An air tightness testing apparatus

Abstract

The utility model relates to airtightness test equipment relates to airtightness detection technical field for reducing the temperature compensation calculation error caused by the inside and outside temperature difference when gas injection cavity, airtightness test equipment includes test instrument, contrast jar, temperature regulation equipment, temperature sensor and pressure sensor, test instrument has the gas delivery pipe and contrast gas pipe of gas delivery to the cavity to be detected, contrast jar is connected with the contrast gas pipe of test instrument, temperature regulation equipment sets up at the gas inlet of test instrument, and temperature regulation equipment is used for making the gas through test instrument close or equal to ambient temperature, temperature sensor sets up two, two temperature sensors are arranged in contrast jar and the cavity to be detected respectively, pressure sensor sets up at the cavity to be detected and is used for detecting the air pressure in the cavity to be detected.

Description

Technical Field

[0001] This application relates to the field of airtightness testing technology, and in particular to an airtightness testing device. Background Technology

[0002] In modern industrial production, airtightness testing is a key step in ensuring product quality and is widely used in fields such as automobile manufacturing, electronic components, and medical devices.

[0003] During the airtightness test, due to the pressure change in the chamber under test and the temperature difference between the test gas and the chamber under test, the temperature of the test gas will also be converted through the ideal gas equation pv=nrt after the pressure holding ends. The pressure effect caused by temperature is corrected by the temperature change value in the chamber under test.

[0004] However, gas compression causes temperature changes, and the initial temperature of the gas before entering the chamber to be tested and the temperature at which it mixes with the chamber after entering will also produce a temperature difference. This temperature difference will also cause changes in gas pressure, and the temperature will change again when the pressure continues to increase. At this time, there is a deviation between the amount of gas introduced and the initial and final temperature difference in the chamber to be tested, which leads to deviations in the calculation results of the airtightness test. Utility Model Content

[0005] This application provides an airtightness testing device to reduce the temperature compensation calculation error caused by the temperature difference between the inside and outside of the gas injection chamber.

[0006] This application provides an airtightness testing device, including a testing instrument, a comparison tank, a temperature control device, a temperature sensor, and a pressure sensor. The testing instrument has a gas supply pipe for supplying gas to the chamber under test and a comparison gas pipe. The comparison tank is connected to the comparison gas pipe of the testing instrument. The temperature control device is located at the air inlet of the testing instrument and is used to make the gas passing through the testing instrument close to or equal to the ambient temperature. Two temperature sensors are provided, one in the comparison tank and the other in the chamber under test. The pressure sensor is located in the chamber under test and is used to detect the gas pressure in the chamber under test.

[0007] The temperature control device in this application can bring the input gas close to the ambient temperature, avoiding pressure fluctuations caused by the temperature difference between the gas and the environment, and reducing the interference of temperature factors on the test data. The comparison tank and the chamber under test are matched to form a reference system. Under the same time and the same gas pressure conditions, the temperature difference between the tank and the temperature difference in the chamber under test can be compared to form a difference value. The actual pressure change value in the chamber under test can be determined by this difference value, further eliminating the interference of temperature on pressure detection.

[0008] In some embodiments of this application, the gas supply pipe and the comparison pipe are made of the same material. Same material means that the pipes have the same physical properties such as thermal conductivity, expansion coefficient, and gas adsorption capacity. This ensures that the resistance and adsorption capacity of the pipes are the same, guaranteeing that the transmission characteristics of the gas output from the testing instrument are consistent in both pipes. This avoids differences in input conditions between the comparison tank and the chamber under test due to differences in the pipes, thus improving the accuracy of the comparison.

[0009] In some embodiments of this application, the temperature control device and the testing instrument are connected via an air inlet pipe, and the air inlet pipe and the air delivery pipe are made of the same material. The consistent material of the air inlet pipe and the air delivery pipe between the temperature control device and the testing instrument further eliminates the influence of material differences in the entire gas path from the temperature control device to the chamber under test.

