A method of leak detection for a pressure sensor

Abstract

The application discloses a pressure sensor leakage detection method, selects a mixed detection tool with multiple detection holes, and installs a mixed detection product group containing at least one high-pressure type pressure sensor and multiple low-pressure type pressure sensors on the multiple detection holes of the mixed detection tool to perform batch detection. The mixed detection method of the high-pressure type pressure sensor and the low-pressure type pressure sensor not only improves the work efficiency of the high-pressure type pressure sensor leakage detection, but also improves the work efficiency of the low-pressure type pressure sensor leakage detection.

Description

Technical Field

[0001] This invention relates to the field of pressure sensor detection technology, specifically a method for detecting pressure sensor leaks. Background Technology

[0002] After the pressure sensor is packaged, its sealing performance needs to be 100% tested. The current leakage detection technology is the helium gas detection method, which has the following three disadvantages:

[0003] 1. The high price of helium as a medium gas increases testing costs and makes market acceptance difficult;

[0004] 2. Helium testing can only perform one test at a time, resulting in low testing efficiency. It is often used for spot checks. Using it for full product inspection directly leads to limited production capacity and cannot meet the market's demand for batch testing.

[0005] 3. Pressure sensors are divided into high-pressure and low-pressure types. The pressure measurement range of low-pressure sensors is much shorter than that of high-pressure sensors. Therefore, high-pressure and low-pressure sensors are usually tested separately. However, when performing leak detection on low-pressure sensors, although it is possible to use gas with a pressure matching the sensor's range, the leakage rate is slow due to the low pressure. This results in a small leakage volume during short pressure holding times, which cannot be used as a reference. Therefore, it is necessary to increase the helium testing holding time and use the presence of a large helium leak as a reference. This leads to an excessively long time spent determining the quality of a low-pressure sensor by checking for helium leaks. Summary of the Invention

[0006] This invention provides a method for detecting leakage in a pressure sensor to solve the above-mentioned technical problems.

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

[0008] A method for detecting leakage of a pressure sensor, step one: select a multi-detection-hole mixed inspection fixture, take a mixed inspection product group consisting of at least one high-pressure pressure sensor and multiple low-pressure pressure sensors, install it at multiple detection holes on the multi-detection-hole mixed inspection fixture for batch inspection.

[0009] Step 2: During batch testing, fill the multi-hole mixed inspection fixture with nitrogen at the specified pressure;

[0010] Step 3: Individually test the pressure output value A1 of one of the high-pressure sensors and maintain the pressure.

[0011] Step 4: After the pressure holding period is completed, retest the pressure output value A2 of the same high-pressure type pressure sensor.

[0012] Step 5: Compare the difference between the pressure output values ​​A1 and A2 before and after pressure holding to determine whether there is leakage when batch testing the mixed inspection product group in the multi-inspection port mixed inspection. If the difference is large, there is leakage, and the mixed inspection product group is set as an unqualified product group; otherwise, it is a qualified product group.

[0013] Step 6: If leakage is found, remove the non-conforming product group from the multi-inspection hole mixed inspection fixture and select a single-inspection hole fixture or a double-inspection hole fixture.

[0014] Then, the high-pressure sensor from the non-conforming product group is installed in the test hole of the single test hole tool for individual testing;

[0015] The low-pressure type pressure sensor from the non-conforming product group is installed in one of the detection holes of the dual detection hole fixture, and the high-pressure type pressure sensor used to assist the low-pressure type pressure sensor for separate detection of qualified products is installed in the other detection hole of the dual detection hole fixture.

[0016] Step 7: Fill the single-hole and double-hole fixtures with nitrogen at the specified pressure respectively;

[0017] Step 8: Test the pressure output values ​​B1 and C1 of the high-pressure type pressure sensor at the single-detection-hole fixture and the double-detection-hole fixture respectively, and maintain the pressure.

[0018] Step 9: After the pressure holding is completed, check the pressure output values ​​B2 and C2 of the high-pressure type pressure sensor at the single-detection-hole fixture and the double-detection-hole fixture respectively.

[0019] Step 10: Compare the difference between the pressure output values ​​B1 and B2 before and after pressure holding to determine whether there is a leak in the high-pressure sensor on the single detection hole tooling. If the difference is large, there is a leak and the product is unqualified; otherwise, it is a qualified product.

[0020] The difference between the pressure output values ​​C1 and C2 before and after pressure holding is used to determine whether there is a leak in the low-pressure sensor on the dual-detection-hole fixture. If the difference is large, there is a leak and the product is unqualified; otherwise, it is a qualified product.

