System and method for detecting air tightness of whole railway vehicle

Abstract

The invention discloses an air tightness detection system for a whole railway vehicle. The air tightness detection system comprises a closed box body, a driving part, a partition plate, a pressure transmission pipe, an air storage tank, an inflation and deflation pump and a controller, the controller is configured to control the driving part to drive the movable plate to move to a specified position relative to the closed box body during static air tightness detection, so that the air pressure in the to-be-detected vehicle is close to a set value; controlling the switch valve and the proportioning valve to enable the air pressure in the to-be-tested vehicle to reach a set value; during dynamic air tightness detection, the switch valve is controlled to be opened and closed periodically, so that dynamic pressure waves are generated in the closed box body. Compared with the prior art, the gas storage tank and the switch valve are periodically opened and closed to generate high-frequency dynamic pressure waves so as to meet the requirement of dynamic gas tightness detection, the static detection function and the dynamic detection function are integrated on the same platform, and gas tightness index integrated evaluation of the whole vehicle under all working conditions is achieved. The limitation that dynamic air tightness test needs real vehicle dynamic adjustment resources is solved, and the cost of air tightness detection is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rail vehicle air tightness detection, and particularly relates to a rail vehicle whole vehicle air tightness detection system and method. BACKGROUND

[0002] The highest running speed of rail transit vehicles (especially high-speed rail) is as high as 300km / h or above, and the operation environment thereof is complex and changeable, including tunnel crossing (the pressure fluctuation outside the vehicle can reach ±6kPa / 0.5-2Hz), wide temperature range environment (-40℃~80℃), high altitude and the like. The air tightness of the vehicle directly affects the passenger comfort (such as tinnitus), equipment reliability (such as door and window abnormal sound) and sound insulation effect: low temperature can cause the hardness of the sealing rubber strip to increase by more than 30%, and high temperature can cause the elasticity thereof to decrease by more than 20%, which can both aggravate the air tightness attenuation; and the dynamic pressure fluctuation can be transmitted to the vehicle interior through the sealing defects, causing passenger discomfort. Therefore, the static and dynamic air tightness performance has become a mandatory requirement for the design, manufacture and factory inspection of rail vehicles.

[0003] Chinese patent application with publication number CN111684255A discloses a product air tightness detection device and a detection method thereof. The detection device places the measured object in a sealed container, drives the piston to move relative to the relatively sealed container to change the sealing volume of the sealed cavity, and then changes the pressure in the sealed cavity, so as to realize air tightness detection. The disadvantage of the device is that when the device is used to detect the air tightness of rail transit vehicles, although static pressure can be achieved, the response frequency is extremely low (usually <0.1Hz) due to the mechanical inertia of the large mass movable plate, and the high frequency dynamic pressure wave of 0.5-2Hz cannot be generated, so dynamic air tightness detection cannot be performed. SUMMARY

[0004] The present application provides a rail vehicle whole vehicle air tightness detection system and method to solve the technical problem that the prior art is limited by the mechanical inertia of the large mass movable plate, cannot generate a high frequency dynamic pressure wave of 0.5-2Hz, and therefore cannot perform dynamic air tightness detection.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions.

[0006] In one aspect, a rail vehicle whole vehicle air tightness detection system is provided, comprising a closed box and a driving member; one end of the closed box in the length direction is an activity plate arranged in sliding seal with the inside of the box; the driving member is connected with the outside of the activity plate, used for driving the activity plate to move relative to the closed box to change the volume of the closed box; further comprising a partition plate, a pressure transmission pipe, a gas storage tank, a gas filling and discharging pump and a controller; the partition plate is arranged opposite to the activity plate and divides the space in the box into a first space and a second space, a pressure transmission hole is formed on the partition plate, one end of the pressure transmission pipe is provided with an interface capable of communicating with the pressure transmission hole, and the other end is provided with an interface capable of communicating with the inside of the vehicle to be detected; one end of the gas filling and discharging pump communicates with the gas storage tank, and the other end communicates with the second space through a pipeline, and a switch valve and a proportional adjusting valve are arranged on the pipeline; the controller is in communication connection with the driving member, the switch valve and the proportional adjusting valve respectively.

[0007] The controller is configured to:

[0008] In static air tightness detection, the driving member is controlled to drive the activity plate to move in the direction of reducing the space inside the box to a specified position, so that the air pressure in the vehicle to be detected reaches the vicinity of the set value; the switch valve and the proportional adjusting valve are controlled to make the air pressure in the vehicle to be detected reach the set value.

[0009] In dynamic air tightness detection, the switch valve is controlled to be periodically opened and closed to generate dynamic pressure waves in the closed box.

[0010] Therefore, the present application realizes static air tightness detection through the activity plate, generates high-frequency dynamic pressure waves through the periodic opening and closing of the switch valve and the gas storage tank to meet the requirements of dynamic air tightness detection, integrates static-dynamic detection functions on the same platform, realizes integrated evaluation of air tightness indicators of the whole vehicle under all working conditions, solves the limitation of real vehicle dynamic adjustment resources required for dynamic air tightness testing, and greatly reduces the cost of air tightness detection.

