A vehicle chassis wind noise optimization method and a new energy vehicle

Abstract

The application discloses a vehicle chassis wind noise optimization method and a new energy vehicle. The energy peak value of the chassis wind noise and the chassis wind noise contribution plate generating the wind noise can be accurately determined by performing a chassis wind noise test on a target vehicle. When the energy peak value exceeds the standard, a flow guide plate is added to the chassis cavity corresponding to the chassis wind noise contribution plate, and / or a stiffness strengthening structure is added to the chassis wind noise contribution plate. The two methods can be independently implemented or work together, so that the optimization scheme can be flexibly selected and adapted according to the specific chassis layout and wind noise characteristics, effectively widening the application range of the method. Through the complete closed-loop process of the above test, determination and optimization, the energy peak value of the chassis wind noise is finally reduced to below the preset energy threshold, thereby systematically solving the chassis wind noise problem of the new energy vehicle caused by the lack of engine noise masking, and improving the in-vehicle driving comfort.

Description

Technical Field

[0001] This invention relates to the field of automotive wind noise technology, and more particularly to a method for optimizing vehicle chassis wind noise and new energy vehicles. Background Technology

[0002] As users' demands for a superior driving experience continue to rise, wind noise's impact on driving comfort is becoming increasingly prominent, especially in new energy vehicles. Due to the lack of masking effect from traditional engine noise, low-frequency rumbling caused by chassis wind noise is more easily perceived by passengers. Furthermore, influenced by the trend towards lightweight vehicle floor designs, chassis wind noise has become increasingly severe, becoming one of the significant noise sources affecting vehicle sound quality. During high-speed driving, the chassis area is prone to generating low-frequency wind noise below 500Hz due to air turbulence, component vibration, and cavity resonance. Moreover, because current chassis wind noise simulation technology is still immature, it is difficult to effectively mitigate this noise through simulation during the early design phase. Therefore, effectively suppressing chassis wind noise is a pressing issue that needs to be addressed. Summary of the Invention

[0003] This application provides a method for optimizing vehicle chassis wind noise and a new energy vehicle, which solves the technical problem in the prior art that it is difficult to effectively locate and suppress structural resonance caused by airflow excitation in the chassis cavity during the early design stage when there is a lack of mature simulation methods, resulting in excessive low-frequency wind noise in the vehicle. It achieves the technical effect of significantly reducing the peak value of chassis wind noise through the dual synergistic means of flow field optimization and structural stiffness compensation, thereby improving driving comfort.

[0004] In a first aspect, this application provides a method for optimizing wind noise in a vehicle chassis, applicable to new energy vehicles, the method comprising: Conduct chassis wind noise tests on the target vehicle to determine the peak energy of the chassis wind noise and the chassis wind noise contributing components. If the energy peak value is greater than or equal to a preset energy threshold, a guide vane is added to the chassis cavity corresponding to the chassis wind noise contributing plate, and / or a stiffness reinforcement structure is added to the chassis wind noise contributing plate to adjust the mode of the chassis wind noise contributing plate, so that the energy peak value of the chassis wind noise of the target vehicle is less than the preset energy threshold.

[0005] Secondly, this application provides a new energy vehicle, including: Chassis; The air deflector and / or stiffness reinforcement structure installed on the chassis are installed based on a vehicle chassis wind noise optimization method provided in the first aspect.

[0006] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: This application embodiment, by conducting chassis wind noise tests on the target vehicle, can accurately determine the peak energy of the chassis wind noise and the chassis wind noise contributing components, thereby precisely locating the in-vehicle noise phenomenon to a specific chassis cavity excitation source and the corresponding body panel transmission path, providing a clear target and quantitative basis for subsequent optimization. Furthermore, by comparing the determined peak energy with a preset energy threshold, objective criteria are provided for determining whether optimization is needed and whether the optimization meets the standard, avoiding the uncertainty and repeated verification costs associated with subjective experience. When the peak energy exceeds the standard, the method adds a deflector to the chassis cavity corresponding to the chassis wind noise contributing component, using the deflector to change the airflow at the cavity inlet. By considering airflow direction and shear layer characteristics, the excitation intensity of vortex-induced acoustic coupling is reduced from the source of the flow field. Alternatively, by adding stiffness reinforcement structures to the chassis wind noise contributing plates, the modal frequencies of these plates are increased to avoid the excitation frequencies, thus preventing resonance amplification through structural transmission paths. These two methods can be implemented independently or in synergy, allowing the optimization scheme to be flexibly selected and adapted according to the specific chassis layout and wind noise characteristics, effectively broadening the applicability of the method. Through the complete closed-loop process combining testing, judgment, and optimization, the peak energy of chassis wind noise is ultimately reduced to below a preset energy threshold, thereby systematically solving the chassis wind noise problem caused by the lack of engine noise masking in new energy vehicles and improving in-vehicle driving comfort. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below only show some embodiments of the present invention. Those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0008] Figure 1 A flowchart illustrating a method for optimizing wind noise in a vehicle chassis, provided in an embodiment of this application; Figure 2 A schematic diagram illustrating the principle of the fluid acoustic resonance model provided in this application embodiment; Figure 3 A schematic diagram illustrating the frequency-energy distribution characteristics provided in an embodiment of this application; Figure 4 This is a cross-sectional schematic diagram of the chassis cavity along the front and rear directions of the target vehicle; Figure 5 This is a top view of the deflector along the direction from the roof to the bottom of the target vehicle. Figure 6 This is a schematic diagram comparing the in-vehicle noise spectrum before and after adding the deflector in an embodiment of this application. Figure 7 The comparison curves of in-vehicle noise and floor vibration before and after adding an elastic support between the battery pack frame and the floor in the embodiments of this application are shown. Figure 8 The above are comparison curves of in-vehicle noise and floor vibration before and after floor modal enhancement in the embodiments of this application. Figure 9 This is a schematic diagram showing the location of the added foam in an embodiment of this application; Figure 10 This is a schematic diagram of the added reinforcing plate provided in an embodiment of this application.

