A new energy vehicle box airtightness detection device and a use method thereof

Abstract

The application discloses a new energy automobile box body air tightness detection device and a use method thereof. The device comprises a detection tool, the detection tool is provided with a detection platform, and a locking mechanism is arranged on the detection platform. A measured workpiece is fixed on one side of the detection platform through the locking mechanism. A standard cavity is arranged opposite to the measured workpiece, and the standard cavity is fixed on the other side of the detection platform through the locking mechanism. A heat conduction medium is arranged between the measured workpiece and the standard cavity. A test assembly is provided with a test gas circuit and test instruments, and the test gas circuit and the test instruments are connected with the measured workpiece and the standard cavity respectively. The device has the advantages of improving detection repeatability precision and improving detection efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile box airtightness detection, in particular to a new energy automobile box airtightness detection device and a use method thereof. BACKGROUND

[0002] At present, with the development of new energy automobile industry, the anti-leakage requirements of various automobile parts are continuously strengthened. The new energy automobile box is an important component with high anti-leakage requirements, and the box with poor airtightness is extremely easy to cause dangerous accidents such as explosion and spontaneous combustion of the automobile, so the airtightness detection is a necessary item for the manufacture of the automobile box.

[0003] The existing airtightness detection methods mainly include helium detection, water detection and gas detection, among which the gas detection has the best comprehensive detection performance and has been widely applied. According to the existing research, the gas detection is prone to errors in actual application, and the detection accuracy is easily affected, and the temperature is the most important factor affecting the gas detection result.

[0004] In the existing common gas detection scheme, the measurement system is usually placed in an air-conditioned room, and the standard cavity is treated for heat preservation, so as to attempt to control the temperature inside the measured workpiece cavity to control the influence of temperature on the detection result. However, due to the complex and changeable environmental heat exchange conditions in the detection process, the flow and heat exchange of the pressure gas in the test pipeline and the cavity during the detection process and other factors, it is difficult to accurately control the gas temperature of a single cavity to not affect the accuracy of the detection result, and the effect of the existing temperature control method is poor.

[0005] At the same time, the temperature also has a certain influence on the detection efficiency of the gas detection. In the existing gas detection scheme, after completing the inflation, a long detection balance stage is usually set before the gas detection detection stage, so as to ensure that the gas inside the measured workpiece cavity and the standard cavity fully flows and exchanges heat during detection, and the cavity temperature is balanced. However, under the existing test device, it is low in efficiency to make the two cavities fully exchange heat through the narrow pipeline, and there is a lack of accurate prediction model for the temperature balance state, and the balance time determined only by experience may be too short to reliably ensure that the temperature state in the two cavities has reached the test condition, or it may be too long to cause the detection beat to be prolonged and the efficiency to be reduced.

[0006] In summary, there are at least the following technical problems:

[0007] Existing technical solutions for reducing the impact of temperature on gas detection results primarily attempt to control the air temperature of both the measured cavity and the standard cavity, including placing the measurement system in an air-conditioned room and insulating the standard cavity. However, due to complex and variable environmental heat exchange conditions, and factors such as the flow and pressure changes of pressurized gas within pipelines and cavities, it is difficult to precisely control the air temperature of a single cavity. In principle, the absolute air temperature of a single cavity has little impact on the measurement results; the main influencing factor is the temperature difference between the two cavities. Therefore, focusing on controlling the absolute air temperature of a single cavity in existing technical solutions does not significantly improve measurement accuracy.

[0008] Another measure taken in existing technical solutions to reduce the impact of temperature on gas detection results is to extend the equilibration time of the chambers, attempting to set a sufficiently long time for the temperature of the two chambers to be evenly distributed to meet the testing conditions. However, in reality, achieving sufficient heat exchange between the two chambers through a narrow pipe is inefficient, and there is a lack of accurate methods for predicting the equilibrium state. In actual measurements, to try to balance the temperature of the two chambers, an exceptionally long equilibration time is often chosen based on experience, typically exceeding 5 minutes, resulting in low testing efficiency and an inability to reliably guarantee that the temperature difference between the two chambers reaches the measurement conditions. Summary of the Invention

[0009] This invention provides an airtightness testing device and method for new energy vehicle body parts. The main objective is to address the impact of temperature on test repeatability, accuracy, and efficiency in existing airtightness testing solutions. Existing solutions primarily aim to control the air temperature of the tested cavity and the standard cavity to reduce the impact of temperature, including placing the measurement system in an air-conditioned room and insulating the standard cavity. However, due to complex and variable environmental heat exchange conditions, the flow and pressure changes of pressurized gas within pipes and cavities, it is difficult to accurately control the air temperature of a single cavity. In principle, the absolute air temperature of a single cavity has little impact on the measurement results; the main influencing factor is the temperature difference between the two cavities. Existing solutions that focus on controlling the absolute air temperature of a single cavity do not significantly improve measurement accuracy. Another measure taken in existing solutions to reduce the impact of temperature on airtightness is to extend the cavity equilibration time, attempting to set a sufficiently long time for the air temperature of the two cavities to be evenly distributed to meet the testing conditions. However, in practice, achieving sufficient heat exchange between the two cavities through narrow pipes is inefficient, and there is a lack of accurate methods for predicting the equilibrium state. In actual measurements, in order to balance the temperature of the two chambers as much as possible, an unusually long balancing time is often chosen based on experience, typically exceeding 5 minutes. This leads to low testing efficiency and also makes it impossible to reliably guarantee that the temperature difference between the two chambers meets the measurement conditions.