[0021] Furthermore, the multi-hole mixed inspection fixture, single-hole fixture, and dual-hole fixture are all block structures, and each has an air inlet that communicates with the inner cavity of the inspection hole on its own body.

[0022] Furthermore, if both the high-pressure sensor on the single-detection-hole fixture and the low-pressure sensor on the dual-detection-hole fixture are defective products in step ten, the defective products are re-inspected using a sniffing detection method.

[0023] Furthermore, the sniffing detection method is as follows: the nitrogen gas filled into the single-detection-hole fixture and the double-detection-hole fixture at a specified pressure is replaced with a hydrogen-nitrogen mixture. After maintaining the pressure for 3-5 minutes, a hydrogen molecule sniffing device is used to sniff and detect the body of the defective product, the connection between the body of the defective product and the detection hole, and the gas inlet of the fixture. The leakage point is determined by the amount of hydrogen molecules leaking per second, thereby determining whether the product is defective because of a leak in the product itself.

[0024] Furthermore, the specified gas pressure is a gas pressure that conforms to the pressure range of a high-pressure type pressure sensor.

[0025] Furthermore, the pressure holding time is 16 hours.

[0026] The beneficial effects of this invention are:

[0027] 1. Based on the product's own pressure detection function, use pressure changes within the tooling to determine whether the product is leaking;

[0028] 2. Compressed nitrogen is used as the medium gas in the tooling to reduce gas costs;

[0029] Third, by employing a multi-hole mixed inspection fixture, batch inspection is carried out on a mixed inspection product group consisting of high-pressure and low-pressure sensors. By detecting the difference in pressure output value before and after pressure holding of the high-pressure sensor, if the difference is small, the mixed inspection product group is a qualified product group, because all the high-pressure and low-pressure sensors in the mixed inspection product group are qualified products. There is no need to detect the difference in pressure output value before and after pressure holding of the low-pressure sensor, thus avoiding the problem of excessive time spent in determining whether the low-pressure sensor is a qualified product. Therefore, the mixed inspection method of high-pressure and low-pressure sensors not only improves the working efficiency of high-pressure sensor leakage detection, but also improves the working efficiency of low-pressure sensor leakage detection.

[0030] Fourth, by detecting the difference in pressure output value before and after the high-pressure type pressure sensor is pressure held, if the difference changes significantly, the mixed inspection product group is set as a non-conforming product group. Using single-detection-hole fixtures and double-detection-hole fixtures, the high-pressure type pressure sensor and the low-pressure type pressure sensor in the non-conforming product group are tested one by one to find out which product leaked and caused the entire mixed inspection product group to be judged as a non-conforming product group. Attached Figure Description

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0032] Figure 1 This is a front cross-sectional view of the multi-hole mixed inspection tooling of the present invention.

[0033] Figure 2 This is a top cross-sectional view of the multi-hole mixed inspection tooling of the present invention.

[0034] Figure 3 This is a front sectional view of the single-detection-hole tooling of the present invention.

[0035] Figure 4 This is a top sectional view of the dual-detection-hole tooling of the present invention. Detailed Implementation

[0036] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] like Figure 1-2 As shown, this invention provides a method for detecting leaks in a pressure sensor, employing a combination of high-pressure and low-pressure sensors for detection. The detection steps are as follows:

[0038] Step 1: Select a multi-hole mixed inspection fixture, and install a mixed inspection product group consisting of at least one high-pressure pressure sensor and multiple low-pressure pressure sensors at multiple inspection holes on the multi-hole mixed inspection fixture for batch inspection.

[0039] Step 2: During batch testing, nitrogen gas at a specified pressure is introduced into the multi-hole mixed testing fixture. This specified pressure is the gas pressure that conforms to the pressure range of the high-pressure type pressure sensor. In this application, the gas pressure value that conforms to the pressure range of the high-pressure type pressure sensor is 20 bar.

[0040] Step 3: Individually test the pressure output value A1 of one of the high-pressure sensors and maintain the pressure for 16 hours;

[0041] Step 4: After the pressure holding period is completed, retest the pressure output value A2 of the same high-pressure type pressure sensor.

[0042] Step 5: Compare the difference between the pressure output values ​​A1 and A2 before and after pressure holding to determine whether there is leakage when batch testing the mixed inspection product group in the multi-inspection port mixed inspection. If the difference is large, there is leakage, and the mixed inspection product group is set as an unqualified product group; otherwise, it is a qualified product group.