[0009] Figure label: 1-Chassis, 11-Rear wall, 12-Top wall, 13-Front wall, 2-Cavity, 3-Blower plate, 31-Second edge. Detailed Implementation

[0010] This application provides a method for optimizing vehicle chassis wind noise and a new energy vehicle, which solves the technical problem in the prior art that it is difficult to effectively locate and suppress structural resonance caused by airflow excitation in the chassis cavity during the early design stage when there is a lack of mature simulation methods, resulting in excessive low-frequency wind noise in the vehicle. It achieves the technical effect of significantly reducing the peak value of chassis wind noise through the dual synergistic means of flow field optimization and structural stiffness compensation, thereby improving driving comfort.

[0011] The technical solution of this application embodiment is to solve the above-mentioned technical problems, and the general idea is as follows: This application embodiment, by conducting chassis wind noise tests on the target vehicle, can accurately determine the peak energy of the chassis wind noise and the chassis wind noise contributing components, thereby precisely locating the in-vehicle noise phenomenon to a specific chassis cavity excitation source and the corresponding body panel transmission path, providing a clear target and quantitative basis for subsequent optimization. Furthermore, by comparing the determined peak energy with a preset energy threshold, objective criteria are provided for determining whether optimization is needed and whether the optimization meets the standard, avoiding the uncertainty and repeated verification costs associated with subjective experience. When the peak energy exceeds the standard, the method adds a deflector to the chassis cavity corresponding to the chassis wind noise contributing component, using the deflector to change the airflow at the cavity inlet. By considering airflow direction and shear layer characteristics, the excitation intensity of vortex-induced acoustic coupling is reduced from the source of the flow field. Alternatively, by adding stiffness reinforcement structures to the chassis wind noise contributing plates, the modal frequencies of these plates are increased to avoid the excitation frequencies, thus preventing resonance amplification through structural transmission paths. These two methods can be implemented independently or in synergy, allowing the optimization scheme to be flexibly selected and adapted according to the specific chassis layout and wind noise characteristics, effectively broadening the applicability of the method. Through the complete closed-loop process combining testing, judgment, and optimization, the peak energy of chassis wind noise is ultimately reduced to below a preset energy threshold, thereby systematically solving the chassis wind noise problem caused by the lack of engine noise masking in new energy vehicles and improving in-vehicle driving comfort.

[0012] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0013] First, it should be clarified that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0014] This application provides a method for optimizing wind noise in a vehicle chassis, applicable to new energy vehicles. The method includes steps S11-S12, which can be found in detail below. Figure 1 As shown.

[0015] Step S11: Conduct a chassis wind noise test on the target vehicle to determine the peak energy of the chassis wind noise and the chassis wind noise contributing components. Step S12: If the energy peak value is greater than or equal to a preset energy threshold, a guide vane is added to the chassis cavity corresponding to the chassis wind noise contributing plate, and / or a stiffness reinforcement structure is added to the chassis wind noise contributing plate to adjust the mode of the chassis wind noise contributing plate, so that the energy peak value of the chassis wind noise of the target vehicle is less than the preset energy threshold.

[0016] Regarding step S11, a chassis wind noise test is performed on the target vehicle to determine the peak energy of the chassis wind noise and the chassis wind noise contributing components.

[0017] The target vehicle has three-dimensional acceleration sensors and chassis microphones installed in multiple chassis cavity areas, and an in-cabin microphone is installed at the target location in the passenger compartment of the target vehicle.

[0018] In this embodiment, the chassis cavity region refers to the closed or semi-closed gap space formed between various components of the vehicle chassis due to their structural arrangement. For example, in new energy vehicles, the battery pack is usually laid flat in the middle of the chassis, and typical chassis cavity regions are formed between its front and the front crossbeam of the vehicle body, and between its rear and the rear floor crossbeam. In addition, the rear suspension mounting slot, the area around the exhaust pipe passage, and the spare tire well are also common chassis cavity regions. When the vehicle is traveling at high speed, airflow shear layers easily form at the openings of these cavity regions, thereby generating vortex-induced noise coupling, which is the main excitation source of chassis wind noise.

[0019] The generation mechanism of chassis wind noise can be explained using a fluid acoustic resonance model. Please refer to [link / reference]. Figure 2 As shown, this model takes the longitudinal section of the chassis cavity as the analysis object, where the length L is defined as the cavity dimension along the vehicle's driving direction (i.e., from the front to the rear of the vehicle), the depth H is defined as the cavity dimension along the vertical direction, and the direction of the incoming flow velocity Uc is from the front wall of the cavity to the rear wall (i.e., from the front to the rear of the vehicle). Figure 2 The middle section is from left to right. Figure 4 The middle is from right to left, that is... Figure 2 and Figure 4(The front and rear directions of the vehicle are opposite in the image). When the vehicle is traveling at high speed, a speed difference is created between the fast-moving external airflow passing through the opening of the chassis cavity and the relatively stationary airflow inside the cavity, thus generating an airflow shear layer at the opening. This shear layer itself is unstable and will generate periodic vortex shedding after being slightly disturbed. Taking the front wall of the cavity as an example, the shed vortices move towards the rear wall of the cavity under the influence of the incoming flow. When the vortices reach the rear wall, they collide with and break up, generating a pressure wave. Part of this pressure wave propagates towards the cavity opening (i.e., upstream). When this pressure wave reaches the edge of the opening on the front wall of the cavity, it will disturb the shear layer again, thus inducing a new wave of vortex shedding. Thus, vortex shedding, impact with the rear wall, pressure wave feedback to the front edge, and induction of new vortex shedding form a closed feedback loop. When the vortex shedding frequency in the feedback loop satisfies a specific phase matching relationship with the inherent acoustic frequency of the cavity, the energy in the feedback loop will continue to accumulate and amplify, forming a self-excited oscillation phenomenon of vortex-acoustic coupling. This self-excited oscillation will cause periodic and violent fluctuations in the fluid pressure inside the cavity, which is the source of chassis wind noise.

