Micro-leakage detection device and detection method

Abstract

The application discloses a kind of micro leakage detection device and detection method, detection device includes shell, absolute pressure sensor, micro differential pressure sensor and main circuit board, the shell inside is provided with pressure chamber, the shell one end is provided with the pressure port of intercommunication pressure chamber;The absolute pressure sensor and micro differential pressure sensor are all located in the pressure chamber, the negative pressure end of the micro differential pressure sensor is connected with the pressure chamber, and the positive pressure end of the micro differential pressure sensor is connected with switch module, for realizing the communication and insulation of positive pressure end and pressure chamber;The absolute pressure sensor and micro differential pressure sensor are electrically connected with main circuit board.The application can exclude the inconsistency caused by the inconsistency of temperature change in air pressure, ensure measurement accuracy, while wide applicability and high degree of automation.

Description

Technical Field

[0001] This invention relates to the field of pressure measurement technology, specifically to a micro-leakage detection device and detection method. Background Technology

[0002] Pressure sensors for micro-leak detection measure pressures within a range of ±133 Pa, which is relatively low, necessitating the use of pressure sensors with smaller ranges. For leaks in large pressure chambers, using a pressure reference chamber for differential pressure measurement is a superior approach.

[0003] Existing measurement schemes may include: using the differential pressure method, with one end of the differential pressure sensor connected to a pre-packaged reference pressure and the other end connected to the pressure of the pipe being measured. In existing differential pressure leak detection methods, the pressure reference chamber is typically pre-fabricated and sealed at a fixed pressure, such as 600 kPa. This pressure is significantly affected by temperature. When the same 600 kPa pressure is sealed at different temperatures, with temperature fluctuations ranging from -20°C to 60°C, the pressure changes within the reference chamber and the pressure of the measured gas are not synchronized, resulting in additional differential pressure outputs and potential misjudgments. Because the differential pressure change is unpredictable, the differential pressure fluctuations can be large (e.g., if the reference chamber is sealed at 35°C, but the test is conducted at 20°C, the different gas constants in the pipe and the reference chamber lead to large differential pressure fluctuations). This limits the range of the differential pressure sensor to around 100 kPa, which is unfavorable for measuring micro-leakage.

[0004] Furthermore, the pressures at both the positive and negative terminals of the differential pressure sensor are pre-sealed before use; for example, a combined pressure of 600 kPa is quite high. Even if there is no leakage at the negative pressure reference terminal, the sealing process is complex. The positive pressure terminal also has stringent storage and usage requirements, making it prone to leakage, which can lead to overload damage and failure of the differential pressure sensor.

[0005] Secondly, since the pressure reference chamber is pre-sealed at a fixed pressure, it can only be used for leak detection in pipelines at that corresponding pressure. For pipelines with different pressures, different pressure reference chambers of different pressures are required, resulting in poor adaptability. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a micro-leakage detection device and detection method that eliminates the influence of temperature, in response to the technical problems existing in the prior art.

[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0008] A micro-leakage detection device includes a housing, an absolute pressure sensor, a differential pressure sensor, and a main circuit board. The housing contains a pressure chamber, and one end of the housing has a pressure inlet communicating with the pressure chamber. Both the absolute pressure sensor and the differential pressure sensor are located within the pressure chamber. The negative pressure end of the differential pressure sensor is connected to the pressure chamber, and the positive pressure end of the differential pressure sensor is connected to a switch module for controlling the connection and isolation between the positive pressure end and the pressure chamber. Both the absolute pressure sensor and the differential pressure sensor are electrically connected to the main circuit board.

[0009] As a further improvement to the above technical solution:

[0010] A terminal block is sealed inside the housing to form a pressure chamber between one end of the housing and the terminal block. The main circuit board is installed inside the housing on the other side of the terminal block. Kovar alloy pins are sintered on the terminal block. The absolute pressure sensor, differential pressure sensor and switch module are all electrically connected to the main circuit board through the Kovar alloy pins on the terminal block.

