CN101464168B - Noise source identification method for vehicle acceleration noise - Google Patents

Abstract

The invention relates to a noise source identification method for vehicle acceleration noise, belonging to the technical field of vehicle noise control. During vehicle acceleration and constant speed driving, collect noise source and vibration source signals, vehicle speed signals, response point sound pressure signals, vehicle position signals, etc., calculate the transfer function matrix from noise source, vibration source to response point, and synthesize and calculate the response The change of point sound pressure during acceleration, and calculate the sensitivity and contribution of each noise source and vibration source. The advantage of the present invention is that the noise source and vibration source signal in the vehicle running process, the vehicle running state signal, the sound pressure signal of the ground response point, etc. can be used to accurately identify the noise source of the acceleration passing noise, and obtain the response point noise The quantitative relationship between the signal and each noise source provides a reliable basis for improving the acceleration noise outside the vehicle.

Description

Noise source identification method for vehicle acceleration noise

technical field

The invention relates to a noise source identification method for vehicle acceleration noise, belonging to the technical field of vehicle noise control.

Background technique

Car noise is the main source of noise pollution. Many countries, including my country, have enacted strict regulations to control car noise (such as my country's recently formulated national standard GB1495-2002). Reducing car noise is an important aspect of the development of today's car technology. The topic has received extensive attention from countries around the world and major vehicle manufacturers and parts companies. Accurate identification of the sound source is the key to reducing the acceleration noise outside the vehicle.

The current noise test, including the test for ISO362 and the acoustic holographic test, uses different devices and methods respectively. The former, such as B&K's PULSE system (Vehicle pass-by noise test, www.bksv.com), collects engine speed, throttle opening and CAN bus parameter signals on the vehicle, and collects vehicle speed signals and response point sound pressure signals on the ground. Communication is via a wireless LAN transceiver. This test does not collect the noise source and vibration source information on the vehicle, but mainly records the relationship between the acceleration noise outside the vehicle and the vehicle running speed and accelerator operation, so it cannot identify the noise source outside the vehicle. Acoustic holography test (analysis method for surface sound field of high-speed moving objects, invention patent 00132123.4 China) can test the surface sound field of the vehicle, but cannot identify the noise source and vibration source on the car corresponding to the sound field.

Contents of the invention

The object of the present invention is a noise source identification method of vehicle acceleration noise, which uses the noise source, vibration source, driving state information and the noise signal of the ground response point measured by the vehicle during driving to identify the main noise source during vehicle acceleration. Identify and obtain the influence relationship of each noise source on the noise of the response point, so as to provide an effective basis for noise reduction.

The noise source identification method of the vehicle acceleration noise proposed by the present invention comprises the following steps:

(1) A sensor for measuring the sound pressure signal of the vehicle noise source, the vibration acceleration signal of the vibration source and the vehicle speed signal v (t) is set on the vehicle under test,

Place the two positioning devices on the acceleration start line and the acceleration end line of the vehicle driving road to obtain the vehicle position signal,

Place two microphones on both sides of the test road corresponding to the midpoint of the two positioning devices to measure the noise sound pressure signal at the response point,

Place a thermometer and anemometer next to the microphone above to measure ambient temperature and real-time wind speed;

(2) Make the vehicle under test run along the center line of the test road, and the above-mentioned sensors, positioning devices, and microphones collect signals at the same time before the vehicle accelerates. When the vehicle passes the acceleration termination line, the acceleration process ends. Select a speed from the different speeds of the vehicle during acceleration, make the vehicle run at a constant speed on the test road at this speed, record the signal, select multiple different speeds, and repeat the constant speed. driving, recording signals;

(3) Calculate the distance between the vehicle and the above-mentioned microphone at a specific moment during the test road driving process:

$\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>\underset{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\overset{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; \&Integral;</span>}}\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

Among them, v(t) is the speed of the vehicle at t, t ₀ is the moment when the vehicle passes the acceleration start line, s ₀ is the distance between the acceleration start line and the above-mentioned microphone, and L is the distance from the microphone to the center line of the test road ;

(4) According to the above-mentioned vehicle speed signal v(t) and the distance s(t) between the vehicle and the above-mentioned microphone, the sound pressure signal of the microphone is processed to eliminate the Doppler effect, the process is as follows:

According to the distance s(t) between the vehicle and the microphone at time t, calculate the time t _s for the noise emitted by the vehicle to propagate to the microphone at this time:

${\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; c</span>}}$

Where c is the speed of sound at that time, the noise of the vehicle will propagate to the microphone at the response point at time t+t _s , and the sound pressure signal collected by the above microphone is converted into the noise sound pressure signal of the response point at the moment of noise emission by using the time domain interpolation method;

(5) From the time _t0 when the vehicle passes the acceleration starting line, the sound pressure signal of the noise source, the vibration acceleration signal of the vibration source and the sound pressure signal of the response point recorded for each set distance traveled by the vehicle are taken as a signal interval, The transfer function matrix H(f) from the noise source and the vibration source to the response point in the signal interval is obtained as:

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>}$

Where h _i (f) is the transfer function from the i-th noise source or vibration source to the response point on the vehicle, a _i (f) is the noise sound pressure signal or vibration acceleration signal of the i-th noise source or vibration source on the vehicle The Fourier transform result, p _i (f) is the Fourier transform result of the noise sound pressure signal generated by the i-th noise source or vibration source on the vehicle at the response point, and this process is repeated to obtain the transfer function matrix H(f );

(6) Using the transfer function matrix H(f) of all the different signal intervals above, the response sound pressure time domain signal P(t) of the vehicle acceleration process is spliced out as follows:

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>$

Among them, P _i (t) is the response sound pressure time-domain signal of the i-th signal interval, P _i (f) is the response sound pressure frequency-domain signal of the i-th signal interval, A _i,n (f) is the i-th The frequency-domain signal of the noise source sound pressure signal of the signal interval and the vibration source vibration acceleration signal, H _{, n * m} (f) is the transfer function matrix of the i-th signal interval calculated according to the above method;

(7) Using the transfer function matrix of the above-mentioned vehicle acceleration process, calculate the sensitivity and contribution of each noise source and vibration source on the vehicle to the sound pressure signal of the response point:

The sensitivity L _total (L _p -Δ) of the total noise of the response point to the pth noise source is:

${\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 20</span>}{\mathrm{<span\; class="notranslate">\; log</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}\frac{\sqrt{\frac{\underset{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\overset{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; fft</span>}<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; ]</span>}^{<span\; class="notranslate">\; \&prime;</span><span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; m</span>}}}}{{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}$

Where p ₀ is the standard reference pressure, m is the number of sampling points in a signal interval, [A|S]″ represents the noise source signal matrix after the sound pressure level L _n of the pth noise source is reduced by Δ, and Δ is the set The reduction in sound pressure level,

The contribution of the noise source or vibration source to the sound pressure signal at the response point is:

${\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}{\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span>$

Among them, A _{i, n-1} (f) is the frequency domain signal of the sound pressure signal of the noise source and the vibration acceleration signal of the vibration source after removing the pth noise source or vibration source, H _{i, (n-1)×( m-1)} is the transfer function matrix after removing the pth noise source or vibration source.

The noise source identification method of the vehicle acceleration noise proposed by the present invention has the advantages of:

1. Using the method of the present invention, the noise source and vibration source signals measured during the vehicle running process, the vehicle running state signal, the sound pressure signal of the ground noise monitoring position, etc. can be used to identify the noise source, and the vehicle acceleration can be identified. The position of the noise source of the acceleration passing noise outside the vehicle while driving.

2. Using the method of the present invention, the quantitative relationship between the noise signal at the response point and each noise source can be obtained, so the identification result of the present invention can be used as a reliable basis for improving the noise of acceleration outside the vehicle.

Description of drawings

Fig. 1 is a schematic diagram of the arrangement of various sensors used to obtain relevant information in the method of the present invention.

Fig. 2 is a flowchart of the method of the present invention.

In Fig. 1, 1 is the positioning device, 2 is the starting line of vehicle acceleration, 3 is the vehicle under test, 4 is the microphone, 5 is the vehicle driving road, and 6 is the vehicle acceleration termination line.

Detailed ways

When performing the identification of the acceleration passing noise outside the vehicle specified in the national standard, it is necessary to collect the noise and vibration signals on the vehicle and the driving information of the vehicle. In addition, it is necessary to collect the sound pressure signal, vehicle position signal, and environmental signal of the response point at the monitoring position on the ground. wait.

In one embodiment of the present invention, the acquisition process of each signal on the vehicle is described by taking the external acceleration pass noise sound source identification test of a front-rear drive vehicle as an example.