[0020] Furthermore, the period of the aforementioned self-excited oscillation is equal to the sum of the time required for the vortex to move from the leading edge to the trailing edge and the time required for the pressure wave to propagate from the trailing edge to the leading edge. Based on fluid acoustics theory, the frequency of the self-excited oscillation can be predicted using a semi-empirical formula, the expression of which is:

[0021] in, For the incoming flow velocity, The length of the cavity along the direction from the front to the rear of the vehicle. The modal order (take a positive integer, i.e., n=1,2,3,...). For the Mach number of the incoming flow, The value is 1.75, which is used for the calibration of the test. Since both automobiles and trains are ground transportation vehicles operating at high Reynolds numbers and low Mach numbers, their chassis cavity flow characteristics satisfy the applicable conditions of the aforementioned semi-empirical formula. When the self-excited oscillation frequency predicted by this empirical formula is close to the natural frequency of the body panel structure corresponding to the chassis cavity wall panel, pressure fluctuations will excite resonance in the panel structure. This structural vibration is further transmitted to the passenger compartment through the body connection structure or holes, ultimately forming a perceptible low-frequency rumbling noise inside the vehicle, i.e., the chassis wind noise described in the embodiments of this application.

[0022] In this embodiment, the three-dimensional acceleration sensors are deployed on the body sheet metal structures corresponding to the various chassis cavity areas, including but not limited to the floor sheet metal, rear bumper mounting plate, and wheel arch inner panels. During deployment, it must be ensured that the three measurement directions of the sensors are strictly aligned with the X-axis (front to rear direction), Y-axis (vehicle width direction), and Z-axis (vertical direction) of the vehicle coordinate system, respectively, to avoid distortion of vibration component measurements due to installation angle deviations. This setup enables accurate acquisition of vibration acceleration signals of the body panels in three directions caused by chassis airflow excitation, providing a reliable data foundation for subsequent spectrum analysis and modal identification.

[0023] In this embodiment, the target location within the passenger compartment refers to the placement point of the microphone used to collect in-vehicle noise signals. Specifically, the target location includes the left ear near the driver's head position and the right ear near the head position of the rear right-side passenger. These two locations are the benchmark points for measuring in-vehicle noise in the front and rear rows as specified in national standards such as GB / T 18697, effectively characterizing the actual in-vehicle noise level perceived by the driver and rear passengers, thus providing a unified test basis for the objective evaluation of chassis wind noise optimization effects.

[0024] The target vehicle is subjected to chassis wind noise test to determine the peak energy of the chassis wind noise and the chassis wind noise contributing components, including steps S111-S112.

[0025] Step S111: Control the target vehicle to drive on a road with preset road surface characteristics at a preset speed and during the driving process, acquire the body vibration signal from each three-dimensional acceleration sensor, the chassis cavity noise signal from multiple chassis microphones, and the passenger compartment noise signal from the cabin microphone. Step S112 involves performing spectrum analysis on the vehicle body vibration signal, chassis cavity noise signal, and passenger compartment noise signal, and filtering and replaying the passenger compartment noise signal to determine the peak energy of the chassis wind noise of the target vehicle and the chassis wind noise contributing components.

[0026] Step S111 establishes standardized acquisition conditions for chassis wind noise testing. Specifically, the target vehicle is controlled to travel on a smooth, straight road surface at a preset speed, typically a constant speed of 100 km / h or higher, as this speed range is where chassis wind noise is most prominent. While the vehicle maintains a constant speed, three types of signals are simultaneously acquired: body vibration signals collected by three-dimensional accelerometers positioned on the corresponding sheet metal areas of each chassis cavity; chassis cavity noise signals collected by chassis microphones positioned in each chassis cavity area; and passenger compartment noise signals collected by in-cabin microphones positioned at the target location within the passenger compartment. Simultaneously, vehicle speed signals are also acquired to monitor whether the vehicle strictly maintains the preset constant speed. The entire acquisition process lasts at least 10 seconds to ensure that the acquired signals have sufficient statistical stability and representativeness, avoiding insufficient frequency resolution in subsequent spectrum analysis due to insufficient signal length.

[0027] Among them, smooth and straight road surface refers to a special test section used to carry out standard tests on vehicle power, economy, braking safety and handling stability, and its geometric shape and physical adhesion coefficient must meet the preset tolerance range.

[0028] For example, regarding the geometric dimension of "straightness," the core is to eliminate the additional interference of slope and curvature on vehicle driving resistance. Specifically, the road surface must ensure that the maximum gap within any 3-meter length is no greater than 3 millimeters in the longitudinal direction (i.e., smoothness ≤ 3mm / 3m), and the longitudinal slope should be controlled within 0.5% to eliminate the influence of gravity components on acceleration or coasting tests; in the transverse direction, the road surface cross slope should also be less than 1.5% to ensure that the load distribution on the left and right wheels of the vehicle is uniform and that there is no lateral deviation due to road inclination. At the same time, the test section should have sufficient length (usually no less than 2 kilometers) and width (no less than 6 to 8 meters) to ensure that the vehicle trajectory does not need to be drastically corrected during the test, thus forming a "straight segment" in a physical sense on a macroscopic level.

