A bench simulation test and analysis method for dynamic sealing performance of automobiles

Abstract

The present invention discloses a bench simulation test and analysis method for the dynamic sealing performance of an automobile. The method obtains the pressure distribution diagram of the flow field outside the vehicle body of the vehicle to be tested on a specific road section based on simulation software, and determines the positions of various leakage points on the windows and doors through the pressure distribution diagram of the flow field outside the vehicle body, and each leakage point position is the test point position; the vehicle to be tested is fixed on a four-column bench and pressurized into its cockpit at the same time, and the four-column bench simulates the road surface excitation of the vehicle to be tested on the specific road section, and the pressure difference between the inside and outside of the vehicle to be tested is the pressure difference formed when the vehicle to be tested actually drives on the specific road section; a sound source is placed in the cockpit, and the size of the sound source leakage at each test point position is tested based on a sound source leak detector; the structural design of the sealing strip is optimized based on the sound source leakage at the test point position. The present invention can simulate the actual environment where wind noise occurs, efficiently analyze the dynamic sealing performance of the automobile, and has low cost and is easy to operate.

Description

Background Art

[0002] When a car is driving at high speed, it usually produces obvious wind noise, which makes passengers feel uncomfortable. The wind noise heard inside the car is directly related to the exterior shape of the car body and the sealing and sound insulation performance of the door opening parts. The sealing performance of the door plays a key role. The sealing performance of the door is easy to evaluate through sound insulation testing under static conditions, but when the car is driving at high speed, there is a pressure difference between the inside and outside of the car, which causes the sealing performance of the door to decrease. At the same time, the vibration of the car body at high speed will also cause the door to deform and cause changes in the sealing performance, making it difficult to evaluate the sealing performance of the door at high speed.

[0003] The current test method for evaluating the sealing performance of vehicle doors is mainly carried out in an acoustic wind tunnel. The vehicle is fixed and the wind tunnel simulates a wind speed of 100 to 140 km / h. However, the test cost is relatively high (about 200,000 yuan per day) and cannot simulate the vibration impact of the vehicle body under high-speed dynamic conditions.

[0004] The specification of Chinese invention patent CN104132817B discloses a detection method for a dynamic intelligent detection platform for the external characteristics of motor vehicles. The detection platform is used to simulate the actual driving of motor vehicles, with various speed and load changes, and different road surface docking, opening and other conditions, to quickly complete all indicators of external characteristics such as axle weight, side slip, high and low speed braking, power, fuel consumption, exhaust emissions, sealing, headlights, turn signals, fog lights, markers and appearance contours at one time, and form a graphical curve, which is uploaded to the network as a public data resource for social sharing. Since the endogenous factors of the vehicle itself are excluded, it is possible to measure ABS, EBD, ESP, and cruise control systems. A unified standard for judging the external characteristics of motor vehicles is formulated in the automotive industry chain, and external characteristics detection is carried out in the links of research and development, factory inspection, in-use vehicle inspection, maintenance and repair, etc., which has made a historic breakthrough in site, time, mode and management. It provides a standard for the Internet of Things, public safety, and automotive energy conservation and environmental protection worldwide.

[0005] The specification of Chinese utility model patent CN2874457Y discloses a comprehensive test bench for the sealing performance of the passenger cabin of a passenger car and the air volume of the vehicle air conditioner, which is composed of a variable frequency fan, a circulation pipeline, a large flow pipeline and a small flow pipeline. The small flow pipeline is connected in parallel with the large flow pipeline. A large valve and a large flow meter are arranged in the large flow pipeline, and a small valve and a small flow meter are arranged on the small flow pipeline. The inlet end of the large flow pipeline is connected to the air outlet of the variable frequency fan. An air intake pipeline is connected to the air inlet of the variable frequency fan, and the circulation pipeline is arranged between the air intake pipeline and the large flow pipeline. The utility model uses the air outlet of the variable frequency fan to supply air to the vehicle cabin, and can measure the sealing performance of the cabin by detecting the air supply flow rate and the vehicle cabin pressure; the suction and pumping action of the variable frequency fan is used to offset the pipeline resistance and the resistance of the flow meter, so that the air conditioner is in a normal back pressure, and the air volume of the vehicle cabin air conditioner can be accurately measured.