Use the acquisition device on the vehicle to collect the noise signals and vibration signals of various noise sources and vibration sources, and the driving information of the vehicle (such as engine speed, vehicle speed, throttle opening, etc., the engine speed signal is collected in the example), and use wireless transceiver The device transmits the signal on the vehicle to the acquisition device on the ground or receives the signal sent by the acquisition device on the ground, so as to realize the synchronous acquisition and real-time communication of the signal on the ground and the vehicle. Use the microphone to collect the noise sound pressure signal of the noise source on the vehicle, and fix the microphone near the noise source under test according to the vehicle structure (the distance from the sound source should not exceed 100mm). The acceleration sensor is used to measure the vibration signals of each vibration source on the vehicle, and the acceleration sensor is also fixed near the vibration source according to the vehicle structure (the distance from the vibration source is not more than 100mm).

The placement of the sensor is described below based on an example. The vehicle noise sources are divided into airborne sound sources and structural vibration sources. For the air sound source, the microphone is used to measure the noise sound pressure signal, and for the structural vibration source, the acceleration sensor is used to measure the vibration acceleration signal. Airborne sound sources of vehicles can be mainly divided into mechanical sound, combustion sound, airflow sound and tire sound. The mechanical sound is mainly produced by the engine timing gear chamber, the engine oil pan, the transmission, and the final reducer; the combustion noise is mainly the radiation noise produced by the engine block and cylinder head; the airflow sound source is mainly the cooling fan and air filter , intake pipe, exhaust manifold, exhaust tailpipe and the outside of the vehicle body; tire noise comes from the four wheels, so microphones are installed near the above positions to measure the noise sound pressure signals at the corresponding positions. The vehicle structural vibration sources are mainly the connection position between the power transmission mechanism and the body, the connection position between the driving system and the body, and other suspension structures. Therefore, the main vibration source measurement points are the engine mount, transmission mount, drive shaft Reducer suspension, exhaust pipe suspension, connection position between suspension and body, connection position between suspension and axle housing, etc., place acceleration sensors at these positions to measure their vibration acceleration signals. For structures such as engine mounts and final reducer mounts, the three-way acceleration signals should be measured simultaneously when measuring vibration acceleration signals.

On the ground, it is necessary to collect the noise sound pressure signal of the response point, the position signal of the vehicle, and environmental information (including wind speed, temperature, etc.). Place microphones at the test positions on both sides of the experimental road (recommended placement is 7.5m on both sides of the road centerline, and the microphone is 1.2m above the ground) to measure the noise sound pressure signal at the test position; place a thermometer and wind speed beside the road The meter is used to measure the ambient temperature and real-time wind speed, and is used to correct the measured sound pressure signal; at the start position and end position of the vehicle acceleration (recommended acceleration start point and end point are 20m on both sides of the noise test position) ) each install a set of positioning devices, when the vehicle passes the position of the positioning device, the vehicle will block the laser, so a step signal will be generated in the positioning device, so as to determine the moment when the front of the vehicle reaches the positioning device, the two sets of positioning devices can be used Determine the moment when the vehicle passes through the acceleration start position and end position, so as to calculate the position of the vehicle; use the wireless transceiver device to transmit the signal collected by the ground collection device to the vehicle collection device or receive the signal transmitted by the vehicle to realize The synchronous acquisition and real-time communication between the vehicle and the ground, the specific method of sending on the vehicle and receiving on the ground is determined by the operator according to the actual situation. In the example, the signal sent by the ground is used, and the received signal on the vehicle is used for synchronous acquisition. The way.

During the test process, the arrangement of various sensors for obtaining relevant information is shown in Figure 1, and the test process is illustrated by taking the noise source identification of a front-rear drive vehicle as an example.

(1) Test site conditions

According to the measurement conditions stipulated in national regulations, there are no large sound reflectors within a radius of 50m around the test site, such as fences, rocks, bridges or buildings, etc. The test road surface and the rest of the site surface are dry, and the test road surface is basically level, solid and flat. During the test, the wind speed at the response point does not exceed 5m/s, the background noise (A-weighted sound pressure level) is at least 10dbB lower than the noise of the vehicle under test, and the acceleration area is 20m long.

(2) Test device installation

Debug the vehicle under test 3 to be in a normal driving state, and arrange the on-board acquisition device on the vehicle. Perform collection operations.