[0029] In terms of the physical dimension of "smoothness," it does not refer to an extremely low friction like a mirror surface, but rather specifically to a road surface having a specific and stable coefficient of adhesion (or coefficient of friction) to meet the boundary conditions of different test conditions. For example, "smoothness" usually refers to a dry, clean asphalt concrete or cement concrete road surface, with its peak coefficient of adhesion generally controlled between 0.75 and 0.85, and the road surface must not have loose gravel, oil stains, or standing water to ensure good repeatability of test results. However, if ABS braking or ESC (electronic stability control) testing is involved, this "smoothness" characteristic needs to be further quantified as a low coefficient of adhesion road surface, that is, the coefficient of adhesion of the road surface needs to be precisely controlled near a specific value (such as peak coefficient of adhesion ≤ 0.3), and a special polished cement layer or tile road surface paving process is required to achieve this.

[0030] Step S112 is used to analyze and process the various signals collected in step S111 to determine the source of abnormal noise and its transmission path. Specifically, the vehicle body vibration signal, chassis cavity noise signal, and passenger compartment noise signal are first subjected to spectral analysis to obtain their respective frequency-energy distribution characteristics.

[0031] Frequency-energy distribution characteristics, for example, Figure 3 The image shows the spectral analysis results for a certain vehicle model. It can be seen that vehicle body vibration, chassis cavity noise, and interior noise have a significant correlation in the frequency domain. Overall, all three exhibit a distribution characteristic of first increasing and then decreasing with frequency, reaching their respective energy peaks near 120Hz: the floor Z-axis vibration acceleration reaches its maximum amplitude at this frequency, and the sound pressure levels of both chassis cavity noise and interior noise also reach their highest points at this frequency. Within the frequency range of 20Hz to 120Hz, as the frequency increases, the vibration acceleration amplitude gradually increases, and the sound pressure levels of both chassis cavity noise and interior noise also increase synchronously, showing good consistency among the three. Within the frequency range of 120Hz to 220Hz, all three show a gradual attenuation trend, indicating that the coupling degree between vibration and noise in this frequency band decreases with increasing frequency. It is noteworthy that the sound pressure levels of chassis cavity noise and interior noise are highly similar at each frequency point, further illustrating that the chassis wind noise perceived inside the vehicle mainly originates from fluid pressure pulsations in the chassis cavity and is transmitted to the passenger compartment through the vehicle body structure. The aforementioned spectral characteristics provide clear data support for determining the peak energy frequency of chassis wind noise and its corresponding excitation source in the chassis cavity and the contribution of body panels.

[0032] While obtaining the frequency-energy distribution characteristics of each component, the passenger compartment noise signal is filtered and replayed. This involves using a bandpass filter to retain specific frequency band components and performing subjective listening to determine the abnormal frequency corresponding to the abnormal noise inside the vehicle. Based on this, the frequency of the abnormal noise inside the vehicle is compared with the peak frequency of the noise spectrum of each chassis cavity and the peak frequency of the vibration spectrum of the corresponding body panel in each chassis cavity area. When all three show a significant energy peak at the same frequency, it can be determined that the abnormal noise inside the vehicle is caused by airflow excitation at the corresponding chassis cavity, resulting in vibration of the body panel at that location, which is then transmitted to the passenger compartment, forming chassis wind noise. In this case, the chassis cavity is identified as the excitation source of chassis wind noise, and the body panel is identified as the contributing component of chassis wind noise.

[0033] Furthermore, for the identified chassis wind noise contributing plates, several acceleration sensors were placed in their vicinity, and local modal testing was conducted using a hammer impact method. The weak points of the plate were determined by analyzing the collected acceleration data and modal shapes. If the modal frequency of the plate is close to the aforementioned chassis wind noise frequency, the generation mechanism of chassis wind noise is confirmed from a vibration theory perspective. That is, air turbulence and cavity resonance in the chassis area cause fluid pressure fluctuations, which excite modal resonance in the plate structure, thereby transmitting noise into the vehicle interior.

[0034] In this embodiment, the cooperation of steps S111 and S112 achieves at least the following technical effects. First, by setting standardized test conditions (smooth, straight road surface, specific constant vehicle speed, and a sampling duration of no less than 10 seconds), the interference of random road surface excitation and transient conditions on the test results can be effectively eliminated, ensuring good consistency and repeatability of the signals used in subsequent analysis, providing a reliable test basis for accurately identifying chassis wind noise. Second, by simultaneously collecting vehicle vibration signals, chassis cavity noise signals, and passenger compartment noise signals and performing joint spectrum analysis, and utilizing the consistency matching relationship of frequency characteristics, the noise faults perceived inside the vehicle can be accurately traced to the specific chassis cavity excitation source and the specific vehicle body panel transmission path, achieving precise localization of chassis wind noise problems and avoiding the blindness and uncertainty caused by relying on subjective experience for troubleshooting. Third, by filtering and replaying the passenger compartment noise signal, and using the subjective judgment of human hearing to assist the objective results of spectrum analysis, the interference of other noise components in non-wind noise frequency bands can be effectively eliminated, improving the accuracy of abnormal frequency identification. Fourth, by further conducting force hammer impact modal tests on the chassis wind noise contributing plates, the agreement between the plate modal frequencies and wind noise frequencies can be verified from the perspective of structural dynamics. This confirms that resonant coupling is the root cause of noise amplification and provides a clear mechanical basis for the placement of stiffness-enhancing structures in subsequent optimization schemes.

[0035] Regarding step S12, if the energy peak value is greater than or equal to a preset energy threshold, a guide vane is added to the chassis cavity corresponding to the chassis wind noise contributing plate, and / or a stiffness reinforcement structure is added to the chassis wind noise contributing plate to adjust the mode of the chassis wind noise contributing plate, so that the energy peak value of the chassis wind noise of the target vehicle is less than the preset energy threshold.

