Vehicle air tightness evaluation method and system

Abstract

The invention provides a vehicle air tightness evaluation method and system, and the method comprises the steps: starting all smoke generators, reading the concentration values of first smoke sensors at different positions in a vehicle through an upper computer at a fixed time interval, and calculating the average concentration of all the concentration values; constructing a gas permeation dynamic model, and analyzing by using a variable regression analysis method to obtain a relation function between the gas tightness and the in-vehicle smoke concentration; and substituting the average concentration into the relation function to obtain an in-vehicle air tightness score. The problems that in the prior art, an inflatable method can only reflect the overall sealing performance of the automobile, and the position where the sealing defect occurs to the automobile cannot be positioned are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a vehicle air tightness assessment method and system. Background Art

[0002] The sealing of a car plays a very important role in improving vehicle safety and energy efficiency, especially for electric cars. Poor sealing of the car will reduce the cooling and heating effects of the air conditioner, thereby affecting energy efficiency. After a fire occurs in the car, a large amount of smoke will quickly enter the car and endanger driving safety. Therefore, the sealing of the car needs to be considered during the development process.

[0003] At present, most of the sealing tests on automobiles are carried out by inflation method. The sealing of the automobile is judged by filling gas into the car and detecting the change of air pressure in the car during the filling process. However, this method can only reflect the overall sealing performance of the car, but cannot reflect the change of air pressure in a local position of the car, and cannot locate the position where the sealing defects of the car occur. It has certain limitations. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a vehicle air tightness assessment method and system, which solves the problem that the inflation method in the prior art can only reflect the overall sealing performance of the vehicle but cannot locate the position where the sealing defects of the vehicle occur.

[0005] According to an embodiment of the present invention, a vehicle airtightness assessment method includes:

[0006] All smoke generators are started, and the host computer reads the concentration values ​​of the first smoke sensors installed at different positions in the vehicle at fixed time intervals, and calculates the average concentration of all concentration values;

[0007] A dynamic model of gas penetration was constructed and analyzed using multivariate regression analysis to obtain the relationship function between air tightness and smoke concentration in the vehicle.

[0008] Substitute the average concentration into the relationship function to obtain the vehicle interior air tightness score.

[0009] Preferably, the interior space of the vehicle is divided into a plurality of measuring areas, and at least one of the first smoke sensors is arranged in each measuring area.

[0010] Preferably, a corresponding weight coefficient is set for each measurement area, and when calculating the average concentration value, each concentration value in the first smoke concentration group needs to be multiplied by the corresponding weight coefficient.

[0011] Preferably, after starting the smoke generator, the host computer also controls the camera to capture the smoke image in the experimental box in real time and generate an RGB distribution map of the smoke image. After the RGB values ​​of all pixels in the RGB distribution map reach preset values, the smoke generator is turned off.

[0012] Preferably, after the smoke generator is turned off, the camera continues to capture the smoke image in the experimental box in real time, detects the position of the smoke generator in the smoke image, and generates a corresponding RGB distribution map for the smoke image, and then divides the RGB distribution map into multiple detection areas according to the position of the smoke generator.

[0013] Preferably, the host computer reads the latest generated RGB distribution map at a fixed time interval, and calculates the ratio of the number of pixels in each detection area in the RGB distribution map whose RGB value is less than a preset value to the total number of pixels in the corresponding detection area;

[0014] If the ratio is less than 90%, the smoke generator corresponding to the detection area is turned on until the RGB values ​​of all pixels in the RGB distribution map reach the preset values.

[0015] On the other hand, according to an embodiment of the present invention, a vehicle air tightness assessment system is also provided. The system adopts the above-mentioned vehicle air tightness assessment method, including a host computer, a sealable experimental box and multiple first smoke sensors, the host computer is arranged outside the experimental box, and multiple smoke generators, second smoke sensors and cameras are evenly arranged on all side walls, upper walls and lower walls of the experimental box. The first smoke sensors are all arranged inside the vehicle, and the smoke generators, first smoke sensors, second smoke sensors and cameras are all electrically connected to the host computer.

[0016] Preferably, the smoke generator generates colored smoke.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The car is placed in a sealable experimental box for experiment to avoid contact with the outside air, so as to avoid the outside heat and ensure the stability of the overall test environment. The smoke generator emits colored smoke and the cooperation of the camera and the second smoke sensor ensures that the smoke concentration in the experimental box remains unchanged. The first smoke sensor set at different positions in the car detects the change of smoke concentration in various areas of the car to reflect the sealing performance of the car at different positions and locate the position where the car has sealing defects. Then the relationship function between air tightness and smoke concentration in the car is used to evaluate the overall sealing performance of the car. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG. 4 is an architecture diagram of an evaluation system according to an embodiment of the present invention.

[0020] Figure 2The figure is a flow chart of an evaluation method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0022] like Figure 1 As shown, an embodiment of the present invention proposes a vehicle air tightness assessment system, including a host computer, a sealable experimental box and multiple first smoke sensors, the host computer is arranged outside the experimental box, the first smoke sensors are all arranged inside the vehicle, and the smoke generator, the first smoke sensor, the second smoke sensor and the camera are all electrically connected to the host computer.