[0010] In some embodiments of this application, the temperature control device includes a gas storage tank and a copper pipe. The gas storage tank is connected to the copper pipe, which is exposed to the outside air. The copper pipe is connected to a testing instrument through an air inlet pipe, supplying room temperature gas to the testing instrument. The copper pipe is exposed to the air, utilizing natural heat exchange to gradually bring the gas temperature inside the gas storage tank closer to the ambient temperature, requiring no additional energy and resulting in low energy consumption.

[0011] In some embodiments of this application, the initial air pressure in the comparison tank and the chamber to be tested are equal. Equal initial air pressure is a prerequisite for airtightness testing. Once the initial air pressure is consistent, the difference in subsequent air pressure changes between the chamber to be tested and the comparison tank can be uniquely attributed to leakage.

[0012] In some embodiments of this application, a pressure sensor is installed inside the comparison tank. By simultaneously monitoring the pressure in both the comparison tank and the chamber under test, the causes of pressure changes can be further distinguished. For example, a sudden increase in ambient temperature may lead to misjudgment. The pressure sensor in the comparison tank can serve as a reference benchmark, allowing for real-time correction of fluctuations caused by the testing instrument itself. Attached Figure Description

[0013] The accompanying drawings are provided to further illustrate the technical solution of this utility model and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solution of this utility model and do not constitute a limitation on the technical solution of this utility model.

[0014] Figure 1 This is a schematic diagram of an airtightness testing device provided in an embodiment of this application.

[0015] Figure labels: 1-Temperature control equipment; 2-Testing instrument; 3-Cavity to be tested; 4-Comparison tank; 5-Comparison air tube; 6-Air delivery tube; 7-Air inlet tube. Detailed Implementation

[0016] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0018] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0019] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, when describing pipelines, the terms "connected" and "linked" as used in this application have the meaning of establishing electrical connection. The specific meaning needs to be understood in conjunction with the context.

[0020] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0021] In modern industrial production, airtightness testing is a key step in ensuring product quality and is widely used in fields such as automobile manufacturing, electronic components, and medical devices.

[0022] During the airtightness test, due to the pressure change in the chamber under test and the temperature difference between the test gas and the chamber under test, the temperature of the test gas will also be converted through the ideal gas equation pv=nrt after the pressure holding ends. The pressure effect caused by temperature is corrected by the temperature change value in the chamber under test.

[0023] However, gas compression causes temperature changes, and the initial temperature of the gas before entering the chamber to be tested and the temperature at which it mixes with the chamber after entering will also produce a temperature difference. This temperature difference will also cause changes in gas pressure, and the temperature will change again when the pressure continues to increase. At this time, there is a deviation between the amount of gas introduced and the initial and final temperature difference in the chamber to be tested, which leads to deviations in the calculation results of the airtightness test.

[0024] Therefore, please refer to Figure 1 This application provides an airtightness testing device, including a testing instrument 2, a comparison tank 4, a temperature control device 1, a temperature sensor, and a pressure sensor.

[0025] Please refer to Figure 1 The testing instrument 2 has a gas supply pipe 6 for supplying gas to the chamber 3 under test and a comparison gas pipe 5. The main function of the testing instrument 2 is to precisely control the gas supply and collect pressure data. The same initial conditions are applied to the chamber 3 under test and the comparison tank 4 through the gas supply pipe 6 and the comparison gas pipe 5, respectively, and then the pressure change difference between the two is monitored to determine the leakage situation.

[0026] The testing instrument 2 can be a differential pressure airtightness detector or a flow rate airtightness detector. Both the gas supply tube 6 and the control gas tube 5 can be made of nylon or fluoroplastic tubing.

[0027] Please refer to Figure 1 The comparison tank 4 is connected to the comparison gas tube 5 of the testing instrument 2. The comparison tank 4 serves as a reference in the airtightness testing system, so it can be made of high-strength materials such as stainless steel or aluminum alloy to ensure that it will not deform due to pressure changes. The volume of the comparison tank 4 can be similar to that of the chamber to be tested 3, such as within 20%, to improve the consistency of gas pressure change characteristics.

[0028] The connection between the comparison tank 4 and the comparison gas pipe 5 meets the requirements of leak-free operation, no throttling, and detachability. It can be a threaded connection or a flange connection. Sealing can be achieved using a sealing ring or a metal sealing structure. To ensure the accuracy of the comparison tank 4, the sealing pressure of the comparison tank 4 can be tested periodically.

