A device and method for detecting the performance of a filter

Abstract

The application discloses a device and a detection method for filter performance detection, which is composed of a cabinet, a plugging assembly, an exhaust assembly, a mechanical arm assembly, a pipeline system, a liquid level measuring assembly and a computer control system. The plugging assembly and the exhaust assembly and the computer control system are installed on the cabinet, the pipeline system and the liquid level measuring assembly are installed inside the cabinet, and the mechanical arm assembly is located on one side of the cabinet. The plugging assembly blocks the oil inlet and outlet of the filter to be detected to detect the air tightness of the filter. The exhaust assembly is used for exhausting the filter, and the negative pressure parameter of the filter can be further measured. The whole test process is controlled by the computer system to realize automatic detection of the whole equipment without manual participation, and the measurement is efficient and accurate, and the detection of the air tightness and the negative pressure parameter of the filter is realized.

Description

Technical Field

[0001] This invention belongs to the field of filter production and testing equipment, and particularly relates to a device and testing method for testing filter performance. Background Technology

[0002] In recent years, with the development of automated production lines, traditional filter performance testing methods have fallen far short of production demands. During the production and assembly process, filters typically require positive pressure airtightness testing and negative pressure water extraction testing. Filter components are mostly die-cast aluminum parts; porosity inherent in die casting and defective sealing rings can lead to poor sealing performance in the finished product. After assembly, airtightness testing is often required. However, previous manual testing involved immersing the filter in liquid and observing for bubbling to determine pass / fail status. After testing, drying and cooling processes were also necessary. After passing the airtightness test, a negative pressure water extraction test was required to determine if the filter could completely expel air during initial installation and use. Currently, filter performance testing is still mainly based on manual, segmented inspection, which is not only inefficient but also carries the risk of missed or incorrect inspections due to manual judgment, and the process is cumbersome. Therefore, it can no longer meet the needs of enterprises for efficient production. Automated testing, identification, and sorting of filter performance has become a development trend, bringing significant economic and social benefits to enterprises. Summary of the Invention

[0003] To overcome the above problems, this invention proposes a device and method for testing the performance of filters. The device has the advantages of high automation, high testing efficiency, and accurate testing.

[0004] The technical solution adopted in this invention is: a device and method for testing the performance of filters. The filter performance testing device consists of a cabinet, a sealing component, an exhaust component, a robotic arm component, a liquid level measuring component, a piping system, and a computer control system. The sealing component, the exhaust component, and the computer control system are installed on the cabinet, and the robotic arm component is located on one side of the cabinet.

[0005] The sealing assembly consists of a first sealing cylinder, a first sealing device, a second sealing cylinder, a second sealing device, and a filter mounting base;

[0006] The exhaust assembly consists of a press cylinder and an exhaust rod;

[0007] The robotic arm assembly consists of a robotic arm and a robotic arm controller;

[0008] The liquid level measurement component consists of an open water tank, a transparent graduated tube, a first liquid level sensor, and a second liquid level sensor.

[0009] The pipeline system consists of an air pump, pipeline, first pressure regulating valve, second pressure regulating valve, first solenoid valve, second solenoid valve, third solenoid valve, fourth solenoid valve, fifth solenoid valve, sixth solenoid valve, and pressure sensor.

[0010] The computer control system consists of a computer, a PLC programmable controller, and equipment control and management system software installed on the computer; the computer is communicatively connected to the pressure sensor, the first liquid level sensor, the second liquid level sensor, and the PLC programmable controller; the PLC programmable controller is communicatively connected to the first solenoid valve, the second solenoid valve, the third solenoid valve, the fourth solenoid valve, the fifth solenoid valve, the sixth solenoid valve, and the robotic arm controller.

[0011] The airtightness testing method for the filter is as follows:

[0012] Step 1: The robotic arm assembly places the filter to be tested onto the filter holder of the sealing assembly;

[0013] Step 2: The sealing assembly seals the oil inlet and outlet pipes of the filter;

[0014] Step 3: Close the second and third solenoid valves, and simultaneously open the first and fourth solenoid valves. Use the air pump to inflate the filter until the pressure sensor displays P.

[0015] Step 4: Close the first solenoid valve to seal the filter into an independent space. After the internal pressure of the filter has balanced for 20 seconds and stabilized, the pressure sensor will start reading the internal pressure value P1 of the filter as the initial pressure value.