Arrange the microphone 4 on both sides of the experimental road 5 at a distance of 7.5m from the center line as shown in the figure. Device 1, to ensure that the laser emitted by the positioning device can be covered by the vehicle body when the vehicle passes the acceleration start line 2 and the acceleration end line 7, and generate a corresponding step signal to determine the moment of passing the start and end positions, so as to calculate the vehicle speed. to the position s(t) of the microphone. The acquisition device is used to collect the signals of the laser positioning device, microphone, anemometer and thermometer, and the collected signals are transmitted to the vehicle by the wireless transceiver device, and the operator performs synchronous collection and recording on the vehicle.

(3) Test process

Firstly, the vehicle acceleration test is carried out. When testing the external acceleration noise source of a certain gear, the tested vehicle 3 runs along the centerline of the experimental road 5. When the vehicle approaches the test road section, the operator on the vehicle controls the acquisition system to start collecting signals. , when the front of the car reaches the acceleration start line 2, step on the accelerator pedal with all your strength, and the vehicle under test 3 accelerates along the road centerline with full throttle. When the vehicle passes the acceleration end line 7, release the accelerator pedal, and the acceleration process ends. Do this 3 to 4 times. Then carry out the constant-speed driving test. According to the speed variation range of the tested vehicle during the acceleration process, select several speeds, let the tested vehicle 3 drive through the tested road section at a constant speed at these speeds, and record the signal. The total number of times of acceleration and constant speed driving shall not be less than the sum of the number of noise sources and vibration sources to be analyzed.

For example, the tested vehicle 3 in the example, test and analyze its 3rd gear acceleration passing noise, a total of 33 sensors are arranged on the vehicle to measure its noise source and vibration source signals. Firstly, four times of vehicle acceleration passing experiments are carried out, and the vehicle speed changes from 15km/h to about 65km/h when the vehicle passes through the acceleration section. Then allow the tested vehicle 38 to travel through the measured road section at a constant speed of 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65km/h respectively, and record the signal, and test 3 times at every speed. A total of 33 constant-speed driving tests and 4 accelerated driving tests were carried out, totaling 37 times, which is greater than the total number of noise sources and vibration sources to be analyzed.

When it is necessary to measure the acceleration noise source in multiple gears, the measurement experiment should be carried out for each gear according to the above requirements.

The specific process of noise source identification of vehicle acceleration noise is shown in Figure 2:

1. Calculate vehicle speed and position

Use the collected vehicle speed signal and position signal to calculate the vehicle speed change and driving position information during the driving process of the vehicle.

In the example, the engine speed signal n(t) of the vehicle is recorded, and the vehicle speed v(t) can be calculated according to the following formula

$\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 60</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;R</span>}$

Among them, v(t) is the speed of the vehicle at t, n(t) is the engine speed signal of the vehicle at this moment, i _g is the transmission ratio at this moment, _id is the transmission ratio of the final drive at this moment, R is the radius of the tire of the driving wheel of the vehicle,

The distance s(t) from the vehicle to the microphone at the response point at time t is:

$\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>\underset{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\overset{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; \&Integral;</span>}}\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

Among them, _t0 is the moment when the vehicle passes the acceleration start line, _s0 is the distance from the vehicle to the microphone at time _t0 , that is, the distance from the acceleration start position to the microphone at the response point, and L is the distance from the microphone at the response point to the centerline of the road;

Using the vehicle speed and vehicle position information, the sound pressure signal of the response point is processed to eliminate the Doppler effect.

From the position of the vehicle at time t, the time t _s for the noise emitted by the vehicle to propagate to the microphone at the response point can be calculated as:

${\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; c</span>}}$

where s(t) is the distance from the vehicle to the microphone at the response point at time t, and c is the sound speed at that time, so the noise of the vehicle at this moment will propagate to the microphone at the response point at time t+t _s , thus using the time domain interpolation The method converts the sound pressure signal collected by the microphone at the response point into the noise sound pressure signal at the moment of noise emission.

From the starting time _t0 , the noise source, vibration source signal and sound pressure signal of the response point recorded every time the vehicle travels a short distance (0.25m) as a signal interval, the noise source and vibration source on the vehicle to the response point The point transfer function H(f) is

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>}$

Where h _i (f) is the transfer function from the i-th excitation source (noise source or vibration source) to the response point, a _i (f) is the signal of the i-th excitation source (noise sound pressure signal or vibration acceleration signal) Fourier transform result, p _i (f) is the Fourier transform result of the noise sound pressure signal generated by the i-th excitation source at the response point.