[0011] In order to solve the problems of pressure attenuation, phase delay and uneven distribution caused by air flow inertia and viscous resistance when transmitting high-frequency pressure fluctuations, in some embodiments, a micro-pore array composed of a plurality of micro-pores is further formed on the partition plate; in dynamic air tightness detection, the pressure transmission hole is closed and the micro-pore array is opened; in static air tightness detection, the pressure transmission hole is opened and the micro-pore array is closed. The micro-pore array can ensure the formation of a uniform and synchronous dynamic pressure field on the surface of the vehicle.

[0012] In some embodiments, the parameter optimization method of the micro-pore array comprises:

[0013] A fluid domain model including the closed box, the partition plate provided with the micro-pore array and the outer surface of the vehicle to be detected is established;

[0014] The model is imported into a fluid dynamics simulation software, simulation parameters and boundary conditions are set, and the micro-hole array is optimized by taking the micro-hole diameter, the hole center distance, the opening rate and the hole arrangement mode as the design variables, and taking the minimum pressure value deviation, the phase difference and the attenuation rate as the optimization target to obtain the optimal parameters of the micro-hole array.

[0015] The pressure value deviation is the relative standard deviation of the pressure amplitude of the plurality of virtual pressure monitoring points on the outer surface of the vehicle to be tested; the phase difference is the phase difference between the pressure waveform of each monitoring point and the input waveform; and the attenuation rate is the attenuation rate of the side pressure amplitude of the vehicle relative to the input amplitude.

[0016] According to the above method, the optimal parameters of the micro-hole array are determined as follows: a regular triangle array, a hole diameter of 0.5 mm, a hole center distance of 0.8 mm, and an opening rate of 38%.

[0017] In some embodiments, the inside and outside of the vehicle to be tested are provided with pressure sensors, and the pressure sensors are in communication connection with the controller.

[0018] In some embodiments, a temperature sensor is arranged at the sealing rubber strip of the vehicle to be tested, and the temperature sensor is in communication connection with the controller.

[0019] A rail vehicle whole vehicle air tightness detection method applied to the rail vehicle whole vehicle air tightness detection system, comprising the following steps:

[0020] During static air tightness detection,

[0021] S11, the vehicle to be tested is placed in the second space, one end of the pressure transmission pipe is communicated with the pressure transmission hole, and the other end is communicated with the inside of the vehicle to be tested;

[0022] S12, the driving member is controlled to drive the movable plate to move to a specified position in the direction of reducing the internal space of the box, so that the air pressure in the vehicle to be tested reaches the vicinity of the first set value P1;

[0023] S13, the on-off valve and the proportional regulating valve are controlled to make the air pressure in the vehicle to be tested reach the first set value P1, and the air pressure outside the vehicle to be tested at this time is recorded ;

[0024] S14, when the air pressure in the vehicle to be tested decays to the second set value P2, the air pressure outside the vehicle to be tested at this time and the time length t required for the air pressure in the vehicle to be tested to decay from the first set value P1 to the second set value P2 are obtained;

[0025] S15, the static air tightness index of the vehicle to be tested is calculated according to P1, P2, 、 and t;

[0026] In the dynamic air tightness detection,

[0027] S21, placing the vehicle to be detected in the second space;

[0028] S22, periodically opening and closing the on-off valve to generate a dynamic pressure wave in the sealed box;

[0029] S23, obtaining the pressure inside and outside the vehicle to be detected, and calculating the dynamic air tightness index of the vehicle to be detected according to the pressure inside and outside the vehicle to be detected.

[0030] It should be noted that the calculation methods of the static air tightness index and the dynamic air tightness index are prior art.

[0031] In some embodiments, in steps S12 and S13, the air pressure in the vehicle to be detected is controlled to reach a set compensation value by driving the movable plate, the on-off valve and the proportional regulating valve, and the set compensation value is the sum of a first set value and a pressure compensation value.

[0032] The calculation method of the pressure compensation value comprises:

[0033] According to the temperature of the sealing rubber strip of the vehicle to be detected and the mapping relationship between the elastic modulus and the hardness value of the sealing rubber strip and the temperature, the elastic modulus and the hardness value of the sealing rubber strip of the vehicle to be detected at the current temperature are determined.

[0034] According to the elastic modulus and the hardness value of the sealing rubber strip of the vehicle to be detected at the current temperature and the mapping relationship between the elastic modulus and the hardness value of the sealing rubber strip and the equivalent leakage area, the equivalent leakage area of the sealing rubber strip of the vehicle to be detected at the current temperature is determined.

[0035] The pressure compensation value is determined according to the equivalent leakage area of the sealing rubber strip of the vehicle to be detected at the current temperature.

[0036] Therefore, the change of the leakage rate caused by the change of the physical properties of the sealing material due to the change of the temperature can be compensated by the pressure compensation value, so as to ensure that the pressure decay curve mainly reflects the fixed leakage defect rather than the change of the material itself when the static detection is performed at different temperatures, and the detection result is more accurate.

[0037] In another aspect, a computer device is provided, which comprises a memory, a processor and a computer program stored in the memory, and the processor executes the computer program to realize the steps of the above method.

[0038] In another aspect, a computer readable storage medium is provided, which stores a computer program or instructions, and the computer program / instructions is executed by a processor to realize the steps of the above method.

[0039] In yet another aspect, a computer program product is provided, comprising computer programs or instructions which, when executed by a processor, implement the steps of the above method.