[0016] Step 5: After maintaining the pressure for another 30 seconds, the pressure sensor reads the remaining pressure value inside the filter again, which is used as the final pressure value P2;

[0017] Step 6: The computer reads the values ​​of P1 and P2 and automatically calculates ▽P=P1-P2;

[0018] Step 7: Compare ▽P with the set standard leakage rate P s The size, if ▽P>P s If the filter is deemed defective, the robotic arm will remove it and place it in the defective products area. If ▽P≤P s If it passes the test, proceed to the next step of negative pressure testing;

[0019] The negative pressure detection method for the filter is as follows:

[0020] Step 1: Open the third solenoid valve to discharge excess gas from the oil outlet of the oil outlet pipe;

[0021] Step 2: Open the second solenoid valve, and continue to close the first and fourth solenoid valves to connect the filter with the liquid level measurement component;

[0022] Step 3: The exhaust assembly repeatedly presses the exhaust handle of the filter to expel the gas in the filter, making it an independent negative pressure chamber. The liquid in the liquid level measuring assembly begins to rise. When it reaches the position of the second liquid level sensor, the exhaust assembly stops venting. The exhaust assembly is pressed repeatedly up to N times. If the position of the second liquid level sensor is not reached within the specified number of times, it is immediately judged as a defective product and is taken away by the robotic arm assembly and placed in the defective area.

[0023] Step 4: If the filter reaches the position of the second liquid level sensor within N repeated presses to release the air, maintain the pressure for 5 seconds. During this process, the liquid level in the transparent scale tube of the liquid level measuring component will drop. As long as the drop in liquid level does not reach or exceed the position of the first liquid level sensor, it is qualified; otherwise, it is unqualified.

[0024] Step 5: Open the third and fourth solenoid valves to balance the air pressure inside the filter. After the air pressure is balanced, the sealing component is released, and the robotic arm component removes the filter to complete the negative pressure test.

[0025] Furthermore, during the measurement of filter air tightness, the inflation pressure P and the set pressure difference ▽P should be set according to the quality qualification requirements of filters of different specifications and sizes.

[0026] Furthermore, during the measurement of the negative pressure of the filter, the liquid level height N, and the height difference ▽N between the first liquid level sensor and the second liquid level sensor are set according to the quality qualification requirements of filters of different specifications and sizes.

[0027] Furthermore, the first plug blocks one inlet of the oil inlet pipe and one outlet of the oil outlet pipe on one side of the filter, and the second plug blocks one inlet of the oil inlet pipe and one outlet of the oil outlet pipe on the other side of the filter.

[0028] Furthermore, the pipeline with the first pressure regulating valve, the first solenoid valve, the pressure sensor, and the fourth solenoid valve, and the pipeline with the second solenoid valve and the liquid level measuring component are simultaneously connected to one oil inlet of the filter, and the pipeline with the third solenoid valve is connected to one oil outlet of the filter.

[0029] Furthermore, the pipeline system is divided into a power pipeline system and a test management system. The power pipeline system is connected to a second pressure regulating valve via an air pump. The second pressure regulating valve is connected to a fifth solenoid valve and a sixth solenoid valve. The fifth solenoid valve is connected to a first sealing cylinder and a second sealing cylinder via pipelines. The sixth solenoid valve is connected to a pressing cylinder via pipelines. The test pipeline system is connected to a first pressure regulating valve via an air pump. The first pressure regulating valve is connected to a first solenoid valve. The first solenoid valve is connected to a pressure sensor. The pressure sensor is connected to a fourth solenoid valve. The fourth solenoid valve is connected to a filter and a second solenoid valve. The second solenoid valve is connected to a liquid level measuring component. The filter is connected to a third solenoid valve.

[0030] The beneficial effects of this invention are:

[0031] The filter performance testing device of the present invention consists of a cabinet, a sealing assembly, an exhaust assembly, a robotic arm assembly, a liquid level measuring assembly, a piping system, and a computer control system. This structure can realize the automated testing of the airtightness and negative pressure performance of the filter. The robotic arm assembly can load and unload the filter on the testing device, and the sealing assembly, exhaust assembly, liquid level measuring assembly, piping system, and computer control system realize the automated testing of the filter.

