Method for testing noise in passenger vehicle on cement sculptured pavement

Abstract

The invention discloses a passenger vehicle cement sculptured pavement interior noise test method, which comprises the steps of setting a pavement test condition of passenger vehicle interior noise based on a cement sculptured pavement, the pavement test condition comprising a preset vehicle speed and test time; noise information and vehicle speed information in the cabin are collected according to the road surface test working condition; setting a noise sampling frequency, and carrying out sampling processing on noise information to obtain a processed time domain signal; fourier transform is carried out on the time domain signal, a frequency domain signal of a noise spectrum is obtained, an in-vehicle sound pressure value noise spectrum curve is generated, and objective evaluation is carried out on the size of the in-vehicle sound pressure value; the time domain signal is processed to obtain sharpness, and the sharpness is objectively evaluated; according to the method, the test analysis and evaluation method of the impact noise is defined, and aiming at the complaint problem possibly existing in a customer, the real passenger car tire is adjusted through a tested objective data result in the whole car development process, so that the squeal noise is optimized, and the NVH quality of the whole car is improved.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle noise testing, and in particular to a method for testing in-vehicle noise of a passenger car on a cement-grained road surface. Background Art

[0002] When a passenger car is driving, the noise generated by the rolling tires and contact with the road is called tire / road noise. Studies have shown that when the vehicle speed is higher than 40-80km / h, road / tire noise is the main noise source for passenger cars in good condition. This noise is not only related to the tires themselves but also closely related to the road surface on which the vehicle is driving.

[0003] Among them, cement grooved pavement is a common cement concrete pavement on secondary roads. When a passenger car travels on the cement grooved pavement at a certain speed, sharp high-frequency noise will be generated in the car, and the noise frequency will increase or decrease with the increase or decrease of the vehicle speed. The so-called whistling noise of the cement grooved pavement, especially with the increasing market share of electric vehicles, without the shielding of the engine and exhaust system, this sound will be more prominent, becoming an important factor affecting the driving comfort of the whole vehicle. Domestic and foreign OEMs have paid more attention to this sound during the product development process, and the above problems need to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to provide a method for testing the interior noise of a passenger car on a cement-engraved pavement, and to test and evaluate the "howling" noise of a passenger car on a cement-engraved pavement. The method describes the test, analysis and evaluation methods for the interior noise of different types of passenger cars passing through a cement-engraved pavement, provides a reliable and effective test and evaluation method for the development of the cement-engraved noise performance of the whole vehicle, provides support for the positive development of the interior noise of passenger cars, and solves the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for testing the in-vehicle noise of a passenger car on a cement-grained road surface, comprising:

[0006] A road test condition for passenger car interior noise is set based on a cement-grained road surface, wherein the road test condition includes a preset vehicle speed and a test time;

[0007] Collect the noise information in the cabin and the vehicle speed information according to the road test conditions;

[0008] Set the noise sampling frequency, sample and process the noise information, and obtain the processed time domain signal;

[0009] Perform Fourier transform on the time domain signal to obtain the frequency domain signal of the noise spectrum and generate the noise spectrum curve of the in-vehicle sound pressure value, so as to form an objective evaluation of the in-vehicle sound pressure value;

[0010] The time domain signal is processed to obtain the sharpness, and the sharpness is objectively evaluated.

[0011] Furthermore, the road test condition for passenger car interior noise is set based on the cement textured road surface, and further includes:

[0012] Set the groove width of the cement grooved road surface, test the air temperature and wind speed of the road surface, and set the tire pressure according to the test requirements.

[0013] Furthermore, collecting the noise information in the cabin according to the road test conditions also includes:

[0014] Noise collection points are set at the inner and outer ears of the driver's seat, and at the inner and outer ears of the right rear seat.

[0015] Furthermore, the time domain signal is subjected to Fourier transform to obtain the frequency domain signal of the noise spectrum and generate the noise spectrum curve of the in-vehicle sound pressure value, which also includes the Fourier transform formula of the time domain signal:

[0016]

[0017] Where: ω is frequency, t is time, e -iωt is a complex function, f(t) is a time function, and F(ω) is a frequency function;

[0018] The noise spectrum curve of the sound pressure value in the vehicle is obtained by formula (1), and the first howling frequency is obtained by the peak interval of the noise spectrum curve of the sound pressure value in the vehicle.