[0010] To achieve the above objectives, according to one aspect of the present invention, a device for detecting the airtightness of a new energy vehicle body is provided, comprising:

[0011] The testing fixture has a testing platform and a locking mechanism on the testing platform;

[0012] The workpiece to be tested is fixed to one side of the testing platform by a locking mechanism;

[0013] A standard cavity is provided, which is positioned opposite to the workpiece being tested, and is fixed to the other side of the testing platform by a locking mechanism.

[0014] A heat-conducting medium is disposed between the workpiece being tested and the standard cavity;

[0015] The test assembly includes a test gas path and a test instrument, which are respectively connected to the workpiece under test and a standard cavity.

[0016] Preferably, the testing instrument includes a pressure sensor, a detection sensor, a measured temperature sensor, and a standard temperature sensor. The pressure sensor is connected to the workpiece under test and measures the pressure data of the workpiece under test in real time. The detection sensor is connected to both the workpiece under test and the standard cavity and measures the detection data in real time. The measured temperature sensor is located inside the cavity of the workpiece under test, and the standard temperature sensor is located inside the standard cavity. The measured temperature sensor and the standard temperature sensor are used to measure the temperature difference between the cavity of the workpiece under test and the standard cavity.

[0017] Preferably, the test gas path includes:

[0018] Gas source, the gas source being used to provide gas;

[0019] A pressure regulating valve, which is connected to a gas source;

[0020] The first inflation valve is connected to the pressure regulating valve and is connected to the workpiece being tested through the first pipeline.

[0021] The second inflation valve is connected to the pressure regulating valve and is connected to the standard cavity through the second pipeline.

[0022] A balancing valve, one end of which is connected to a first pipeline and the other end of which is connected to a second pipeline;

[0023] A pressure relief valve, which is connected to a second inflation valve;

[0024] A silencer, which is connected to a pressure relief valve.

[0025] Preferably, the detection sensor is a differential pressure sensor or a flow sensor.

[0026] Preferably, during the gas testing process, the workpiece under test and the standard cavity are in full contact with the heat-conducting medium, and there is sufficient heat exchange between the workpiece under test and the standard cavity. The heat-conducting medium can fully exchange the temperature changes caused by fluctuations in ambient temperature conditions and gas flow pressure inside the cavity during the testing process, thereby eliminating the temperature difference between the workpiece under test and the standard cavity during the testing process and ensuring that the workpiece under test and the standard cavity are tested under the same conditions.

[0027] Preferably, the temperature sensor inside the workpiece under test and the standard temperature sensor inside the standard cavity are used to measure the temperature inside the test cavity and the standard cavity in real time, reflecting the gas temperature difference data in the two cavities in real time. When the temperature difference between the workpiece under test and the standard cavity is controlled within a certain threshold, it indicates that the pressure gas flow inside the workpiece under test and the standard cavity has become stable and sufficient heat exchange has been achieved, and the state of the two cavities has met the test conditions.

[0028] Preferably, the test component uses the differential pressure method in gas testing to detect the air tightness of the workpiece under test.

[0029] Preferably, according to the gas law, assuming the gas parameters inside the standard cavity are P1, T1, n1, and the volume of the standard cavity is V1; and the gas parameters inside the workpiece being measured are P2, T2, n2, and the volume of the workpiece cavity is V2, then the pressure difference data can be expressed as:

[0030]

[0031] Wherein, P1 is the gas pressure in the standard cavity, T1 is the gas temperature in the standard cavity, n1 is the amount of substance of the gas in the standard cavity, V1 is the volume of the standard cavity, P2 is the gas pressure in the cavity of the workpiece being tested, T2 is the gas temperature in the cavity of the workpiece being tested, n2 is the amount of substance of the gas in the cavity of the workpiece being tested, V2 is the volume of the cavity of the workpiece being tested, and R is the molar gas constant.

[0032] Taking the partial derivatives of the important influencing factors T1 and T2, we can see that the effects of the gas temperature T1 in the standard cavity and the gas temperature T2 in the workpiece cavity on the pressure difference result offset are as follows:

[0033]

[0034] Where ΔP is the pressure difference between the measured cavity and the standard cavity, T1 is the gas temperature in the standard cavity, n1 is the amount of substance of the gas in the standard cavity, V1 is the volume of the standard cavity, T2 is the gas temperature in the measured workpiece cavity, n2 is the amount of substance of the gas in the measured workpiece cavity, V2 is the volume of the measured workpiece cavity, and R is the molar gas constant.

