Quantification-oriented vehicle air conditioner refrigerant leakage test method

Abstract

The invention relates to the technical field of vehicle air conditioner testing, and discloses a quantitative vehicle air conditioner refrigerant leakage testing method, which comprises the following steps: estimating the total volume of a vehicle air conditioner test piece and a bracket to obtain a net volume initial value of a test cabin; assembling a test piece according to a drawing, putting the test piece into a test cabin, and establishing a calibration curve by injecting a quantitative refrigerant to accurately calibrate the net volume of the test cabin; then performing filling leakage detection, compressor running-in and steady-state permeation treatment on the test piece to enable the test piece to reach a real operation leakage state; then real temperature circulation and working condition start and stop are simulated, a 48-hour dynamic leakage test is carried out, and related data are collected; and finally, based on the net increment of the refrigerant concentration, calculating the annual leakage amount of the refrigerant under the test and real use conditions, and realizing quantitative result output. The technical problem that an existing quantitative standard test scene is disjointed with real use is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle air conditioner testing, and particularly relates to a quantitative vehicle air conditioner refrigerant leakage testing method. BACKGROUND

[0002] Hydrofluorocarbons (HFCs) are one of the fastest growing non-CO2 greenhouse gases, with greenhouse effect of several tens to tens of thousands times of CO2, and the reduction and control of HFCs emissions has become an international focus. Vehicle air conditioner refrigerant is one of the main sources of consumption and emissions, with annual consumption of more than 30,000 tons in China , corresponding to more than 40 million tons of CO2 equivalent emissions. Vehicle refrigerant leakage not only causes environmental pressure, but also affects air conditioner energy efficiency and driver safety, and causes additional greenhouse gas emissions. Therefore, major countries around the world have launched or are preparing to launch vehicle refrigerant leakage control. At present, the conventional detection methods for vehicle air conditioner refrigerant leakage mainly include soap water leak detection method, tracer leak detection method, halogen lamp leak detection method, positive / negative pressure leak detection method, portable electronic instrument leak detection method, helium leak detector leak detection method, and leakage monitoring method based on refrigerant static pressure or evaporator outlet temperature. Such methods can only qualitatively detect whether vehicle air conditioner refrigerant leakage occurs, and cannot quantitatively determine the leakage amount, and the applicable scenarios are limited, and generally can only be applied to air conditioner product factory inspection or maintenance inspection links, and it is difficult to meet the quantitative detection needs of vehicle air conditioner refrigerant leakage control.

[0003] At present, the conventional detection methods for vehicle air conditioner refrigerant leakage mainly include soap water leak detection method, tracer leak detection method, halogen lamp leak detection method, positive / negative pressure leak detection method, portable electronic instrument leak detection method, helium leak detector leak detection method, and leakage monitoring method based on refrigerant static pressure or evaporator outlet temperature. Such methods can only qualitatively detect whether vehicle air conditioner refrigerant leakage occurs, and cannot quantitatively determine the leakage amount, and the applicable scenarios are limited, and generally can only be applied to air conditioner product factory inspection or maintenance inspection links, and it is difficult to meet the quantitative detection needs of vehicle air conditioner refrigerant leakage control.

[0004] ​The standards related to the leakage quantitative detection of vehicle refrigerant are as follows: JASO Z123 and SAE 2762 are based on the whole vehicle test method, are an in-service test method for in-use vehicles, are suitable for evaluating the leakage emission in the real use scene of the vehicle, are mostly used for monitoring the leakage emission in the running stage of the vehicle fleet, and the test period is generally 1-2 years, and only can provide benchmark data for the bench leakage test. EC 706 / 2007 (and converted standard T / CAS 599) and SAE 2763 are bench test methods, EC 706 / 2007 is a pre-test method for new vehicles air conditioners of the European Union, is only suitable for evaluating the refrigerant leakage of R134a vehicle air conditioner, and the air conditioner is in the static mode during the whole test, cannot simulate the real running condition, has the problems of single refrigerant type, cannot adapt to the diversified development trend of current vehicle air conditioner refrigerant, does not consider the dynamic emission caused by the actual working condition of the air conditioner and the change of the environmental temperature, the test result has low fitting degree with the real use scene, and the test period is too long, and it takes at least 15 days to complete one test, and it is difficult to meet the detection demand of large scale and high efficiency; although SAE 2763 takes into account the actual influence of the dynamic running of the vehicle air conditioner and the change of the environmental temperature on the leakage, the test period is long, and the air conditioner state needs to be changed the next day during the test process, the operation process is complicated, and the test efficiency is low. SUMMARY

[0005] The present application aims to provide a quantitative vehicle air conditioner refrigerant leakage test method to solve the technical problem that the existing quantitative standard test scene is disconnected with the real use.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: a quantitative vehicle air conditioner refrigerant leakage test method, comprising: S1, estimating the total volume of the vehicle air conditioner test piece and the air conditioner test piece support by numerical simulation or size measurement V MAC , using the calibrated internal volume of the leakage test cabin V shed Subtracting V MAC to obtain the initial estimated value of the internal net volume of the leakage test cabin; S2, mounting each component of the vehicle air conditioner on the air conditioner test piece support according to the design drawing, tightening all the connecting fittings to the tightest state, and not performing the refrigerant charging operation at this time; S3, placing the assembled vehicle air conditioner test piece and its support into the leakage test cabin, injecting a known mass of refrigerant into the leakage test cabin to establish a concentration-injection mass calibration curve, and accurately calibrating the internal net volume of the leakage test cabin after installing the test piece V net ; S4, the air conditioner test piece is charged with refrigerant, and assembly leak detection, compressor running-in and steady-state permeation treatment are performed to eliminate assembly errors and make the air conditioner test piece reach the leakage state of real operation; S5, simulate the temperature cycle and working condition start-stop state of the real use of the vehicle air conditioner, and perform 48h dynamic leakage test in the leakage test chamber, collect the refrigerant concentration, temperature and pressure data during the whole test; S6, based on the net increase of refrigerant concentration in the test chamber, the refrigerant annual leakage under test conditions and the refrigerant annual leakage under real use conditions are calculated respectively to realize quantitative result output.

