus identifying a sealing ring aging failure.

[0149] In the field of airtightness testing, a common challenge is that the aging problem of the sealing ring is not significant under low pressure, but it is exposed under high pressure. If only low-pressure or high-pressure testing is used, it is difficult to accurately determine whether the general pressure drop is caused by the high pressure itself or the abnormal amplification caused by the aging of the sealing component. This invention extracts the abnormal amplification feature under high pressure by comparing the rate difference change trend of adjacent high pressure levels, which is more suitable for identifying sealing ring aging faults.

[0150] In summary, the embodiments of the present invention can determine the aging fault of the sealing ring based on the rate change law of normal low pressure and increased high pressure, avoiding the omission of high pressure sensitive defects by single pressure detection, and finally solving the technical problem that the existing technology is difficult to identify the aging of the sealing ring due to the lack of a high pressure stage trend analysis mechanism.

[0151] Furthermore, in specific implementation, when the initial decay rate under all test pressure levels is greater than the preset threshold for the initial decay rate of severe leakage, and the linear fitting correlation coefficient between the initial decay rate of each level and the corresponding test pressure is greater than the preset correlation coefficient threshold, the intake valve is determined to have a valve body sand hole fault; if any of the judgment conditions for valve seat scratch fault, sealing ring aging fault, and valve body sand hole fault are not met, the intake valve is determined to have an unknown leakage fault; the judgment results of valve seat scratch fault, sealing ring aging fault, valve body sand hole fault, and unknown leakage fault are summarized to generate air tightness test results;

[0152] Specifically, the initial decay rate threshold for severe leaks is used to identify whether each pressure level is in a state of significant leakage; the linear fitting correlation coefficient is used to measure whether there is a near-linear positive correlation between the initial decay rate and the test pressure; and the unknown leak fault refers to the phenomenon that a leak is confirmed but the rate change pattern does not conform to the aforementioned classification.

[0153] The leakage channel of the valve body pinhole is a fixed aperture model, and its pressure difference and flow rate have a stable positive correlation. Therefore, this invention requires that the initial attenuation rate of each stage has a high linear fitting correlation coefficient with the corresponding test pressure. When the initial attenuation rate under each test pressure is greater than the preset threshold for the initial attenuation rate of severe leakage, and its linear fitting correlation coefficient with respect to the pressure point is greater than the preset correlation coefficient threshold, it is determined to be a valve body pinhole fault. If none of the above three types of fault characteristics are met, it is classified as an unknown leakage fault, ensuring that each leaking component can obtain a clear classification output.

[0154] Unlike traditional detection methods that only perform simple judgment processing when serious air leakage occurs, this invention further determines the leakage type based on the relationship between the initial decay rate and pressure, and separates the pinhole characteristics of serious overall leakage that increases almost linearly, which helps to accurately locate quality problems;

[0155] In summary, the embodiments of the present invention can identify valve body sand hole faults based on the judgment of severe leakage threshold and the analysis of pressure-rate linear relationship, and supplement the output of complete air tightness test results by unknown leakage faults, avoiding omissions or rough classification in the fault classification of the prior art, and finally solving the technical problem that the leakage location is difficult to distinguish due to the lack of fault rule judgment mechanism in the prior art.

[0156] In practical applications, the intake valve airtightness testing system of the present invention can be deployed at the intake valve factory testing station; after the intake valve under test is connected to the main test circuit through the sealing connection assembly, the control processing unit automatically performs step-by-step pressurization and pressure holding according to multiple preset test pressure levels; the micro-pressure sensor sends the pressure data of each pressure holding stage to the data acquisition module; the leakage rate calculation module calculates the leakage rate and initial decay rate of each stage according to the pressure decay curve; the leakage level determination module writes a qualified mark, a micro-leak mark, or a serious leakage mark;

[0157] For intake valves with minor or severe leaks, the fault location module further outputs faults such as valve seat scratches, sealing ring aging, valve body pinholes, or unknown leaks. Finally, the system outputs multi-level pressure gradient test curves, leakage rate calculation results, leakage level, and fault type for subsequent processing. This embodiment of the invention achieves accurate classification of minor and severe leaks by using multi-level pressurization and segmented pressure holding timing control, combined with exponential decay fitting and multi-level judgment thresholds. At the same time, based on the phased trend characteristics of the initial decay rate, it can accurately locate specific fault types such as valve body pinholes, effectively solving the technical problem that existing technologies are unable to reliably identify minor leaks and accurately trace the cause of faults.

[0158] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An intake valve airtightness testing system, characterized in that, include: The components to be tested include an intake valve, an air source device, a sealing connection assembly, a micro-pressure sensor, and a control processing unit that is communicatively connected to the air source device, the sealing connection assembly, and the micro-pressure sensor. The control processing unit includes: The pressurization control module is used to acquire test pressure levels including multiple levels, control the air source device and the sealing connection assembly to perform multi-stage pressurization and pressure holding control on the air intake valve under test, the multi-stage pressurization includes a low-pressure test stage and a high-pressure test stage, and outputs pressure holding timing data; The data acquisition module is used to acquire the internal pressure of the intake valve under test through the micro-pressure sensor based on the pressure holding time sequence data, and generate pressure decay curves corresponding to each level of test pressure. The leakage rate calculation module is used to perform exponential fitting on the pressure decay curves under each level of test pressure, extract decay parameters, and calculate the leakage rate under each level of test pressure; it also extracts the absolute value of the pressure derivative with respect to time at the initial moment under each level of test pressure as the initial decay rate under each level of test pressure. The leakage level determination module is used to obtain the leakage determination threshold corresponding to the preset test pressure at each level, compare the leakage rate at each level with the corresponding leakage determination threshold, write the corresponding leakage level mark to the intake valve, and output the leakage level determination result. The fault location module is used to extract the initial decay rate under each test pressure according to the leakage level determination result, analyze the changing trend of the initial decay rate according to the preset fault rules, determine the leakage fault type, and output the airtightness test result.