[0035] If the tested cavity and the standard cavity have undergone sufficient heat exchange during the test, and their internal temperatures are approximately equal, this is denoted as T. s At this point, the effect of temperature on the pressure difference can be quantified as follows:

[0036]

[0037] Where, ΔT s The gas temperature inside the cavity is the change in temperature of the gas inside the cavity caused by the change in temperature of the external environment during the test. n1 is the amount of substance of the gas in the standard cavity, V1 is the volume of the standard cavity, n2 is the amount of substance of the gas inside the cavity of the workpiece being tested, V2 is the volume of the cavity of the workpiece being tested, and R is the molar gas constant.

[0038] Preferably, the heat-conducting medium material should have good thermal conductivity and good rigidity, so that the pressurized gas inside the workpiece under test and the standard cavity can fully exchange heat through the heat-conducting medium, and ensure that the temperature difference between the two cavities is controlled within a reasonable threshold range during the test; the temperature difference between the workpiece under test and the standard cavity is directly measured by a temperature sensor, the equilibrium time of the gas test is accurately calculated, and the test cycle of the gas test is controlled.

[0039] When the internal temperatures of the workpiece under test and the standard cavity are approximately equal, the impact of temperature on detection accuracy is minimized. The main method of this invention is to set a heat-conducting medium to ensure sufficient heat exchange between the workpiece cavity and the standard cavity during the detection process. By controlling the internal temperature difference between the workpiece cavity and the standard cavity, the influence of temperature on detection accuracy can be better controlled. At the same time, since the setting of the heat-conducting medium can improve the heat exchange efficiency between the workpiece under test and the standard cavity, this invention uses the temperature sensor of the workpiece under test and the standard temperature sensor to measure the gas temperature difference inside the two cavities during the detection process. By using the criterion that the temperature difference between the two cavities has decreased to a certain threshold range, it predicts that the two cavities have completed sufficient heat exchange and predicts the optimal equilibrium time for the two cavities to reach the test state. This replaces the method of setting the equilibrium time based on experience in the existing gas detection scheme, thereby improving the gas detection efficiency.

[0040] According to another aspect of the present invention, a method for using a new energy vehicle body airtightness testing device is provided, comprising:

[0041] During testing, first open the first inflation valve, the second inflation valve, and the balance valve to ensure that the workpiece being tested and the standard cavity are fully inflated;

[0042] After the inflation stage is completed, the measured temperature sensor detects the temperature data of the gas inside the workpiece and the standard temperature sensor detects the temperature data of the gas inside the standard cavity. When the measured temperature sensor data and the standard temperature sensor data are approximately equal, it can be considered that the gas inside the workpiece cavity and the standard cavity has completed sufficient heat exchange and reached a temperature equilibrium state, and the airtightness test stage can begin.

[0043] The airtightness of the workpiece under test is determined by the results of the differential pressure sensor.

[0044] The technical solution of this invention has the following technical effects and advantages:

[0045] The airtightness testing device of this invention enables sufficient heat exchange between the workpiece under test and the gas inside the standard cavity, reducing the impact of temperature on testing accuracy. Compared to existing gas testing methods that individually control the internal temperature of the cavity by placing it in an air-conditioned room or insulating the standard cavity, this invention controls the influence of temperature on the testing results in principle by controlling the temperature difference between the workpiece under test and the standard cavity. The heat-conducting medium described in this invention ensures sufficient heat exchange between the workpiece under test and the standard cavity throughout the testing process. By controlling the temperature difference, it ensures that the temperatures of the gas inside the workpiece cavity and the standard cavity are approximately equal during testing, further reducing the impact of temperature on the gas testing results and improving testing accuracy.

[0046] In the detection method described in this invention, the temperature difference between the gas inside the workpiece and the standard cavity is measured using a temperature sensor and a standard temperature sensor to accurately predict the time required for the internal pressure gas temperature to reach equilibrium in the workpiece. This allows for control of the detection cycle and improves detection efficiency. In existing gas detection schemes, the workpiece and the standard cavity are mostly connected only through a test gas path, resulting in low heat exchange efficiency of the internal pressure gas. Consequently, current detection schemes often use an empirically set, excessively long equilibrium time to achieve sufficient temperature equilibrium between the two cavities. In the detection device of this invention, the workpiece and the standard cavity are tightly connected through a heat-conducting medium, creating excellent heat exchange conditions and allowing for accurate prediction of the gas detection equilibrium process. Therefore, by using a temperature sensor and a standard temperature sensor to measure the temperature difference between the workpiece cavity and the standard cavity, this invention can determine whether sufficient heat exchange has been completed between the two cavities, accurately predict the equilibrium time of the workpiece during the gas detection process, and improve detection efficiency. Attached Figure Description

[0047] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0048] Figure 1A schematic diagram of the key structure of the new energy vehicle body airtightness testing device according to the present invention is shown.

[0049] Figure 2 It shows Figure 1 Internal analysis view of the testing device for airtightness testing of new energy vehicle bodies;

[0050] Figure 3 It shows Figure 1 A pneumatic principle diagram of a new energy vehicle body airtightness testing device.

[0051] Figure 4 It shows Figure 1 A schematic diagram of the air circuit principle of a common differential pressure testing method for airtightness testing devices for new energy vehicle bodies.