[0007] The principle and advantages of the scheme are: in actual application, the scheme realizes the accurate quantification of the refrigerant leakage of the vehicle air conditioner through the closed loop process of "volume accurate calibration-test piece state preprocessing-air conditioner working condition simulation-quantitative result calculation".

[0008] First, the volume of the test piece is estimated through appearance measurement and numerical simulation, and then known mass refrigerant is injected into the leakage test chamber to establish a concentration-injection mass calibration curve, accurately calibrate the net volume of the test chamber, and provide a reliable volume reference for subsequent leakage calculation.

[0009] Through refrigerant charging, assembly leak detection, high and low temperature compressor running-in and steady-state permeation treatment, the sealing parts, hoses and other components of the air conditioner test piece are brought to the aging and permeation state consistent with real use, improper assembly errors are eliminated, and it is ensured that the test results can reflect the real leakage characteristics.

[0010] Through 48 hours of temperature cycle and real working condition start-stop, the environmental temperature change and air conditioner running state in actual vehicle use are simulated, and data such as refrigerant concentration, temperature and pressure are collected to capture the dynamic leakage law.

[0011] Based on the net increase of refrigerant concentration in the test chamber, combined with temperature and pressure data and net volume, the annual leakage under test conditions is calculated, and through real working condition conversion, the annual leakage close to the actual use scene is obtained, realizing the breakthrough from qualitative to quantitative.

[0012] The traditional method can only determine whether there is leakage, and the present scheme directly outputs the annual leakage through quantitative calculation of the net increase of concentration and temperature and pressure data, meeting the quantitative demand of carbon emission reduction control and regulatory limits. The existing standard adopts static test, and the present scheme simulates the environmental temperature change and air conditioner running state in actual vehicle use through 48 hours of temperature cycle and real working condition start-stop, so that the test results are more close to the real leakage situation, avoiding the problem that the deviation of static test results from actual emissions is too large.

[0013] The scheme is designed based on the general physical and chemical principles of refrigerants, and can be adapted to multiple refrigerants such as R134a, R1234yf and R152a by calculating parameters such as relative molecular mass, saturated vapor pressure and dynamic viscosity, thereby breaking through the limitation of the existing standard which is only applicable to a single refrigerant. The existing standard requires a minimum of 7 days for testing, and the core testing process of the scheme is optimized to 48 hours of dynamic testing, thereby greatly shortening the testing period, improving the detection efficiency, and meeting the large-scale and high-efficiency industry detection requirements.

[0014] Preferably, as an improvement, the specific sub-step of calibrating the internal net volume of the leakage test cabin in step S3 comprises: S3.1, flushing the analysis equipment pipeline with high-purity nitrogen, and completing zero point and range calibration of the analysis equipment; S3.2, opening the leakage test cabin door and starting the gas purging device until the analysis equipment detects that the cabin refrigerant concentration reading is stable, closing the cabin door and continuously starting the gas mixing device, setting the cabin temperature to 20℃, and stabilizing at 20℃±1℃ for 1h~2h; S3.3, continuously measuring the cabin refrigerant concentration for not less than 10min, if the relative deviation of the reading is ≥10%, troubleshooting the analysis equipment failure or refrigerant infiltration problem; if the deviation is <10%, recording the last refrigerant concentration reading as the initial refrigerant concentration , cabin temperature , cabin pressure ; S3.4, selecting at least 5 refrigerant concentrations as calibration points, calculating the pure refrigerant mass to be injected at each calibration point according to the calibration point concentration, refrigerant relative molecular mass, cabin temperature and pressure, and initial estimated value of the net volume, and completing the injection through the airtight injector from the airtight injection port of the leakage test cabin; The refrigerant injection mass formula is:

[0015] The pure refrigerant mass to be injected at each calibration point is calculated, and the injection is completed through the airtight injector from the airtight injection port of the leakage test cabin; Wherein, is the refrigerant injection mass during the volume calibration process, g; is the relative molecular mass of the refrigerant, g / mol; is the internal volume of the leakage test cabin, ; is the estimated volume of the air conditioning test piece and its bracket, ; is the pressure in the leakage test cabin, Pa; is the net increase of the refrigerant concentration in the leakage test cabin, R is the gas constant, 8.314 J / (mol) K); T is the temperature inside the leakage test chamber, K; S3.5 After injection, continuously measure the refrigerant concentration inside the chamber for at least 10 minutes. When the deviation between the last two concentration readings is within ±10%, record the final concentration. cabin temperature cabin pressure If the absolute values ​​of the initial and final temperature and pressure deviations are within 1℃ and 200Pa respectively, calculate the net increase in concentration:

[0016] in, This represents the net increase in refrigerant concentration. This represents the final concentration of the refrigerant. This represents the initial concentration of the refrigerant. S3.6 Repeat sub-steps S3.2~3.5 to obtain the net concentration increment of all calibration points. Establish a calibration curve with the mass of injected refrigerant as the vertical axis and the net concentration increment as the horizontal axis, and calculate the slope K of the curve. S3.7, According to the calibrated internal net volume formula:

[0017] Calculate the net internal volume of the leakage test chamber after installing the test specimen, and complete the calibration; among which, The calibrated net internal volume of the leakage test chamber after the installation of the air-conditioning test components. K is the slope of the calibration curve.

[0018] The beneficial effects of this improvement are as follows: Through a closed-loop process of equipment calibration, concentration baseline establishment, multi-point injection, and curve fitting, precise calibration of the net volume inside the leak test chamber is achieved; systematic errors such as zero-point drift of the analytical equipment and residual refrigerant in the pipeline are eliminated, ensuring the accuracy of concentration measurements; and the use of at least five calibration points for curve fitting avoids the randomness of single-point calibration and improves the net volume. The accuracy and reliability of the test results are guaranteed; it provides an accurate volume benchmark for subsequent leakage calculations, ensuring the credibility of quantitative test results from the source.