[0040] The present application has at least the following technical effects or advantages:

[0041] 1. Static air tightness detection is realized by the movable plate, dynamic air tightness detection is realized by periodic opening and closing of the high-frequency dynamic pressure wave generated by the gas storage tank and the switch valve, static-dynamic detection functions are integrated on the same platform, integrated evaluation of air tightness indexes of the vehicle under all working conditions is realized, the limitation of real vehicle dynamic adjustment resources for dynamic air tightness testing is solved, and the cost of air tightness detection is greatly reduced.

[0042] 2. The problem of pressure attenuation, phase delay and uneven distribution caused by air flow inertia and viscous resistance when transmitting high-frequency pressure wave is solved by the micro-pore array, and uniform and synchronous dynamic pressure field on the surface of the vehicle is ensured.

[0043] 3. The change of leakage rate caused by the change of physical properties of the sealing material due to temperature change is compensated by pressure compensation, and the pressure attenuation curve mainly reflects the fixed leakage defect rather than the change of the material itself when static detection is performed at different temperatures, so that the detection result is more accurate. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 Fig. 1 is a structural schematic diagram of a rail vehicle whole vehicle air tightness detection system according to an embodiment of the present application;

[0045] Figure 2 Fig. 2 is a schematic diagram of the connection between the closed box and the gas storage tank according to an embodiment of the present application;

[0046] Figure 3 Fig. 3 is a structural schematic diagram of the partition plate according to an embodiment of the present application. DETAILED DESCRIPTION

[0047] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with the drawings in the specification and specific embodiments.

[0048] Embodiment One

[0049] Referring to Figure 1 A rail vehicle whole vehicle air tightness detection system, comprising a closed box 1, a driving member 3, a partition plate 4, a pressure transmission pipe 5, a gas storage tank 6, a gas filling and discharging pump and a controller.

[0050] The one end of the length direction of the closed box 1 is the movable plate 2 which is slidingly sealed with the inside of the box. The driving member 3 is connected with the outside of the movable plate 2, and is used to drive the movable plate 2 to move relative to the closed box 1 to change the volume of the closed box 1. The driving member 3 can be a hydraulic telescopic rod, the fixed end of which is fixed on the wall, and the movable end of which is connected with the outside of the movable plate 2. The hydraulic telescopic rod drives the movable plate 2 to move when it is extended or retracted, so as to change the volume of the closed box 1. The partition plate 4 is arranged opposite to the movable plate 2, and divides the inside of the box into the first space and the second space. The partition plate 4 is provided with the pressure transmission hole 9. One end of the pressure transmission pipe 5 is provided with the interface which can be communicated with the pressure transmission hole 9, and the other end of the pressure transmission pipe 5 is provided with the interface which can be communicated with the inside of the vehicle 8 to be tested. The pressure transmission hole 9 is essentially a through hole provided on the partition plate 4. The two ends of the pressure transmission pipe 5 are respectively provided with the quick interface. The pressure transmission hole 9 and the vehicle 8 to be tested are provided with the quick connector which is matched with the quick interface, so as to realize the communication between the pressure transmission hole 9 and the inside of the vehicle 8 to be tested. The O-shaped fluorine rubber sealing ring is embedded in the quick connector to ensure the air tightness of the connection. When the pressure transmission pipe 5 is not installed, the pressure transmission hole 9 is communicated with the outside of the vehicle 8 to be tested.

[0051] As shown in Figure 2 , one end of the gas charging and discharging pump (flow rate 0.5 m³ / s) is communicated with the gas storage tank 6 (pre-charged with 6 kPa compressed air), and the other end is communicated with the inside of the closed box 1 through the pipeline. The pipeline is provided with the on-off valve 71 and the proportional adjusting valve 72. The controller is respectively communicated with the driving member 3, the on-off valve 71 (for example, a high-speed electromagnetic valve, model: VQ110U-5LO, response time ≤ 50 ms, pressure resistance 10 kPa) and the proportional adjusting valve 72.

[0052] The controller is configured to:

[0053] During the static air tightness detection, the driving member 3 is first controlled to drive the movable plate 2 to move to the specified position in the direction of reducing the inside space of the box, so as to make the air pressure in the vehicle 8 to be tested reach the set value. Then the air pressure in the vehicle 8 to be tested is controlled to reach the set value by controlling the on-off valve and the proportional adjusting valve.

[0054] During the dynamic air tightness detection, the on-off valve is controlled to be periodically opened and closed, so as to make the closed box 1 generate the dynamic pressure wave required for detection (for example, frequency 0.5-2 Hz, amplitude ± 6 kPa).

[0055] As a preferred scheme, the partition plate 4 is further provided with the micro-pore array 41 which is composed of a plurality of micro-pores. During the dynamic air tightness detection, the pressure transmission hole is closed, and the micro-pore array is opened. During the static air tightness detection, the pressure transmission hole is opened, and the micro-pore array is closed. Specifically, the pressure transmission hole can be closed by the plug, and the micro-pore array can be arranged on the outer periphery of the pressure transmission hole. When the quick connector is connected with the pressure transmission hole, the micro-pore array is blocked by the base of the quick connector, so as to close the micro-pore array, as shown in Figure 3 .

