Batch automatic single-point leak detection system

Abstract

The invention relates to a batch automatic single-point leak detection system, and belongs to the technical field of leak detection. Comprising an automatic leak detection control system, a leak detector, a vacuum pump, a leak detection cover box 1, a leak detection cover box 2, a leak detection cover box 3, a leak detection cover box 4 and a positive pressure standard leak hole. The automatic leak detection control system comprises a detection valve Vd1, a detection valve Vd2, a comparison valve Vb, a calibration valve Vc, a vacuum pump valve Vp, a leak detector valve VL, a vacuum gauge 1, a vacuum gauge 2, a vacuum gauge 3, a mass flow controller MFC1, a mass flow controller MFC2 and a mass flow controller MFC3. According to the invention, the detection efficiency can be improved, the labor intensity is reduced, and the requirement of automatic rapid leakage detection in a batch production mode is met.

Description

Technical Field

[0001] This invention belongs to the field of leak detection technology and relates to a batch automatic single-point leak detection system. Background Technology

[0002] During the construction of satellite propulsion systems, sealing tests are conducted on welded and bolted joints. Current testing methods primarily utilize a helium mass spectrometer leak detector for single-point leak detection. During testing, the background helium reaction value in the ambient atmosphere is measured first. Then, helium gas is introduced into the propulsion system at a certain pressure. The leaking helium is then smelled through the leak detector's suction gun, and the reaction value corresponding to the leaked helium is measured. The difference between this reaction value and the background helium reaction value is calculated, and calibration is performed using a positive pressure standard leak hole to obtain the leak rate of the tested area.

[0003] Because helium mass spectrometer leak detectors come with a single suction gun, they can only test one sealed area at a time. Therefore, the detection method for satellite propulsion systems is manual, one-by-one testing. Moreover, depending on the testing needs, the same tested area often requires multiple tests, resulting in a huge number of testing items. When facing mass production of satellites, the traditional single-point leak detection method using a helium mass spectrometer suction gun is inefficient and labor-intensive. To improve the leak detection method, a multi-channel automatic single-point leak detection system adapted to mass production is proposed, increasing detection efficiency and reducing labor intensity. The technical challenge in implementing a multi-channel automatic single-point leak detection system lies in controlling the sampling flow rate of each detection channel to maintain consistency in measurement conditions, or in correcting for different flow rates to ensure consistent test results and reduce detection response time.

[0004] Patent application CN201410256343.4 discloses a single-point leak detection system and method for mass spectrometry under atmospheric conditions based on the pressure-limiting-splitting method. This method uses a fine-tuning valve to adjust the sampling flow rate and the flow rate entering the mass spectrometry chamber. However, for quantitative detection, the sampling flow rate cannot be precisely set and automatically detected in real time, and the split ratio of the sampling gas flow cannot be accurately obtained. Quantification can only be achieved by comparing with a standard leak, similar to traditional leak detection methods, only addressing the requirement for single-channel long-distance measurement. In multi-channel automatic measurement, because the fine-tuning valve flow rate cannot be precisely set and automatically detected in real time, the sampling flow rates of different branches are not entirely the same, affecting the consistency of helium background reaction values. Furthermore, the sampling flow rate in this scheme cannot be accurately measured, making it impossible to correct the corresponding measurement values ​​according to the sampling flow rate. These factors result in the inability to accurately measure the leak rate of all tested locations; therefore, the patented method is not suitable for multi-channel automatic measurement requirements. Moreover, because the detection sampling flow rate is very small, when the flow channel is long and the internal cavity volume is large, the time it takes for the sampling gas to reach the leak detector from the sampling port, i.e., the detection reaction time, can be as long as several minutes. The patent with application number CN201410256343.4 uses a split pump to increase the pumping speed and reduce the reaction time. However, the split pump will reduce the flow rate of the sampling gas entering the leak detector, thus reducing the leak detection sensitivity. Therefore, this solution has shortcomings. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a batch automatic single-point leak detection system that can improve detection efficiency, reduce labor intensity, and meet the requirements of automated rapid leak detection in batch production mode.