[0032] The air tightness testing method for the filter described above measures the air tightness by pressurizing and maintaining the filter with air. This method has the advantages of accurate detection and high detection efficiency in detecting the air tightness of the filter.

[0033] The aforementioned method for testing the negative pressure performance of a filter involves venting the gas inside the filter to form a negative pressure sealed cavity, and then using the formed negative pressure cavity to test its water pumping performance. This method has the advantages of being intuitive, accurate, and efficient in determining the negative pressure performance of a filter. Attached Figure Description

[0034] Figure 1 This is a three-dimensional structural diagram of a device for testing filter performance proposed in this invention.

[0035] Figure 2 This is a partial three-dimensional structural schematic diagram of a device for testing filter performance proposed in this invention;

[0036] Figure 3 This is a three-dimensional structural diagram of the exhaust assembly of a device for testing filter performance proposed in this invention.

[0037] Figure 4 This is a three-dimensional structural diagram of a filter for a filter performance testing device proposed in this invention.

[0038] Figure 5This is a schematic diagram of a pipeline system for a filter performance testing device proposed in this invention;

[0039] Figure 6 This is a schematic diagram of the liquid level measurement component structure of a device for testing filter performance proposed in this invention;

[0040] Figure 7 This is a schematic diagram of a computer control system for filter performance testing proposed in this invention.

[0041] Figure 8 This is a schematic diagram of the logical steps of a filter performance testing device and testing method proposed in this invention.

[0042] Explanation of reference numerals in the attached figures:

[0043] 100-Cabinet, 200-Sealing assembly, 210-First sealing cylinder, 220-First sealing device, 230-Second sealing cylinder, 240-Second sealing device, 250-Filter mounting base, 300-Exhaust assembly, 310-Pressing cylinder, 320-Exhaust rod, 400-Robotic arm assembly, 500-Computer, 600-Filter, 610-Inlet pipe, 620-Outlet pipe, 630-Exhaust handle, 710-Open water tank, 720-Transparent graduated tube, 730-First liquid level sensor, 740-Second liquid level sensor. Detailed Implementation

[0044] The specific embodiments of the present invention are described below with reference to the accompanying drawings and examples:

[0045] It should be noted that the structures, proportions, sizes, etc. illustrated in the accompanying drawings of this specification are only used to complement the content disclosed in the specification, so that those skilled in the art can understand and read them, and are not intended to limit the conditions under which the present invention can be implemented. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0046] Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity of description and are not intended to limit the scope of the invention. Any changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0047] like Figures 1-8 The figure shows a specific embodiment of the present invention;

[0048] like Figure 1As shown, this invention discloses an apparatus and method for testing the performance of filters. The filter performance testing apparatus consists of a cabinet 100, a sealing assembly 200, an exhaust assembly 300, a robotic arm assembly 400, a liquid level measuring assembly, a piping system, and a computer control system. The sealing assembly 200, the exhaust assembly 300, the liquid level measuring assembly, the piping system, and the computer control system are installed on the cabinet 100, and the robotic arm assembly 400 is located on one side of the cabinet 100.

[0049] like Figure 2 As shown, the sealing assembly 200 consists of a first sealing cylinder 210, a first sealing device 220, a second sealing cylinder 230, a second sealing device 240, and a filter mounting base 250. In this invention, the filter mounting base 250 is located in the middle, the first sealing cylinder 210 and the first sealing device 220 are located on one side of the filter mounting base 250, and the second sealing cylinder 230 and the second sealing device 240 are located on the other side of the filter mounting base 250. After the filter 600 is placed on the mounting base by the robotic arm, the first sealing device 220 and the second sealing device 240 will seal the two oil inlets of the oil inlet pipe 610 and the two oil outlets of the oil outlet pipe 620 of the filter 600 from both sides under the push of the first sealing cylinder 210 and the second sealing cylinder 230.

[0050] like Figure 3 As shown, the exhaust assembly 300 consists of a pressing cylinder 310 and an exhaust rod 320. In this invention, the pressing cylinder 310 and the exhaust rod 320 are connected. The exhaust rod 320 can make linear reciprocating motion under the action of the pressing cylinder 310, repeatedly pressing the exhaust handle 630 of the filter 600 to exhaust the filter 600 into a negative pressure state.