[0056] Micro-pore array is composed of thousands of extremely tiny holes (0.5mm ± 0.05mm in diameter) arranged in a specific pattern (such as an equilateral triangle), with the design goal of achieving an optimal open area ratio (such as 38%). Its core role is to act as a high-frequency pressure conduction interface, ensuring that the dynamic pressure fluctuations generated in the main cavity can be quickly, uniformly, and without delay transmitted to the vehicle's outer surface, simulating the real pressure field around the vehicle body when the train is running in the tunnel. It focuses on the overall uniformity of the pressure field.

[0057] As a preferred solution, the parameter optimization method of the micro-pore array includes:

[0058] 1. 3D modeling and meshing

[0059] Modeling: Use CAD software (such as SolidWorks) to establish a 1:1 simplified fluid domain model containing a sealed box, a partition plate with a micro-pore array, and the outer surface of the vehicle to be tested. The vehicle model can be simplified as a standard rectangular body to reduce the amount of calculation.

[0060] Meshing: Import the model into fluid dynamics simulation software (such as ANSYS Fluent or STAR-CCM+). Perform local mesh refinement on the micro-pore area, use polyhedral mesh, and set at least 5 layers of prism layer mesh in the boundary layer near the orifice to ensure that the flow field details of the orifice are captured. The global mesh quantity should be controlled at the level of ten million to ensure the balance between calculation efficiency and accuracy.

[0061] 2. Set simulation parameters and boundary conditions

[0062] Solver settings: Choose a pressure-based transient solver, considering the compressibility of air (ideal gas model).

[0063] Turbulence model: Choose the SST model, which can better handle near-wall flow and separated flow.

[0064] Boundary conditions:

[0065] Inlet boundary (moving plate side): Set as a pressure inlet boundary condition, input the target alternating pressure waveform (such as a sine wave, frequency 0.5-2Hz, amplitude ±6kPa).

[0066] Outlet boundary (vehicle side): Set as a pressure outlet boundary condition, with an initial value of atmospheric pressure.

[0067] Wall: All walls are set as no-slip boundary conditions.

[0068] 3. Simulation calculation and optimization target

[0069] ​Start transient calculation, calculate at least 5 complete pressure fluctuation cycles to ensure stable results, optimization target:

[0070] Uniformity: Monitor the pressure values of 20 virtual pressure monitoring points arranged on the vehicle surface. The optimization target is that the relative standard deviation (RSD) of the pressure amplitude at all monitoring points is less than 5%.

[0071] Phase consistency: The phase difference between the pressure waveform of each monitoring point and the input waveform should be less than 5 degrees (or time delay < 5ms).

[0072] Amplitude attenuation: The attenuation rate of the vehicle side pressure amplitude relative to the input amplitude should be less than 3%.

[0073] 4、Optimization iteration process

[0074] Design variables: The design variables are the micro-hole diameter 0.4-0.6mm, hole center distance, opening rate 30%-45%, and hole arrangement mode (equilateral triangle, square, honeycomb, etc.).

[0075] Optimization method: Response surface optimization method (RSM) or genetic algorithm (GA) is used. By automatically running simulation cases with different parameter combinations through an automated script, a response surface model is constructed according to the above optimization targets, and automatic optimization is performed to finally determine the optimal micro-hole array geometric parameters.

[0076] 5、Verification and implementation

[0077] The optimized baffle design scheme is processed into a sample, and actual measurement is performed on the prototype platform. Real pressure sensors are arranged at key positions on the vehicle surface, and a standard fluctuation signal is input to verify whether the uniformity and response speed of the pressure field meet the simulation prediction indicators. The final optimal parameters are: equilateral triangle arrangement, hole diameter 0.5mm, hole center distance 0.8mm, and opening rate 38%.

[0078] As a preferred scheme, the inside and outside of the vehicle to be tested are provided with pressure sensors, and the pressure sensors are in communication connection with the controller, for acquiring the air pressure of the inside and outside of the vehicle to be tested.

[0079] As a preferred scheme, a temperature sensor is arranged at the sealing rubber strip of the vehicle to be tested, and the temperature sensor is in communication connection with the controller. Further, the sealed box 1 is also provided with a temperature adjusting system.

[0080] Embodiment two

[0081] A rail vehicle whole vehicle air tightness detection method applied to the above-mentioned rail vehicle whole vehicle air tightness detection system, comprising the following steps:

[0082] When detecting static air tightness,

[0083] S11, placing the vehicle to be tested in the second space, and connecting one end of the pressure transmission pipe to the pressure transmission hole and the other end to the interior of the vehicle to be tested;

[0084] S12, controlling the driving member to drive the movable plate to move to a specified position in a direction of reducing the interior space of the box, so that the air pressure in the vehicle to be tested reaches a first set value P1;

[0085] S13, controlling the on-off valve and the proportional regulating valve, so that the air pressure in the vehicle to be tested reaches the first set value P1 (e.g. 6000 Pa), and recording the air pressure outside the vehicle to be tested at this time ;

[0086] S14, when the air pressure in the vehicle to be tested decays to a second set value P2 (e.g. 1000 Pa), obtaining the air pressure outside the vehicle to be tested at this time and the time length t required for the air pressure in the vehicle to be tested to decay from the first set value P1 to the second set value P2;

[0087] S15, calculating the static air tightness index of the vehicle to be tested according to P1, P2, 、 and t, and the calculation formula is as follows:

[0088] ;

[0089] In dynamic air tightness detection,

[0090] S21, placing the vehicle to be tested in the second space;

[0091] S22, controlling the on-off valve to periodically open and close, so that dynamic pressure waves are generated in the sealed box;

[0092] S23, obtaining the air pressure inside and outside the vehicle to be tested, and calculating the dynamic air tightness index of the vehicle to be tested according to the air pressure inside and outside the vehicle to be tested.