[0052] The above figures include the following reference numerals:

[0053] 1-Inspection fixture, 101-Workpiece to be tested, 102-Standard cavity, 103-Inspection platform, 104-Workpiece clamping mechanism; 2-Test air path, 201-Air source, 202-Pressure regulating valve, 203-First inflation valve, 204-Second inflation valve, 205-Balance valve, 206-Pressure sensor, 207-Differential pressure sensor, 208-Measured temperature sensor, 209-Standard temperature sensor, 210-Pressure relief valve, 211-Silencer. Detailed Implementation

[0054] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0055] like Figures 1 to 4 As shown, this embodiment of the invention provides a device for testing the airtightness of a new energy vehicle body, comprising: a testing fixture 1, the testing fixture 1 having a testing platform 103, the testing platform 103 being provided with a locking mechanism; a workpiece 101 to be tested, the workpiece 101 to be tested being fixed to one side of the testing platform 103 by the locking mechanism; a standard cavity 102, the standard cavity 102 being disposed opposite to the workpiece 101 to be tested, the standard cavity 102 being fixed to the other side of the testing platform 103 by the locking mechanism; a heat-conducting medium, the heat-conducting medium being disposed between the workpiece 101 to be tested and the standard cavity 102; and a testing assembly, the testing assembly having a testing air path 2 and a testing instrument, the testing air path 2 and the testing instrument being respectively connected to the workpiece 101 to be tested and the standard cavity 102.

[0056] This invention primarily addresses the problems of poor repeatability and low efficiency in existing gas detection methods. According to current research, temperature is the main factor contributing to poor repeatability and accuracy in gas detection. Theoretical analysis reveals that temperature variations within the cavity of the tested workpiece 101 and the standard cavity 102 have opposite effects on the detection results. Furthermore, the influence of temperature on the detection results is minimal when the internal temperatures of the tested workpiece 101 and the standard cavity 102 are approximately equal. Existing detection methods control the internal temperatures of the tested workpiece 101 and the standard cavity 102 by placing the measurement system in an air-conditioned room or by insulating the standard cavity 102. However, these methods cannot accurately control the internal temperature of a single cavity, nor can they guarantee that the gas temperatures inside the two cavities are approximately equal. This invention innovatively proposes a device to improve detection accuracy and efficiency by controlling the temperature difference between the gases inside two chambers. The detection device uses a heat-conducting medium between the workpiece 101 and the standard chamber 102 to allow for sufficient heat exchange between them, thereby controlling the internal temperature difference and ensuring that the internal temperatures of the two chambers are approximately equal. This also effectively prevents the detection results from being disturbed by sudden temperature fluctuations during the detection process, thus improving the existing detection accuracy. Since the heat-conducting medium can achieve better heat exchange efficiency between the gases inside the two chambers, the equilibrium state of the workpiece 101 during gas detection can be predicted by measuring the internal temperature difference between the workpiece 101 and the standard chamber 102. In this embodiment of the invention, temperature sensors are installed inside both the cavity of the workpiece 101 under test and the standard cavity 102. The air temperature inside the two cavities is measured simultaneously to obtain the real-time temperature difference between the two cavities. When the temperature difference data decreases to a certain threshold range and the air temperature inside the two cavities is approximately equal, it indicates that the gas temperature inside the two cavities has reached approximately equality through heat exchange. At this time, the temperature no longer has a significant impact on the test results, and the balancing stage of the conventional gas detection method can be considered to be completed. The airtightness test can be started immediately, avoiding the excessive redundancy of the long balancing time in the existing implementation method and improving the detection efficiency.

[0057] In this embodiment, the testing fixture 1 has a testing platform 103, on which a locking mechanism is provided. The workpiece 101 to be tested is fixed to one side of the testing platform 103 by the locking mechanism. The standard cavity 102 is arranged opposite to the workpiece 101 to be tested, and the standard cavity 102 is fixed to the other side of the testing platform 103 by the locking mechanism. A heat-conducting medium is placed between the workpiece 101 to be tested and the standard cavity 102. The airtightness of the workpiece 101 to be tested is tested using the differential pressure method in air testing. The testing assembly includes a test gas path 2 and testing instruments. The test gas path 2 and testing instruments are connected to the workpiece under test 101 and the standard cavity 102, respectively. The testing instruments include a temperature sensor 208, a pressure sensor 206, a detection sensor, and a standard temperature sensor 209. The temperature sensor 208 is located inside the cavity of the workpiece under test 101 and is used to directly measure the internal temperature of the cavity of the workpiece under test 101. The pressure sensor 206 is connected to the workpiece under test 101 and measures the pressure of the workpiece under test 101 in real time. The detection sensor is connected to the workpiece under test 101 and the standard cavity 102 and is used to measure the detection data in real time. The standard temperature sensor 209 is located inside the standard cavity 102 and is used to measure the temperature inside the standard cavity in real time. The detection sensor is connected to both the workpiece under test 101 and the standard cavity 102. The test gas path 2 includes: a gas source 201 for supplying gas; a pressure regulating valve 202 connected to the gas source 201; a first inflation valve 203 connected to the pressure regulating valve 202 and connected to the workpiece 101 under test via a first pipeline; a second inflation valve 204 connected to the pressure regulating valve 202 and connected to the standard cavity 102 via a second pipeline; a balancing valve 205 connected at one end to the first pipeline and at the other end to the second pipeline; a pressure relief valve 210 connected to the second inflation valve 204; and a silencer 211 connected to the pressure relief valve 210. The detection sensor is either a differential pressure sensor 207 or a flow sensor.