[0043] Combining steps one through five, a multi-hole mixed inspection fixture is used to perform batch testing on a mixed inspection product group consisting of high-pressure and low-pressure sensors. By detecting the difference in pressure output value before and after pressure holding of the high-pressure sensor, if the difference is small, the mixed inspection product group is considered a qualified product group. This is because all the high-pressure and low-pressure sensors in the mixed inspection product group are qualified products, and there is no need to detect the difference in pressure output value before and after pressure holding of the low-pressure sensor. This avoids the problem of excessive time spent determining whether the low-pressure sensor is a qualified product. Therefore, the mixed inspection method of high-pressure and low-pressure sensors not only improves the efficiency of high-pressure sensor leakage detection but also improves the efficiency of low-pressure sensor leakage detection.

[0044] If the difference between A1 and A2 is large, a leak is present, and the mixed inspection product group is designated as a non-conforming product group. To identify which specific product in the mixed inspection product group has a leak that causes the entire mixed inspection product group to be deemed non-conforming, the following steps are taken:

[0045] Step 6: If leakage is found, remove the non-conforming product group from the multi-inspection hole mixed inspection fixture and select a single-inspection hole fixture or a double-inspection hole fixture.

[0046] Then, the high-pressure sensor from the non-conforming product group is installed in the test hole of the single test hole tool for individual testing;

[0047] Install the low-pressure sensor from the non-conforming product group in one of the detection holes of the dual detection hole fixture. In order to improve the detection efficiency of the low-pressure sensor, nitrogen gas with the same gas pressure as in step two is required. However, since the low-pressure sensor cannot detect gas pressures of 20 bar and above, a high-pressure sensor is installed in the other detection hole of the dual detection hole fixture to assist the low-pressure sensor in performing separate detection of qualified products.

[0048] Step 7: Fill the single-detection-hole fixture and the double-detection-hole fixture with nitrogen gas at a specified pressure. The specified pressure is the gas pressure that meets the pressure range of the high-pressure type pressure sensor. In this application, the gas pressure that meets the pressure range of the high-pressure type pressure sensor is 20 bar.

[0049] Step 8: Test the pressure output values ​​B1 and C1 of the high-pressure type pressure sensor at the single-detection-hole fixture and the double-detection-hole fixture respectively, and hold the pressure for 16 hours.

[0050] Step 9: After the pressure holding is completed, check the pressure output values ​​B2 and C2 of the high-pressure type pressure sensor at the single-detection-hole fixture and the double-detection-hole fixture respectively.

[0051] Step 10: Compare the difference between the pressure output values ​​B1 and B2 before and after pressure holding to determine whether there is a leak in the high-pressure sensor on the single detection hole tooling. If the difference is large, there is a leak, indicating that the corresponding high-pressure sensor is a defective product; otherwise, it is a qualified product.

[0052] The difference between the pressure output values ​​C1 and C2 before and after pressure holding is used to determine whether there is a leak in the low-pressure sensor on the dual-detection-hole fixture. If the difference is large, there is a leak, indicating that the corresponding low-pressure sensor is a defective product; otherwise, it is a qualified product. The reason for using the difference between the pressure output values ​​C1 and C2 of the high-pressure sensor on the dual-detection-hole fixture before and after pressure holding to determine whether there is a leak in the low-pressure sensor is on the dual-detection-hole fixture is as follows: If the difference between C1 and C2 is large, it means that the dual-detection-hole fixture is not holding pressure and there is a leak. The two detection holes on the dual-detection-hole fixture itself are equipped with a low-pressure sensor and a qualified high-pressure sensor, respectively. Since the high-pressure sensor is a qualified product, it means that the low-pressure sensor has a leak and is a defective product.

[0053] By combining steps six through ten, using single-hole and double-hole fixtures, the high-pressure and low-pressure sensors in the unqualified product group are tested one by one. This can identify which specific product leaked, causing the entire mixed product group to be judged as unqualified.

[0054] In this invention, the multi-hole mixed inspection fixture, the single-hole fixture, and the dual-hole fixture are all block structures, and each has an air inlet communicating with the inner cavity of the inspection hole on its respective body. (See also...) Figures 1-4 .