[0093] Step S23 specifically includes:

[0094] Step one: data preprocessing and alignment

[0095] Down-sampling: down-sampling the air pressure data p i (t) (500 Hz) to the same frequency (100 Hz) as the air pressure data p e (t) to simplify subsequent calculations.

[0096] Filtering: low-pass filtering (e.g. using a Butterworth filter with a cutoff frequency of 10 Hz) the data pe(t) and pi(t), to retain low-frequency pressure changes reflecting air tightness, while filtering out high-frequency mechanical vibrations, electrical signal noise and other interference.

[0097] Data alignment: Ensure the data of two channels are completely aligned in time axis.

[0098] Step two: Calculate the instantaneous differential pressure

[0099] At each time point, directly subtract the pre-processed pressure values inside and outside the vehicle:

[0100] Thus, a curve of instantaneous differential pressure changing with time is obtained .

[0101] Step three: Calculate the rate of change of pressure inside the vehicle ;

[0102] The rate of change of pressure is the derivative of pressure with respect to time, which needs to be estimated from discrete data by numerical differentiation.

[0103] Calculation method: Central difference method, which is a high-precision numerical differentiation method. For the rate of change of pressure at time point, the calculation formula is:

[0104] ;

[0105] Where, is the sampling time interval of the pressure sensor (unit: s), is the pressure value inside the vehicle body collected at time (unit: Pa), is the pressure value inside the vehicle body collected at time (unit: Pa), obtained by measuring the pressure inside the vehicle body.

[0106] Subsequent smoothing: Numerical differentiation will amplify the noise in the data. Therefore, the calculated sequence needs to be filtered again by moving average (such as window size of 5 data points) to obtain a smooth and reliable pressure rate curve.

[0107] Step four: Calculate the instantaneous dynamic air tightness index

[0108] At each time point, substitute the results obtained in steps two and three into the formula:

[0109]

[0110] Thus, a curve of instantaneous dynamic air tightness index changing with time is obtained.

[0111] Step five: Extract the final result

[0112] ​The dynamic air tightness test usually lasts for several pressure fluctuation periods (e.g. > 30 seconds). The final vehicle dynamic air tightness index Instead of taking data from a single moment, the average of the whole curve obtained in step four is taken in one or more complete periods.

[0113] This processing method can eliminate accidental errors of single-point data, and make the results more representative and stable.

[0114] As a preferred solution, in steps S12 and S13, the air pressure in the vehicle to be tested is controlled to reach a set compensation value by driving the driving member to drive the movable plate, the on-off valve and the proportional regulating valve, and the set compensation value is the sum of a first set value and a pressure compensation value;

[0115] The calculation method of the pressure compensation value includes:

[0116] According to the temperature of the sealing rubber strip of the vehicle to be tested and the mapping relationship between the elastic modulus and the hardness value of the sealing rubber strip and the temperature, the elastic modulus and the hardness value of the sealing rubber strip of the vehicle to be tested at the current temperature are determined;

[0117] According to the elastic modulus and the hardness value of the sealing rubber strip of the vehicle to be tested at the current temperature, and the mapping relationship between the elastic modulus and the hardness value of the sealing rubber strip and the equivalent leakage area, the equivalent leakage area of the sealing rubber strip of the vehicle to be tested at the current temperature is determined.

[0118] The pressure compensation value is determined according to the equivalent leakage area of the sealing rubber strip of the vehicle to be tested at the current temperature.

[0119] Specifically, the method for obtaining the pressure compensation value includes:

[0120] 1. Establish a sealing material property database

[0121] The elastic modulus and hardness (Shore A) of the sealing rubber strip used in the door and window components are measured by a material testing machine (such as a dynamic mechanical analyzer DMA) at intervals of 10°C in the temperature range of -40°C to 80°C, and a look-up table is formed or an empirical formula of the material parameters with respect to temperature T is fitted (such as E(T) = a + b*T + c*T², a, b, and c are fitting constants).

[0122] 2. System modeling and pressure compensation feedforward

[0123] Based on the ideal gas state equation and fluid mechanics, a system leakage model is established, and the leakage rate can be represented as

[0124] In the formula, is the leakage rate, is a constant, is the pressure difference, A0is the equivalent leakage area, which is a function of the hardness and compression of the sealing material, and the hardness is a function of temperature T.

[0125] To maintain the same initial leakage rate at different temperatures (to ensure that the pressure decay curve only reflects the fixed leakage defect, not the fluctuation of material performance), the change of A (T) needs to be offset by adjusting the pressure compensation value:

[0126] Set the initial pressurization target value at room temperature (such as 25°C) as P1 (such as 6000 Pa), the corresponding equivalent leakage area is A0, and the leakage rate is (P0 is atmospheric pressure);

[0127] When the temperature changes to T, the equivalent leakage area becomes A (T), and if the original target pressure P1 is still used, the leakage rate will become , which deviates from the target leakage rate Q0;

[0128] To make Q(T)=Q0, the pressure compensation value needs to be adjusted to P1'=P1+ , and by substituting into the leakage model, we get:

[0129]

[0130] After simplifying, the pressure compensation value can be calculated, which needs to be derived from A (T) (derived from E (T)) and the change in pressure difference, and cannot be directly obtained by temperature table lookup.