[0036] In this embodiment, the preset energy threshold is a criterion used to determine whether chassis wind noise is within an acceptable range. This threshold can be determined in the following ways: First, by referring to the statistical distribution of chassis wind noise energy levels of similar or comparable new energy vehicles under the same test conditions, the industry-recognized or internally defined comfort target value can be used as a benchmark. Second, by combining the driving experience ratings of a subjective evaluation team, the energy level corresponding to when most evaluators determine it as "acceptable" or "without significant chassis wind noise complaints" can be calibrated as the threshold. Third, the limits for in-vehicle noise in relevant national standards or industry specifications can be referred to, and after conversion, used as the preset energy threshold. In practical engineering applications, the above three methods can be used individually or determined by a comprehensive consideration, ensuring that the preset energy threshold objectively reflects the vehicle's acoustic comfort level while also being engineering-operable.

[0037] In this embodiment, if the peak energy level determined after chassis wind noise testing is less than a preset energy threshold, it indicates that the current chassis wind noise level of the target vehicle is within an acceptable range, and no further optimization is required. In this branch case, it can be directly determined that the design of the current chassis cavity and body panels meets the wind noise performance requirements, without making any structural modifications or flow field adjustments to the vehicle, thus ending the current optimization process. This branch processing method helps avoid unnecessary engineering modifications, saving development costs and time.

[0038] In this embodiment, when the energy peak is greater than or equal to a preset energy threshold, optimization is required. Optimization methods include adding a deflector to the chassis cavity, adding a stiffening reinforcement structure to the chassis wind noise contributing plate, or a combination of both.

[0039] In specific selection, the deflector plate mainly intervenes at the source of the flow field. By changing the airflow direction at the edge of the incoming flow in the chassis cavity, it disrupts the stability of the shear layer, disrupts the periodicity of vortex shedding, and thus cuts off the feedback loop of vortex-acoustic coupling, reducing the intensity of fluid pressure fluctuations. This method acts directly on the noise source itself and is suitable for scenarios with obvious cavity resonance characteristics.

[0040] Stiffness-enhancing structures intervene in the structural transmission path by adding stiffeners, plates, or elastic supports to weak points in the chassis wind noise-contributing plates. This raises the modal frequency of the plate, causing it to avoid the excitation frequency of chassis wind noise, thus preventing vibration amplification and noise radiation caused by structural resonance. This method is suitable for scenarios where the modal frequency of the plate is close to the wind noise frequency.

[0041] In practical applications, the two methods can be used independently or in combination. Specifically, when the vortex-induced acoustic coupling characteristics of the chassis cavity are significant and the structural layout allows for the installation of a deflector, the deflector solution can be used alone as a priority. When the body panel modes are significantly insufficient and the problem cannot be completely solved through flow field optimization, the stiffness-enhancing structure solution can be used alone as a priority. When the chassis wind noise problem is severe, or when there is still insufficient margin after implementing either solution individually, the two methods can be used in combination to work synergistically from the perspectives of sound source control and transmission path blocking, so as to ensure that the energy peak is reduced to below the preset energy threshold. The combination and implementation order of the two methods can be flexibly determined according to the actual test results and layout space, and this application embodiment does not impose specific limitations on this.

[0042] For example, first, a deflector is added to the chassis cavity corresponding to the chassis wind noise contributing plate. If the peak energy of the chassis wind noise of the target vehicle cannot be made less than the preset energy threshold, then a stiffness-enhancing structure is added to the chassis wind noise contributing plate to adjust the mode of the chassis wind noise contributing plate so that the peak energy of the chassis wind noise of the target vehicle is less than the preset energy threshold.

[0043] In this embodiment, this step defines the execution order between adding a deflector and adding a stiffening reinforcement structure. Specifically, the deflector addition operation is performed first, and then the stiffening reinforcement structure addition operation is determined based on the verification results. Specifically, a deflector is first added to the chassis cavity corresponding to the chassis wind noise contributing plate. The installation position and parameters of the deflector can be referenced in the aforementioned specific setting method for the deflector. After the deflector addition is completed, the target vehicle undergoes a chassis wind noise test again according to step S11. The vehicle body vibration signal, chassis cavity noise signal, and passenger compartment noise signal are obtained, and a spectrum analysis is performed to determine whether the current chassis wind noise energy peak is less than a preset energy threshold. If the energy peak is less than the threshold, it indicates that the optimization goal can be achieved simply by adding the deflector, and no further subsequent operations are required. If the energy peak is still greater than or equal to the threshold, it indicates that relying solely on flow field intervention is insufficient to completely eliminate the structural resonance caused by vortex-induced acoustic coupling. In this case, a stiffening reinforcement structure is added to the chassis wind noise contributing plate to further cut off the vibration transmission path by increasing the plate's modal frequency. The principle is as follows: the baffle plate mainly functions at the sound source end, reducing the excitation intensity of fluid pressure pulsation by changing the airflow direction and shear layer stability at the cavity inlet; while the stiffness-enhancing structure functions at the structural response end, avoiding resonance with the residual excitation frequency by increasing the plate's natural frequency. When intervention at the sound source end is insufficient to reduce the energy below the threshold, it means that even with a reduction in excitation intensity, the plate still exhibits a significant vibration response at that frequency. In this case, supplementary intervention from the structural end can achieve synergy between the source and path ends, ultimately reducing the in-vehicle noise energy to an acceptable range.