[0019] Preferably, as an improvement, the specific sub-steps of the preprocessing of the vehicle air conditioning test parts in step S4 are as follows: S4.1 Remove the air-conditioning test components from the leakage test chamber, and charge the refrigerant and lubricating oil according to their rated refrigerant type and rated charge amount, and open the refrigerant flow pipeline valve; S4.2 Use a portable refrigerant leak detector to check all parts and connections of the test piece. If assembly errors or airtightness are found, reassemble or replace with qualified parts. S4.3, flush the analysis equipment pipeline with high-purity nitrogen, complete the zero point and range calibration of the analysis equipment, put the test piece and support back into the leakage test chamber, open the purging device until the concentration reading is stable, close the chamber door and continuously open the gas mixing device, and set the temperature in the chamber to 20°C; S4.4, after the temperature in the chamber is stable at 20°C±1°C for 10 minutes, measure and record the refrigerant concentration in the chamber for 1 hour continuously, and if an abnormal rapid increase in concentration occurs, reassemble or replace the parts; S4.5, keep the temperature in the chamber at 20°C±1°C, and perform compressor running-in according to low-temperature scenarios, and check for concentration abnormalities after running-in is completed; S4.6, increase the temperature in the chamber to 38°C within 2 hours at a linear rate, and after stabilizing at 38°C±1°C, perform compressor running-in operation according to high-temperature scenarios, and check for concentration abnormalities; S4.7, decrease the temperature in the chamber to 20°C within 2 hours at a linear rate, and keep the temperature at 20°C±1°C for 16-24 hours, so that the refrigerant permeation and emission of the air conditioner hose reaches a steady state, and the pretreatment is completed.

[0020] The improved beneficial effects are: through the pretreatment of charging for leak detection, high and low temperature running-in, and steady state permeation, the air conditioner test piece reaches a leakage state consistent with actual use: the charging for leak detection link can exclude assembly errors and obvious leakage points in advance, avoiding invalid testing; the high and low temperature compressor running-in simulates the operation of the air conditioner under different working conditions, making the sealing performance of components such as seals and pipe joints stable; the steady state permeation at 20°C for 16-24 hours makes the refrigerant permeation and emission of components such as air conditioner hoses balanced, ensuring that the test results reflect the true long-term leakage characteristics.

[0021] Preferably, as an improvement, the setting conditions of the low-temperature scenario and high-temperature scenario compressor running-in process in step S4.5 are: 0-1.0h, turn off the air conditioner, compressor speed 0rpm; 1.0-1.5h, turn on the air conditioner, compressor speed 2000±10rpm; 1.5-3.5h, turn off the air conditioner, compressor speed 0rpm.

[0022] The improved beneficial effects are: the typical working conditions of the air conditioner from static to operation to static are simulated, effectively promoting the fit and aging of the seals, making the leakage characteristics of the test piece closer to the actual vehicle state; avoiding test result deviations caused by differences in running-in conditions, improving the consistency and repeatability of the test.

[0023] Preferably, as an improvement, the specific sub-steps of the vehicle air conditioner refrigerant dynamic leakage test in step S5 are: S5.1 If pretreatment is completed in other sealed chambers, transfer the air-conditioning test piece to the leak test chamber where the net volume calibration has been completed; flush the analysis equipment pipelines and complete the zero point and range calibration, turn on the purging device until the concentration in the chamber is stable, close the chamber door and keep the gas mixing device running, and set the temperature in the chamber to 20°C. S5.2 After the temperature inside the chamber stabilizes at 20℃±1℃, set the 48h temperature cycle program of the leakage test chamber within 10 minutes. The temperature change shall be executed according to the preset curve, with instantaneous temperature deviation ≤±2℃ and average temperature deviation ≤1℃. S5.3 Start the temperature control program and record the initial refrigerant concentration. cabin temperature cabin pressure Let t=0 be the start time of the test. S5.4 During the test, the air conditioning test component was started at a specified time according to the real vehicle use scenario, the compressor speed was kept at 2000±10rpm, and the temperature inside the compartment changed with the temperature cycle curve. After the S5.5, 48h temperature cycle is completed, the final refrigerant concentration inside the cabin is measured and recorded within 5 minutes. cabin temperature cabin pressure .

[0024] The benefits of this improvement are: the temperature cycling program simulates the changes in ambient temperature of the vehicle throughout the day, capturing the impact of temperature on refrigerant leakage; the air conditioning is started and stopped according to real-world driving scenarios, restoring the actual operating state of the air conditioning in use, making the leakage test more representative; and the accurate collection of temperature, pressure, and concentration data provides comprehensive and reliable dynamic data support for subsequent leakage calculations.

[0025] Preferably, as an improvement, the specific sub-steps for calculating refrigerant leakage in step S6 are as follows: S6.1 Calculate the net mass of the refrigerant in the leakage test chamber after 48 hours of testing, according to the formula for the net mass of the refrigerant in the leakage test chamber. ; The formula for net mass is:

[0026] S6.2, according to the formula The net mass over 48 hours is converted into the annual refrigerant leakage under test conditions. The unit is g / y; S6.3, Set the actual operating conditions, according to the formula Calculate the annual refrigerant leakage when the air conditioner is fully turned off. The unit is g / y; in, Saturation vapor pressure of refrigerant at average temperature of month when air conditioner is off, kPa Saturation vapor pressure of refrigerant at average temperature of month when air conditioner is on, kPa Atmospheric pressure, 101.3 kPa S6.4, according to the formula Calculate the annual leakage of refrigerant under real use conditions , unit: g / y.

[0027] The beneficial effects of this improvement are: based on the net mass formula corrected by temperature and pressure, the influence of temperature and pressure changes during the test on concentration measurement is eliminated, ensuring the accuracy of 48h leakage calculation; the 48h test results are converted into annual leakage, directly meeting the annual evaluation needs of regulations and carbon emission reduction control; by distinguishing the leakage of air conditioner on / off state, the actual emission of vehicle in different seasons is more truly reflected, and the practical guiding significance of the results is improved.