[0019] Furthermore, according to Euler's formula, we get:

[0020] e -iωt =cos(ωt)-isin(ωt)——Formula (2);

[0021] Where cos(ωt) is the cosine signal superimposed on the frequency, and sin(ωt) is the sine signal superimposed on the frequency.

[0022] Furthermore, a second howling frequency formula is also included:

[0023] F = v*0.2778 / L - formula (3);

[0024] Where, v is the vehicle speed, L is the groove width, and F is the second howling frequency;

[0025] The first howling frequency is corrected by the second howling frequency.

[0026] Furthermore, an objective evaluation of the sound pressure value inside the vehicle is formed, which also includes:

[0027] The peak interval of the noise spectrum curve of the in-vehicle sound pressure value is divided into multiple continuous sound pressure level ranges from large to small, and an objective scoring value a is set for each sound pressure level range.

[0028] Furthermore, the sharpness in the time domain signal is processed to form an objective evaluation of the sharpness, which also includes:

[0029] Based on the proportion of high-frequency components in the sound spectrum, the time domain signal is processed to obtain a curve showing the change of sharpness over time;

[0030] The sharpness range is divided into a plurality of continuous sharpness ranges from large to small, and an objective score value b is set for each sharpness range.

[0031] Furthermore, a high-fidelity playback system is used to play back the collected data for subjective evaluation to obtain a subjective score c.

[0032] Furthermore, a subjective and objective evaluation model is established, and the score calculation formula is:

[0033] S=αa+βb+γc——Formula (4), where α+β+γ=1;

[0034] In the formula, α is the weight of the objective score value A, β is the weight of the objective score value B, γ is the weight of the subjective score value c, and S is the subjective and objective evaluation score.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention clarifies the test analysis and evaluation methods of this type of impact noise, and in response to possible complaints from customers, during the vehicle development process, the objective test data results are used to adjust the actual passenger car tires to optimize the "howling" noise and improve the NVH quality of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart of a method for testing interior noise of a passenger car on a cement-grained road surface according to an embodiment of the present invention;

[0037] Figure 2 A schematic diagram of a cement textured pavement in an embodiment of the present invention;

[0038] Figure 3 Schematic diagram of noise measurement points in the cabin according to an embodiment of the present invention;

[0039] Figure 4 A top view of the arrangement of microphones at noise measurement points in an embodiment of the present invention;

[0040] Figure 5 A side view of the microphone arrangement at the noise measurement point in an embodiment of the present invention;

[0041] Figure 6Schematic diagram of a spectrum curve of the sound pressure value in a vehicle according to an embodiment of the present invention;

[0042] Figure 7 Schematic diagram of a sharpness curve in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the 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.

[0044] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0045] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] Please refer to the instruction manual Figures 1 to 7 As shown, the present invention provides a technical solution: Figure 1 As shown, a method for testing the in-vehicle noise of a passenger car on a cement-grained road surface comprises the following steps:

[0047] S102, setting a road test condition for interior noise of a passenger car based on a cement-grained road surface, wherein the road test condition includes a preset vehicle speed and a test time;

[0048] Specifically, the groove width of the cement grooved road surface is set, the air temperature and wind speed of the test road surface are tested, and the tire pressure is set according to the test requirements.

[0049] The test road is a straight cement-grained road surface, such as Figure 2As shown, the preferred groove width is 2mm, the depth is 3mm, and the interval between the grooves is 20mm; the road surface needs to be dry; preferably, the OEM can build the road according to the parameters in the figure to meet the consistency requirements; during the measurement process, the distance between the test vehicle and large objects or other vehicles should be greater than 20m; preferably, the following meteorological conditions should be met during the test: the temperature is between 5℃ and 40℃; the wind speed at a height of 1.2m along the measurement route should be less than 5m / s, and the tire pressure should meet the design requirements.