When the vehicle is running, the sound pressure signal of the response point on the left and right sides of the ground is the superposition of the responses caused by the vibration sources and sound source excitation on the vehicle, and the sound pressure signal of the response point is

p(f)＝a ₁ (f)h ₁ (f)+a ₂ (f)h ₂ (f)+...+a _n (f)h _n (f)

Where a ₁ (f) to a _n (f) are the Fourier transform results of n noise sources and vibration source signals respectively, h ₁ (f) to h _n (f) are the n noise sources and vibration sources to the response The transfer function of the point, p(f) is the Fourier transform result of the sound pressure signal of the response point.

For a group of "excitation-response" signals (corresponding to a signal interval) with n excitation signal sources (noise source and vibration source) and m response points, there are m equations and m×n unknowns. Assuming that there are k groups of "excitation-response" signals, the sound pressure signal at the response point can be expressed as:

P _k×m (f)＝A _k×n (f)H _n×m (f)

In the formula, h _{i, j} (f) (i<n, j<m) is the transfer function from the i-th sound source reference point to the j-th response point, a _{o, i} (f) (o<k, i< n) is the Fourier transform result of the i-th sound source reference point signal in the o-th measurement, p _{o, j} (f) (o<k, j<m) is the j-th response point in the o-th measurement The Fourier transform result of the signal.

The principal component analysis method can be used to solve the transfer function matrix, and the transfer function matrix can be expressed as:

${\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}^{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; Sr</span>}}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>$

Where U _r is the eigenvector matrix, D _r is the diagonal matrix, Z _Sr is the principal component matrix, and P _k×m (f) is the response signal.

(6) Synthesize the change of sound pressure at the response point during the whole acceleration process:

After the transfer function matrix of each signal interval is obtained, a certain group of excitation signals is used to synthesize and calculate the corresponding response signal, so that the response sound pressure change of the entire vehicle acceleration process is superimposed as follows:

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>$

Among them, P(t) is the response time domain signal of the acceleration driving process, P _i (t) is the response time domain signal of the i-th signal interval, P _i (f) is the response frequency domain signal of the i-th signal interval, A _i,n (f) is the excitation frequency domain signal of the i-th signal interval, H _i,n×m (f) is the transfer function matrix of the i-th signal interval calculated according to the above method

(7) Using the transfer function matrix of the vehicle acceleration process, the sensitivity and contribution of each noise source and vibration source to the sound pressure signal of the response point can be calculated.

The sensitivity L _total (L _p -Δ) of the total noise of the response point to the pth noise source can be calculated by the following formula

${\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 20</span>}{\mathrm{<span\; class="notranslate">\; log</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}\frac{\sqrt{\frac{\underset{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\overset{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; fft</span>}<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; ]</span>}^{<span\; class="notranslate">\; \&prime;</span><span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; m</span>}}}}{{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}$

Where p ₀ =2·10 ^-5 Pa is the standard reference pressure, Δ is the set sound pressure level reduction, and the effective sound pressure used when calculating the sound pressure level, that is, for a certain period of sampling time (from time t ₁ to t _m , a total of m sampling points) take the root mean square value of the instantaneous sound pressure. [A|S]″ represents the noise source signal matrix after the sound pressure level L _n of the pth noise source is reduced by Δ, that is, the other noise source signals remain unchanged, and only the noise source signal becomes the original 10 ^-Δ/20 Times:

[A|S]″=[a ₁ ′, a ₂ , …, 10 ^−Δ/20 · a _p , …, a _n ]

The noise source or vibration source to be analyzed is removed from the transfer function matrix and the excitation signal, and the response signal is fitted and calculated. From this, the contribution of the noise source or vibration source to the sound pressure signal at the response point can be obtained as:

${\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}{\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span>$

Among them, A _{i, n-1} (f) is the excitation signal for eliminating the pth noise source, and H _{i, (n-1)×(m-1)} is the transfer signal matrix for eliminating the pth noise source.

Claims (1)