[0131] Therefore, in order to maintain the same initial leakage rate at low temperature (the rubber strip becomes hard, and the equivalent leakage area A increases), the initial pressurization target value P1 needs to be compensated (such as increasing from 6000 Pa to 6050 Pa).

[0132] 3. Real-time control execution process

[0133] Step 1: After adjusting the temperature to the target temperature, obtain the real-time average temperature T of each sealing rubber strip of the vehicle.

[0134] Step 2: Call the material database, and according to the current temperature T, look up or calculate the elastic modulus and hardness of the material, and further calculate the required pressure compensation value and active plate displacement compensation amount .

[0135] Step 3: In the static pressurization stage, the driving part 3 drives the active plate 2 to move. Its target displacement is no longer a fixed value, but . Its movement rate PID control is adopted, but the set point is fine-tuned according to the feedback of the real-time pressure sensor to ensure the pressure to rise smoothly to , and the controller also makes the pressure in the vehicle to be tested rise smoothly to by controlling the on-off valve and the proportional regulating valve.

[0136] The displacement change of the movable plate directly changes the volume of the closed box, which in turn affects the pressure in the cavity: the displacement decreases (the volume is compressed) and the pressure rises, and the displacement increases (the volume expands) and the pressure decreases. The correlation between the two is derived based on the following parameters:

[0137] The cross-sectional area S of the closed box (determined by the width 3.5m and the height 3m of the closed box, S=10.5m²);

[0138] The displacement change ΔL of the movable plate;

[0139] The initial volume V0 of the closed box (200m³);

[0140] The gas compression coefficient (based on the ideal gas equation of state, which is approximately constant at normal temperature and pressure).

[0141] The relationship between the pressure change ΔP and the displacement change ΔL can be simplified as:

[0142] ΔP=k·(ΔL·S) / V0

[0143] In the formula, k is a proportional constant determined by the characteristics of the gas and the sealing characteristics of the main cavity.

[0144] Substitute the pressure compensation value calculated in the foregoing into the above formula, and the required displacement compensation amount ΔL of the movable plate can be deduced:

[0145] ΔL= ( ·V0) / (k·S)

[0146] Finally, the target displacement of the sealing movable plate is (ΔL0 is the basic displacement at normal temperature), which ensures that the pressurization process accurately reaches the compensated target pressure P1+ .

[0147] Step 4: After the pressurization is completed, enter the decay monitoring stage. At this time, because the leakage area has been compensated, the measured pressure decay curve can more truly reflect the inherent leakage defects of the vehicle that do not change with temperature.

[0148] Since the "equivalent leakage area A" cannot be directly calculated theoretically from the elastic modulus E and the hardness H, because it not only depends on the properties of the material itself (E, H), but also extremely depends on the specific structure of the sealing system (such as the cross-sectional shape of the sealing strip, the compression amount, the roughness of the contact surface, etc.).

[0149] Therefore, the present application directly measures the leakage amount under a specific working condition by designing a controllable leakage test, and then inversely calculates the "equivalent leakage area A" under the working condition according to the leakage model, so as to pair each group of (E, H) data points with a measured A value. Through a large number of such (E, H, A) data pairs, the data basis for constructing the mapping relationship is formed.

[0150] I. Data acquisition: special test and data collection

[0151] 1. Test object: prepare hundreds of special sealing strips for rail vehicles covering different formulations and different aging degrees, as well as the real vehicle door and window mounting frames matched therewith.

[0152] 2. Performance parameter measurement: use a material testing machine (such as DMA) and a hardness tester to measure the elastic modulus E(T) and the hardness H(T) of each sample at a temperature interval of -40°C to 80°C (every 10°C). This provides the input dimension of the mapping relationship.

[0153] 3. Leakage test and A value inversion: install the sealing strip sample on the test tool to form a closed cavity with a known volume V.

[0154] At a specific temperature T, inflate the cavity to a standard pressure difference ΔP (such as 6000 Pa).

[0155] Monitor the time Δt for the pressure to decay from ΔP1 to ΔP2.

[0156] According to the static air tightness decay formula (i.e. the leakage formula derived from the ideal gas state equation), directly calculate the leakage rate Q_leak under the working condition.

[0157] Substitute Q_leak into the leakage model described in the patent.

[0158] Since Q_leak and ΔP are known, the constant C can be determined by calibration, so the equivalent leakage area A under the current temperature T and the current material state can be inversely calculated. This A value is the target value corresponding to the currently measured E(T) and H(T).

[0159] 4. Data scale: repeat the test at different temperature points for each sample, and finally accumulate 1000+ groups of effective (E, H, A) data triples.

[0160] II. Model Building: From Data Triples to Mapping Model

[0161] After obtaining massive data, find a function relationship in three-dimensional space (E, H, A) that best fits all these data points, i.e. A = f(E, H).