[0058] In this embodiment, during the gas detection process, the workpiece 101 under test and the standard cavity 102 are in full contact with the heat-conducting medium, and there is sufficient heat exchange between the workpiece 101 under test and the standard cavity 102. The heat-conducting medium can fully exchange the temperature changes of the workpiece 101 under test and the standard cavity 102 during the detection process, control the temperature difference generated between the workpiece 101 under test and the standard cavity 102 during the detection process, and make the workpiece 101 under test and the standard cavity 102 under the same temperature conditions for detection. The temperature sensor 208 inside the workpiece 101 and the standard temperature sensor 209 inside the standard cavity 102 are used to measure the temperature difference between the test cavity and the standard cavity 102 in real time, reflecting the temperature balance of the internal pressurized gas in real time. When the reading of the temperature sensor 208 inside the workpiece 101 and the reading of the standard temperature sensor 209 inside the standard cavity 102 are consistent, and the temperature difference between the two cavities is approximately 0, it proves that the gas temperature inside the test workpiece 101 and the standard cavity has been fully balanced through heat exchange, and the airtightness of the test workpiece 101 can be tested immediately.

[0059] In this embodiment, a heat-conducting medium is used to facilitate sufficient heat exchange between the cavity of the workpiece under test 101 and the standard cavity 102, and the temperature difference between the cavity under test and the standard cavity 102 is controlled to ensure that the internal temperatures of the two cavities are approximately equal during the detection process. The temperature difference change between the cavity of the workpiece under test 101 and the standard cavity is directly measured by a temperature sensor, the equilibrium time of the gas detection is accurately calculated, the detection cycle of the gas detection is controlled, and the detection efficiency is improved.

[0060] Specifically, the airtightness testing device in this embodiment includes a testing fixture 1, a heat-conducting medium, a testing component, and a standard cavity 102. The cavity testing fixture 1 includes a workpiece locking mechanism and a testing platform 103. The workpiece locking mechanism is fixedly connected to the testing platform 103 for fixing the cavity under test. The heat-conducting medium is made of a material with good combined thermal conductivity and rigidity, ensuring good thermal conductivity while also ensuring that the heat-conducting medium is not affected by the pressure of the high-pressure gas inside the cavity. The testing assembly includes a test gas path 2 and testing instruments. The testing instruments include a temperature sensor, a pressure sensor 206, and a detection sensor. The temperature sensor is located inside the cavity of the workpiece under test 101, directly measuring the internal temperature of the cavity. The pressure sensor 206 is connected to the workpiece under test 101, measuring its pressure in real time. The detection sensor is connected to both the workpiece under test 101 and a standard cavity 102, measuring data in real time. The standard cavity 102 is in close contact with the workpiece under test 101 through a heat-conducting medium, allowing for sufficient heat exchange between the workpiece under test 101 and the standard cavity 102 during the inflation process and when temperature changes occur due to other environmental factors. The standard cavity 102 can be a sealed cavity with the same volume as the workpiece under test 101 or a standard, well-tested piece that has already undergone testing. The detection sensor is a differential pressure sensor 207.

[0061] The pressure sensor 206 and the detection sensor should be installed close to the workpiece 101 and the standard cavity 102. The test air path 2 should be as short as possible. The temperature sensor should be installed inside the workpiece 101 and the standard cavity 102 to measure the temperature change inside the cavity.

[0062] Specifically, the repeatability and efficiency of the gas testing scheme in airtightness testing are improved through the following main implementation methods. During the gas testing process, the workpiece 101 under test and the standard cavity 102 must be in full contact with the heat-conducting medium to establish sufficient heat exchange conditions between them. The temperature control method in existing implementations is replaced by controlling the temperature difference between the workpiece 101 and the standard cavity 102, ensuring that the internal temperatures of the two cavities are approximately equal and that the test results are not affected by sudden temperature fluctuations during the testing process. Temperature sensors are installed inside both the workpiece 101 cavity and the standard cavity 102 to measure the real-time temperature difference between the two cavities. When the temperature difference decreases to a certain threshold, it indicates that the gas temperatures inside the two cavities are approximately equal, and the workpiece 101 has reached equilibrium through heat exchange. At this point, temperature no longer significantly affects the test results, and airtightness testing can begin. Measuring the temperature difference between the two chambers can effectively predict the equilibration time of the gas detection equilibration process, avoiding excessive redundancy in the equilibration time set by existing experience, and improving detection efficiency.