[0055] If, in step ten, both the high-pressure sensor on the single-detection-hole fixture and the low-pressure sensor on the dual-detection-hole fixture are defective products, there are numerous potential leakage factors. Besides the product itself, the connection between the product body and the detection hole, as well as the air inlet of the fixture, could be leakage points. Therefore, to prevent originally qualified products from being marked as defective due to these other factors, a sniffing detection method is used to re-inspect the defective products. The sniffing detection method is as follows:

[0056] The nitrogen gas supplied to the single-detection-hole fixture and the dual-detection-hole fixture at a specified pressure is replaced with a hydrogen-nitrogen mixture. This specified pressure is the gas pressure that matches the pressure range of the high-pressure sensor. In this application, the gas pressure that matches the pressure range of the high-pressure sensor is 20 bar. After maintaining the pressure for 3-5 minutes, a hydrogen molecule sniffing device is used to sniff and detect the body of the defective product, the connection between the body of the defective product and the detection hole, and the gas inlet of the fixture. The leakage point is determined by the amount of hydrogen molecules leaking per second, thereby determining whether the product is defective due to leakage in the product itself. If it is not caused by the product itself, it is still considered a qualified product.

[0057] The embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for detecting leakage in a pressure sensor, characterized by comprising the following steps: Step 1: Select a multi-hole mixed inspection fixture, and install a mixed inspection product group consisting of at least one high-pressure pressure sensor and multiple low-pressure pressure sensors at multiple inspection holes on the multi-hole mixed inspection fixture for batch inspection. Step 2: During batch testing, fill the multi-hole mixed inspection fixture with nitrogen at the specified pressure; Step 3: Individually test the pressure output value A1 of one of the high-pressure sensors and maintain the pressure. Step 4: After the pressure holding period is completed, retest the pressure output value A2 of the same high-pressure pressure sensor. Step 5: Compare the difference between the pressure output values ​​A1 and A2 before and after pressure holding to determine whether there is leakage when batch testing the mixed inspection product group in the multi-inspection port mixed inspection. If the difference is large, there is leakage, and the mixed inspection product group is set as an unqualified product group; otherwise, it is a qualified product group. Step 6: If leakage is found, remove the non-conforming product group from the multi-hole mixed inspection fixture and select a single-hole fixture or a double-hole fixture. Then, the high-pressure sensor from the non-conforming product group is installed in the test hole of the single test hole tool for individual testing; The low-pressure type pressure sensor from the non-conforming product group is installed in one of the detection holes of the dual detection hole fixture, and the high-pressure type pressure sensor used to assist the low-pressure type pressure sensor for separate detection of qualified products is installed in the other detection hole of the dual detection hole fixture. Step 7: Fill the single-hole and double-hole fixtures with nitrogen gas at the specified pressure, respectively. Step 8: Test the pressure output values ​​B1 and C1 of the high-pressure type pressure sensor at the single-detection-hole fixture and the double-detection-hole fixture respectively, and maintain the pressure. Step 9: After the pressure holding is completed, check the pressure output values ​​B2 and C2 of the high-pressure type pressure sensor at the single detection hole fixture and the double detection hole fixture respectively. Step 10: Compare the difference between the pressure output values ​​B1 and B2 before and after pressure holding to determine whether there is a leak in the high-pressure sensor on the single detection hole tooling. If the difference is large, there is a leak and the product is unqualified; otherwise, it is a qualified product. The difference between the pressure output values ​​C1 and C2 before and after pressure holding is used to determine whether there is a leak in the low-pressure sensor on the dual-detection-hole fixture. If the difference is large, there is a leak and the product is unqualified; otherwise, it is a qualified product.

2. The pressure sensor leakage detection method according to claim 1, characterized in that... The multi-hole mixed inspection fixture, single-hole fixture, and dual-hole fixture are all block structures and each has an air inlet that communicates with the inner cavity of the inspection hole on its own body.

3. The pressure sensor leakage detection method according to claim 2, characterized in that... If both the high-pressure sensor on the single-detection-hole fixture and the low-pressure sensor on the dual-detection-hole fixture are unqualified products in step ten, the unqualified products shall be re-inspected by sniffing detection method.

4. The pressure sensor leakage detection method according to claim 3, characterized in that... The sniffing detection method is as follows: Replace the nitrogen gas that fills the single-detection-hole fixture and the double-detection-hole fixture at the specified pressure with a hydrogen-nitrogen mixture. After maintaining the pressure for 3-5 minutes, use a hydrogen molecule sniffing device to sniff and detect the body of the defective product, the connection between the body of the defective product and the detection hole, and the gas inlet of the fixture. The leakage point is determined by the amount of hydrogen molecules leaking per second, thereby determining whether the product defect is caused by a leak in the product itself.

5. The pressure sensor leakage detection method according to claim 1, characterized in that... The specified gas pressure is the gas pressure that conforms to the pressure range of the high-pressure type pressure sensor.

6. The pressure sensor leakage detection method according to claim 1, characterized in that... The pressure holding time is 16 hours.

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