[0011] The other end of the housing is provided with a top cover, on which an electrical connector is installed, and the electrical connector is electrically connected to the main circuit board.

[0012] Both the absolute pressure sensor and the differential pressure sensor are mounted in the pressure chamber via a fixing bracket, which is shaped like a cross and suspended on the inner wall of the housing.

[0013] Gaskets are provided between the absolute pressure sensor and the differential pressure sensor and the mounting bracket.

[0014] The switching module is a straight-through solenoid valve.

[0015] The present invention also discloses a detection method based on the micro-leakage detection device described above, comprising the following steps:

[0016] 1) Turn on the switch module to connect the positive pressure end of the differential pressure sensor to the pressure chamber; during the process of pressurizing the test piece to the predetermined pressure, the absolute pressure sensor detects the pressure in the pressure chamber in real time;

[0017] 2) When the absolute pressure sensor detects that the pressure in the pressure chamber is stable, leakage detection is performed: the switch module is closed, so that the positive pressure end of the differential pressure sensor closes the pressure in the pressure chamber at the start of leakage detection, and the negative pressure end connects to the pressure chamber to detect the pressure in the pressure chamber after the start of leakage detection, and the output signal of the differential pressure sensor is detected in real time.

[0018] 3) When the differential pressure sensor has an output signal, it is determined that the component under test is leaking; otherwise, it is not leaking.

[0019] As a further improvement to the above technical solution:

[0020] In step 3), when the magnitude of the output signal exceeds a preset value, the switch module is turned on to connect the positive pressure end of the differential pressure sensor to the pressure chamber, so as to avoid damage to the differential pressure sensor.

[0021] In step 3), when the rate of change of the output signal exceeds the preset rate of change value, the switch module is turned on to connect the positive pressure end of the differential pressure sensor to the pressure chamber in order to avoid damage to the differential pressure sensor.

[0022] After the switch module is turned on, the pressure in the pressure chamber is detected by the absolute pressure sensor. When the pressure in the pressure chamber is greater than the preset pressure value and is stable, leakage detection is performed again.

[0023] Compared with the prior art, the advantages of the present invention are as follows:

[0024] The differential pressure sensor of the present invention is immersed in the same environmental conditions as the gas in the pressure chamber (pipeline). When the pipeline is heated or cooled, the gas temperature at the positive pressure end and the negative pressure end of the differential pressure sensor rises and falls in the same way. This can eliminate the inconsistency in gas pressure caused by inconsistent temperature, thereby ensuring the measurement accuracy of the measuring device.

[0025] This invention uses a switch module to sample pipeline pressure on-site. The pipeline pressure sampled at a certain moment is used as a reference pressure (the pressure at the positive pressure end of the micro differential pressure sensor sealed by the switch module). The pipeline pressure detected subsequently is compared with this reference pressure to determine whether the pipeline is leaking. According to P=nKT, during the later detection process, the temperature change causes the pressure change in the reference chamber to be the same as the pipeline pressure change, thereby eliminating the influence of temperature.

[0026] The reference pressure of this invention is taken from the pressure after the pipeline is pressurized and stabilized, and is not affected by the absolute pressure of the pipeline. It can be applied to both high-pressure and low-pressure pipelines, and the product has wide adaptability.

[0027] The detection method of the present invention is based on the micro-leakage detection device described above. It not only has the advantages of the micro-leakage detection device, but also the entire detection process is controlled by a program, automatically detects and judges, requires no manual intervention, and has a high degree of automation. Attached Figure Description

[0028] Figure 1 This is a cross-sectional view of the device of the present invention in an embodiment.

[0029] Figure 2 for Figure 1 AA view.

[0030] Figure 3 forFigure 1 BB view.

[0031] Figure 4 for Figure 1 The CC view.

[0032] Figure 5 This is a schematic diagram of the micro differential pressure sensor in an embodiment of the present invention.