[0063] Specifically, the workpiece 101 to be tested and the standard cavity 102 are respectively pressed and fixed on both sides of the testing platform 103 by the workpiece clamping mechanism 104 in the testing fixture 1, forming a "back-to-back" form. At the same time, the testing platform 103 is made of a material with good thermal conductivity, which also serves as a heat conduction medium in this embodiment. This ensures that the workpiece 101 to be tested and the standard cavity 102 can fully exchange heat during the airtightness test, thereby effectively controlling the internal temperature difference of the two cavities and ensuring that the internal temperature conditions of the two cavities are approximately equal during the test, minimizing the influence of temperature on the test results.

[0064] In this embodiment, the differential pressure method in gas testing is used to test the airtightness of the workpiece 101. During the test, the first inflation valve 203, the second inflation valve 204, and the balance valve 205 are first opened to ensure that the workpiece 101 and the standard cavity 102 are fully inflated. After the inflation stage is completed, the temperature sensor 208 detects the temperature data of the gas inside the workpiece 101, and the standard temperature sensor 209 detects the temperature data of the gas inside the standard cavity 102. When the data of the temperature sensor 208 and the data of the standard temperature sensor 209 are approximately equal, it can be considered that the gas inside the cavity of the workpiece 101 and the standard cavity 102 has completed sufficient heat exchange and reached the test conditions, and the airtightness test stage can begin.

[0065] During the testing process, such as Figure 2 As shown, according to the gas state equation, assuming the gas parameters inside the standard cavity 102 are P1, T1, and n1, and the cavity volume is V1; and the gas parameters inside the workpiece 101 being measured are P2, T2, and n2, and the cavity volume is V2, then the pressure difference data can be expressed as:

[0066]

[0067] Wherein, P1 is the gas pressure inside the standard cavity, T1 is the gas temperature inside the standard cavity, n1 is the amount of substance of the gas inside the standard cavity, V1 is the volume of the standard cavity 102, P2 is the gas pressure inside the cavity of the workpiece under test 101, T2 is the gas temperature inside the cavity of the workpiece under test, n2 is the amount of substance of the gas inside the cavity of the workpiece under test 101; V2 is the volume of the cavity of the workpiece under test 101, and R is the molar gas constant.

[0068] Taking the partial derivatives of the important influencing factors T1 and T2, we can see that the effects of the standard cavity temperature T1 and the measured cavity temperature T2 on the pressure difference result deviation are as follows:

[0069]

[0070] Where ΔP is the pressure difference between the measured cavity and the standard cavity, T1 is the gas temperature in the standard cavity, n1 is the amount of substance of the gas in the standard cavity, V1 is the volume of the standard cavity 102, T2 is the gas temperature in the measured workpiece cavity, n2 is the amount of substance of the gas in the measured workpiece 101 cavity, V2 is the volume of the measured workpiece 101 cavity, and R is the molar gas constant.

[0071] During the test, the cavity of the workpiece 101 under test and the standard cavity 102 have undergone sufficient heat exchange, and their internal temperatures are equal, denoted as T. s At this point, the effect of temperature on the pressure difference can be quantified as follows:

[0072]

[0073] Where, ΔT s The gas temperature change inside the chamber caused by the change in ambient temperature during testing is given by n1, where n1 is the amount of gas in the standard chamber, V1 is the volume of the standard chamber 102, n2 is the amount of gas in the chamber of the workpiece 101 being tested, V2 is the volume of the chamber of the workpiece 101 being tested, and R is the molar gas constant.

[0074] This embodiment is compared with common detection methods, such as... Figure 4 As can be seen from the commonly used differential pressure method for air tightness testing, the relationship between temperature and the differential pressure test results is as follows:

[0075]

[0076] Wherein, ΔT1 is the temperature change of the gas inside the standard cavity 102 caused by the change in the external ambient temperature during the test, ΔT2 is the temperature change of the gas inside the tested cavity caused by the change in the external ambient temperature during the test, n1 is the amount of gas in the standard cavity, V1 is the volume of the standard cavity 102, n2 is the amount of gas in the cavity of the tested workpiece 101, V2 is the volume of the cavity of the tested workpiece 101, and R is the molar gas constant.

[0077] Compared to common detection methods that focus on the impact of temperature on differential pressure results, the detection device of this invention addresses the influence of temperature changes within the measured cavity on the differential pressure results. Reduce to The effect of temperature on the differential pressure detection results after the improvement of this invention is approximately 0 after calculation. This theoretically proves that the detection device described in this invention can effectively reduce the influence of temperature on the deviation of differential pressure results compared with conventional detection schemes.

[0078] The test volume of the workpiece 101 is 0.1m³. 3 Taking an inflation pressure of 5 kPa and an ambient temperature of 299 K as an example, when the leakage of the tested workpiece 101 is n... l When the concentration is 0.001 mol, the theoretical pressure difference can be calculated to be 24.86 Pa. The effect of temperature on the pressure difference result obtained using the detection device of this invention is as follows:

[0079] ΔP = 0.08314ΔT s

[0080] The effect of temperature on the differential pressure results obtained by conventional differential pressure detection methods is as follows:

[0081] ΔP = 354.515ΔT1 - 354.432ΔT2

[0082] Assuming that the temperature of the workpiece 101 being tested rises by 0.02K under environmental disturbance, in the detection device of the present invention, the internal temperature rise of the workpiece 101 being tested will be rapidly heat exchanged to the standard cavity 102. However, in conventional detection methods, because the standard cavity 102 is too far away from the workpiece 101 being tested and the insulation layer is used for heat insulation protection, the synchronous heat change process cannot be carried out.