[0050] S104, collecting noise information and vehicle speed information in the cabin according to the road test conditions;

[0051] Specifically, Figures 3 to 5 As shown, the noise information in the cockpit is collected according to the road test conditions, and also includes:

[0052] Noise collection points are set at the inner and outer ears of the driver's seat, and at the inner and outer ears of the right rear seat.

[0053] Among them, the test equipment is mainly composed of a front end, a microphone sensor, a GPS sensor, a test computer equipped with software matching the front end, and a test application installed on the test computer; microphones and GPS are arranged in the car to collect vehicle speed signals; microphones are arranged at the inner and outer ears of the driver's seat and at the inner and outer ears of the right rear row. The adjustable seats should be adjusted to the middle position horizontally, front and back, and vertically. If the seat back is also adjustable, it should be in a vertical position as much as possible. The adjustable headrest should be in the middle position. The test computer, front end, and sensor are connected.

[0054] S106, setting the noise sampling frequency, sampling and processing the noise information, and obtaining a processed time domain signal;

[0055] The microphone is calibrated. Preferably, the microphone needs to be calibrated with a 1000Hz 94dB calibrator. In this embodiment, the noise sampling frequency is preferably set to 25600Hz for the data acquisition parameter. During the test, the vehicle windows and the sound-generating electrical equipment in the vehicle are closed, and the air conditioner is set to internal circulation. The vehicle is in gear D and the vehicle is driving at a constant speed of 60km / h. Figure 2 For the cement grooved pavement shown, the test time is not less than 30s.

[0056] S108, performing Fourier transform on the time domain signal to obtain a frequency domain signal of the noise spectrum and generate a noise spectrum curve of the in-vehicle sound pressure value, so as to form an objective evaluation of the in-vehicle sound pressure value;

[0057] Specifically, Figure 6 As shown, the time domain signal is Fourier transformed to obtain the frequency domain signal of the noise spectrum and generate the noise spectrum curve of the sound pressure value in the vehicle, which also includes the Fourier transform formula of the time domain signal:

[0058]

[0059] Where: ω is frequency, t is time, e -iωt is a complex function, f(t) is a time function, and F(ω) is a frequency function;

[0060] The noise spectrum curve of the sound pressure value in the vehicle is obtained by formula (1), and the first howling frequency is obtained by the peak interval of the noise spectrum curve of the sound pressure value in the vehicle.

[0061] Specifically, according to Euler's formula:

[0062] e -iωt =cos(ωt)-isin(ωt)——Formula (2);

[0063] Where cos(ωt) is the cosine signal superimposed on the frequency, and sin(ωt) is the sine signal superimposed on the frequency.

[0064] It is understandable that the meaning of this formula is that a time domain waveform can be superimposed by countless sine and cosine signals of different frequencies, and then reveal the relationship between the intensity and frequency of these sine and cosine signals. This formula ultimately converts an unknown signal f(t) into a curve function F(ω) in the frequency domain; the frequency spectrum obtained by averaging the Fourier transform spectrum is as follows Figure 6 , we can see that there is an obvious peak in the figure, and it is a fixed frequency, which is the first howling frequency.

[0065] Specifically, the second howling frequency formula is also included:

[0066] F = v*0.2778 / L - formula (3);

[0067] Where, v is the vehicle speed, L is the groove width, and F is the second howling frequency;

[0068] The first howling frequency is corrected by the second howling frequency.

[0069] Among them, the howling frequency is mainly related to the width of the cement road surface and the vehicle speed. Because the howling frequency is fixed, the full-band analysis usually used for analysis cannot clearly show the size of the howling sound. Therefore, the howling frequency is used as the center frequency, and the RMS value is taken as one of the assessment indicators with a bandwidth of 20Hz before and after 40Hz. During the development process, this value needs to be benchmarked and analyzed to establish a target to characterize the noise of the tire solution on the cement road surface. The size of the noise can be improved by adjusting the tire solution. This processing method can better characterize the sound pressure level of the "howling" noise of passenger cars on cement grooved roads.

[0070] Specifically, an objective evaluation of the sound pressure value inside the vehicle also includes:

[0071] The peak interval of the noise spectrum curve of the in-vehicle sound pressure value is divided into multiple continuous sound pressure level ranges from large to small, and an objective scoring value a is set for each sound pressure level range.