[0033] Figure 6 This is an installation structure diagram of the device of the present invention in a specific application (installed outside the pipeline).

[0034] Figure 7 This is an installation structure diagram of the device of the present invention in a specific application (installed inside a pipe).

[0035] Legend: 1. Threaded interface; 2. Pressure chamber; 3. Lower bracket; 4. Fixing bracket; 5. Absolute pressure sensor; 6. Terminal block; 7. Screw; 8. Main circuit board; 9. Top cover; 10. Electrical connector; 11. Upper bracket; 12. Wire; 13. Micro differential pressure sensor; 14. Gasket; 15. Switch module; 16. Base; 17. Pressure inlet; 18. Detection chip; 19. Positive pressure end; 20. Negative pressure end. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0037] like Figures 1-4 As shown, the micro-leakage detection device of this invention is used to detect leaks in components such as pipelines. Its specific structure includes a housing, an absolute pressure sensor 5, a differential pressure sensor 13, and a main circuit board 8. A pressure chamber 2 is provided inside the housing, and a pressure inlet 17 connecting to the pressure chamber 2 is provided at one end of the housing. Both the absolute pressure sensor 5 and the differential pressure sensor 13 are located within the pressure chamber 2. The absolute pressure sensor 5 is used to measure the pressure of the pipeline being tested during inflation, with a range generally between 400 kPa and 2 MPa (unlimited). The negative pressure end 20 of the differential pressure sensor 13 is connected to the pressure chamber 2, and the positive pressure end 19 of the differential pressure sensor 13 is connected to a switch module 15 to achieve communication and isolation between the positive pressure end 19 and the pressure chamber 2. The differential pressure sensor 13 is used for specific leak detection. Both the absolute pressure sensor 5 and the differential pressure sensor 13 are electrically connected to the main circuit board 8.

[0038] Specifically, the aforementioned absolute pressure sensor 5 is used to measure the pressure of the pipeline being tested during inflation and pressure maintenance. When no detection is being performed, the switch module 15 is in the open state, connecting the positive pressure end 19 of the differential pressure sensor 13 to the pressure chamber 2. When leak detection is being performed, the switch module 15 is closed, causing the positive pressure end 19 of the differential pressure sensor 13 to block the pressure in the pressure chamber 2 at the start of leak detection, while the negative pressure end 20 connects to the pressure chamber 2 to detect the pressure in the pressure chamber 2 after the start of leak detection. Thus, the output signal of the differential pressure sensor 13 can be detected in real time to determine whether a leak has occurred (see the detection method described later for specific leak detection methods).

[0039] The differential pressure sensor 13 of the present invention is immersed in the same environmental conditions as the gas in the pipeline. When the pipeline is heated or cooled, the gas temperature at the positive pressure end 19 and the negative pressure end 20 of the differential pressure sensor 13 rises and falls in the same way. This can eliminate the inconsistency in gas pressure caused by inconsistent temperature, thereby ensuring measurement accuracy.

[0040] This invention uses a switch module 15 to sample pipeline pressure on-site. The pipeline pressure sampled at a certain moment is used as a reference pressure (the positive pressure end 19 of the micro differential pressure sensor 13 sealed by the switch module 15). The pipeline pressure detected subsequently is compared with this reference pressure to determine whether the pipeline is leaking. According to P=nKT, during the later detection process, the temperature change causes the reference pressure change to be the same as the pipeline pressure change, which can eliminate the influence of temperature.

[0041] The reference pressure of this invention is taken from the pressure after the pipeline is pressurized and stabilized, and is not affected by the absolute pressure of the pipeline. It can be applied to both high-pressure and low-pressure pipelines, and the product has wide adaptability.

[0042] In one specific embodiment, the switch module 15 adopts a leak-free straight-through solenoid valve. When the solenoid valve is working, the pressure difference between the inlet and outlet is very small, and the solenoid valve is not prone to leakage. The pressure leakage at the positive pressure end 19 of the differential pressure sensor 13 is almost zero, thereby ensuring detection accuracy.