[0023] The test box should be large enough and have a heat-insulating, fully sealed structure. There should be no air and heat exchange with the outside. There should only be an open door on the side. The side and upper walls of the test box should be at least 40 cm away from the position where the vehicle is placed inside. The car should be placed in a sealable test box for testing to avoid contact with the outside air, thereby avoiding heat from the outside and ensuring the stability of the overall test environment.

[0024] Multiple smoke generators, second smoke sensors and cameras are evenly arranged on all side walls, upper wall and lower wall of the experimental box. The function of the smoke generator is to produce colored smoke, which can be white, black or other easily observable colors, and the number is several.

[0025] The first smoke sensor and the second smoke sensor are used to detect the smoke concentration in the car and the experimental box respectively, the camera is used to detect the smoke distribution in the experimental box, the second smoke sensor, the smoke generator and the camera cooperate with each other, the camera detects the smoke distribution and the second smoke sensor detects the smoke concentration at the location (the two cover and verify each other), when the smoke concentration at a certain location is low, the smoke color at the corresponding location will also be relatively light, the upper computer will control the smoke generator at the corresponding location to generate smoke, so that the smoke concentration in the laboratory always remains stable, at the same time, the smoke generator emits colored smoke and the camera and the second smoke sensor cooperate to ensure that the smoke concentration in the experimental box remains unchanged, the first smoke sensors set at different locations in the car detect the changes in smoke concentration in various areas of the car, so as to reflect the sealing performance of the car at different locations and locate the location where the car has sealing defects.

[0026] On the other hand, an embodiment of the present invention further provides a vehicle air tightness assessment method, which is applied to the above-mentioned vehicle air tightness assessment system, comprising:

[0027] All smoke generators are started, and the host computer reads the concentration values ​​of the first smoke sensors installed at different positions in the vehicle at fixed time intervals, and calculates the average concentration of all concentration values;

[0028] After placing the car inside the experimental box, close the side door to seal the entire experimental box, and then send control instructions to all smoke generators through the host computer to make them start to produce colored smoke.

[0029] Afterwards, the host computer controls the camera to take real-time pictures of the smoke in the experimental box and send them back to the host computer. The host computer generates a corresponding RGB distribution map based on the smoke image and detects the RGB values ​​of all pixels in the RGB distribution map. When the RGB values ​​of all pixels in the RGB distribution map reach the preset values ​​at a certain moment, the smoke generator is turned off.

[0030] At the same time, after the smoke generator is started, the host computer reads the concentration values ​​of all first smoke sensors at a fixed time interval (generally set to 2 minutes). In addition, since smoke at different locations has different effects on the human body, the space inside the car is divided into 5 measurement areas according to height. Each measurement area is equipped with at least one first smoke sensor. The weight of each measurement area is determined by considering the following aspects:

[0031] Bottom of the car: The concentration of smoke at the bottom of the car is relatively low because smoke tends to rise, so the weight of the bottom of the car is low, ω 车底 =1.

[0032] Seat cushion: The smoke concentration at the seat cushion will not have a particularly high impact on passenger activities, so the weight can be moderate. 坐垫 =2.

[0033] Seat waist: The waist is one of the main breathing areas of passengers and should be given a higher weight. 腰部 =2.5.

[0034] Seat head: The head position is the main breathing area for passengers and should be given the highest weight. 头部 =3.

[0035] Car top: The smoke concentration at the top of the car is higher, but the direct impact on passengers is small, so the weight is moderate, ω 车顶 =1.5.

[0036] The mean concentration value is calculated as follows:

[0037]

[0038] Among them, ω i is the weight value corresponding to different measurement areas, C n is the average smoke density of the i-th first smoke density group.

[0039] After the smoke generator is turned off, the camera continues to capture the smoke image in the experimental box in real time, detects the position of the smoke generator in the smoke image, and generates a corresponding RGB distribution map for the smoke image. The RGB distribution map is then divided into multiple detection areas according to the position of the smoke generator.

[0040] The host computer reads the most recently generated RGB distribution map at fixed time intervals, and calculates the ratio of the number of pixels in each detection area in the RGB distribution map whose RGB values ​​are less than a preset value to the total number of pixels in the corresponding detection area. Since the colors of the vehicle, smoke generator and the second smoke sensor itself will affect the RGB values ​​of the corresponding pixels in the RGB distribution map, when calculating the RGB values ​​of the pixels in the RGB distribution map, certain corrections should be made to the RGB values ​​of the pixels where the vehicle, smoke generator and the second smoke sensor are located.

[0041] If the ratio is less than 90%, the smoke generator corresponding to the detection area is turned on until the RGB values ​​of all pixels in the RGB distribution map reach the preset values, so as to keep the smoke concentration in the experimental box unchanged.

[0042] A dynamic model of gas penetration was constructed and analyzed using multivariate regression analysis to obtain the relationship function between air tightness and smoke concentration in the vehicle.