[0162] 1. Relationship Property Analysis: A and E, H are negatively correlated (E increases / hardness increases, usually leading to poor sealing, A increases). But its specific relationship is nonlinear, and E and H themselves also have strong correlation (collinearity).

[0163] 2. Modeling Method Selection: Response Surface Method (RSM) and Regression Analysis. Take A as the response variable, E and H as independent variables. Use statistical software (such as Minitab, Design-Expert) to perform multivariate nonlinear regression analysis on the data, and the model is a quadratic polynomial: A = β0 + β1*E + β2*H + β3*E² + β4*H² + β5*E*H + ε

[0164] Where β0~β5 are coefficients fitted by regression, and ε is the error term. The software will automatically evaluate the significance of the model and optimize the coefficients.

[0165] 3. Model Validation and Integration: The final fitted regression equation is integrated into the controller in the form of code or lookup table. During actual detection, the system only needs to input the real-time queried E(T) and H(T), and the predicted equivalent leakage area A(T) can be calculated through the model.

[0166] Example Three

[0167] A computer-readable storage medium having stored thereon a computer program or instructions, which, when executed by a processor, implement the steps of the above method.

[0168] Example Four

[0169] A computer program product comprising a computer program or instructions, which, when executed by a processor, implement the steps of the above method.

[0170] In the specification provided herein, a large number of specific details are described. However, it can be understood that embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail in order not to obscure the understanding of the present specification.

[0171] Similarly, it is to be understood that the embodiments of the present application can be alternately grouped together in a single embodiment, figure, or description of embodiments, for the purpose of brevity in the foregoing detailed description of the illustrative embodiments. However, it is not the intention of the disclosure to reflect only the features of the preferred embodiments rather the intention is to cover all alternative embodiments and modifications that can come within the scope of the present application as defined by the claims. Thus, the following claims are in no way intended to limit the scope of the present application to the specific embodiments described above. In addition, any combination of the above-described elements in all possible variations thereof is encompassed by the application unless otherwise indicated herein or otherwise clearly contradicted by context.

[0172] Those skilled in the art will understand that the modules, or units, or groups of elements in the examples disclosed herein can be arranged in a device as described in the examples, or can be located in one or more devices that are different from the device in the examples. The modules in the foregoing examples can be combined into a single module or further divided into multiple sub-modules.

[0173] Those skilled in the art will understand that the modules in the device in the examples can be adaptively changed and arranged in one or more devices different from the examples. The modules or units or groups in the examples can be combined into a module or unit or group, and further can be divided into multiple sub-modules or sub-units or sub-groups. Except that at least some of such features and / or processes or units are mutually exclusive, all combinations of all features disclosed in this specification (including the accompanying claims, abstract and drawings), and all processes or units of any methods or apparatuses so disclosed are encompassed by the present application. Each feature disclosed in this specification (including the accompanying claims, abstract and drawings) can be replaced by alternative features providing the same, equivalent, or similar functionality without departing from the scope of the application.

[0174] Further, those skilled in the art will understand that the combination of features of different embodiments means within the scope of the application and forms different embodiments, although some of the examples described herein include certain features included in other examples but not others.

[0175] Further, some of the examples described herein are combinations of methods or method elements, implemented by or with the aid of a processor of a computer system or other apparatus for performing the described functions. Thus, a processor with the necessary instructions for performing such methods or element of a method forms a means for implementing the method or element of a method. Further, an element of a method described herein functions as a means for implementing a function performed by an element of the method for the purpose of performing the invention.

[0176] The various techniques described herein can be implemented in connection with hardware or software or, where appropriate, with a combination of both. Thus, the methods and apparatus of the present application, or certain aspects or portions thereof, can take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the subject application.

[0177] Where the program code is executed in a machine, such as a computer, the computing device generally includes a processor, a storage medium readable by the processor (including volatile and non-volatile memory and / or storage elements), at least one input device, and at least one output device. The storage medium is configured to store program code whose execution implements the methods of the present application. One will appreciate that the methods of the present application can be practiced by combining program code stored on computer-readable media with appropriate virtual or physical equipment, such as a computer system.

[0178] Computer readable media includes computer storage media and communication media. Computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer readable media tangibly embodied in an information carrier excludes signals per se. Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. Combinations of the any of the above are also included within the scope of computer readable media.

[0179] As used herein, unless otherwise specified, the use of the ordinal adjectives "first," "second," "third," etc., merely to distinguish different instances of an object, and does not imply a time, spatial, ranking, or any other kind of

[0180] Although the application has been described in connection with limited number of embodiments, it will be evident for a person skilled in the art that many modifications and variations can be made thereto without departing from the scope of the application as set forth in the claims. Furthermore, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes and can not have been selected to expressly delimit the subject matter of the application. Thus, the scope of the application is indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalents are intended to be embraced therein. The disclosure is illustrative of the application and is not intended to be limiting of the scope of the application as defined by the appended claims.

[0181] Finally, it is to be understood that the application is not limited in its application to the details of the construction and the arrangement of the components set forth in the description or illustrated in the drawings. The application is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and not of limitation.