[0051] The robotic arm assembly 400 consists of a robotic arm and a robotic arm controller;

[0052] like Figure 6 As shown, the liquid level measuring assembly consists of an open water tank 710, a transparent graduated tube 720, a first liquid level sensor 730, and a second liquid level sensor 740. In this invention, the transparent graduated tube is made of glass, with one end connected to the open water tank 710 and the other end connected to the pipeline system. The first liquid level sensor 730 and the second liquid level sensor 740 are mounted on the transparent graduated tube 720, with the second liquid level sensor 740 positioned higher than the first liquid level sensor 730.

[0053] like Figure 5As shown, the pipeline system comprises an air pump, pipelines, a first pressure regulating valve, a second pressure regulating valve, a first solenoid valve, a second solenoid valve, a third solenoid valve, a fourth solenoid valve, a fifth solenoid valve, a sixth solenoid valve, and a pressure sensor. Preferably, the pipeline system is divided into a power pipeline system and a test management system. The power pipeline system is connected to the second pressure regulating valve via an air pump. The second pressure regulating valve is connected to the fifth and sixth solenoid valves. The fifth solenoid valve is connected to the first sealing cylinder 210 and the second sealing cylinder 230 via pipelines. The sixth solenoid valve is connected to the pressing cylinder 310 via a pipeline. The test pipeline system is connected to the first pressure regulating valve via an air pump. The first pressure regulating valve is connected to the first solenoid valve. The first solenoid valve is connected to the pressure sensor. The pressure sensor is connected to the fourth solenoid valve. The fourth solenoid valve is connected to the filter 600 and the second solenoid valve. The second solenoid valve is connected to the liquid level measuring component. The filter 600 is connected to the third solenoid valve.

[0054] like Figure 8 As shown, the computer control system consists of a computer 500, a PLC programmable controller, and equipment control and management system software installed on the computer 500; the computer 500 is communicatively connected to the pressure sensor, the first liquid level sensor 730, the second liquid level sensor 740, and the PLC programmable controller; the PLC programmable controller is communicatively connected to the first solenoid valve, the second solenoid valve, the third solenoid valve, the fourth solenoid valve, the fifth solenoid valve, the sixth solenoid valve, and the robotic arm controller.

[0055] like Figure 7 As shown, the airtightness testing method for the filter described in this invention is as follows:

[0056] Step 1: The robotic arm 400 places the filter 600 to be tested on the filter holder 250 of the sealing assembly 200;

[0057] Step 2: The sealing assembly 200 seals the oil inlet pipe 610 and the oil outlet pipe 620 of the filter.

[0058] Step 3: Close the second and third solenoid valves, and simultaneously open the first and fourth solenoid valves. Use the air pump to inflate the filter 600 until the pressure sensor displays P.

[0059] Step 4: Close the first solenoid valve to seal the filter 600 into an independent space. After the pressure inside the filter 600 has stabilized for 20 seconds, the pressure sensor will start reading the internal pressure value P1 of the filter as the initial pressure value.

[0060] Step 5: After maintaining the pressure for another 30 seconds, the pressure sensor reads the remaining pressure value inside the filter 600 again, which is used as the final pressure value P2;

[0061] Step 6: Computer 500 reads the values ​​of P1 and P2 and automatically calculates ▽P=P1-P2;

[0062] Step 7: Compare ▽P with the set standard leakage rate P s The size, if ▽P>P s If filter 600 is deemed defective, the robotic arm 400 will remove filter 600 and place it in the defective product area. If ▽P≤P s If it passes the test, proceed to the next step of negative pressure testing;

[0063] like Figure 7 As shown, the negative pressure detection method of the filter 600 described in this invention is as follows:

[0064] Step 1: Open the third solenoid valve to discharge excess gas in the filter 600 from the oil outlet of the oil outlet pipe 620;

[0065] Step 2: Open the second solenoid valve, and continue to close the first and fourth solenoid valves to connect the filter 600 with the liquid level measurement component.

[0066] Step 3: The exhaust assembly 300 repeatedly presses the exhaust handle 630 of the filter 600 to expel the gas in the filter 600, making it an independent negative pressure chamber. The liquid in the liquid level measuring assembly begins to rise and rises to the position of the second liquid level sensor 740. The exhaust assembly 300 stops venting. The exhaust assembly 300 is pressed repeatedly up to N times. If the position of the second liquid level sensor 740 is not reached within the specified number of times, it is immediately judged as a defective product and is taken away by the robotic arm assembly 400 and placed in the defective area.