[0028] Preferably, as an improvement, in 6.4, the calculation is simplified by conversion factor CF:

[0029] Then .

[0030] The beneficial effects of this improvement are: simplifying the complex two-step calculation into one-step multiplication, greatly improving the data processing efficiency; retaining the flexibility of calculation for other refrigerants, balancing efficiency and universality.

[0031] Preferably, as an improvement, in S3, S4, the temperature recording frequency is not less than 1 time / min, the pressure recording frequency is not less than 1 time / min, and the refrigerant concentration measurement frequency is not less than 1 time / 2min; and in S5, the gas mixing device is turned on throughout the process.

[0032] The beneficial effects of this improvement are: high-frequency temperature, pressure and concentration recording can accurately capture the dynamic changes during the test, avoiding the loss of key data; the gas mixing device is turned on throughout the process, ensuring the uniformity of the refrigerant concentration in the cabin and eliminating the influence of local concentration difference on the measurement results; the combination of the two effectively improves the accuracy, continuity and reliability of the test data, providing a high-quality data basis for quantitative calculation.

[0033] Preferably, as an improvement, the real use condition set in step S6.3 is: the air conditioner is turned on for 5 months from May to September each year, with an average temperature of 26.5℃, corresponding to the test conditions; the air conditioner is turned off for the remaining 7 months each year, with an average temperature of 4.0℃, and the atmospheric pressure is uniformly taken as the standard atmospheric pressure 101.3 kPa.

[0034] The improved beneficial effects are: the converted results of annual leakage amount are more in line with the actual driving habits in most regions of China, and the regional applicability of the test results is improved; the unified working condition setting ensures the comparability of the results between different vehicle models and different test institutions, facilitating industry evaluation and policy making.

[0035] Preferably, as an improvement, the temperature change of the 48h temperature cycle curve in step S5.2 is linear and smooth, gradually increasing from 20.0℃ to a peak of 35.0℃ at 0-11 hours, and then gradually falling back to 20.0℃ at 12-24 hours; and repeating the temperature rise-fall cycle at 25-48 hours. The opening period of the air conditioning test piece in step S5.4 is: 7.0-8.0h, 17.0-18.0h, 31.0-32.0h, 41.0-42.0h each for 1h, 11.5-12.0h, 36.5-37.0h each for 0.5h.

[0036] The improved beneficial effects are: the 48h temperature rise-fall cycle curve accurately simulates the environmental temperature change of the vehicle on a typical summer day, making the test conditions more close to the real use scenario; the air conditioning opening period is set in the frequent driving time period in the morning, noon and evening, restoring the real behavior of the user starting the air conditioner in the high temperature period, making the dynamic leakage test more representative; the combination of the two comprehensively covers the leakage characteristics of the air conditioner under different temperatures and operating states, so that the test results can more accurately reflect the actual emission level of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The flowchart of the embodiment of the application. DETAILED DESCRIPTION

[0038] The following will be further described in detail through specific embodiments: EMBODIMENT The leakage test related equipment includes a leakage test cabin, a gas mixing device, a gas purging device, a pressure compensation device and an air conditioning test piece support.

[0039] The leakage test cabin is a sealed box equipment, and the core function is to simulate the temperature and humidity environment of the real use of the automobile air conditioner, collect the leaked refrigerant of the air conditioning test piece, and provide a sealed and controllable test space for the leakage test; the volume is required to be ≥3 , equipped with temperature / pressure adjustment, gas mixing / purging, sampling port and other devices, and the cabin body material is non-permeable and non-reactive with refrigerant.

[0040] Gas mixing device, auxiliary device of leakage test chamber, mostly circulating fan, the role is to let the refrigerant leaked in the test chamber and air fully mixed, ensure the uniformity of refrigerant concentration in the chamber, avoid local concentration deviation leading to inaccurate analysis data, and the airflow cannot directly blow the air conditioning test piece.

[0041] Gas purging device, test chamber auxiliary device, containing fan, blower or nitrogen purging equipment, open before / after test, reduce the refrigerant concentration in the chamber to below the laboratory environment concentration, avoid the interference of residual refrigerant on subsequent test, at the same time ensure the safety of test operation.

[0042] Pressure compensation device, mostly impermeable gas expansion bag, the core role is to automatically adjust the volume of the chamber according to the temperature change in the test chamber and gas sampling operation, keep the pressure difference between the chamber and the atmosphere within ±500Pa, ensure the test in the isobaric state, eliminate the influence of pressure change on the measurement of refrigerant concentration.

[0043] Air conditioning test piece support, used to fix air conditioning compressor, evaporator, condenser and other parts, requires to ensure that the parts have no relative displacement during test, fit the installation state of real vehicle, the material is consistent with the inner wall of test chamber, impermeable and low adsorption refrigerant.

[0044] As shown in the accompanying Figure 1 , the quantitative air conditioning refrigerant leakage test method for vehicle, comprising: S1, air conditioning and support volume estimation, the total volume of air conditioning test piece and air conditioning test piece support is preliminarily estimated by numerical simulation or appearance size measurement, recorded as ; air conditioning test piece includes compressor, condenser, throttling element and other refrigerant directly flowing through the total volume of parts. V shed Provided by the equipment manufacturer.

[0045] The calibrated internal volume of the leakage test chamber Subtract , get the initial estimate of the net volume inside the leakage test chamber, provide the basis for subsequent accurate net volume calibration.

[0046] S2, air conditioning test piece assembly, install each part of air conditioning according to the design drawing on the air conditioning test piece support, tighten all the connecting fittings to the tightest state; This step does not charge refrigerant, nor connect the electrical circuit of air conditioning test piece, ensure the consistency of assembly state with real vehicle, avoid the leakage test deviation caused by assembly error.