[0006] Comparative Document 1 (CN104132817B) can utilize a detection platform to simulate a motor vehicle in actual driving, with various speeds and load changes and docking on different road surfaces. Comparative Document 2 (CN2874457Y) discloses a structure and method for statically testing the sealing performance of a passenger car cabin. However, the combination of Comparative Document 1 and Comparative Document 2 does not provide any technical inspiration for the present invention. The difficulty in testing the dynamic sealing performance of a vehicle based on a test bench lies in accurately obtaining the leakage test points of the vehicle, because the leakage points when the vehicle is in driving state are completely different from the leakage points when the vehicle is stationary. If the leakage test is performed directly using the test points in the stationary state under a dynamic test environment, the leakage data of the vehicle cannot be accurately simulated, thereby failing to accurately guide the direction of optimizing the design structure of the door and sealing strip and improve the high-speed dynamic sealing performance of the vehicle. Summary of the invention

[0007] In view of the technical problems existing in the prior art, the present invention provides a bench simulation test and analysis method for the dynamic sealing performance of an automobile, which can simulate the environment in which actual wind noise occurs, use ultrasound to detect leaks at various leakage points, and can efficiently analyze the dynamic sealing performance of the automobile. It is low-cost and easy to operate.

[0008] The invention discloses a bench simulation test and analysis method for the dynamic sealing performance of an automobile. The method comprises the following steps: obtaining a pressure distribution diagram of an external flow field of a vehicle body of a test vehicle on a specific road section based on simulation software, and determining the positions of various leakage points on windows and doors of the test vehicle through the pressure distribution diagram of the external flow field of the test vehicle, wherein each leakage point position is a test point position; fixing the test vehicle on a four-post bench and applying pressure to a cockpit thereof at the same time, the four-post bench simulating road surface excitation of the test vehicle on the specific road section, and the pressure difference between the inside and outside of the test vehicle is the pressure difference formed when the test vehicle actually drives on the specific road section; placing a sound source in the cockpit, and testing the size of the sound source leakage at each test point position based on a sound source leak detector; and optimizing the structural design of the sealing strip based on the sound source leakage at the test point position.

[0009] In a preferred embodiment of the present invention, a method for determining the positions of various leakage points on the windows and doors of a vehicle to be tested based on a pressure distribution diagram of the flow field outside the vehicle body includes: selecting test point positions located at the edge of the door frame and the edge of the window; selecting test point positions with a pressure between -2300 and 100 Pa; and the interval between any two adjacent test point positions is 200 mm.

[0010] In a preferred embodiment of the present invention, a method for obtaining road surface excitation of the vehicle to be tested on the specific road section includes: attaching four three-dimensional vibration acceleration sensors to the front and rear wheels of the vehicle to be tested respectively, and connecting the three-dimensional vibration acceleration sensors to an LMS data acquisition device, with a vibration acquisition frequency of 4000 Hz, driving the vehicle to be tested at a speed of 140 km / h on the specific road section to collect road surface excitation signals, and the collection time is 20 s.

[0011] In a preferred embodiment of the present invention, the leakage test device pressurizes the cockpit of the vehicle to be tested, and the pressure difference between the inside and the outside is 70-110Pa.

[0012] In a preferred embodiment of the present invention, the leakage test device comprises a pressure gauge, a blower and an air blast duct, and the air blast duct is sealed and connected to an opening on a sunroof or a side window of the vehicle to be tested.

[0013] In a preferred embodiment of the present invention, when the four-post test bench is not working, the vehicle is in a stationary condition, a sound source is placed in the cockpit, and the sound source leakage amount Q1 of each test point position under the stationary condition is tested based on the sound source leak detector; when the four-post test bench is working, the vehicle is in a simulated condition, a sound source is placed in the cockpit, and the sound source leakage amount Q2 of each test point position under the simulated condition is tested based on the sound source leak detector, and the leakage change difference is calculated, Δ=Q2-Q1.

[0014] In a preferred embodiment of the present invention, a method for testing the size of the sound source leakage at each test point based on a sound source leak detector includes: S1, placing the sound source at the front shift handle, and testing the size of the sound source leakage at each test point on the front door frame and the front window; S2, placing the sound source in the middle of the rear seats, and testing the size of the sound source leakage at each test point on the rear door frame and the rear window.