[0067] Step 4: If the filter 600 reaches the position of the second liquid level sensor 740 within N repeated presses to release the air, maintain the pressure for 5 seconds. During this process, the liquid level in the transparent scale tube 720 of the liquid level measuring component 700 will drop. As long as the drop in liquid level does not reach or exceed the position of the first liquid level sensor 730, it is qualified; otherwise, it is unqualified.

[0068] Step 5: Open the third and fourth solenoid valves to balance the air pressure inside the filter 600. After the air pressure is balanced, the sealing component 200 is unsealed, and the robotic arm 400 component removes the filter 600 to complete the negative pressure test.

[0069] Preferably, during the measurement of the air tightness of the filter 600, the inflation pressure P value and the set pressure difference value ▽P of the holding pressure should be set according to the quality qualification requirements of the filter 600 of different specifications and sizes.

[0070] Preferably, during the measurement of negative pressure in the filter 600, the liquid level height N and the height difference ▽N between the first liquid level sensor and the second liquid level sensor are set according to the quality qualification requirements of filters 600 of different specifications and sizes.

[0071] Preferred, such as Figure 2 As shown, the first plug 220 plugs one oil inlet of the oil inlet pipe 610 and one oil outlet of the oil outlet pipe 620 on one side of the filter 600, and the second plug 240 plugs one oil inlet of the oil inlet pipe 610 and one oil outlet of the oil outlet pipe 620 on the other side of the filter 600.

[0072] Preferred, such as Figure 2 , Figure 5 As shown, a pipeline with a first pressure regulating valve, a first solenoid valve, a pressure sensor, and a fourth solenoid valve, and a pipeline with a second solenoid valve and a liquid level measuring component are simultaneously connected to one oil inlet of the filter 600, and a pipeline with a third solenoid valve is connected to one oil outlet of the filter 600.

[0073] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

[0074] Many other changes and modifications can be made without departing from the concept and scope of this invention. It should be understood that this invention is not limited to the specific embodiments, and the scope of this invention is defined by the appended claims.

Claims

1. A device for testing the performance of filters, characterized in that: The filter performance testing device includes a cabinet (100), a sealing assembly (200), an exhaust assembly (300), a robotic arm assembly (400), a liquid level measuring assembly, a piping system, and a computer control system; the sealing assembly (200), the exhaust assembly (300), the liquid level measuring assembly, the piping system, and the computer control system are installed on the cabinet (100), and the robotic arm assembly (400) is located on one side of the cabinet (100); The sealing assembly (200) consists of a first sealing cylinder (210), a first sealing device (220), a second sealing cylinder (230), a second sealing device (240), and a filter mounting base (250); The exhaust assembly (300) consists of a press cylinder (310) and an exhaust rod (320); The robotic arm assembly (400) consists of a robotic arm and a robotic arm controller; The liquid level measuring component consists of an open water tank (710), a transparent graduated tube (720), a first liquid level sensor (730), and a second liquid level sensor (740); The pipeline system consists of an air pump, pipeline, first pressure regulating valve, second pressure regulating valve, first solenoid valve, second solenoid valve, third solenoid valve, fourth solenoid valve, fifth solenoid valve, sixth solenoid valve, and pressure sensor. The computer control system consists of a computer (500), a PLC programmable controller, and equipment control and management system software installed on the computer (500); the computer (500) is communicatively connected to a pressure sensor, a first liquid level sensor (730), a second liquid level sensor (740), and the PLC programmable controller; the PLC programmable controller is communicatively connected to a first solenoid valve, a second solenoid valve, a third solenoid valve, a fourth solenoid valve, a fifth solenoid valve, a sixth solenoid valve, and a robotic arm controller. The first plug (220) plugs one inlet of the oil inlet pipe (610) and one outlet of the oil outlet pipe (620) on one side of the filter (600), and the second plug (240) plugs one inlet of the oil inlet pipe (610) and one outlet of the oil outlet pipe (620) on the other side of the filter (600). The pipeline with the first pressure regulating valve, the first solenoid valve, the pressure sensor, and the fourth solenoid valve, and the pipeline with the second solenoid valve and the liquid level measuring assembly are connected to one oil inlet of the filter (600), and the pipeline with the third solenoid valve is connected to one oil outlet of the filter (600). The pipeline system is divided into a power pipeline system and a test pipeline system. The power pipeline system is connected to a second pressure regulating valve by an air pump. The second pressure regulating valve is connected to a fifth solenoid valve and a sixth solenoid valve. The fifth solenoid valve is connected to a first sealing cylinder (210) and a second sealing cylinder (230) through pipelines. The sixth solenoid valve is connected to a pressing cylinder (310) through pipelines. The test pipeline system is connected to a first pressure regulating valve by an air pump. The first pressure regulating valve is connected to a first solenoid valve. The first solenoid valve is connected to a pressure sensor. The pressure sensor is connected to a fourth solenoid valve. The fourth solenoid valve is connected to a filter (600) and a second solenoid valve. The second solenoid valve is connected to a liquid level measuring component. The filter (600) is connected to a third solenoid valve.