[0043] In one specific embodiment, a terminal block 6 is sealed inside the housing, forming a pressure chamber 2 between one end of the housing at the pressure inlet 17 and one side of the terminal block 6. The main circuit board 8 is mounted inside the housing on the other side of the terminal block 6 by screws 7. Kovar alloy pins are sintered onto the terminal block 6 via glass insulators. The absolute pressure sensor 5, the differential pressure sensor 13, and the switch module 15 are all connected to the Kovar alloy pins on the terminal block 6 via wires 12, and then electrically connected to the main circuit board 8 via wires 12. The overall structure described above is simple and compact.

[0044] The housing is formed by combining an upper support 11 and a lower support 3. A base 16 is welded to one end of the housing, and a threaded interface 1 for connecting to a pipe is provided on the base 16. A pressure inlet 17 passes through the threaded interface 1 and the base 16, communicating with a pressure chamber 2. During leak detection, gas in the pipe enters the pressure chamber 2 through the pressure inlet 17. A top cover 9 is welded to the other end of the housing, and an electrical connector 10 is installed on the top cover 9, electrically connected to the main circuit board 8. The main circuit board 8 contains an MCU and a remote communication circuit, supplies power to two sensors and a solenoid valve, acquires the output signals of each sensor, controls the opening and closing of the solenoid valve based on the sensor signals, determines whether there is a pressure leak, and sends the measurement results to the monitoring terminal via the remote communication circuit.

[0045] In one specific embodiment, both the absolute pressure sensor 5 and the differential pressure sensor 13 are mounted in the pressure chamber 2 via a mounting bracket 4, which is shaped like a cross and suspended on the inner wall of the housing. Both the absolute pressure sensor 5 and the differential pressure sensor 13 are fastened to the mounting bracket 4 by their own threads. Furthermore, to ensure that the two sensors are securely fastened, gaskets 14 are provided between the absolute pressure sensor 5 and the differential pressure sensor 13 and the mounting bracket 4.

[0046] Since the aforementioned mounting bracket 4 is cross-shaped and suspended inside the housing, the absolute pressure sensor 5 and the differential pressure sensor 13 on the mounting bracket 4 are suspended and fully immersed in the gas in the pressure chamber 2. This ensures that the temperature of the absolute pressure sensor 5 and the differential pressure sensor 13 is the same as the temperature of the gas in the pressure chamber 2. That is, the temperature and pressure of each sensor change synchronously with the temperature and pressure of the pressure chamber 2 (pipe). According to P=nKT, the pressure change value is the same, thereby reducing the error caused by the difference between the temperature of the gas inside the sensor and the temperature of the gas in the pressure chamber 2 (i.e., the gas in the pipe).

[0047] In one specific embodiment, the differential pressure sensor 13 has the following requirements: 1) Very small measurement range, such as 1 kPa to 3 kPa, using a silicon piezoresistive sensing chip 18, the resolution can be infinitely small, and a signal will be output as long as the pressure changes; 2) Strong overload capacity, at least 10 times the rated pressure, to prevent pressure fluctuations from damaging the sensor; 3) High accuracy requirements, with a room temperature accuracy of not less than 0.05%FS, such as ±0.5Pa for a 1 kPa range; 4) Small error across the entire temperature range, such as no more than 0.1%FS in the range of -20℃ to 60℃, ensuring high accuracy. These requirements guarantee that the error will not exceed 2 Pa when measuring a 133 Pa change, ensuring measurement accuracy.

[0048] The aforementioned detection device can be installed close to the outside of the pipeline, such as... Figure 6 As shown; it can also be installed inside a pipe, such as Figure 7As shown. Of course, in other embodiments, leakage detection of other components (such as sealed cabinets) can also be achieved.