[0006] The solution of the present invention is:

[0007] A batch automatic single-point leak detection system includes an automatic leak detection control system, a leak detector, a vacuum pump, leak detection housing 1, leak detection housing 2, leak detection housing 3, leak detection housing 4, and a positive pressure standard leak hole; wherein, the automatic leak detection control system includes detection valve Vd1, detection valve Vd2, comparison valve Vb, calibration valve Vc, vacuum pump valve Vp, leak detector valve VL, vacuum gauge 1, vacuum gauge 2, vacuum gauge 3, mass flow controller MFC1, mass flow controller MFC2, and mass flow controller MFC3;

[0008] The leak detection enclosure 1 is connected to the air inlet of the detection valve Vd1 via a pipeline, forming the first detection path; the leak detection enclosure 2 is connected to the air inlet of the detection valve Vd2 via a pipeline, forming the second detection path; the leak detection enclosure 3 is connected to the air inlet of the comparison valve Vb via a pipeline, forming the comparison path; a positive pressure standard leak hole extends into the leak detection enclosure 4; the leak detection enclosure 4 is connected to the air inlet of the calibration valve Vc via a pipeline, forming the calibration path; the first detection path, the second detection path, the comparison path, and the calibration path are connected in parallel and then divided into two paths; the first path is connected sequentially via a pipeline to the mass flow controller MFC1, the leak detector valve VL, and... The leak detector is connected; vacuum gauge 1 is installed on the front end of the mass flow controller MFC1; the first path is connected to the mass flow controller MFC2, vacuum pump valve Vp, and vacuum pump in sequence via pipeline; vacuum gauge 2 is installed on the pipeline in front of the mass flow controller MFC2; vacuum gauge 3 is installed on the pipeline between the mass flow controller MFC2 and the vacuum pump; one end of the mass flow controller MFC3 is connected to the pipeline between the mass flow controller MFC2 and the vacuum pump; the other end of the mass flow controller MFC3 is connected to the front end of the mass flow controller MFC1 pipeline.

[0009] In the aforementioned batch automatic single-point leak detection system, the automatic leak detection control system further includes an industrial computer and a PLC; the industrial computer and PLC are used to control and acquire data from various internal solenoid valves, vacuum gauges, mass flow controllers, as well as externally connected leak detectors and vacuum pumps.

[0010] In the aforementioned batch automatic single-point leak detection system, the detection valve Vd1, detection valve Vd2, comparison valve Vb, and calibration valve Vc are each equipped with two air outlets; the two air outlets are switched by valves to connect to a vacuum pump or leak detector, so that the air path is always in a pumping state.

[0011] In the aforementioned batch automatic single-point leak detection system, the mass flow controller MFC1 controls and measures the gas flow rate entering the leak detector; the mass flow controller MFC2 controls and measures the gas flow rate entering the vacuum pump; and the mass flow controller MFC3 splits the sampled gas flow and measures the split gas flow rate.

[0012] In the above-mentioned batch automatic single-point leak detection system, vacuum gauge 1 detects the vacuum level in the pipeline before MFC1; vacuum gauge 2 detects the vacuum level in the pipeline before MFC2; vacuum gauge 3 detects the vacuum level in the pipeline at the front end of the vacuum pump; vacuum pump valve Vp controls the opening and closing of the vacuum pump gas path; and leak detector valve VL controls the opening and closing of the leak detector gas path.

[0013] In the above-mentioned batch automatic single-point leak detection system, the leak detection box 1, leak detection box 2, leak detection box 3 and leak detection box 4 have the same structure and are all provided with a detection interface for connecting the detection gas path; the inner cavity of the detection interface is provided with a sampling flow limiter, which is connected to the sampling gas space of the leak detection box.

[0014] In the aforementioned batch automatic single-point leak detection system, the side walls of the leak detection box 1, leak detection box 2, leak detection box 3, and leak detection box 4 are all provided with vents; the vents are used to replenish the gas in the corresponding leak detection box during sampling.

[0015] In the aforementioned batch automatic single-point leak detection system, the sampling current limiter is a capillary type current limiter, which achieves a specific sampling flow rate and maintains a certain vacuum in the pipeline when the first detection path, second detection path, comparison path, or calibration path is continuously evacuated, thereby reducing the detection response time.

[0016] In the above-mentioned batch automatic single-point leak detection system, the leak detection box 1 contains the part to be inspected 1; the leak detection box 2 contains the part to be inspected 2; and the leak detection box 3 contains the comparison part; the leak rate of the comparison part is 0, or the leak detection box 3 is left empty.

[0017] In the aforementioned batch automatic single-point leak detection system, the vacuum pump's pumping speed is more than 10 times the sum of the flow rates of the calibration path, comparison path, first detection path, and second detection path; the ultimate vacuum degree of the vacuum pump is better than 100 Pa; the leak detector has a vacuum leak detection mode, and the minimum detectable leak rate is better than 1E-12 Pam. 3 / s, ultimate vacuum better than 20Pa, pumping speed not less than 10L / s.