[0044] In this embodiment, by adopting the sequence of "dredging first, then reinforcement," the following objectives can be achieved: First, as a non-structural modification, the deflector's installation does not require irreversible operations such as welding or drilling on the body sheet metal, resulting in relatively low implementation difficulty and modification costs. Prioritizing this approach helps solve the problem at a lower engineering cost. Second, when the deflector alone can achieve the desired effect, any reinforcement operations on the body structure can be completely avoided, thereby maximizing the maintenance of the original body's mass distribution, structural rigidity, and manufacturing process, avoiding the increased processes and weight associated with welding reinforcing ribs or installing reinforcing plates. Third, when the deflector... When the implementation of the flow deflector alone is insufficient to meet the requirements, the clear information of "the residual wind noise frequency and energy level after the implementation of the flow deflector" is already available. This information can provide more accurate target frequencies and required modal enhancement amplitudes for the subsequent design of stiffness-enhancing structures, making the parameter selection of stiffness-enhancing structures more targeted and supported by data. Fourth, this sequence provides a clear technical decision-making path for engineering development, namely, to proceed according to the progressive logic of "trying the lower-cost and less modified solutions first, and upgrading to a more thorough solution if it is ineffective." This avoids the over-design that may result from directly adopting complex solutions without verifying the effectiveness of simple solutions.

[0045] Regarding the method of adding a deflector: Can be combined Figure 4 and Figure 5 As shown, Figure 4 This is a cross-sectional view of the cavity 2 of chassis 1 along the direction of the front and rear of the target vehicle, where the right side represents the location of the front of the vehicle and the left side represents the location of the rear of the vehicle. Figure 5 This is a top view of the deflector 3 along the direction from the roof to the bottom of the target vehicle, where the upper side is the location of the front of the vehicle and the lower side is the location of the rear of the vehicle.

[0046] First, the chassis 1 cavity 2 is defined as including a front wall 13 and a top wall 12. The front wall 13 refers to the side wall of the chassis 1 cavity 2 near the front of the target vehicle, and the top wall 12 refers to the side wall of the chassis 1 cavity 2 near the passenger compartment of the target vehicle.

[0047] The first edge of the guide plate 3 (i.e. Figure 4 The right edge of the middle guide vane 3 is also Figure 5The upper edge of the guide vane 3 is disposed at the bottom of the front wall 13 of the cavity 2 of the chassis 1. Regarding the installation position, in this embodiment, the first edge of the guide vane 3 is disposed at the bottom of the front wall 13 of the cavity 2 of the chassis 1, that is, at the lower edge of the side wall of the cavity 2 near the front of the vehicle. This position is located at the upstream edge of the inflow at the opening of the cavity 2, which is the starting area for the formation of the airflow shear layer and the shearing of vortices. By placing the guide vane 3 here, the flow direction of the airflow can be intervened before it enters the cavity 2, changing the incident angle and flow direction of the airflow from the source, preventing high-speed airflow from directly scouring the interior of the cavity 2, thereby reducing the accumulation of airflow energy inside the cavity 2.

[0048] Along the width direction of the target vehicle, the projected width of the deflector 3 on the plane where the front wall 13 is located is greater than or equal to the width of the front wall 13, combined with Figure 5 As shown, the projected width of the guide plate 3 on the plane of the front wall 13 is A, and the width of the front wall 13 is K, where A ≥ K. Further, the projection of the guide plate 3 on the plane of the front wall 13 extends beyond both sides of the front wall 13, and the width of the projection on each side extending beyond the front wall 13 can be 5mm-10mm, that is, the length of the left and right sides extending beyond K in A can be 5mm-10mm. Regarding the projected width of the guide plate 3 in the vehicle width direction, in this embodiment, the projected width of the guide plate 3 on the plane of the front wall 13 is set to be greater than or equal to the width of the front wall 13 itself, that is, the guide plate 3 completely covers the lateral range of the opening of the cavity 2 in the vehicle width direction. This setting ensures that the airflow at all positions along the vehicle width direction is guided by the guide plate 3, avoiding airflow from bypassing the guide plate 3 laterally and directly entering the cavity 2 due to partial uncovering. Furthermore, the guide plate 3 is set to extend 5mm to 10mm beyond the front wall 13 on both sides in terms of projected width. This can compensate for the installation tolerances and positional deviations that may exist during the actual assembly process, ensuring that even under extreme deviation conditions, the guide plate 3 can still completely cover the entire opening width of the cavity 2, preventing airflow from entering the cavity 2 from the gaps on both sides.

[0049] The projected length of the guide plate 3 along the front and rear directions of the target vehicle on the plane of the top wall 12 is less than the vertical height of the front wall 13. Figure 4As shown, the projected length of the deflector 3 along the front-to-rear direction of the target vehicle on the plane of the top wall 12 is 'a', and the vertical height of the front wall 13 is 'H', where a < H. Further, the projected length of the deflector 3 on the plane of the top wall 12 is 1 / 3 to 1 / 2 of the height of the front wall 13, i.e., a = [H / 3, H / 2]. Regarding the projected length of the deflector 3 along the vehicle length direction, in this embodiment, the projected length of the deflector 3 along the front-to-rear direction on the plane of the top wall 12 is designed to be one-third to one-half of the vertical height of the front wall 13 of the cavity 2. This projected length corresponds to the effective horizontal length of the deflector 3 extending from the bottom of the front wall 13 towards the rear of the vehicle. If the extension length is too short, the guide vane 3 will have a limited range for guiding the airflow, and the core high-speed airflow can still bypass the end of the guide vane 3 and enter the cavity 2, weakening the guiding effect. If the extension length is too long, the guide vane 3 will extend excessively into the flow field below the chassis 1, which will excessively interfere with the overall airflow direction of the chassis 1, potentially increasing the aerodynamic drag of the entire vehicle and affecting the high-speed driving stability of the vehicle. Limiting the extension length to one-third to one-half of the height of the front wall 13 can effectively guide the airflow away from the inlet of the cavity 2 while minimizing additional interference with the overall flow field of the chassis 1.