[0083] Assuming that the average temperature rise of the gas inside the cavity is 0.01 K after sufficient heat exchange, then ΔT in the above two equations... s =0.01K, ΔT1=0K, ΔT2=0.02K, then the effect of temperature on the theoretical pressure difference result when using the detection device of this invention is 8.314×10 -4The temperature effect of conventional detection methods is 7.09 Pa. Comparing this to actual theoretical pressure difference data, it is evident that the conventional method of controlling the temperature of the tested workpiece 101 cavity alone accounts for nearly one-third of the actual pressure difference data, a significant impact. In contrast, the method described in this invention, which uses the temperature difference between the tested workpiece 101 cavity and the standard cavity 102 to control the temperature, results in a pressure difference effect of less than one-tenth of the actual pressure difference data, effectively eliminating the influence of temperature on the gas detection results.

[0084] Meanwhile, in this embodiment of the invention, the placement of the heat-conducting medium not only eliminates the influence of temperature on the results of the differential pressure airtightness testing process, but also improves the heat exchange efficiency between the workpiece 101 under test and the standard cavity 102, allowing the internal air temperature of the workpiece 101 to reach the test conditions more quickly. This embodiment of the invention, through the measurement of the temperature difference between the gases inside the two cavities using temperature sensors within the workpiece 101 and the standard cavity 102, can provide an accurate prediction method for the equilibrium time during the gas testing equilibrium process, thereby improving detection efficiency.

[0085] Another embodiment of the present invention provides a method for using a new energy vehicle body airtightness testing device, comprising:

[0086] During testing, first open the first inflation valve 203, the second inflation valve 204 and the balance valve 205 to ensure that the workpiece 101 to be tested and the standard cavity 102 are fully inflated;

[0087] After the inflation stage is completed, the temperature sensor 208 detects the temperature data of the gas inside the workpiece 101 under test, and the standard temperature sensor 209 detects the temperature data of the gas inside the standard cavity 102. When the data of the temperature sensor 208 under test and the data of the standard temperature sensor 209 are approximately equal, it can be considered that the gas inside the cavity of the workpiece 101 under test and the standard cavity 102 has completed sufficient heat exchange, and the workpiece 101 under test has met the test conditions, and the airtightness test stage can begin.

[0088] The airtightness of the workpiece 101 under test is determined by the result of the differential pressure sensor 207.

[0089] Therefore, this embodiment of the invention controls the impact of temperature on the accuracy and efficiency of gas tightness testing by controlling the temperature difference. The heat-conducting medium in the testing device allows for sufficient heat exchange between the cavity of the workpiece 101 under test and the standard cavity 102, ensuring that the internal air temperatures of the workpiece 101 and the standard cavity 102 are approximately equal during the testing process, thus minimizing the impact of temperature on the testing results. This embodiment of the invention includes temperature sensors inside both the cavity of the workpiece 101 and the standard cavity 102, which together measure the temperature difference between the two cavities during the equilibrium phase of the gas tightness test. When the temperature difference between the two cavities decreases to a certain threshold range, it indicates that the gas temperatures inside the two cavities are approximately equal, and the workpiece 101 under test has met the testing conditions. At this point, temperature no longer significantly affects the testing results, and the gas tightness test can begin, avoiding the redundancy of the long equilibrium time in conventional testing schemes and improving testing efficiency.

[0090] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0091] In the detection process of this invention, the influence of temperature on the detection results is controlled by controlling the internal temperature difference between the two chambers. The heat-conducting medium enables sufficient heat exchange between the two chambers, ensuring that the gas temperature inside the tested chamber and the standard chamber 102 is approximately equal during the detection process, minimizing the influence of temperature on the detection results and improving the accuracy of gas detection.

[0092] In the testing process of this invention, temperature sensors are installed in both the workpiece under test 101 and the standard cavity 102 to jointly measure the internal temperature difference between the two cavities. Since the two cavities can exchange heat sufficiently through the heat-conducting medium in the device, the temperature measurement of the internal temperature difference of the two cavities by the temperature sensors in this embodiment can serve as an effective predictive basis for setting the gas tightness test equilibration time. When the internal temperature sensors of the two cavities measure that the internal temperature difference has decreased to within a certain threshold and the internal air temperatures of the two cavities are approximately equal, it indicates that the workpiece under test 101 has met the testing conditions, and the air tightness test can be started immediately. This improves the testing efficiency compared to setting the equilibration time based on experience.