[0049] Embodiments of the present invention also disclose a detection method based on the micro-leakage detection device described above, comprising the following steps:

[0050] 1) Turn on the switch module 15 so that the positive pressure end 19 of the differential pressure sensor 13 is connected to the pressure chamber 2; during the process of pressurizing the test piece to the predetermined pressure (holding pressure value), the absolute pressure sensor 5 detects the pressure in the pressure chamber 2 in real time;

[0051] 2) When the absolute pressure sensor 5 detects that the pressure in the pressure chamber 2 is stable, leakage detection is performed: the switch module 15 is closed, so that the positive pressure end 19 of the differential pressure sensor 13 closes the pressure in the pressure chamber 2 at the start of leakage detection, and the negative pressure end 20 connects to the pressure chamber 2 to detect the pressure in the pressure chamber 2 after the start of leakage detection, and the output signal of the differential pressure sensor 13 is detected in real time.

[0052] 3) When the differential pressure sensor 13 has an output signal, it is determined that the component under test is leaking; otherwise, it is not leaking.

[0053] The detection method of the present invention is based on the micro-leakage detection device described above. It not only has the advantages of the micro-leakage detection device described above, but also the entire detection process is controlled by a program, automatically detects and judges, requires no manual intervention, and has a high degree of automation.

[0054] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0055] Connect the detection device to the pipe being tested via threaded interface 1 and supply power. Pressurize the pipe until the pressure reaches the holding pressure value. The pressure inside the pipe reaches the pressure chamber 2 through pressure inlet 17. At this time, the solenoid valve is de-energized and in the open state, the pressure at both ends of the differential pressure sensor 13 is equal, and the output is zero. The absolute pressure sensor 5 detects the pressure in the pressure chamber 2. During inflation, the output of the absolute pressure sensor 5 gradually increases and outputs the real-time pressure value to the main circuit board 8 through wire 12. After the pipe pressure stabilizes, the output of the absolute pressure sensor 5 remains unchanged.

[0056] When the main circuit board 8 detects that the output of the absolute pressure sensor 5 remains essentially unchanged, it considers the pressure chamber 2 and the pipeline pressure to be equal, and leakage detection analysis can begin. At this time, the main circuit board 8 energizes the zero-leakage direct-connect solenoid valve, the solenoid valve closes, and the positive pressure end 19 of the differential pressure sensor 13 seals the pressure in the pipeline at the start of leakage detection, while the negative pressure end 20 connects to the pressure chamber 2 to detect the pressure in the pipeline after the leakage begins. When there is a leak in the pipeline, the pressure at the positive pressure end 19 of the differential pressure sensor 13 remains unchanged, while the pressure at the negative pressure end 20 decreases, and the output of the differential pressure sensor 13 increases. When there is no leak, the pressure at the positive pressure end 19 and the negative pressure end 20 of the differential pressure sensor 13 are equal, and the output is zero, thus completing the leakage detection.

[0057] Because a differential pressure sensor 13 is used to measure the pressure difference before and after a leak, when the pressure leaks very rapidly, the pressure difference across the differential pressure sensor 13 becomes very large. If this exceeds the overload allowable value, the differential pressure sensor 13 will be damaged. Therefore, when the output of the differential pressure sensor 13 is very large and the output changes very rapidly, the main circuit board 8 controls the solenoid valve to open, making the pressure across the differential pressure sensor 13 equal and protecting it from damage. When the absolute pressure sensor 5 detects a pressure greater than 100 kPa and the output is stable, the leak detection can be restarted to eliminate interference from human operation. The output values ​​of the absolute pressure sensor 5 and the differential pressure sensor 13, as well as the calculation results of the main circuit board 8, are all transmitted to the monitoring terminal via remote communication.

[0058] By detecting the output value of the differential pressure sensor 13 as described above, not only can leakage be detected, but also the damage to the differential pressure sensor 13 caused by excessively rapid pressure leakage (overload) can be avoided, thus ensuring the normal operation of the detection device.