[0018] The advantages of this invention compared to the prior art are:

[0019] (1) The present invention uses a combination of sampling flow limiter and mass flow controller to control flow and leak detection response time. It can overcome the shortcomings of long detection response time in long pipelines, and can also control and measure flow. In particular, when there are differences in the nominal flow of the sampling flow limiter in each branch, it can make the flow of each branch consistent and ensure the consistency of measurement conditions in each branch.

[0020] (2) The present invention uses a vacuum pump to maintain the vacuum state of the branch to be tested in real time. After switching to the detection state, the sampling flow rate can be quickly stabilized. Compared with the method of starting to pump air from atmospheric pressure, the detection reaction time can be greatly shortened and the detection efficiency can be improved. Compared with the method of using a shunt pump to reduce the detection reaction time, the shunt pump can avoid reducing the leak detection sensitivity.

[0021] (3) The present invention uses a combination of sampling current limiter and mass flow controller to enable the leak detection system to have two detection modes at the same time: fixed flow test and non-fixed flow test, to meet different needs; in the non-fixed flow mode, the sampling current limiter controls the flow and the mass flow controller measures the flow. The vacuum degree in the sampling branch tube is more likely to be consistent in the maintenance state and the detection state. After switching, the detection stabilization time is shorter and the detection efficiency is higher; in the fixed flow mode, the sampling current limiter controls the sampling tube pressure and the mass flow controller controls the sampling flow of each branch to be stable and the detection conditions are consistent, resulting in higher detection accuracy.

[0022] (4) The present invention is provided with a diversion path to divert and precisely control and measure the sampling gas of the detection path, which can measure the sampling gas exceeding the maximum flow rate of the leak detector, thereby realizing parallel detection of multiple branches and having the ability to measure the total leak rate of multiple branches.

[0023] (5) This invention avoids the disadvantages of using a fine-tuning valve as a flow limiting device, such as complex structure, large size, inconvenience of use, and easy flow change due to moving parts. It adopts a fixed flow sampling flow limiter, which is small in size, has no moving parts, has a fixed flow, is less affected by external factors, and is easy to use.

[0024] (6) This invention overcomes the drawback that inconsistent flow rates of the sampling current limiter can lead to measurement errors, and allows the flow rate of the sampling current limiter to vary within a certain range, thereby reducing the difficulty of processing, selecting and matching the sampling current limiter;

[0025] (7) The present invention can accurately measure the sampling flow rate and the diversion flow rate during the detection process of each branch, and can calculate the background signal in each branch through the correction algorithm. It can obtain the accurate leak rate of the tested part under any flow rate.

[0026] (8) The above advantages of the present invention can be organically combined to adapt to batch testing under various conditions. The testing fixtures for multiple testing parts are installed in batches during the preparation stage and automated testing is carried out during the testing stage. The testing process is optimized, repetitive operations are avoided, testing efficiency is improved, and the overall performance is high. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the batch automatic single-point leak detection system of the present invention;

[0028] Figure 2 This is a schematic diagram of the control principle of the batch automatic single-point leak detection system of the present invention;

[0029] Figure 3 This is a schematic diagram of the gas path of the batch automatic single-point leak detection system of the present invention;

[0030] Figure 4 This is a schematic diagram of the leak detection cover box structure of the present invention;

[0031] Figure 5 The schematic diagram of the batch automatic single-point leak detection system includes ten detection paths. Detailed Implementation

[0032] The present invention will be further described below with reference to the embodiments.

[0033] This invention provides a batch automatic single-point leak detection system, which can improve detection efficiency, reduce labor intensity, and meet the requirements of automated rapid leak detection in batch production mode.

[0034] Batch automatic single-point leak detection system, such as Figure 1 As shown, it specifically includes an automatic leak detection control system, a leak detector, a vacuum pump, leak detection housing 1, leak detection housing 2, leak detection housing 3, leak detection housing 4, and a positive pressure standard leak hole. Figure 3 As shown, the automatic leak detection control system includes detection valve Vd1, detection valve Vd2, comparison valve Vb, calibration valve Vc, vacuum pump valve Vp, leak detector valve VL, vacuum gauge 1, vacuum gauge 2, vacuum gauge 3, mass flow controller MFC1, mass flow controller MFC2, and mass flow controller MFC3. The leak detection enclosure 1 is connected to the air inlet of detection valve Vd1 via a pipeline, forming the first detection path; the leak detection enclosure 2 is connected to the air inlet of detection valve Vd2 via a pipeline, forming the second detection path; the leak detection enclosure 3 is connected to the air inlet of comparison valve Vb via a pipeline, forming the comparison path; a positive pressure standard leak hole extends into the leak detection enclosure 4; the leak detection enclosure 4 is connected to the air inlet of calibration valve Vc via a pipeline, forming the calibration path; the first detection path, second detection path, comparison path, and calibration path are connected in parallel and then divided into two paths; the first path is connected sequentially via pipelines to mass flow controller MFC1, leak detector valve VL, and... The leak detector is connected; vacuum gauge 1 is installed on the front end of the mass flow controller MFC1; the first path is connected to the mass flow controller MFC2, vacuum pump valve Vp, and vacuum pump in sequence via pipeline; vacuum gauge 2 is installed on the pipeline in front of the mass flow controller MFC2; vacuum gauge 3 is installed on the pipeline between the mass flow controller MFC2 and the vacuum pump; one end of the mass flow controller MFC3 is connected to the pipeline between the mass flow controller MFC2 and the vacuum pump; the other end of the mass flow controller MFC3 is connected to the front end of the mass flow controller MFC1 pipeline.