[0029] The chamber to be tested 3 can refer to any closed or semi-closed space that needs to be tested for airtightness, such as mobile phones, watches, car fuel tanks, air conditioning compressors, etc.

[0030] Please refer to Figure 1 Temperature regulating device 1 is installed at the air inlet of testing instrument 2. Temperature regulating device 1 is used to regulate the airflow through testing instrument 2. Figure 1 (where a℃ is the original temperature) is close to or equal to the ambient temperature. Figure 1(b℃ represents the ambient temperature). The function of temperature control device 1 is to eliminate the difference between gas temperature and ambient temperature, and to avoid interference with test results due to air pressure changes caused by temperature fluctuations.

[0031] According to the ideal gas law PV=nRT, even small temperature changes can lead to significant fluctuations in air pressure.

[0032] The temperature control device 1 can adopt a "gas tank + copper pipe" structure, such as including a gas tank, copper pipe and bracket, to store compressed gas and provide buffer volume. The copper pipe, as a heat exchange medium, can be arranged in a spiral or serpentine shape to increase the heat dissipation area, so that the gas and air can exchange heat quickly, making the temperature of the gas entering the chamber to be tested 3 close to room temperature. The bracket can support the above structure.

[0033] After the compressed gas enters the copper tube from the gas storage tank, it exchanges heat with the surrounding air through the copper tube wall. Due to the high thermal conductivity of copper (approximately 400 W / (m·K)), the gas temperature rapidly approaches the ambient temperature and is finally delivered to the testing instrument 2 through the inlet pipe 7.

[0034] For applications requiring high precision, an active temperature control regulator can be added. This regulator uses a temperature sensor to detect the gas temperature at the inlet and outlet of the temperature control device 1 in real time. Depending on the working environment, heating elements and cooling mechanisms can be added. Based on the feedback from the temperature sensor, the heating or cooling power can be adjusted to ensure that the outlet gas temperature accurately matches the ambient temperature.

[0035] At this point, the heating or cooling capacity can be dynamically adjusted using a PID control algorithm, for example:

[0036] When the ambient temperature is 35℃ and the gas temperature output from the gas tank is 25℃, the controller starts the heating unit to raise the gas temperature to 35℃; conversely, when the ambient temperature is 10℃ and the gas temperature is 20℃, the cooling unit is started to cool down.

[0037] Two temperature sensors are used, one in the comparison tank 4 and the other in the chamber to be tested 3. The temperature sensors can be NTC thermistors or PTC thermistors, or they can be K-type thermocouples or T-type thermocouples.

[0038] Temperature sensors can be configured as insertion type, flange type, or surface mount type.

[0039] A pressure sensor is installed in the chamber 3 to detect the air pressure inside the chamber 3. The pressure sensor can be a piezoresistive pressure sensor, a capacitive pressure sensor, or a piezoelectric pressure sensor, and it can also be installed using a probe-type mounting method.

[0040] Please refer to Figure 1The temperature control device 1 in this application can bring the input gas close to the ambient temperature, avoiding pressure fluctuations caused by the temperature difference between the gas and the environment, and reducing the interference of temperature factors on the test data. The comparison tank 4 and the chamber to be tested 3 are used to form a reference system. Under the same time and the same gas pressure conditions, the temperature difference between the comparison tank 4 and the temperature difference in the chamber to be tested 3 can be used to form a difference value, and the actual pressure change value in the chamber to be tested 3 can be determined by the difference value, further eliminating the interference of temperature on pressure detection.

[0041] Please refer to Figure 1 In some examples, the gas supply pipe 6 and the comparison pipe 5 are made of the same material. The same material means that the pipes have the same physical properties such as thermal conductivity, expansion coefficient, and gas adsorption capacity. This ensures that the resistance and adsorption capacity of the pipes are the same, guaranteeing that the transmission characteristics of the gas output from the testing instrument 2 are consistent in both pipes. This avoids differences in the input conditions between the comparison tank 4 and the chamber under test 3 due to differences in the pipes, thus improving the accuracy of the comparison.