2. The intake valve airtightness detection system according to claim 1, characterized in that, The pressurization control module is specifically used for: Multiple fixed test pressure levels are obtained, and the internal cavity volume parameters of the intake valve and the response time parameters of the micro-pressure sensor are extracted, as well as the preset charging rate and preset stabilization margin time are obtained. The ratio of the internal cavity volume parameter to the preset pressurization rate, plus the response time parameter of the micro-pressure sensor and the preset stabilization margin time, is taken as the shortest pressure holding time required to reach a stable state. The intake valve is pressurized and held at each stage according to the shortest holding time, thereby generating the holding time sequence data.

3. The intake valve airtightness detection system according to claim 1, characterized in that, The data acquisition module is specifically used for: The pressure holding timing data is acquired, and the actual pressure value inside the intake valve is collected through the micro-pressure sensor. Extract the absolute pressure value at the initial holding time under the current test pressure level; The absolute pressure value and the actual pressure value are arranged in chronological order to generate a pressure decay curve corresponding to the test pressure level.

4. The intake valve airtightness detection system according to claim 1, characterized in that, The leakage rate calculation module is specifically used for: Obtain the pressure decay curves and read the discrete data points in each pressure decay curve; Nonlinear fitting is performed on the discrete data points to calculate the decay parameters that conform to the exponential decay law under each level of test pressure; The attenuation parameter is used as the leakage rate under this test pressure.

5. The intake valve airtightness detection system according to claim 1, characterized in that, The leakage level determination module is specifically used for: Obtain multi-level calibration test data, extract the average leakage rate and standard deviation of qualified intake valves, and the average leakage rate and standard deviation of leaking intake valves; obtain the preset first multiple and preset second multiple; The average leakage rate of the qualified intake valves is added to the standard deviation of the leakage rate of the qualified intake valves by the preset first multiple, and this is used as the qualified leakage rate threshold for the current test pressure level. The average leakage rate of the leaking inlet valve is subtracted from the standard deviation of the leakage rate of the leaking inlet valve by the preset second multiple, and the severe leakage rate threshold of the current test pressure level is used as the leakage judgment threshold under each test pressure level. The severe leakage rate threshold is greater than the qualified leakage rate threshold.

6. The intake valve airtightness detection system according to claim 5, characterized in that, The leakage level determination module is also used for: Compare the leakage rates at each level with the corresponding acceptable leakage rate threshold and the severe leakage rate threshold; Write the qualified mark on the air intake valve whose leakage rate does not exceed the qualified leakage rate threshold under all test pressure levels. For air intake valves with at least one level of leakage rate greater than the acceptable leakage rate threshold and less than the severe leakage rate threshold, and with all levels of leakage rate less than the severe leakage rate threshold, write a micro-leak mark. An intake valve with a leakage rate of at least one level not less than the severe leakage rate threshold is marked with a severe leakage mark to obtain the leakage level determination result.

7. The intake valve airtightness detection system according to claim 6, characterized in that, The fault location module is specifically used for: Based on the leakage level determination results, the intake valves marked with micro-leakage and severe leakage are selected. For the selected intake valves, their initial decay rates at various test pressures are called.

8. The intake valve airtightness detection system according to claim 7, characterized in that, The fault location module is also used for: Obtain the initial attenuation rate, and read the initial attenuation rates of the low-voltage test phase and the high-voltage test phase in sequence; When the initial decay rate during the low-pressure test phase is greater than the preset initial decay rate threshold, and the difference between the initial decay rates corresponding to the two adjacent test pressures during the high-pressure test phase is less than the preset difference threshold, the intake valve is determined to have a valve seat scratch fault.

9. The intake valve airtightness detection system according to claim 8, characterized in that, The fault location module is also used for: When the initial decay rate during the low-pressure test phase is not greater than the preset initial decay rate threshold, and the difference between the initial decay rates corresponding to the two adjacent test pressures during the high-pressure test phase increases with the increase of the test pressure, it is determined that the intake valve has a sealing ring aging fault.

10. The intake valve airtightness detection system according to claim 9, characterized in that, The fault location module is also used for: When the initial decay rate at all test pressure levels is greater than the preset threshold for the initial decay rate of severe leakage, and the linear correlation coefficient between the initial decay rate at each level and the corresponding test pressure is greater than the preset correlation coefficient threshold, the intake valve is determined to have a valve body sand hole fault. If any of the following criteria are not met: valve seat scratch fault, sealing ring aging fault, or valve body sand hole fault, then the intake valve is determined to have an unknown leakage fault. The results of the assessments of the valve seat scratches, the sealing ring aging, the valve body pinholes, and the unknown leakage are summarized to generate the airtightness test results.

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