Claims

1. A rail vehicle airtightness testing system, comprising a sealed enclosure and a drive unit; one end of the sealed enclosure along its length is a movable plate that is slidably sealed to the interior of the enclosure; the drive unit is connected to the outside of the movable plate and is used to drive the movable plate to move relative to the sealed enclosure to change the volume of the sealed enclosure; further comprising a partition, a pressure transmission pipe, an air storage tank, a charging / discharging pump, and a controller; the partition is disposed opposite to the movable plate and divides the internal space of the enclosure into a first space and a second space, the partition has a pressure transmission hole, one end of the pressure transmission pipe has an interface that can communicate with the pressure transmission hole, and the other end has an interface that can communicate with the interior of the vehicle under test; one end of the charging / discharging pump is connected to the air storage tank, and the other end is connected to the second space through a pipeline, the pipeline has a switching valve and a proportional regulating valve, and the controller is communicatively connected to the drive unit, the switching valve, and the proportional regulating valve respectively; The controller is configured as follows: During static air tightness testing, the control drive unit drives the movable plate to move in the direction of reducing the internal space of the chamber to a designated position so that the air pressure inside the vehicle under test reaches a set value; the control switch valve and proportional adjustment valve are used to make the air pressure inside the vehicle under test reach the set value. During dynamic airtightness testing, the control valve is periodically opened and closed to generate dynamic pressure waves inside the sealed chamber.

2. The system for detecting the air tightness of the whole rail vehicle according to claim 1, characterized in that: The partition plate is also provided with a micropore array consisting of multiple micropores; during dynamic airtightness testing, the pressure transmission hole is closed and the micropore array is open; during static airtightness testing, the pressure transmission hole is open and the micropore array is closed.

3. The system for detecting the air tightness of the whole rail vehicle according to claim 2, characterized in that: The parameter optimization method for the micropore array includes: A fluid domain model was established, including a sealed enclosure, a partition with a microporous array, and the outer surface of the vehicle under test. The above model was imported into fluid dynamics simulation software, simulation parameters and boundary conditions were set, and the micropore diameter, pore center distance, porosity and pore arrangement were used as design variables. The optimization objectives were to minimize pressure deviation, phase difference and attenuation rate, so as to obtain the optimal parameters of the micropore array. Wherein, the pressure value deviation is the relative standard deviation of the pressure amplitude at multiple virtual pressure monitoring points on the outer surface of the vehicle under test; the phase difference is the phase difference between the pressure waveform at each monitoring point and the input waveform; and the attenuation rate is the attenuation rate of the vehicle-side pressure amplitude relative to the input amplitude.

4. The system for detecting the air tightness of the whole rail vehicle according to any one of claims 1-3, characterized in that: The vehicle under test is equipped with pressure sensors both inside and outside, and the pressure sensors are communicatively connected to the controller.

5. The system for detecting the air tightness of the whole rail vehicle according to any one of claims 1-3, characterized in that: A temperature sensor is installed at the sealing strip of the vehicle under test, and the temperature sensor is communicatively connected to the controller.

6. A method for detecting the air tightness of a whole rail vehicle, applied to the rail vehicle air tightness detection system according to any one of claims 1-5, characterized in that, Includes the following steps: During static airtightness testing, S11. Place the vehicle to be tested in the second space, connect one end of the pressure transmitting tube to the pressure transmitting hole, and connect the other end to the interior of the vehicle to be tested. S12. Control the drive unit to drive the movable plate to move in the direction of reducing the internal space of the box to the designated position, so that the air pressure in the vehicle under test reaches the first set value P1. S13, control the on-off valve and the proportional regulating valve to make the air pressure in the vehicle to be tested reach a first set value P1, and record the air pressure outside the vehicle to be tested at this time ; S14, when the air pressure in the vehicle to be tested attenuates to the second set value P2, obtaining the air pressure outside the vehicle to be tested at this time and the time length t required for the air pressure in the vehicle to be tested to attenuate from the first set value P1 to the second set value P2; S15. According to P1, P2, , and t to calculate the static air tightness index of the vehicle to be tested; During dynamic airtightness testing, S21. Place the vehicle to be tested in the second space; S22. Control the periodic opening and closing of the switch valve to generate dynamic pressure waves inside the sealed box; S23. Obtain the interior and exterior pressures of the vehicle under test, and calculate the dynamic airtightness index of the vehicle under test based on the interior and exterior pressures.

7. The method for detecting the airtightness of a rail vehicle as described in claim 6, characterized in that, In steps S12 and S13, the moving plate, the switching valve and the proportional regulating valve are driven by the control drive component to make the air pressure in the vehicle under test reach the set compensation value. The set compensation value is the sum of the first set value and the pressure compensation value. The method for calculating the pressure compensation value includes: Based on the temperature of the sealing strip of the vehicle under test and the mapping relationship between the elastic modulus and hardness value of the sealing strip and temperature, the elastic modulus and hardness value of the sealing strip of the vehicle under test at the current temperature are determined. Based on the elastic modulus and hardness values ​​of the sealing strip of the vehicle under test at the current temperature, and the mapping relationship between the elastic modulus and hardness values ​​of the sealing strip and the equivalent leakage area, the equivalent leakage area of ​​the sealing strip of the vehicle under test at the current temperature is determined. The pressure compensation value is determined based on the equivalent leakage area of ​​the sealing strip of the vehicle under test at the current temperature.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method of claim 6 or 7.

9. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method described in claim 6 or 7.

10. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method described in claim 6 or 7.

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