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for detecting the airtightness of a new energy vehicle body, characterized in that, include: The testing fixture has a testing platform and a locking mechanism on the testing platform; The workpiece to be tested is fixed to one side of the testing platform by a locking mechanism; A standard cavity is provided, which is positioned opposite to the workpiece being tested, and is fixed to the other side of the testing platform by a locking mechanism. A heat-conducting medium is disposed between the workpiece being tested and the standard cavity; The test assembly includes a test gas path and a test instrument, which are respectively connected to the workpiece under test and a standard cavity; The testing instrument includes a temperature sensor, a pressure sensor, a detection sensor, and a standard temperature sensor. The temperature sensor is located inside the cavity of the workpiece being tested and is used to directly measure the internal temperature of the workpiece cavity. The pressure sensor is connected to the workpiece being tested and measures the pressure of the workpiece in real time. The standard temperature sensor is located inside a standard cavity and is used to measure the temperature inside the standard cavity in real time. The detection sensor is connected to both the workpiece being tested and the standard cavity and is used to measure detection data in real time. The detection sensor is a differential pressure sensor; During the gas testing process, the workpiece under test and the standard cavity are in full contact with the heat-conducting medium, and the workpiece under test and the standard cavity exchange heat fully. The heat-conducting medium can fully exchange the temperature changes of the workpiece under test and the standard cavity during the testing process, eliminate the temperature difference generated between the workpiece under test and the standard cavity during the testing process, and make the workpiece under test and the standard cavity test under the same temperature conditions. Based on the gas law, assume the gas parameters inside the standard cavity are as follows: , , The cavity volume is The internal gas parameters of the workpiece being tested are: , , The cavity volume is Then the differential pressure data at this time is expressed as: ； in, Standard intracavitary gas pressure, The standard cavity gas temperature, This represents the amount of substance of the gas in the standard cavity. For standard cavity volume, The gas pressure inside the cavity of the workpiece being measured. , The amount of gas in the cavity of the workpiece being measured; The volume of the cavity in the workpiece being measured. The molar gas constant; Important influencing factors and Find the partial derivative of the standard cavity temperature. and the temperature inside the cavity being measured The effects on the offset of the differential pressure results are as follows: ； ； in, The pressure difference between the cavity of the workpiece being tested and the standard cavity. The standard cavity gas temperature, This represents the amount of substance of the gas in the standard cavity. For standard cavity volume, , The amount of gas in the cavity of the workpiece being measured; The volume of the cavity in the workpiece being measured. The molar gas constant; During testing, the cavity of the workpiece being tested and the standard cavity have undergone sufficient heat exchange, and their internal temperatures are equal, denoted as . At this point, the effect of temperature on the pressure difference is quantified as follows: ； in, This refers to the temperature change of the gas inside the cavity of the workpiece under test due to changes in the external ambient temperature during the test. This represents the amount of substance of the gas in the standard cavity. For standard cavity volume, The amount of gas inside the cavity of the workpiece being measured. The volume of the cavity in the workpiece being measured. is the molar gas constant.

2. The new energy vehicle body airtightness testing device as described in claim 1, characterized in that, The test gas path includes: Gas source, the gas source being used to provide gas; A pressure regulating valve, which is connected to a gas source; The first inflation valve is connected to the pressure regulating valve and is connected to the workpiece being tested through the first pipeline. The second inflation valve is connected to the pressure regulating valve and is connected to the standard cavity through the second pipeline. A balancing valve, one end of which is connected to a first pipeline and the other end of which is connected to a second pipeline; A pressure relief valve, which is connected to a second inflation valve; A silencer, which is connected to a pressure relief valve.

3. The new energy vehicle body airtightness testing device as described in claim 1, characterized in that, The temperature sensor inside the workpiece under test and the standard temperature sensor inside the standard cavity are used to measure the temperature inside the test cavity and the standard cavity in real time, reflecting the gas balance state in real time. After the gas exchange in the test gas path and the gas heat exchange in the heat-conducting medium, when the reading of the temperature sensor inside the workpiece under test and the reading of the standard temperature sensor inside the standard cavity are consistent, the gas inside the test workpiece cavity and the standard cavity are fully balanced, and the airtightness test of the workpiece under test is immediately performed.

4. The new energy vehicle body airtightness testing device as described in claim 1, characterized in that, The test assembly uses the differential pressure method in air testing to detect the air tightness of the workpiece under test.

5. The new energy vehicle body airtightness testing device as described in claim 1, characterized in that, By using a heat-conducting medium to fully exchange heat between the cavity of the workpiece under test and the standard cavity, the internal temperature of the cavity under test and the standard cavity is kept consistent during the testing process. Temperature sensors are used to directly measure the temperature changes inside the cavity of the workpiece under test and the standard cavity, accurately calculate the equilibrium time of the gas test, and control the testing cycle of the gas test.

6. A method of using a new energy vehicle body airtightness testing device, based on the new energy vehicle body airtightness testing device according to claim 2, characterized in that, include: During testing, first open the first inflation valve, the second inflation valve, and the balance valve to ensure that the workpiece being tested and the standard cavity are fully inflated; After the inflation stage is completed, the measured temperature sensor detects the temperature data of the gas inside the workpiece under test, and the standard temperature sensor detects the temperature data of the gas inside the standard cavity. When the measured temperature sensor data and the standard temperature sensor data are approximately equal, it is considered that the gas inside the workpiece cavity and the standard cavity has completed sufficient heat exchange, and the workpiece under test has met the test conditions, that is, the airtightness test stage begins. The airtightness of the workpiece under test is determined by the results of the differential pressure sensor.

Images