[0050] The angle between the plane of the guide plate 3 and the plane of the front wall 13 is greater than 90°; for example Figure 4As shown, the angle between the plane of the deflector 3 and the plane of the front wall 13 is α+90°. Further, if the front wall 13 is replaced with the top wall 12, then the angle α between the plane of the deflector 3 and the plane of the top wall 12 is 15°-30°. That is, the angle between the plane of the deflector 3 and the plane of the front wall 13 is 105°-120°. Regarding the tilt angle of the deflector 3, in this embodiment, the angle between the plane of the deflector 3 and the plane of the top wall 12 is set to 15° to 30°, or the angle between the plane of the deflector 3 and the plane of the front wall 13 is set to 105° to 120°. It should be noted that the highest point of the deflector 3 is located near the front of the vehicle (i.e., where it connects to the bottom of the front wall 13), and the lowest point is located near the rear of the vehicle (i.e., at the suspended second edge 31). The deflector 3 tilts downwards from front to back. If the tilt angle is too small (i.e., the guide vane 3 is too close to horizontal), the airflow will not change direction significantly when passing over the surface of the guide vane 3, and most of the high-speed airflow will still rush into the cavity 2 in its original direction, making it difficult to block the flow. If the tilt angle is too large (i.e., the guide vane 3 is too close to vertical), the guide vane 3 itself will become a protruding obstacle under the chassis 1, causing severe airflow separation and circumduction at that point, which may generate additional aerodynamic drag and new vortex noise. Limiting the tilt angle to the range of 15° to 30° can guide the airflow downward to bypass the inlet of the cavity 2 while maintaining the adhesion of the flow on the surface of the guide vane 3, thus avoiding severe airflow separation.

[0051] The second edge 31 of the guide plate 3 is suspended and is toothed. The second edge 31 is either arc-shaped or sawtooth-shaped, and the spacing b between two adjacent teeth (see...) Figure 5 The diameter (as shown) is 30mm-50mm. Regarding the toothed design of the second edge 31 of the guide plate 3, in this embodiment, the second edge 31 (i.e., the suspended end) of the guide plate 3 is set as a toothed structure, specifically an arc toothed or sawtooth shape, with the spacing between adjacent teeth controlled within the range of 30mm to 50mm. It should be noted that when any blunt body structure of finite thickness is placed in airflow, its trailing edge may generate its own vortex shedding phenomenon. If the end of the guide plate 3 is a straight edge, the straight edge will generate a periodic wake vortex street under the action of high-speed airflow. If the frequency of this vortex street matches the natural frequency of the cavity 2 or the frequency of other structures, it may become a new noise source. After setting the second edge 31 as a toothed structure, the wake vortices generated between different teeth have differences in frequency and phase. The vortices generated by each tooth will interfere with and cancel each other, thereby avoiding the formation of a periodic vortex street of a single frequency and reducing the risk of the guide plate 3 itself becoming an additional noise source. The spacing between adjacent teeth is limited to 30mm to 50mm, which can ensure the crushing effect of the tooth structure on the tail vortex and facilitate actual processing and manufacturing.

[0052] The air deflector 3 is made of modified PP plastic; the thickness of the air deflector 3 is 2mm-3mm. Regarding the material and thickness of the air deflector 3, in this embodiment, the air deflector 3 is made of modified PP plastic, and the thickness is set to 2mm to 3mm. Modified PP plastic has the characteristics of low density, good weather resistance, and excellent impact resistance. It can meet the lightweight requirements of chassis 1 components while withstanding the continuous impact of airflow and accidental impacts from road debris during high-speed driving. Limiting the thickness to the range of 2mm to 3mm ensures that the air deflector 3 has sufficient structural rigidity, making it less prone to flutter or excessive deformation under airflow, thus maintaining a stable airflow guiding posture. On the other hand, this thickness range is well achievable in the injection molding process, and the material usage is moderate, without significantly affecting the overall weight and economy of the vehicle.

[0053] In this embodiment, the principle of the deflector suppressing chassis wind noise is mainly reflected in the following three aspects.

[0054] First, the deflector is installed upstream of the opening of the chassis cavity. Its first edge is fixed to the bottom of the front wall of the cavity, while its second edge is suspended and extends obliquely towards the rear and downwards of the vehicle. When the high-speed incoming flow reaches the cavity opening, the deflector, through its tilt angle, guides the airflow that was originally rushing into the cavity along the chassis plane downwards, causing it to deviate from the direction of the cavity inlet. This disrupts the stability of the airflow shear layer at the cavity opening, disrupts the periodic vortex shedding pattern of the shear layer, and prevents the vortex from forming periodic energy accumulation.

[0055] Secondly, due to the shielding and guiding effect of the deflector, the airflow entering the cavity is significantly reduced, the strength of the shear layer is weakened, and the power source required for vortex generation is reduced at the source. At the same time, because the original stable development rhythm of the shear layer is disrupted, the originally regular periodic vortex shedding is destroyed. What is generated is no longer a vortex cluster with a single frequency and concentrated energy, but a scattered small vortex with dispersed frequency and different phase. These vortices of different frequencies interfere with and cancel each other out, making it difficult to form a vortex cluster with a unified frequency and concentrated energy. Therefore, it is impossible to excite resonance amplification that matches the acoustic mode of the cavity.

[0056] Finally, the deflector also serves to cut off the acoustic feedback loop. Even if a small number of residual vortices are generated within the cavity and impact the rear wall to form sound waves, the physical obstruction of the deflector blocks the path of the sound waves from the cavity towards the opening. The sound waves are blocked by the deflector before reaching the opening, preventing them from disturbing the shear layer and inducing a new wave of vortex shedding. Simultaneously, some of the sound wave energy is scattered and dissipated upon encountering the deflector surface, preventing it from continuing along the original feedback path. Therefore, the acoustic energy within the cavity cannot form effective feedback excitation, new vortices cannot receive continuous energy replenishment, and the closed loop of self-excited oscillation is completely severed, thus failing to maintain a continuously amplified low-frequency roar.