[0059] As shown in this disclosure and the claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "comprising" or "including" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. The terms "connected" or "linked" are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect.

[0060] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A micro-leakage detection device, characterized in that, The system includes a housing, an absolute pressure sensor (5), a differential pressure sensor (13), and a main circuit board (8). The housing contains a pressure chamber (2), and one end of the housing has a pressure inlet (17) that connects to the pressure chamber (2). The absolute pressure sensor (5) and the differential pressure sensor (13) are both located inside the pressure chamber (2). The negative pressure end (20) of the differential pressure sensor (13) is connected to the pressure chamber (2), and the positive pressure end (19) of the differential pressure sensor (13) is connected to a switch module (15) to enable communication and isolation between the positive pressure end (19) and the pressure chamber (2). The absolute pressure sensor (5) and the differential pressure sensor (13) are both electrically connected to the main circuit board (8). A terminal block (6) is sealed inside the housing so that a pressure chamber (2) is formed between one end of the housing and the terminal block (6). The main circuit board (8) is installed inside the housing on the other side of the terminal block (6). Kovar alloy pins are sintered on the terminal block (6). The absolute pressure sensor (5), the differential pressure sensor (13), and the switch module (15) are all electrically connected to the main circuit board (8) through the Kovar alloy pins on the terminal block (6).

2. The micro-leakage detection device according to claim 1, characterized in that, The other end of the housing is provided with a top cover (9), and an electrical connector (10) is installed on the top cover (9). The electrical connector (10) is electrically connected to the main circuit board (8).

3. The micro-leakage detection device according to claim 1 or 2, characterized in that, The absolute pressure sensor (5) and the differential pressure sensor (13) are both installed in the pressure chamber (2) by a fixing frame (4). The fixing frame (4) is in the shape of a cross and is suspended on the inner wall of the housing.

4. The micro-leakage detection device according to claim 3, characterized in that, Gaskets (14) are provided between the absolute pressure sensor (5) and the differential pressure sensor (13) and the fixing frame (4).

5. The micro-leakage detection device according to claim 1 or 2, characterized in that, The switch module (15) is a direct-flow solenoid valve.

6. A detection method based on the micro-leakage detection device according to any one of claims 1-5, characterized in that, Including the following steps: 1) Turn on the switch module (15) so that the positive pressure end (19) of the differential pressure sensor (13) is connected to the pressure chamber (2); during the process of pressurizing the test piece to the predetermined pressure, the absolute pressure sensor (5) detects the pressure in the pressure chamber (2) in real time; 2) When the absolute pressure sensor (5) detects that the pressure in the pressure chamber (2) is stable, leakage detection is performed: the switch module (15) is closed, so that the positive pressure end (19) of the differential pressure sensor (13) closes the pressure in the pressure chamber (2) at the start of leakage detection, and the negative pressure end (20) connects to the pressure chamber (2) to detect the pressure in the pressure chamber (2) after the start of leakage detection, and the output signal of the differential pressure sensor (13) is detected in real time. 3) When the differential pressure sensor (13) has an output signal, it is determined that the component under test is leaking; otherwise, it is not leaking.

7. The detection method according to claim 6, characterized in that, In step 3), when the magnitude of the output signal exceeds the preset value, the switch module (15) is turned on so that the positive pressure end (19) of the differential pressure sensor (13) is connected to the pressure chamber (2) to avoid damage to the differential pressure sensor (13).

8. The detection method according to claim 6, characterized in that, In step 3), when the rate of change of the output signal exceeds the preset rate of change value, the switch module (15) is turned on so that the positive pressure end (19) of the differential pressure sensor (13) is connected to the pressure chamber (2) to avoid damage to the differential pressure sensor (13).

9. The detection method according to claim 7 or 8, characterized in that, After the switch module (15) is turned on, the pressure in the pressure chamber (2) is detected by the absolute pressure sensor (5). When the pressure in the pressure chamber (2) is greater than the preset pressure value and is stable, leakage detection is performed again.

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