2. The device for testing filter performance according to claim 1, characterized in that: During the measurement of the air tightness of the filter (600), the inflation pressure P value and the set pressure difference value ▽P of the holding pressure should be set according to the quality qualification requirements of the filter (600) of different specifications and sizes.

3. The device for testing filter performance according to claim 1, characterized in that: During the measurement of the negative pressure of the filter (600), the liquid level height N, the height difference ▽N between the first liquid level sensor and the second liquid level sensor are set according to the quality qualification requirements of filters (600) of different specifications and sizes.

4. The testing method of the apparatus for testing filter performance according to any one of claims 1-3, characterized in that: The airtightness test method for filters is as follows: Step 1: The robotic arm assembly (400) places the filter to be tested (600) on the filter holder (250) of the sealing assembly (200); Step 2: The sealing assembly (200) seals the oil inlet pipe (610) and oil outlet pipe (620) of the filter; Step 3: Close the second and third solenoid valves, and at the same time open the first and fourth solenoid valves. Use the air pump to inflate the filter (600) until the pressure sensor displays P. Step 4: Close the first solenoid valve to seal the filter (600) into an independent space. After the pressure inside the filter (600) has been balanced for 20 seconds and stabilized, the pressure sensor starts to read the internal pressure value P1 of the filter as the initial pressure value. Step 5: After maintaining the pressure for another 30 seconds, the pressure sensor reads the remaining pressure inside the filter (600) again, which is used as the final pressure value P. 2； Step 6: The computer (500) reads the values ​​of P1 and P2 and automatically calculates ▽P=P1-P2; Step 7: Compare ▽P with the set standard leakage rate P s The size, if ▽P>P s If filter (600) is deemed unqualified, the robotic arm assembly (400) will remove filter (600) and place it in the non-conforming product area. If ▽P≤P s If it passes the test, proceed to the next step of negative pressure testing; The negative pressure detection method for filter (600) is as follows: Step 1: Open the third solenoid valve to discharge excess gas in the filter (600) from the oil outlet of the oil outlet pipe (620); Step 2: Open the second solenoid valve, and continue to close the first and fourth solenoid valves to connect the filter (600) with the liquid level measuring component; Step 3: The exhaust assembly (300) repeatedly presses the exhaust handle (630) of the filter (600) to expel the gas in the filter (600) and make it an independent negative pressure chamber. The liquid in the liquid level measuring assembly begins to rise and rises to the position of the second liquid level sensor (740). The exhaust assembly (300) stops venting. The exhaust assembly (300) is repeatedly pressed up to N times. If the position of the second liquid level sensor (740) is not reached within the specified number of times, it is immediately judged as a non-conforming product and is taken away by the robotic arm assembly (400) and placed in the non-conforming area. Step 4: If the filter (600) reaches the position of the second liquid level sensor (740) within N times of repeated pressing to release the air, maintain the pressure for 5 seconds. During this process, the liquid level in the transparent scale tube (720) of the liquid level measuring component (700) will drop. As long as the drop in liquid level does not reach or exceed the position of the first liquid level sensor (730), it is qualified; otherwise, it is unqualified. Step 5: Open the third and fourth solenoid valves to balance the air pressure in the filter (600). After the air pressure is balanced, the sealing component (200) is unsealed, and the robotic arm component (400) removes the filter (600) to complete the negative pressure test.

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