[0042] In some examples, the gas supply pipe 6 and the comparison gas pipe 5 can be equipped with shut-off valves at the ports near the test chamber 3 and the comparison tank 4, respectively, so that the gas in the test chamber 3 and the comparison tank 4 can be maintained for a certain period of time to determine whether there is a leak.

[0043] Please refer to Figure 1 In some examples, the temperature control device 1 and the testing instrument 2 are connected by an air inlet pipe 7, which is made of the same material as the gas delivery pipe 6. The fact that the air inlet pipe 7 and the gas delivery pipe 6 from the temperature control device 1 to the testing instrument 2 are made of the same material further eliminates the influence of material differences in the entire gas path from the temperature control device 1 to the chamber under test 3.

[0044] For example, the gas supply pipe 6, the contrast gas pipe 5, and the air inlet pipe 7 can all be made of stainless steel, or they can be made of aluminum or copper.

[0045] In some examples, the temperature control device 1 includes a gas storage tank and a copper pipe. The gas storage tank is connected to the copper pipe, which is exposed to the outside air. The copper pipe is connected to the testing instrument 2 through an air inlet pipe 7, supplying room temperature gas to the testing instrument 2. The copper pipe is exposed to the air, utilizing natural heat exchange to gradually bring the gas temperature inside the gas storage tank closer to the ambient temperature, requiring no additional energy and resulting in low energy consumption.

[0046] At this point, for routine airtightness testing procedures, the temperature difference between the gas and the environment can be controlled within 1℃, which can achieve high accuracy. For precision testing, it is necessary to add a corresponding temperature control structure to control the temperature difference between the gas and the environment within 0.1℃, thereby ensuring accurate test results.

[0047] In some examples, the initial air pressure in the comparison tank 4 and the chamber under test 3 are equal. Equal initial air pressure is a prerequisite for airtightness testing. Once the initial air pressure is consistent, the difference in air pressure between the chamber under test 3 and the comparison tank 4 can be uniquely attributed to leakage.

[0048] For example, both chambers can be simultaneously filled with air from the same air source (such as an air tank) via a three-way valve to ensure a consistent rate of pressure increase. This allows the changes in air pressure and temperature over time within the comparison tank 4 to serve as a baseline reference, facilitating the elimination of errors caused by temperature changes in that part of the chamber 3 under test.

[0049] In some examples, a pressure sensor is installed inside the comparison tank 4. By simultaneously monitoring the pressure in the comparison tank 4 and the chamber under test 3, the causes of pressure changes can be further distinguished. For example, a sudden increase in ambient temperature may lead to misjudgment. The pressure sensor in the comparison tank 4 can serve as a reference benchmark to correct for fluctuations in the testing instrument 2 itself in real time.

[0050] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0051] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An airtightness testing device, characterized in that, include: The testing instrument has a gas supply tube for supplying gas to the cavity to be tested and a comparison gas tube; The comparison tank is connected to the comparison gas tube of the testing instrument; A temperature regulating device is installed at the air inlet of the testing instrument. The temperature regulating device is used to make the gas passing through the testing instrument close to or equal to the ambient temperature. Two temperature sensors are provided, one of which is respectively installed in the comparison tank and the chamber to be tested. A pressure sensor is installed in the cavity to be tested to detect the air pressure inside the cavity.

2. The airtightness testing equipment according to claim 1, characterized in that, The gas delivery pipe is made of the same material as the comparison gas pipe.

3. The airtightness testing equipment according to claim 2, characterized in that, The temperature control device is connected to the testing instrument via an air inlet pipe, and the air inlet pipe and the air delivery pipe are made of the same material.

4. The airtightness testing equipment according to claim 3, characterized in that, The temperature control device includes a gas storage tank and a copper pipe. The gas storage tank is connected to the copper pipe, which is exposed to the outside air. The copper pipe is connected to the testing instrument through the air inlet pipe to supply room temperature gas to the testing instrument.

5. The airtightness testing device according to any one of claims 1 to 4, characterized in that, The initial air pressure in the comparison tank is equal to that in the chamber to be tested.

6. The airtightness testing equipment according to claim 1, characterized in that, A pressure sensor is installed inside the comparison tank.

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