[0015] In a preferred embodiment of the present invention, when Δ corresponding to the test point position is less than 3, the dynamic seal at the test point position is qualified; if Δ corresponding to the test point position is greater than 3, the dynamic seal corresponding to the test point position is unqualified.

[0016] In a preferred embodiment of the present invention, the method for optimizing the structural design of the sealing strip based on the sound source leakage at the test point position comprises:

[0017] S1, perform leakage test and leakage difference calculation with fixed width and variable height, and enter the corresponding table;

[0018] S2, perform leakage test at fixed height and variable width and calculate leakage difference, and enter into corresponding table;

[0019] S3, perform leakage test and leakage difference calculation at fixed width, fixed height and variable hardness, and enter the data into the corresponding table;

[0020] S4, the data recorded in the tables of S1, S2 and S3 were processed by multivariate linear regression in the data processing software to obtain the relationship between the leakage amount and the width, height and hardness. The fitting curve is as follows:

[0021] Δ=a1*H+a2*L+a3*S+b

[0022] Among them, a1, a2, a3 are the partial regression coefficients of regression processing, and b is the intercept.

[0023] In a preferred embodiment of the present invention, when evaluating the sealing effect of sealing strips of different sizes and hardnesses, the leakage differences of multiple leakage measurement points are averaged.

[0024] The beneficial effects of the present invention are as follows: the present invention provides a simple method for testing and analyzing the dynamic sealing performance of vehicle doors, wherein a road excitation signal is collected by a real vehicle at a vehicle speed of 140 kmh, the signal is loaded on a four-pillar test bench of the whole vehicle to simulate road excitation, the pressure distribution is analyzed according to the vehicle body flow field simulation, the vehicle body leakage measurement position is selected, the vehicle door is completely closed, and a leakage test system is used to add the pressure difference between the inside and outside of the vehicle during high-speed driving to the vehicle, a sound source is placed between the auxiliary instrument and the rear seat in the vehicle, an ultrasonic leak detector is used to test the leakage of the door frame sealing strip and the edge of the window outside the vehicle, sealing strips of different heights, widths and hardnesses are replaced to calculate the leakage difference under dynamic and static conditions, a linear regression method is used to obtain the relationship between the leakage and the sealing strip parameters, the direction of the door and sealing strip design structure optimization is guided, and the high-speed dynamic sealing performance of the vehicle is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a pressure distribution diagram of the flow field outside the vehicle body of a bench simulation test analysis method for the dynamic sealing performance of an automobile according to the present invention;

[0026] Figure 2 It is a schematic diagram of the locations of various leakage points in a bench simulation test and analysis method for dynamic sealing performance of an automobile according to the present invention;

[0027] Figure 3 It is a schematic diagram of a four-column bench for a bench simulation test and analysis method of dynamic sealing performance of an automobile according to the present invention;

[0028] Figure 4 It is a schematic diagram of a leakage test device of a bench simulation test analysis method for dynamic sealing performance of an automobile according to the present invention;

[0029] Figure 5 It is a schematic diagram of a sealing strip of a bench simulation test and analysis method for dynamic sealing performance of an automobile according to the present invention;

[0030] In the figure, A-rear door glass; B-front door glass; C-rear door; D-front door; E-vibration platform;

[0031] F-four-column vibration control console; G-air duct; H-blower; I-press; J-window opening; K-installation clamping position; S-compression sealing position. DETAILED DESCRIPTION

[0032] The technical solution of the present invention (including the preferred technical solution) is further described in detail below by means of the accompanying drawings and by listing some optional embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The invention discloses a bench simulation test and analysis method for the dynamic sealing performance of an automobile. The method comprises the following steps: obtaining a pressure distribution diagram of an external flow field of a vehicle body of a test vehicle on a specific road section based on simulation software, and determining the positions of various leakage points on windows and doors of the test vehicle through the pressure distribution diagram of the external flow field of the test vehicle, wherein each leakage point position is a test point position; fixing the test vehicle on a four-post bench and applying pressure to a cockpit thereof at the same time, the four-post bench simulating road surface excitation of the test vehicle on the specific road section, and the pressure difference between the inside and outside of the test vehicle is the pressure difference formed when the test vehicle actually drives on the specific road section; placing a sound source in the cockpit, and testing the size of the sound source leakage at each test point position based on a sound source leak detector; and optimizing the structural design of the sealing strip based on the sound source leakage at the test point position.