[0035] Place the part to be inspected 1 inside the leak detection box 1; place the part to be inspected 2 inside the leak detection box 2; place the comparison part inside the leak detection box 3; the leakage rate of the comparison part is 0, or leave the leak detection box 3 empty.

[0036] The vacuum pump's pumping speed is more than 10 times the sum of the flow rates of the calibration path, comparison path, first detection path, and second detection path; the ultimate vacuum of the vacuum pump is better than 100 Pa; the leak detector has a vacuum leak detection mode, with a minimum detectable leak rate better than 1E-12 Pam.3 The ultimate vacuum level is better than 20 Pa, and the pumping speed is not less than 10 L / s. The maximum range is selected as 150 Pa·L / s for MFC1, 1500 Pa·L / s for MFC2, and 3000 Pa·L / s for MFC3. The measurement accuracy is 0.1 Pa·L / s for all of them.

[0037] like Figure 2 As shown, the automatic leak detection control system also includes an industrial computer and a PLC; the industrial computer and PLC are used to control and acquire data from various internal solenoid valves, vacuum gauges, mass flow controllers, as well as externally connected leak detectors and vacuum pumps.

[0038] Detection valves Vd1, Vd2, Vb, and Vc are each equipped with two outlets. These outlets are switched via valves to connect to either a vacuum pump or a leak detector, ensuring the gas path is always under evacuation. Mass flow controller MFC1 controls and measures the gas flow rate entering the leak detector; mass flow controller MFC2 controls and measures the gas flow rate entering the vacuum pump; and mass flow controller MFC3 splits the sampling gas flow and measures the split gas flow rate. Vacuum gauge 1 checks the vacuum level in the pipeline before MFC1; vacuum gauge 2 checks the vacuum level in the pipeline before MFC2; and vacuum gauge 3 checks the vacuum level in the pipeline before the vacuum pump. Vacuum pump valve Vp controls the on / off state of the vacuum pump's gas path; and leak detector valve VL controls the on / off state of the leak detector's gas path.

[0039] The left air inlet of the detection valve, comparison valve, and calibration valve is connected to a 0.5mm small-diameter pipe. Figure 4 The leak detection enclosure shown has multiple leak detection enclosures installed at the inspected part 1, inspected part 2, comparison part, and positive pressure standard leak detection port, forming an enclosed space. The leakage rate at the comparison part is zero, or the corresponding leak detection enclosure is left empty. The detection valve, comparison valve, and calibration valve each have two outlets on the right side, which respectively switch the connected detection gas path to the leak detector path or the vacuum pump path, ensuring each gas path is always in a vacuum state. All pipelines connecting the outlets of the detection valve, comparison valve, and calibration valve to the mass flow controller MFC1 are 0.5mm small-diameter pipes. All detection valves, comparison valves, and calibration valves are connected in parallel, each corresponding to a single-point detection gas path, forming two detection paths, one comparison path, and one calibration path. MFC1 is used to control and measure the gas flow rate entering the leak detector, and vacuum gauge 1 is used to detect the vacuum level in the pipeline before MFC1. MFC2 is used to control and measure the gas flow rate entering the vacuum pump, and vacuum gauge 2 is used to detect the vacuum level in the pipeline before MFC2. MFC3 is used to split the sampling gas flow and measure the flow rate of the split gas flow. A vacuum gauge 3 is installed at the front end of the vacuum pump to monitor the vacuum level in the front-end pipeline of the vacuum pump. Vacuum pump valve Vp is located at the front end of the vacuum pump and is used to control the on / off state of the vacuum pump gas path. Leak detector valve VL is used to control the on / off state of the leak detector gas path.