[0047] S3, calibrate the internal net volume of the leakage test chamber, place the assembled vehicle air conditioner test piece and its bracket into the leakage test chamber, establish a concentration-injection mass calibration curve by injecting a known mass of refrigerant into the leakage test chamber, and accurately calibrate the internal net volume of the leakage test chamber after the test piece is installed The specific calibration sub-steps are as follows: S3.1, flush the analysis equipment pipeline with high-purity nitrogen to remove residual water vapor and refrigerant in the pipeline, and complete zero point and range calibration of the analysis equipment according to the manufacturer's instructions; S3.2, open the leakage test chamber door and start the gas purging device until the analysis equipment detects a stable refrigerant concentration reading in the chamber; close the chamber door and continue to start the gas mixing device, set the chamber temperature to 20℃, and stabilize at 20℃±1℃ for 1h~2h; S3.3, continuously measure the refrigerant concentration in the chamber for not less than 10min, if the relative deviation of the reading is ≥10%, troubleshoot the analysis equipment failure or refrigerant infiltration problem; if the deviation is <10%, select and record the last refrigerant concentration reading as the initial refrigerant concentration , chamber temperature , chamber pressure ; S3.4, select at least 5 refrigerant concentrations as calibration points, according to the calibration point concentration, relative molecular mass of refrigerant, chamber temperature and pressure, and initial estimated value of net volume, calculate the pure refrigerant mass required for each calibration point according to the refrigerant injection mass formula:

[0048] Calculate the pure refrigerant mass required for each calibration point according to the refrigerant injection mass formula: Wherein, is the refrigerant injection mass during the volume calibration process, g; is the relative molecular mass of the refrigerant, g / mol; is the internal volume of the leakage test chamber, ; is the estimated volume of the air conditioner test piece and its bracket, ; is the pressure in the leakage test chamber, Pa; is the net increase of refrigerant concentration in the leakage test chamber, ; R is the gas constant, 8.314 J / (mol K); T is the temperature in the leakage test chamber, K.

[0049] Taking R134a refrigerant as an example, the refrigerant concentration of the calibration point is 10 , temperature 20℃, pressure 101325Pa, the estimated value of the net volume of the cabin after installing the air conditioning test piece is 2 , the refrigerant injection mass is 0.08g.

[0050] S3.5, continuously measure the refrigerant concentration in the cabin for not less than 10 minutes after the injection is completed, and when the deviation of the last two concentration readings is within ±10%, record the final concentration , the cabin temperature , the cabin pressure ; if the absolute value of the deviation of the initial and final temperature and pressure is within 1℃ and 200Pa respectively, calculate the net increase of the concentration:

[0051] , wherein, is the net increase of the concentration of the refrigerant, is the final concentration of the refrigerant, is the initial concentration of the refrigerant.

[0052] S3.6, repeat sub-steps S3.2-S3.5 to obtain the concentration net increase of all calibration points, establish a calibration curve with the refrigerant injection mass as the vertical coordinate and the concentration net increase as the horizontal coordinate, and calculate the slope K of the curve; S3.7, calculate the internal net volume of the leakage test cabin after installing the test piece according to the calibrated internal net volume formula:

[0053] , wherein, is the calibrated internal net volume of the leakage test cabin after installing the air conditioning test piece, ; In this step, the temperature recording frequency is not less than 1 time / minute, the pressure recording frequency is not less than 1 time / minute, and the refrigerant concentration measurement frequency is not less than 1 time / 2 minutes.

[0054] S4, pretreatment of the air conditioning test piece for vehicle, refrigerant charging is carried out on the air conditioning test piece, and assembly leak detection, compressor running-in and steady-state permeation treatment are carried out to eliminate assembly errors, so that the air conditioning test piece reaches the leakage state of real operation, the specific pretreatment sub-steps are: S4.1, take out the air conditioning test piece in the leakage test cabin, complete the charging of refrigerant and lubricating oil according to the rated refrigerant type and rated injection amount, and open the refrigerant flow pipeline valve; S4.2, use a portable refrigerant leakage detector to check each component and connection of the test piece, if assembly errors or air tightness are found, reassemble or replace qualified components; S4.3 Use high-purity nitrogen to flush the analysis equipment pipeline to remove any residual water vapor and refrigerant in the pipeline, and complete the zero point and range calibration of the analysis equipment. Put the test specimen and support back into the leak test chamber, turn on the purging device until the concentration reading is stable, close the chamber door and keep the gas mixing device running, and set the temperature inside the chamber to 20°C. S4.4 After the cabin temperature stabilizes at 20℃±1℃ for 10 minutes, continuously measure and record the refrigerant concentration inside the cabin for 1 hour. If any abnormality such as a rapid increase in concentration occurs, reassemble or replace the parts. S4.5. Maintain the internal temperature at 20℃±1℃ and perform compressor break-in according to low-temperature scenarios: The settings for the low-temperature compressor break-in process include: Turn off the air conditioner from 0 to 1.0 hours; the compressor speed will be 0 rpm. Turn on the air conditioner at 1.0~1.5 hours, with the compressor speed at 2000±10 rpm; Turn off the air conditioner after 1.5 to 3.5 hours; the compressor speed will be 0 rpm. After the break-in period, check for any abnormal concentrations. S4.6. Raise the chamber temperature to 38℃ within 2 hours at a linear heating rate, stabilize it at 38℃±1℃, and then perform compressor break-in operation according to the high temperature scenario, and check for abnormal concentrations. The setting conditions for the compressor break-in process under high-temperature conditions include: Turn off the air conditioner from 0 to 1.0 hours; the compressor speed will be 0 rpm. Turn on the air conditioner at 1.0~1.5 hours, with the compressor speed at 2000±10 rpm; Turn off the air conditioner after 1.5 to 3.5 hours; the compressor speed will be 0 rpm. S4.7. Reduce the cabin temperature to 20℃ within 2 hours at a linear cooling rate, and maintain it at 20℃±1℃ for 16h~24h to allow the refrigerant permeation and discharge of the air conditioning hose to reach a steady state, thus completing the pretreatment. The temperature, pressure, and concentration recording frequency in this step are consistent with those in S3, and the pretreatment can be completed in this leak test chamber or other closed chambers with the same / similar configuration.