[0034] Preferably, the method for determining the positions of various leakage points on the windows and doors of the vehicle to be tested based on the pressure distribution diagram of the flow field outside the vehicle body includes: selecting test point positions located at the edge of the door frame and the edge of the window; selecting test point positions with a pressure between -2300 and 100 Pa; the interval between any two adjacent test point positions is 200 mm.

[0035] Preferably, the method for obtaining the road surface excitation of the vehicle to be tested on the specific road section includes: attaching four three-dimensional vibration acceleration sensors to the front and rear wheels of the vehicle to be tested respectively, and connecting the three-dimensional vibration acceleration sensors to the LMS data acquisition equipment, the vibration acquisition frequency is 4000Hz, driving the vehicle to be tested at a speed of 140km / h on the specific road section to collect road surface excitation signals, and the acquisition time is 20s.

[0036] Preferably, the leakage test device pressurizes the cockpit of the vehicle to be tested, and the pressure difference between the inside and the outside is 70-110Pa.

[0037] Preferably, the leakage test device comprises a pressure gauge, a blower and an air blast duct, and the air blast duct is sealedly connected to an opening on a sunroof or a side window of the vehicle to be tested.

[0038] Preferably, when the four-post test bench is not working, the vehicle is in a stationary condition, a sound source is placed in the cockpit, and the sound source leakage amount Q1 of each test point position under the stationary condition is tested based on the sound source leak detector; when the four-post test bench is working, the vehicle is in a simulated condition, a sound source is placed in the cockpit, and the sound source leakage amount Q2 of each test point position under the simulated condition is tested based on the sound source leak detector, and the leakage amount change difference is calculated, Δ=Q2-Q1.

[0039] Preferably, the method for testing the size of the sound source leakage at each test point based on the sound source leak detector includes: S1, placing the sound source at the front shift handle, and testing the size of the sound source leakage at each test point on the front door frame and the front window; S2, placing the sound source in the middle of the rear seats, and testing the size of the sound source leakage at each test point on the rear door frame and the rear window.

[0040] Preferably, when Δ corresponding to the test point position is less than 3, the dynamic seal at the test point position is qualified; if Δ corresponding to the test point position is greater than 3, the dynamic seal corresponding to the test point position is unqualified.

[0041] Preferably, the method for optimizing the structural design of the sealing strip based on the sound source leakage at the test point position includes:

[0042] S1, perform leakage test and leakage difference calculation with fixed width and variable height, and enter the corresponding table;

[0043] S2, perform leakage test at fixed height and variable width and calculate leakage difference, and enter into corresponding table;

[0044] S3, perform leakage test and leakage difference calculation at fixed width, fixed height and variable hardness, and enter the data into the corresponding table;

[0045] S4, the data recorded in the tables of S1, S2 and S3 were processed by multivariate linear regression in the data processing software to obtain the relationship between the leakage amount and the width, height and hardness. The fitting curve is as follows:

[0046] Δ=a1*H+a2*L+a3*S+b

[0047] Among them, a1, a2, a3 are partial regression coefficients (pre-calibrated) of regression processing, and b is the intercept.

[0048] Preferably, when evaluating the sealing effects of sealing strips of different sizes and hardnesses, the leakage differences of multiple leakage measurement points are averaged.

[0049] The present invention simulates and tests the dynamic sealing performance of a car at high speed through a test bench. The road spectrum is loaded on a four-column test bench. The leakage test position is selected by body flow field simulation. An ultrasonic leak detection system is used to perform leak detection and analysis. The relationship between the leakage and the width, height and hardness of the sealing strip is obtained by replacing different sealing strips. The invention has important engineering applications and practical guiding value, reduces the development cycle and cost, and the detailed steps for guiding the design of sealing strips are as follows:

[0050] The first step is to attach a total of 4 three-dimensional vibration acceleration sensors to the front and rear wheels of the vehicle, and connect the sensors to the LMS data acquisition equipment. The vibration acquisition frequency range is set to 4000Hz. The vehicle is driven at a speed of 140km / h on a straight and smooth asphalt road to collect road spectra for 20s and save the signals.