[0040] like Figure 4 As shown, leak detection boxes 1, 2, 3, and 4 have identical structures and are all equipped with a detection interface for connecting to the detection gas path. The inner cavity of the detection interface is equipped with a sampling flow limiter, which communicates with the sampling gas space of the leak detection box. Each of the leak detection boxes 1, 2, 3, and 4 has a vent on its side wall; the vent allows for the replenishment of gas within the corresponding leak detection box during sampling.

[0041] In this invention, a capillary-type current limiter is selected for sampling to obtain a specific sampling flow rate and to maintain a certain vacuum in the pipeline when the first detection path, the second detection path, the comparison path, or the calibration path is continuously evacuated, thereby reducing the detection response time.

[0042] The automatic leak detection and control system includes one calibration path, one comparison path, and two detection paths, for a total of four branches. In practice, multiple detection paths can be configured as needed, with each detection path connected in parallel.

[0043] All detection processes are controlled by system control software, which also performs data reading, judgment, and leak detection rate calculation.

[0044] As an extended example of a batch automatic single-point leak detection system Figure 5 The principle of a leak detection system with 10 detection channels is demonstrated, with each detection channel connected in parallel.

[0045] The usage method is as follows:

[0046] (I) Examples of System Selection and Control Methods

[0047] 1) Determination of the optimal flow rate of the sampling current limiter at the leak detection cover box:

[0048] Based on a leak detector pumping speed of 10 L / s at the leak detection port and a working vacuum of 5 Pa, the optimal flow rate of the sampling flow limiter is calculated using the following formula:

[0049] Q L =S L ×P L =10×5=50Pa·L / s

[0050] The formula for calculating the flow error limit of the sampling current limiter is:

[0051] ΔQ L =Q L / 100=50 / 100=0.5Pa·L / s

[0052] 2) Detect the settings of MFC1:

[0053] Based on the flow rate of the corresponding sampling current limiter in the four branches, detection branch 1 (50.1 Pa·l / s), detection branch 2 (50.2 Pa·l / s), comparison branch (50.3 Pa·l / s), and calibration branch (50.0 Pa·l / s), the minimum value Q is taken. min

[0054] Q t =Q min =50.0 Pa·L / s

[0055] 3) Calculation of the setpoint for vacuum pump holding circuit MFC2:

[0056] There are 4 channels in total, one of which is in detection mode, and the other 3 need to be maintained. Adjust the flow rate value Qv of MFC2 to keep the vacuum level at vacuum gauge 2 at a suitable level. The calculation method is as follows:

[0057] Q v =nQ min =3 × 50.0 = 150.0 Pa·L / s

[0058] 4) Method for detecting the flow rate of path 1: Adjust MFC2 to full scale, switch the detection valve Vd1 of the gas path to be tested to the vacuum pump interface, so that the gas from the leak detection box flows to the vacuum pump, record the vacuum level P1 = 10000Pa and the flow rate Q1 = 50.1Pa·l / s.

[0059] 5) Method for total flow rate of detection path 1 and detection path 2: Adjust MFC2 to full scale, switch detection valves Vd1 and Vd2 to the vacuum pump interface, so that the gas from the leak detection box flows to the vacuum pump, and record the vacuum level P of vacuum gauge 2. total =10000Pa, record the total flow rate Q total =100.3 Pa·l / s.

[0060] (II) Examples of Preparations Before Testing

[0061] 1) Detection system preparation: Operate the leak detector and vacuum pump through the automatic leak detection control system, and keep all valves closed.

[0062] 2) Install leak detection boxes: Install the corresponding leak detection boxes on all inspected parts 1, inspected parts 2, comparison parts, and positive pressure standard leak detection ports. Connect the corresponding 4 leak detection boxes to the detection path, comparison path, and calibration path respectively using 0.5mm diameter pipes.

[0063] (III) Examples of Leakage Rate Detection and Calculation

[0064] (1) Fixed flow mode test method

[0065] 1) Vacuum pump pressure maintenance regulation: 4 branches, of which 3 are in maintenance state when 1 branch is being tested. Calculate the MFC2 control flow value Q. v =3×Q min =150.0 Pa·l / s. Setting the MFC2 flow rate to 150.0 Pa·l / s will ensure the vacuum level at vacuum gauge 2 is at a suitable level. Each time the detection gas path is switched subsequently, the control flow rate Q of MFC2 will be recalculated and set. v In practice, under these circumstances, regardless of which path is tested, the Q... v =150.0 are all equal.