1. A noise source identification method of vehicle acceleration noise, characterized in that the method comprises the following steps: (1) The sensor for measuring the sound pressure signal of the noise source of the vehicle under test, the vibration acceleration signal of the vibration source and the vehicle speed signal v (t) of the vehicle under test is set on the vehicle under test, Place the two positioning devices on the acceleration start line and the acceleration end line of the vehicle driving road to obtain the position signal of the vehicle under test, Two microphones are placed on both sides of the vehicle driving road corresponding to the midpoint of the two positioning devices to measure the noise sound pressure signal at the response point, Place a thermometer and anemometer next to the microphone above to measure ambient temperature and real-time wind speed; (2) Make the vehicle under test run along the center line of the vehicle's driving road, and the above-mentioned sensors, positioning devices, and microphones collect signals simultaneously before the vehicle under test accelerates. When the vehicle under test passes the acceleration termination line, the acceleration process ends. Select a vehicle speed from the different speeds of the vehicle under test during acceleration, so that the vehicle under test can run at a constant speed on the vehicle driving road at this speed. , record the sound pressure signal of the noise source of the vehicle under test, the vibration acceleration signal of the vibration source, the vehicle speed signal, the position signal and the noise sound pressure signal of the response point, select multiple different vehicle speeds, repeat the constant speed driving, and record the noise source of the vehicle under test Sound pressure signal, vibration acceleration signal of vibration source, vehicle speed signal, position signal and noise sound pressure signal of response point; (3) Calculate the distance between the tested vehicle and the above-mentioned microphone at a specific moment during the vehicle's driving on the road:

Among them, v(t) is the speed of the vehicle under test at t, _t0 is the moment when the vehicle under test passes the acceleration starting line, _s0 is the distance between the acceleration starting line and the above-mentioned microphone, and L is the distance between the microphone and the vehicle. the distance from the centerline of the road; (4) According to the above-mentioned vehicle speed signal v(t) and the distance s(t) between the vehicle under test and the above-mentioned microphone, the sound pressure signal of the microphone is processed to eliminate the Doppler effect, the process is as follows: According to the distance s(t) between the vehicle under test and the above-mentioned microphone at time t, calculate the time t _s for the noise emitted by the vehicle under test to propagate to the microphone at this time: ${\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; c</span>}}$ Where c is the sound velocity at that time, the noise of the vehicle under test will propagate to the microphone at the response point at time t+t _s , and the sound pressure signal collected by the above microphone is converted into the noise sound pressure of the response point at the time of noise emission by using the time domain interpolation method Signal; (5) From the time _t0 when the vehicle under test passes the acceleration starting line, the sound pressure signal of the noise source, the vibration acceleration signal of the vibration source and the sound pressure signal of the response point recorded for each set distance traveled by the vehicle under test are taken as A signal interval, the transfer function matrix H(f) from the noise source and the vibration source to the response point in the signal interval is obtained as: $\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>}$ Where h _i (f) is the transfer function from the i-th noise source or vibration source on the tested vehicle to the response point, a _i (f) is the noise sound pressure signal or The Fourier transform result of the vibration acceleration signal, p _i (f) is the Fourier transform result of the noise sound pressure signal produced by the ith noise source or vibration source on the vehicle under test at the response point, and repeat step (5) to obtain all different signals Interval transfer function matrix H(f); (6) Using the transfer function matrix H(f) of all the different signal intervals above, splicing out the response sound pressure time domain signal P(t) of the vehicle under test during acceleration is: $\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>$ Among them, P _i (t) is the response sound pressure time-domain signal of the i-th signal interval, P _i (f) is the response sound pressure frequency-domain signal of the i-th signal interval, A _i,n (f) is the i-th The frequency-domain signal of the noise source sound pressure signal of the signal interval and the vibration source vibration acceleration signal, H _{, n * m} (f) is the transfer function matrix of the i-th signal interval calculated according to the above method; (7) Using the transfer function matrix of the above-mentioned measured vehicle acceleration process, calculate the sensitivity and contribution of each noise source and vibration source on the measured vehicle to the sound pressure signal at the response point: The sensitivity L _total (L _p -Δ) of the total noise of the response point to the pth noise source is: ${\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; 20</span>}\mathrm{<span\; class="notranslate">\; log</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}\frac{\sqrt{\frac{\underset{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\overset{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; fft</span>}<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; ]</span>}^{<span\; class="notranslate">\; \&prime;</span><span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; m</span>}}}}{{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}$ Where p ₀ is the standard reference pressure, m is the number of sampling points in a signal interval, [A|S]″ represents the noise source signal matrix after the sound pressure level Lp of the pth noise source is reduced by Δ, and Δ is the set sound pressure level reduction, The contribution of the noise source or vibration source to the sound pressure signal at the response point is: ${\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}{\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; ifft</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span>$ Among them, A _{i, n-1} (f) is the frequency domain signal of the sound pressure signal of the noise source and the vibration acceleration signal of the vibration source after removing the pth noise source or vibration source, H _{i, (n-1)×( m-1)} is the transfer function matrix after removing the pth noise source or vibration source.