[0051] In the second step, the vehicle CFD software is used for modeling and simulation. The Actran software is used to extract the surface pressure of the vehicle body and obtain the pressure distribution diagram of the flow field outside the vehicle body (color cloud diagram), so as to determine the pressure distribution of the windows and doors, such as Figure 1 The pressure distribution is mainly between -2467Pa and 718Pa. The larger the value, the greater the external pressure, the tighter the door is pressed, which is beneficial to the seal; the smaller the value, the greater the internal pressure, the pressure inside the car causes the door to open outward, and the seal becomes worse. Figure 2 As shown, according to the above pressure distribution, a total of 19 test positions are selected (it should be pointed out that 19 positions are only an embodiment, and the test point positions of a specific vehicle model may be more than 19 or less than 19, and the selection principles include: Principle 1: Select the positions of the door frame edge and the window edge (design analysis shows that these positions may have leakage, door sealing strip leakage, window glass water cutting leakage, and no leakage on other sheet metal); Principle 2: Select the position with a pressure between -2300 and 100pa; Principle 3: The measurement point positions are 200mm apart).

[0052] The third step is to fix the vehicle on a four-post test bench, place the ultrasonic leak detection sound source at the front shift handle, test the leakage of each measuring point on the front door frame and the front window, and then place the sound source in the middle of the rear seat to test the leakage of each measuring point on the rear door frame and the rear window. The leakage in this state is recorded as Q1, as shown in Table 1. This is the test result of the door sealing performance under static conditions.

[0053] Step 4: Load the smooth asphalt road profile (such as Figure 3 Example), 20s road spectrum signal cycle continuous loading, use the leakage test device to open a hole from the skylight or side window, use a blower to pressurize (such as Figure 4As shown, the edges of the sunroof or side window openings are required to be completely sealed with grease or tape) until the pressure difference between the inside and outside of the vehicle reaches 100Pa (the pressure difference between the inside and outside of the vehicle surface is about 70-110Pa when the vehicle is driving at high speed). Repeat the test method in the third step and record the leakage test result Q2 in Table 1. This is the dynamic sealing test result when driving on a smooth asphalt road.

[0054] Step 5: Calculate the difference of leakage change, Δ = Q2-Q1, and add the results in Table 1. The larger the difference, the worse the dynamic seal. Experience shows that if Δ < 3, the dynamic seal is good and no improvement is needed; if 3 < Δ < 6, the structural design needs to be fine-tuned; if Δ > 6, the structural design has defects and needs major structural adjustments.

[0055]

[0056] Table 1 Ultrasonic leakage record

[0057] Step 6: The door seal plays a key role in dynamic sealing. Its structure is as follows: Figure 5 The factors affecting the performance of the sealing strip are mainly the compression section height H, the compression section width L, and the sealing strip rubber hardness S. Replace the sealing strip styles with different structural sizes and hardness to conduct leakage measurement tests. Since the door sealing strips are usually of equal cross-section, when evaluating the sealing effect of sealing strips of different sizes and hardness, it is necessary to average the leakage differences of 19 leakage measurement points. First, conduct a leakage test and leakage difference calculation with fixed width and height, and record them in Table 2. Then conduct a leakage test and leakage difference calculation with fixed height and width, and record them in Table 3. Finally, conduct a leakage test and leakage difference calculation with fixed width, fixed height and hardness, and record them in Table 4.

[0058] Step 7: Perform multiple linear regression on the above data in Excel to obtain the relationship between leakage and width, height, and hardness. The fitting curve is as follows:

[0059] Δ=a1*H+a2*L+a3*S+b

[0060] Among them, a1, a2, a3 are the partial regression coefficients of regression processing, and b is the intercept.