[0066] 2) Batch branch circuit testing: After filling the tested area with helium at the specified pressure, adjust the MFC1 control flow rate to Q. t =50.0 Pa·l / s, adjust the flow rate of MFC3 to 0, first switch the detection valve Vd1 to the leak detector circuit, and after the leak detector output value stabilizes, record the leak detector output value I1 = 2E-6 Pa·m 3 / s, after the test is completed, switch the detection valve to the vacuum pump line; then switch the detection valve Vd2 to the leak detector line. After the leak detector output value stabilizes, record the leak detector output value I2 = 3E-6Pa·m. 3 / s, after the test is completed, switch the test valve to the vacuum pump line. When testing the comparison line, the leak detector output value is I. c =1E-6Pa·m 3 / s; When testing the calibration circuit, the output value of the leak detector is I. s = 4E-6Pa·m 3 / s. Record the nominal leakage rate Q of the positive pressure standard leak. s =6E-6Pa·m 3 / s.

[0067] The inflation process described in this step can be completed at any stage prior to this step.

[0068] 3) Calculate the leak rate for each branch corresponding to the detection point:

[0069] Leakage rate of the tested site 1:

[0070] Leakage rate of the tested site 2:

[0071] (2) Non-constant flow mode test method

[0072] 1) Vacuum pump pressure maintenance regulation: Adjust the flow rate Q controlled by MFC2. v The range is set to its maximum value of 1500 Pa·l / s to ensure that the vacuum level at vacuum gauge 2 is at its optimal level.

[0073] 2) Batch branch line testing: After filling the tested area with helium at the specified pressure, adjust the flow rate of MFC1 to its maximum range and adjust the flow rate of MFC3 to 0. Switch the detection valve Vd1 corresponding to detection line 1 to the leak detector line. After the leak detector output value stabilizes, record the leak detector output value I1 = 2E-6 Pa·m. 3 / s, flow rate Q t1 =50.1 Pa·l / s. After the test is completed, switch the detection valve to the vacuum pump line; switch the detection valve Vd2 corresponding to detection line 2 to the leak detector line. After the leak detector output value stabilizes, record the output value of the leak detector I2 = 3E-6 Pa·m. 3 / s, flow rate Q t2 =50.2 Pa·l / s. After the test is completed, switch the test valve to the vacuum pump circuit. When testing the comparison circuit, the output value of the leak detector is I. c =1E-6Pa·m 3 / s, measured flow rate Q of MFC1 tc = 50.3 Pa·l / s; During the test calibration circuit, the output value of the leak detector is I. s = 4E-6Pa·m 3 / s, measured flow rate Q of MFC1 ts = 50.0 Pa·l / s. Record the nominal leakage rate Q of the positive pressure standard leak. s =6E-6Pa·m 3 / s.

[0074] The inflation process described in this step can be completed at any stage prior to this step.

[0075] 3) Calculate the leak rate for each branch corresponding to the detection point:

[0076] Leakage rate of the tested site 1:

[0077] Leakage rate of the tested site 2:

[0078] Note: The above is only for demonstrating the testing and calculation methods. The data and calculation results are not related to the examples described in other methods.

[0079] (3) Test method for total leakage rate of multiple branches in fixed flow mode

[0080] 1) Vacuum pump pressure maintenance regulation: 4 branches. The first step requires simultaneous measurement of inspected part 1 and inspected part 2, therefore 2 branches are tested, and the other 2 branches are in maintenance state. Calculate the MFC2 control flow value Q. v =2×Q min=100.0 Pa·l / s. Setting the flow rate of MFC2 to 100.0 Pa·l / s will ensure that the vacuum level at vacuum gauge 2 is at a suitable level. In the second step, when performing a comparison path test, one path is tested while the other three are in a maintenance state. At this time, the control flow rate Q of MFC2 is... v =3×Q min =150.0 Pa·l / s. In the third step, during the calibration path test, one path is tested, while the other three are in a maintenance state. At this time, the control flow value Q of MFC2 is... v =3×Q min =150.0 Pa·l / s. When subsequently testing the corresponding gas path, the control flow rate Q should be set according to the above-mentioned value. v Configure MFC2 separately.