[0072] Among them, the sound pressure level is formed into an objective scoring table, and the sound pressure level is represented by A:

[0073] Table 1 Sound pressure level objective value rating table

[0074] Sound pressure level range Rating value a A>62 1 62≥A>61 2 61≥A>60 3 60≥A>59 4 59≥A>58 5 58≥A>57 6 57≥A>56 7 57≥A>56 8 57≥A>56.5 9 56.5≥A 10

[0075] S110, processing the time domain signal to obtain sharpness, and objectively evaluating the sharpness.

[0076] Specifically, Figure 7 As shown, the sharpness in the time domain signal is processed to form an objective evaluation of the sharpness, and also includes:

[0077] Based on the proportion of high-frequency components in the sound spectrum, the time domain signal is processed to obtain a curve showing the change of sharpness over time;

[0078] The sharpness range is divided into a plurality of continuous sharpness ranges from large to small, and an objective score value b is set for each sharpness range.

[0079] Among them, sharpness processing, sharpness is a physical quantity that describes the proportion of high-frequency components in the sound spectrum. Sharpness is defined as the ratio of the level of the high-frequency part of the sound event to the overall level. That is to say, the higher the energy of the sound in the high-frequency part, the sharper it will feel. Numerically, sharpness is obtained by multiplying the characteristic loudness by a weighted function to integrate the frequency domain, and then dividing it by the total loudness. It reflects people's subjective feeling of high-frequency sounds and the harshness of the sound signal. The unit of sharpness is acum, and the sharpness of a 60-decibel narrowband noise with a center frequency of 1kHz and a bandwidth of 160Hz is 1acum. It is the result of frequency domain and time domain processing of sound. The measured time domain signal is calculated by data processing software Figure 4 The curve of sharpness changing with time. Generally, when the sharpness is greater than 0.7acum, people will feel uncomfortable. Generally, the sharpness of cement engraved pavement is controlled below 0.7acum. This sharpness is formed into an objective scoring table, and the sound pressure level is represented by B:

[0080] Table 2 Sharpness objective value scoring table

[0081]

[0082]

[0083] Specifically, a high-fidelity playback system is used to play back the collected data for subjective evaluation to obtain a subjective score c.

[0084] Among them, for subjective evaluation, the collected data is replayed by a high-fidelity playback system for subjective evaluation, and the 10-point absolute scoring method is used to score, and the original data of the subjective evaluation score is obtained. Among them, the number of evaluators for subjective evaluation should be greater than or equal to 2; each evaluator evaluates each vehicle twice and in different time periods; finally, the average score is taken. The scoring criteria and scoring table are shown in Table 1, and the subjective score is represented by c.

[0085] Table 3 Subjective evaluation score table

[0086]

[0087] The subjective feeling is manifested in the harshness and divergence of the howling noise. The harshness is closely related to the maximum sound pressure level of the center frequency of the howling noise; while the divergence is related to the sound pressure level 20Hz before and after the center frequency, which can be understood as Figure 4 The fatter or thinner the curve is, the more harsh it is and the worse the subjective feeling is, and vice versa.

[0088] Specifically, a subjective and objective evaluation model is established, and the score calculation formula is:

[0089] S=αa+βb+γc——Formula (4), where α+β+γ=1;

[0090] In the formula, α is the weight of the objective score a, β is the weight of the objective score b, γ is the weight of the subjective score c, and S is the subjective and objective evaluation score.

[0091] Among them, it should be noted that when one of a, b, and c scores less than 5, it is considered unqualified; the final score is greater than or equal to 7 for qualified, and greater than 5 and less than or equal to 7 for barely acceptable; this patent accurately measures and evaluates the "howling" noise inside a car when it is driving on a cement grooved road. The present invention provides an objective test and analysis method for the noise inside a passenger car when it passes over a cement grooved road. It objectively characterizes and subjectively scores the "howling" noise of the cement grooved road in a relatively comprehensive manner, and establishes a subjective and objective evaluation model to quantify it for adjustment and modification; it can guide the setting of development goals for the "howling" noise of cement grooved roads and the development of NVH performance of actual vehicle tires during the development of complete vehicle products, and create a high-quality comfort for passenger car road noise.