[0061]

[0062]

[0063] Table 2 Leakage Record of Sealing Strip at Fixed Width

[0064]

[0065] Table 3 Sealing strip leakage record at fixed height

[0066]

[0067]

[0068] Table 4 Sealing strip leakage record at fixed height

[0069] It is easy for technicians in the technical field to understand that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, combinations, replacements, improvements, etc. made under the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims

1. A bench simulation test and analysis method for dynamic sealing performance of an automobile, characterized in that: It can simulate the actual environment where wind noise occurs, use ultrasound to detect leaks at various leak points, analyze the dynamic sealing of the car, obtain the pressure distribution diagram of the flow field outside the vehicle body of the test vehicle on a specific road section based on the simulation software, and determine the positions of various leak points on the windows and doors of the test vehicle through the pressure distribution diagram of the flow field outside the vehicle body, and each leak point position is the test point position; fix the test vehicle on a four-post test bench and pressurize its cockpit at the same time, the four-post test bench simulates the road excitation of the test vehicle on the specific road section, and the pressure difference between the inside and outside of the test vehicle is the pressure difference formed when the test vehicle is actually driving on the specific road section; A sound source is placed in the cockpit, and the sound source leakage at each test point is tested based on a sound source leak detector; the structural design of the sealing strip is optimized based on the sound source leakage at the test point; when the four-post bench is not working, the vehicle is in a stationary condition, a sound source is placed in the cockpit, and the sound source leakage at each test point under a stationary condition is tested based on a sound source leak detector; when the four-post bench is working, the vehicle is in a simulated condition, a sound source is placed in the cockpit, and the sound source leakage at each test point under a simulated condition is tested based on a sound source leak detector, and the leakage change difference is calculated, ∆=Q2-Q1; when ∆ corresponding to the test point position is <3, the dynamic sealing at the test point position is qualified; if ∆ corresponding to the test point position is >3, the dynamic sealing at the test point position is unqualified; the method for optimizing the structural design of the sealing strip based on the sound source leakage at the test point position includes: S1, perform leakage test and leakage difference calculation with fixed width and variable height, and enter the corresponding table; S2, perform leakage test at fixed height and variable width and calculate leakage difference, and enter into corresponding table; S3, perform leakage test and leakage difference calculation at fixed width, fixed height and variable hardness, and enter the data into the corresponding table; S4, the data recorded in the tables of S1, S2 and S3 were processed by multivariate linear regression in the data processing software to obtain the relationship between the leakage amount and the width, height and hardness. The fitting curve is as follows: Δ= a1*H+ a2*L+ a3*S+b Among them, a1, a2, and a3 are partial regression coefficients of regression treatment, and b is the intercept; When evaluating the sealing effect of sealing strips of different sizes and hardness, the leakage differences of multiple leakage measurement points are averaged.

2. The bench simulation test and analysis method for dynamic sealing performance of an automobile according to claim 1, characterized in that: The method for determining the positions of various leakage points on the windows and doors of the vehicle to be tested based on the pressure distribution diagram of the flow field outside the vehicle body includes: selecting the test point positions located at the edge of the door frame and the edge of the window; selecting the test point positions with a pressure between -2300~100Pa; the interval between any two adjacent test point positions is 200mm.

3. The bench simulation test and analysis method for dynamic sealing performance of an automobile according to claim 1, characterized in that: The method for obtaining the road surface excitation of the vehicle to be tested on the specific road section includes: attaching four three-dimensional vibration acceleration sensors to the front and rear wheels of the vehicle to be tested respectively, and connecting the three-dimensional vibration acceleration sensors to the LMS data acquisition equipment, the vibration acquisition frequency is 4000Hz, driving the vehicle to be tested at a speed of 140km / h on the specific road section to collect road surface excitation signals, and the acquisition time is 20s.

4. The bench simulation test and analysis method for dynamic sealing performance of an automobile according to claim 1, characterized in that: The leakage test device pressurizes the cockpit of the test vehicle, and the pressure difference between the inside and outside is 70~110Pa.

5. The bench simulation test and analysis method for the dynamic sealing performance of an automobile according to claim 4 is characterized in that: The leakage test device comprises a pressure gauge, a blower and an air blast duct, wherein the air blast duct is sealed and connected to an opening on a sunroof or a side window of a vehicle to be tested.

6. The bench simulation test and analysis method for dynamic sealing performance of an automobile according to claim 1, characterized in that: The method for testing the leakage amount of the sound source at each test point based on the sound source leak detector includes: S1, placing the sound source at the front shift handle, and testing the leakage amount of the sound source at each test point on the front door frame and the front window; S2, placing the sound source in the middle of the rear seats, and testing the leakage amount of the sound source at each test point on the rear door frame and the rear window.

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