[0055] S5. Dynamic Leakage Test of Refrigerant for Automotive Air Conditioning: This test simulates the temperature cycle and start-stop conditions of a real automotive air conditioning system. A 48-hour dynamic leakage test is conducted in a leakage test chamber, collecting refrigerant concentration, temperature, and pressure data throughout the test. Specific test sub-steps are as follows: S5.1 If pretreatment is completed in other sealed chambers, transfer the air-conditioning test piece to the leak test chamber where the net volume calibration has been completed; flush the analysis equipment pipelines and complete the zero point and range calibration, turn on the purging device until the concentration in the chamber is stable, close the chamber door and keep the gas mixing device running, and set the temperature in the chamber to 20°C. S5.2, after the temperature in the cabin is stabilized at 20℃±1℃, set the 48h temperature cycle program of the leakage test cabin within 10min, the temperature change is executed according to the preset curve, the instantaneous temperature deviation is ≤±2℃, and the average temperature deviation is ≤1℃; In the temperature cycle curve, the temperature values of each period are specifically as follows: 0-24 hours (first cycle): 0 / 24 hours: 20.0℃; 1 hour: 20.2℃; 2 hours: 20.5℃; 3 hours: 21.2℃; 4 hours: 23.1℃; 5 hours: 25.1℃; 6 hours: 27.2℃; 7 hours: 29.8℃; 8 hours: 31.8℃; 9 hours: 33.3℃; 10 hours: 34.4℃; 11 hours: 35.0℃; 12 hours: 34.7℃; 13 hours: 33.8℃; 14 hours: 32.0℃; 15 hours: 30.0℃; 16 hours: 28.4℃; 17 hours: 26.9℃; 18 hours: 25.2℃; 19 hours: 24.0℃; 21 hours: 22.0℃; 22 hours: 20.8℃; 23 hours: 20.2℃; 24 hours: 20.0℃.

[0056] 25-48 hours (second cycle): 25 hours: 20.2℃; 26 hours: 20.5℃; 27 hours: 21.2℃; 28 hours: 23.1℃; 29 hours: 25.1℃; 30 hours: 27.2℃; 31 hours: 29.8℃; 32 hours: 31.8℃; 33 hours: 33.3℃; 34 hours: 34.4℃; 35 hours: 35.0℃; 36 hours: 34.7℃; 37 hours: 33.8℃; 38 hours: 32.0℃; 39 hours: 30.0℃; 40 hours: 28.4℃; 41 hours: 26.9℃; 42 hours: 25.2℃; 43 hours: 24.0℃; 44 hours: 23.0℃; 45 hours: 22.0℃; 46 hours: 20.8℃; 47 hours: 20.2℃; 48 hours: 20.0℃.

[0057] The temperature gradually increases from 20.0℃ to the peak value of 35.0℃ at 0-11 hours, and then gradually falls back to 20.0℃ at 12-24 hours; the complete temperature rise-fall cycle is repeated at 25-48 hours, which is used to simulate the temperature environment change of the vehicle air conditioner in actual use, and the temperature change of the 48h temperature cycle curve is linear and smooth.

[0058] S5.3, start the temperature control program, and record the initial refrigerant concentration , the temperature in the cabin , the pressure in the cabin , and mark it as the test starting time t=0; S5.4, during the test, according to the real use scenario, start the air conditioner test piece in the specified period: 7.0~8.0h、17.0~18.0h、31.0~32.0h、41.0~42.0h each open 1h, 11.5~12.0h、36.5~37.0h each open 0.5h, respectively used to simulate different time period of use of air conditioning.

[0059] When the air conditioner is turned on, the compressor speed is kept at 2000±10rpm, and the cabin temperature changes with the temperature cycle curve.

[0060] S5.5, after 48h temperature cycle, measure and record the final refrigerant concentration in the cabin within 5min , cabin temperature , cabin pressure ; The temperature and pressure recording frequency of this step is not less than 1 / min, the refrigerant concentration measurement frequency is not less than 1 / 2min, and the gas mixing device is turned on throughout the process.

[0061] S6, refrigerant leakage calculation Based on the net increase of refrigerant concentration in the test cabin, the refrigerant annual leakage under the test conditions and the refrigerant annual leakage under the real use conditions are calculated respectively to realize the quantitative result output, and the specific calculation sub-steps are: S6.1, according to the net mass formula of refrigerant in the leakage test cabin:

[0062] Calculate the net mass of refrigerant in the leakage test cabin after 48h test ; S6.2, according to formula ; convert the 48h net mass to refrigerant annual leakage under test conditions (unit: g / y); S6.3, set the real use condition: For example, in this embodiment, the air conditioner is turned on from May to September (5 months) every year, with an average temperature of 26.5℃, corresponding to the test conditions; the air conditioner is turned off for the remaining 7 months every year, with an average temperature of 4.0℃, and the atmospheric pressure is uniformly taken as the standard atmospheric pressure 101.3kPa; According to the formula:

[0063] Calculate the refrigerant annual leakage under the condition that the air conditioner is turned off (unit: g / y), wherein, is the saturated vapor pressure of refrigerant at the average temperature (4.0℃) of the month when the air conditioner is turned off, kPa; Pc = 0.1 * P * (T / 273.15) / (1 + 0.2 * (T / 273.15)) for refrigerant saturated vapor pressure at average temperature of air conditioning open months, kPa; P = 101.3 kPa for atmospheric pressure.

[0064] S6.4, according to the formula:

[0065] Calculate the refrigerant annual leakage under real use conditions (unit: g / y); also can be simplified by conversion factor CF: , then ; For R134a, R1234yf, R152a common refrigerants, directly use the preset conversion factor: R134a is 0.544, R1234yf is 0.557, and R152a is 0.543; other refrigerants calculate the conversion factor according to the conversion factor formula.

[0066] Wherein, R is the gas constant, take 8.314 J / (mol K); The relative molecular mass of the refrigerant (unit: g / mol); P is the cabin pressure (unit: Pa); T is the cabin temperature (unit: K); the concentration unit is (1 millionth volume).