[0081] 2) Total Leakage Rate Detection for Multiple Branches: After filling the tested area with helium at the specified pressure, set the MFC2 flow rate to 100.0 Pa·l / s, and adjust the MFC1 flow rate to Q. t = 50.0 Pa·l / s, adjust the flow rate of MFC3 to (m-1)×Q t = 50.0 Pa·l / s (m = 2, which is the number of branches detected simultaneously); switch detection valves Vd1 and Vd2 to the leak detector simultaneously, and record the output value I of the leak detector after the output value of the leak detector stabilizes. m = 2.5E-6 Pa·m 3 / s, measured flow rate Q of MFC1 m1 = 50.0 Pa·l / s, measured flow rate Q of MFC3 m3 = 50.0 Pa·l / s. After the test is completed, switch the test valve to the vacuum pump circuit. Set the MFC2 flow rate to 150.0 Pa·l / s, and maintain the MFC1 flow rate Q. t =50.0 Pa·l / s, adjust the MFC3 flow rate to 0, test the comparison circuit, and record the output value I of the leak detector. c =1E-6Pa·m 3 / s, measured flow rate Q of MFC1 tc = 50.0 Pa·l / s. Set the flow rate of MFC2 to 150.0 Pa·l / s, and maintain the flow rate of MFC1 at Q. t =50.0 Pa·l / s, adjust the MFC3 flow rate to 0, test the calibration circuit, and the leak detector output value is I. s = 4E-6Pa·m 3 / s, measured flow rate Q of MFC1 ts = 50.0 Pa·l / s. Record the nominal leakage rate Q of the positive pressure standard leak. s =6E-6Pa·m 3 / s.

[0082] The inflation process described in this step can be completed at any stage prior to this step.

[0083] 3) Calculate the total leak rate at the two branch detection points:

[0084]

[0085] This invention uses a combination of a sampling flow limiter and a mass flow controller to control flow rate and leak detection response time. This not only overcomes the shortcomings of long detection response time in long pipelines, but also controls and measures flow rate. In particular, when there are differences in the nominal flow rate of the sampling flow limiter in each branch, it makes the flow rate of each branch consistent, ensuring the consistency of measurement conditions in each branch.

[0086] A vacuum pump is used to maintain the vacuum state of the branch under test in real time. After switching to the detection state, the sampling flow rate can be quickly stabilized. Compared with the method of starting the pump from atmospheric pressure, the detection reaction time can be significantly shortened and the detection efficiency can be improved. Compared with the method of using a shunt pump to reduce the detection reaction time, the shunt pump can avoid reducing the leak detection sensitivity.

[0087] By combining a sampling current limiter with a mass flow controller, the leak detection system can simultaneously perform both fixed flow rate testing and non-fixed flow rate testing modes to meet different needs. In non-fixed flow rate mode, the sampling current limiter controls the flow rate, while the mass flow controller measures the flow rate. This makes it easier to ensure that the vacuum level in the sampling branch tube is consistent in both the maintenance and detection states, resulting in shorter detection stabilization time and higher detection efficiency after switching. In fixed flow rate mode, the sampling current limiter controls the pressure in the sampling tube, while the mass flow controller controls the sampling flow rate of each branch to ensure stability and consistency of detection conditions, leading to higher detection accuracy.

[0088] This invention features a flow divider to divert and precisely control the sampling gas from the detection path, enabling measurement of sampling gas exceeding the maximum flow rate of the leak detector. This allows for parallel detection of multiple branches and provides the capability to measure the total leak rate of multiple branches.

[0089] This invention avoids the disadvantages of using a fine-tuning valve as a flow limiting device, such as complex structure, large size, inconvenience of use, and easy flow change due to moving parts. It adopts a fixed flow sampling flow limiter, which is small in size, has no moving parts, has a fixed flow rate, is less affected by external factors, and is easy to use.

[0090] This invention overcomes the drawback that inconsistent flow rates of sampling current limiters can lead to measurement errors, allowing the flow rate of the sampling current limiter to vary within a certain range, thus reducing the difficulty of processing, selecting, and matching the sampling current limiter.

[0091] This invention can accurately measure the sampling flow rate and shunt flow rate during the detection process of each branch, and can calculate the background signal in each branch through a correction algorithm, so as to obtain the accurate leak rate of the tested part under any flow rate.

[0092] The above advantages of the present invention can be organically combined to adapt to batch testing under various conditions. The testing fixtures for multiple testing parts are installed in batches during the preparation stage, and automated testing is carried out during the testing stage. The testing process is optimized, repetitive operations are avoided, testing efficiency is improved, and overall performance is high.