[0043] According to the law of conservation of matter, the rate of change of gas in the system is equal to the inflow minus the outflow. Assuming that the gas is evenly distributed in the system, the gas permeation rate is proportional to the difference in gas concentration inside and outside. Then the gas permeation rate can be expressed as:

[0044]

[0045] According to the law of conservation of matter, the gas flow rate Q can be expressed as Q = kV. Substituting this relationship into the above formula, we get:

[0046]

[0047] Where C is the gas concentration inside the car, Cext is the smoke concentration in the experimental box, and V is the volume of the space inside the car.

[0048] Separating variables and integrating formula (3) yields:

[0049]

[0050] make Therefore, C(t) = C ext (1-e -θt )

[0051] Using multivariate regression analysis to estimate the parameter θ, we assume that we have measurement data at m time points: C(t1), C(t2)…, C(tm ), estimated by the least squares method, we get:

[0052]

[0053] Among them, the parameters An index that reflects the air tightness inside the car.

[0054] Substitute the average concentration value into the relationship function to obtain the vehicle interior air tightness score.

[0055] In the present invention, an example is taken in which there are 5 first smoke sensors in the car. A first smoke sensor is respectively provided at the bottom of the car, the seat cushion, the seat waist, the seat head and the top of the car. The interval at which the host computer reads the indication of the first smoke sensor is 2 minutes. The smoke concentration in the experimental box is fixed at 700ppm. Table 1 shows the change of smoke concentration in the car within 10 minutes.

[0056] Table 1 Changes in smoke concentration in the car

[0057]

[0058] In addition, according to Table 1, it can be seen that in the time period of 2min-8min, the smoke concentration at the waist of the seat is relatively high, indicating that the vehicle has a sealing defect at the same level as the waist of the seat. At the same time, since smoke will accumulate on the top of the car over time, and in the time period of 2min-8min, the smoke concentration at the bottom of the car is higher than the smoke concentration at the top of the car, so the vehicle also has a sealing defect at the bottom of the car.

[0059] From formula (1), we can get:

[0060] t=2, C=201, ln(1-201 / 700)=-0.338

[0061] t=4, C=371, ln(1-371 / 700)=-0.755

[0062] t=6, C=501, ln(1-501 / 700)=-1.258

[0063] t=8, C=601, ln(1-601 / 700)=-1.956

[0064] t=10, C=663.5, ln(1-663.5 / 700)=-2.958

[0065]

[0066] According to the preset airtightness Use the air tightness score comparison table to score the vehicle's air tightness.

[0067] Table 2 Air tightness Comparison table with airtightness score

[0068]

[0069] As can be seen from the above table, the vehicle's sealing performance score is 10 points.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A vehicle air tightness assessment method, characterized in that: include: All smoke generators are started, and the host computer reads the concentration values ​​of the first smoke sensors installed at different positions in the vehicle at fixed time intervals, and calculates the average concentration of all concentration values; A dynamic model of gas penetration was constructed and analyzed using multivariate regression analysis to obtain the relationship function between air tightness and smoke concentration in the vehicle. Substitute the average concentration into the relationship function to obtain the vehicle interior air tightness score.

2. A vehicle air tightness assessment method as claimed in claim 1, characterized in that: The interior space of the vehicle is divided into a plurality of measuring areas according to height, and at least one of the first smoke sensors is arranged in each measuring area.

3. A vehicle air tightness assessment method as claimed in claim 2, characterized in that: A corresponding weight coefficient is set for each measurement area. When calculating the average concentration value, each concentration value in the first smoke concentration group needs to be multiplied by the corresponding weight coefficient.

4. A vehicle air tightness assessment method as claimed in claim 1, characterized in that: After starting the smoke generator, the host computer also controls the camera to capture the smoke image in the experimental box in real time and generate an RGB distribution map of the smoke image. When the RGB values ​​of all pixels in the RGB distribution map reach the preset value, the smoke generator is turned off.

5. A vehicle air tightness assessment method as claimed in claim 4, characterized in that: After the smoke generator is turned off, the camera continues to capture the smoke image in the experimental box in real time, detects the position of the smoke generator in the smoke image, and generates a corresponding RGB distribution map for the smoke image. The RGB distribution map is then divided into multiple detection areas according to the position of the smoke generator.

6. A vehicle air tightness assessment method as claimed in claim 5, characterized in that: The host computer reads the latest generated RGB distribution map at a fixed time interval, and calculates the ratio of the number of pixels in each detection area in the RGB distribution map whose RGB value is less than the preset value to the total number of pixels in the corresponding detection area; If the ratio is less than 90%, the smoke generator corresponding to the detection area is turned on until the RGB values ​​of all pixels in the RGB distribution map reach the preset values.

7. A vehicle air tightness assessment system, characterized in that: The system adopts a vehicle air tightness assessment method as described in any one of claims 1 to 6, including a host computer, a closable experimental box and multiple first smoke sensors, the host computer is arranged outside the experimental box, and multiple smoke generators, second smoke sensors and cameras are evenly arranged on all side walls, upper walls and lower walls of the experimental box, the first smoke sensors are all arranged inside the vehicle, and the smoke generators, first smoke sensors, second smoke sensors and cameras are all electrically connected to the host computer.

8. A vehicle air tightness testing system as claimed in claim 7, wherein the smoke generator generates colored smoke.

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