[0067] Pc = 0.1 * P * (T / 273.15) / (1 + 0.2 * (T / 273.15)) for refrigerant saturated vapor pressure at average temperature of air conditioning open months, kPa; Pc = 0.1 * P * (T / 273.15) / (1 + 0.2 * (T / 273.15)) for refrigerant saturated vapor pressure at average temperature of air conditioning open months, kPa; Pc = 0.1 * P * (T / 273.15) / (1 + 0.2 * (T / 273.15)) for refrigerant saturated vapor pressure at average temperature of air conditioning open months, kPa; Pc = 0.1 * P * (T / 273.15) / (1 + 0.2 * (T / 273.15)) for refrigerant saturated vapor pressure at average temperature of air conditioning open months, kPa; Pc = 0.1 * P * (T / 273.15) / (1 + 0.2 * (T / 273.15)) for refrigerant saturated vapor pressure at average temperature of air conditioning open months, kPa; P = 101.3 kPa for atmospheric pressure; CF is the conversion factor.

[0068] The embodiment discloses a quantitative vehicle air conditioner refrigerant leakage test method, which collects refrigerant leakage through a sealed leakage test cabin, combines concentration net increment and environmental working condition conversion, realizes accurate quantitative test of vehicle air conditioner refrigerant leakage, is suitable for vehicle air conditioner refrigerant leakage test under subcritical state of R134a, R1234yf, R152a and the like, and can be expanded to refrigerant leakage quantitative test of similar refrigeration equipment such as railway vehicle air conditioner and household air conditioner The above-mentioned are only embodiments of the present application, and common technical solutions and / or common knowledge of the scheme are not described in detail. It should be pointed out that, for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, and these will not affect the effect and practicality of the patent. The protection scope claimed in the present application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A quantitative test method for refrigerant leakage in automotive air conditioning systems, characterized in that, include: S1. Estimate the total volume of the vehicle air conditioning component and its bracket through numerical simulation or dimensional measurement. The calibrated internal volume of the leakage test chamber was used. minus To obtain an initial estimate of the net internal volume of the leakage test chamber; S2. Install all components of the vehicle air conditioner onto the air conditioner component bracket according to the design drawings, and tighten all connecting parts to the tightest position. Do not charge refrigerant at this time. S3. Place the assembled vehicle air conditioning test component and its bracket into the leak test chamber. Inject a known mass of refrigerant into the leak test chamber to establish a concentration-injection mass calibration curve, and accurately calibrate the internal net volume of the leak test chamber after the test component is installed. ; S4. Charge the air conditioning unit with refrigerant, and perform assembly leak detection, compressor break-in and steady-state permeation treatment to eliminate assembly errors and bring the air conditioning unit to the actual leakage state of operation. S5 simulates the temperature cycle and start-stop conditions of a real automotive air conditioner, and conducts a 48-hour dynamic leakage test in the leakage test chamber, collecting refrigerant concentration, temperature and pressure data throughout the test. S6. Based on the net increase in refrigerant concentration in the test chamber, calculate the annual refrigerant leakage under test conditions and the annual refrigerant leakage under actual use conditions, and output quantitative results.

2. The quantitative testing method for automotive air conditioning refrigerant leakage according to claim 1, characterized in that, The specific sub-steps for calibrating the net volume inside the leakage test chamber in step S3 include: S3.

1. Use high-purity nitrogen to flush the analysis equipment pipelines and complete the zero point and range calibration of the analysis equipment; S3.2 Open the leak test chamber door, turn on the gas purging device until the analysis equipment detects that the refrigerant concentration reading in the chamber is stable, close the chamber door and continue to turn on the gas mixing device, set the chamber temperature to 20℃, and stabilize it at 20℃±1℃ for 1h~2h. S3.3 Continuously measure the refrigerant concentration inside the chamber for at least 10 minutes. If the relative deviation of the reading is ≥10%, investigate the analysis equipment for malfunction or refrigerant leakage. If the deviation is <10%, record the last refrigerant concentration reading as the initial refrigerant concentration. cabin temperature cabin pressure ; S3.4 Select at least 5 refrigerant concentrations as calibration points. Based on the calibration point concentration, refrigerant relative molecular weight, chamber temperature and pressure, and initial estimated net volume, calculate the mass of pure refrigerant to be injected at each calibration point according to the refrigerant injection mass formula. Inject the refrigerant through the airtight injection port of the leak test chamber using an airtight syringe. The formula for the injection mass of refrigerant is: Calculate the mass of pure refrigerant to be injected at each calibration point, and inject it through the airtight injection port of the leak test chamber using an airtight syringe; in, The mass of refrigerant injected during the volume calibration process, in grams; ρ represents the relative molecular mass of the refrigerant, in g / mol; The internal volume of the leak test chamber, ; Estimated volume of the test component and its support. ; The pressure inside the leakage test chamber, in Pa; This represents the net increase in refrigerant concentration within the leak test chamber. R is the gas constant, 8.314 J / (mol) K); T is the temperature inside the leakage test chamber, K; S3.5 After injection, continuously measure the refrigerant concentration inside the chamber for at least 10 minutes. When the deviation between the last two concentration readings is within ±10%, record the final concentration. cabin temperature cabin pressure If the absolute values ​​of the initial and final temperature and pressure deviations are within 1℃ and 200Pa respectively, calculate the net increase in concentration: in, This represents the net increase in refrigerant concentration. This represents the final concentration of the refrigerant. This represents the initial concentration of the refrigerant. S3.6 Repeat sub-steps S3.2~3.5 to obtain the net concentration increment of all calibration points. Establish a calibration curve with the mass of injected refrigerant as the vertical axis and the net concentration increment as the horizontal axis, and calculate the slope K of the curve. S3.7, According to the calibrated internal net volume formula: Calculate the net internal volume of the leakage test chamber after installing the test specimen, and complete the calibration; among which, The calibrated net internal volume of the leakage test chamber after the installation of the air-conditioning test components. K is the slope of the calibration curve.