[0093] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A batch automatic single-point leak detection system, characterized in that: It includes an automatic leak detection control system, a leak detector, a vacuum pump, leak detection housing 1, leak detection housing 2, leak detection housing 3, leak detection housing 4, and a positive pressure standard leak hole; wherein, the automatic leak detection control system includes detection valve Vd1, detection valve Vd2, comparison valve Vb, calibration valve Vc, vacuum pump valve Vp, leak detector valve VL, vacuum gauge 1, vacuum gauge 2, vacuum gauge 3, mass flow controller MFC1, mass flow controller MFC2, and mass flow controller MFC3; The leak detection enclosure 1 is connected to the air inlet of the detection valve Vd1 via a pipeline, forming the first detection path; the leak detection enclosure 2 is connected to the air inlet of the detection valve Vd2 via a pipeline, forming the second detection path; the leak detection enclosure 3 is connected to the air inlet of the comparison valve Vb via a pipeline, forming the comparison path; a positive pressure standard leak hole extends into the leak detection enclosure 4; the leak detection enclosure 4 is connected to the air inlet of the calibration valve Vc via a pipeline, forming the calibration path; the first detection path, the second detection path, the comparison path, and the calibration path are connected in parallel and then divided into two paths; the first path is connected sequentially via a pipeline to the mass flow controller MFC1, the leak detector valve VL, and... The leak detector is connected; vacuum gauge 1 is installed on the front end of the mass flow controller MFC1; the first path is connected to the mass flow controller MFC2, vacuum pump valve Vp, and vacuum pump in sequence via pipeline; vacuum gauge 2 is installed on the pipeline in front of the mass flow controller MFC2; vacuum gauge 3 is installed on the pipeline between the mass flow controller MFC2 and the vacuum pump; one end of the mass flow controller MFC3 is connected to the pipeline between the mass flow controller MFC2 and the vacuum pump; the other end of the mass flow controller MFC3 is connected to the front end of the mass flow controller MFC1 pipeline.

2. The batch automatic single-point leak detection system according to claim 1, characterized in that: The automatic leak detection control system also includes an industrial computer and a PLC; the industrial computer and PLC are used to control and collect data from various internal solenoid valves, vacuum gauges, mass flow controllers, as well as externally connected leak detectors and vacuum pumps.

3. The batch automatic single-point leak detection system according to claim 1, characterized in that: The detection valve Vd1, detection valve Vd2, comparison valve Vb, and calibration valve Vc are each equipped with two air outlets; the two air outlets are switched by valves to connect to a vacuum pump or leak detector, so that the air path is always in a pumping state.

4. The batch automatic single-point leak detection system according to claim 1, characterized in that: The mass flow controller MFC1 controls and measures the gas flow rate entering the leak detector; the mass flow controller MFC2 controls and measures the gas flow rate entering the vacuum pump. The mass flow controller MFC3 splits the sampled airflow and measures the flow rate of the split airflow.

5. A batch automatic single-point leak detection system according to claim 4, characterized in that: Vacuum gauge 1 is used to detect the vacuum level in the pipeline before MFC1; vacuum gauge 2 is used to detect the vacuum level in the pipeline before MFC2; vacuum gauge 3 is used to detect the vacuum level in the pipeline at the front end of the vacuum pump; vacuum pump valve Vp is used to control the opening and closing of the vacuum pump gas path; leak detector valve VL is used to control the opening and closing of the leak detector gas path.

6. The batch automatic single-point leak detection system according to claim 1, characterized in that: The leak detection boxes 1, 2, 3, and 4 have the same structure and are all equipped with a detection interface for connecting to the detection gas path; the inner cavity of the detection interface is equipped with a sampling flow limiter, which is connected to the sampling gas space of the leak detection box.

7. A batch automatic single-point leak detection system according to claim 6, characterized in that: The side walls of the leak detection box 1, leak detection box 2, leak detection box 3 and leak detection box 4 are all provided with vents; the gas in the corresponding leak detection box is replenished through the vents during sampling.

8. A batch automatic single-point leak detection system according to claim 6, characterized in that: The sampling current limiter is a capillary type current limiter, which can obtain a specific sampling flow rate and maintain a certain vacuum in the pipeline when the first detection path, second detection path, comparison path or calibration path is continuously evacuated, thereby reducing the detection response time.

9. A batch automatic single-point leak detection system according to claim 6, characterized in that: The leak detection box 1 contains the part to be inspected 1; the leak detection box 2 contains the part to be inspected 2; and the leak detection box 3 contains the comparison part; the leakage rate of the comparison part is 0, or the leak detection box 3 is left empty.

10. A batch automatic single-point leak detection system according to claim 1, characterized in that: The vacuum pump's pumping speed is more than 10 times the sum of the flow rates of the calibration path, comparison path, first detection path, and second detection path; the ultimate vacuum of the vacuum pump is better than 100 Pa; the leak detector has a vacuum leak detection mode, with a minimum detectable leak rate better than 1E-12 Pam. 3 / s, ultimate vacuum better than 20Pa, pumping speed not less than 10L / s.

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