[0092] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for testing the noise inside a passenger car on a cement-grained road surface, characterized in that: include: A road test condition for passenger car interior noise is set based on a cement-grained road surface, wherein the road test condition includes a preset vehicle speed and a test time; Collect the noise information in the cabin and the vehicle speed information according to the road test conditions; Set the noise sampling frequency, sample and process the noise information, and obtain the processed time domain signal; Perform Fourier transform on the time domain signal to obtain the frequency domain signal of the noise spectrum and generate the noise spectrum curve of the in-vehicle sound pressure value, so as to form an objective evaluation of the in-vehicle sound pressure value; The time domain signal is processed to obtain the sharpness, and the sharpness is objectively evaluated.

2. A method for testing interior noise of a passenger car on cement-grained pavement according to claim 1, characterized in that: The road test conditions for passenger car interior noise are set based on cement textured pavement, including: Set the groove width of the cement grooved road surface, test the air temperature and wind speed of the road surface, and set the tire pressure according to the test requirements.

3. The method for testing the interior noise of a passenger car on cement-grained pavement according to claim 1, characterized in that: The noise information in the cabin is collected according to the road test conditions, including: Noise collection points are set at the inner and outer ears of the driver's seat, and at the inner and outer ears of the right rear seat.

4. The method for testing the interior noise of a passenger car on cement-grained pavement according to claim 1, characterized in that: Perform Fourier transform on the time domain signal to obtain the frequency domain signal of the noise spectrum and generate the noise spectrum curve of the sound pressure value in the car, including the Fourier transform formula of the time domain signal: Where: ω is frequency, t is time, e -iωt is a complex function, f(t) is a time function, and F(ω) is a frequency function; The noise spectrum curve of the sound pressure value in the vehicle is obtained by formula (1), and the first howling frequency is obtained by the peak interval of the noise spectrum curve of the sound pressure value in the vehicle.

5. A method for testing interior noise of a passenger car on cement-grained pavement according to claim 4, characterized in that: According to Euler's formula: e -iωt =cos(ωt)-isin(ωt)——Formula (2); Where cos(ωt) is the cosine signal superimposed on the frequency, and sin(ωt) is the sine signal superimposed on the frequency.

6. The method for testing the interior noise of a passenger car on cement-grained pavement according to claim 4, characterized in that: Also includes the second howling frequency formula: F = v*0.2778 / L - formula (3); Where, v is the vehicle speed, L is the groove width, and F is the second howling frequency; The first howling frequency is corrected by the second howling frequency.

7. The method for testing the interior noise of a passenger car on cement-grained pavement according to claim 4, characterized in that: The objective evaluation of the sound pressure value in the car also includes: The peak interval of the noise spectrum curve of the in-vehicle sound pressure value is divided into multiple continuous sound pressure level ranges from large to small, and an objective scoring value a is set for each sound pressure level range.

8. The method for testing the interior noise of a passenger car on cement-grained pavement according to claim 7, characterized in that: After processing the sharpness in the time domain signal, an objective evaluation of the sharpness is formed, which also includes: Based on the proportion of high-frequency components in the sound spectrum, the time domain signal is processed to obtain a curve showing the change of sharpness over time; The sharpness range is divided into a plurality of continuous sharpness ranges from large to small, and an objective score value b is set for each sharpness range.

9. A method for testing interior noise of a passenger car on cement-grained pavement according to claim 8, characterized in that: include: The collected data is replayed and subjectively evaluated using a high-fidelity playback system to obtain a subjective score c.

10. A method for testing interior noise of a passenger car on cement-grained pavement according to claim 9, characterized in that: A subjective and objective evaluation model is established, and the score calculation formula is: S=αa+βb+γc——Formula (4), where α+β+γ=1; In the formula, α is the weight of the objective score a, β is the weight of the objective score b, γ is the weight of the subjective score c, and S is the subjective and objective evaluation score.

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