3. The quantitative testing method for automotive air conditioning refrigerant leakage according to claim 2, characterized in that, The specific sub-steps of the preprocessing of automotive air conditioning test parts in step S4 are as follows: S4.1 Remove the air-conditioning test components from the leakage test chamber, and charge them with refrigerant and lubricating oil according to their rated refrigerant type and rated charge amount, and open the refrigerant flow pipeline valve; S4.2 Use a portable refrigerant leak detector to check all parts and connections of the test piece. If assembly errors or airtightness are found, reassemble or replace with qualified parts. S4.

3. Use high-purity nitrogen to flush the analysis equipment pipeline, complete the zero point and range calibration of the analysis equipment, put the test specimen and support back into the leakage test chamber, turn on the purging device until the concentration reading is stable, close the chamber door and keep the gas mixing device running, and set the temperature inside the chamber to 20℃. S4.4 After the cabin temperature stabilizes at 20℃±1℃ for 10 minutes, continuously measure and record the refrigerant concentration inside the cabin for 1 hour. If an abnormal rapid increase in concentration occurs, reassemble or replace the parts. S4.

5. Maintain the temperature inside the chamber at 20℃±1℃ and run the compressor under low temperature conditions. After the run-in is completed, check for abnormal concentrations. S4.

6. Raise the chamber temperature to 38℃ within 2 hours at a linear heating rate, stabilize it at 38℃±1℃, and then perform compressor break-in operation according to the high temperature scenario, and check for abnormal concentrations. S4.

7. Reduce the cabin temperature to 20℃ within 2 hours at a linear cooling rate, and maintain it at 20℃±1℃ for 16h~24h to allow the refrigerant permeation and discharge of the air conditioning hose to reach a steady state, thus completing the pretreatment.

4. The quantitative testing method for automotive air conditioning refrigerant leakage according to claim 3, characterized in that, In step S4.5, the settings for the compressor break-in process under both low-temperature and high-temperature scenarios are as follows: Turn off the air conditioner from 0 to 1.0 hours; the compressor speed will be 0 rpm. Turn on the air conditioner from 1.0 to 1.5 hours, with the compressor speed at 2000±10 rpm; turn off the air conditioner from 1.5 to 3.5 hours, with the compressor speed at 0 rpm.

5. The quantitative testing method for automotive air conditioning refrigerant leakage according to claim 4, characterized in that, The specific sub-steps of the dynamic leakage test of automotive air conditioning refrigerant in step S5 are as follows: S5.1 If pretreatment is completed in other sealed chambers, transfer the air-conditioning test specimen to the leak test chamber where the net volume calibration has been completed; flush the analysis equipment pipelines and complete the zero point and range calibration, turn on the purging device until the concentration in the chamber is stable, close the chamber door and keep the gas mixing device running, and set the temperature in the chamber to 20°C. S5.2 After the temperature inside the chamber stabilizes at 20℃±1℃, set the 48h temperature cycle program of the leakage test chamber within 10 minutes. The temperature change shall be executed according to the preset curve, with instantaneous temperature deviation ≤±2℃ and average temperature deviation ≤1℃. S5.3 Start the temperature control program and record the initial refrigerant concentration. cabin temperature cabin pressure Let t=0 be the start time of the test. S5.4 During the test, the air conditioning test component was started at a specified time according to the real vehicle use scenario, the compressor speed was kept at 2000±10rpm, and the temperature inside the compartment changed with the temperature cycle curve. After the S5.5, 48h temperature cycle is completed, the final refrigerant concentration inside the cabin is measured and recorded within 5 minutes. cabin temperature cabin pressure .

6. The quantitative testing method for automotive air conditioning refrigerant leakage according to claim 5, characterized in that, The specific sub-steps for calculating refrigerant leakage in step S6 are as follows: S6.1 Calculate the net mass of the refrigerant in the leakage test chamber after 48 hours of testing, according to the formula for the net mass of the refrigerant in the leakage test chamber. ; The formula for net mass is: S6.2, according to the formula The net mass over 48 hours is converted into the annual refrigerant leakage under the test conditions. The unit is g / y; S6.3, Set the actual operating conditions, according to the formula Calculate the annual refrigerant leakage when the air conditioner is fully turned off. The unit is g / y; in, The saturated vapor pressure of the refrigerant is given in kPa at the average monthly temperature when the air conditioner is fully off. Let be the saturated vapor pressure of the refrigerant at the average temperature of the month in which the air conditioner is used, in kPa; The pressure is atmospheric pressure, taken as 101.3 kPa; S6.4, according to the formula Calculate the annual refrigerant leakage under real-world operating conditions. The unit is g / y.

7. The quantitative testing method for automotive air conditioning refrigerant leakage according to claim 6, characterized in that, In section 6.4, the calculation is simplified using the conversion factor CF: but .

8. The quantitative test method for automotive air conditioning refrigerant leakage according to claim 7, characterized in that: In S3 and S4, the temperature recording frequency is no less than once per minute, the pressure recording frequency is no less than once per minute, and the refrigerant concentration measurement frequency is no less than once every 2 minutes; and in S5, the gas mixing device is always on.

9. The quantitative testing method for automotive air conditioning refrigerant leakage according to claim 8, characterized in that, The actual operating conditions set in step S6.3 are as follows: the air conditioner is turned on for 5 months from May to September each year, with an average temperature of 26.5℃, corresponding to the test conditions; the air conditioner is turned off for the remaining 7 months of the year, with an average temperature of 4.0℃, and the atmospheric pressure is uniformly taken as the standard atmospheric pressure of 101.3 kPa.

10. The quantitative testing method for automotive air conditioning refrigerant leakage according to claim 9, characterized in that, In step S5.2, the temperature change of the 48-hour temperature cycle curve is linear and smooth, gradually increasing from 20.0℃ to a peak of 35.0℃ in 0–11 hours, and then gradually decreasing back to 20.0℃ in 12–24 hours; this heating-cooling cycle is repeated in 25–48 hours. The opening time periods for the hollow test component in step S5.4 are as follows: 1 hour each from 7.0 to 8.0 h, 17.0 to 18.0 h, 31.0 to 32.0 h, and 41.0 to 42.0 h, and 0.5 hours each from 11.5 to 12.0 h and 36.5 to 37.0 h.

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