[0057] Through the triple synergistic effect of reducing excitation at the source, disrupting the law of disturbance during the process, and blocking feedback in the loop, the guide plate can effectively suppress the formation and amplification of vortex-induced acoustic coupling self-excited oscillation.

[0058] For example, such as Figure 6 The diagram shows a comparison of the in-vehicle noise spectrum before and after adding a deflector in this embodiment of the application. The horizontal axis represents frequency (Hz), and the vertical axis represents sound pressure level (dB(A)). The blue curve represents the in-vehicle noise spectrum after adding the deflector, and the red curve represents the in-vehicle noise spectrum before adding the deflector. The comparison of the two curves clearly shows that without the deflector, the in-vehicle noise spectrum exhibits a significant energy peak within a specific frequency range, and the frequency corresponding to this peak is consistent with the characteristic frequency of vortex-induced acoustic coupling in the chassis cavity. After adding the deflector, the energy peak at this frequency is significantly reduced, with a noticeable decrease. Simultaneously, over a wider frequency range, the blue curve after adding the deflector is generally below the red curve before adding the deflector, indicating that the deflector has a certain degree of suppression effect on in-vehicle noise within this frequency band. In particular, the low-frequency band, which originally exhibited a prominent peak, is effectively suppressed after adding the deflector, and the spectrum curve becomes flatter, indicating that the self-excited oscillation caused by vortex-induced acoustic coupling is effectively cut off, and the sound energy no longer continues to accumulate and amplify. The above spectrum comparison results intuitively verify the actual effect of the air deflector in suppressing vortex-induced acoustic coupling in the chassis cavity and reducing low-frequency roaring noise inside the vehicle.

[0059] Regarding methods to increase stiffness and strengthen the structure: Multiple acceleration sensors are arranged within the first preset area of ​​the chassis wind noise contributing plate; Adding a stiffness-enhancing structure to the chassis wind noise contributing plate to adjust the mode of the chassis wind noise contributing plate includes steps S121-S122.

[0060] Step S121: Tap the chassis wind noise contributing plate to obtain acceleration data collected by each acceleration sensor, and determine the weak point of the chassis wind noise contributing plate based on the acceleration data. Step S122: Add a stiffness-enhancing structure to the weak position of the chassis wind noise contributing plate to adjust the mode of the chassis wind noise contributing plate.

[0061] In this embodiment, the first preset area refers to the local area of ​​the vehicle body where the chassis wind noise contributing plate is located, as determined in step S112. The specific boundary of this area can be defined according to the actual plate size and structural characteristics. Generally, this area at least covers the local structural range formed by the chassis wind noise contributing plate and its adjacent connected plates, to ensure that subsequent modal testing can capture the complete vibration characteristics of the plate and its boundary constraints. Multiple acceleration sensors are arranged within this area. Their function is that when the plate is excited by a hammer, each acceleration sensor can simultaneously collect vibration response acceleration data at different spatial locations of the plate, thereby providing sufficiently dense spatial response measurement point information for subsequent modal parameter identification, to accurately characterize the local modal shape of the plate.

[0062] Regarding step S121, the impact test in step S121 can use a hammer as the excitation source, selecting multiple impact points on the surface of the chassis wind noise contributing plate for point-by-point impact. After each impact, the force sensor built into the hammer records the input force signal, and simultaneously, multiple acceleration sensors arranged on the plate synchronously collect the vibration response acceleration signals of each measuring point, thereby calculating the frequency response function between each impact point and each response measuring point. After obtaining the frequency response function of the entire set of measuring points, the modal parameters of each order of the plate in the target frequency range, including modal frequencies and mode shapes, can be extracted using a modal parameter identification algorithm. The weak point is the area with the largest vibration displacement amplitude in the extracted mode shape. This location bears the largest deformation under resonance conditions and is the area of ​​the plate most easily excited and radiates noise outward. If the modal frequency of the plate is close to the chassis wind noise frequency determined in step S112, the resonant coupling relationship is confirmed from the perspective of structural dynamics. Subsequently, the stiffness-enhancing structure is set at the weak position, which can achieve the best modal enhancement effect with the minimum weight increase cost.

[0063] Regarding step S122, adding a stiffness-enhancing structure at the weak point of the chassis wind noise contributing plate to adjust the mode of the chassis wind noise contributing plate includes steps S1221-S1222.

[0064] Step S1221: If the weak position is within the second preset area of ​​the battery pack of the target vehicle, then the elastic support is filled as a stiffness-enhancing structure between the battery pack frame closest to the weak position and the chassis wind noise contributing plate, so that the mode of the chassis wind noise contributing plate is greater than or equal to 1.2 times the wind noise frequency corresponding to the energy peak. Step S1222: If the weak position is not within the second preset area of ​​the battery pack of the target vehicle, then a reinforcing member is added as a stiffness-enhancing structure to the weak position of the chassis wind noise contributing plate, so that the mode of the chassis wind noise contributing plate is greater than or equal to 1.2 times the wind noise frequency corresponding to the energy peak.

[0065] In this embodiment, the second preset area refers to a spatial region defined with the battery pack of the target vehicle as a reference. This region encompasses the battery pack body and its adjacent areas within a certain distance. The distance can be set according to the actual vehicle body structure layout. It should be noted that the battery pack of a new energy vehicle is usually rigidly connected to the longitudinal beams or floor frame of the vehicle body by high-strength bolts. It has extremely high structural rigidity and mass and hardly generates perceptible vibration during operation. Therefore, it can be used as an ideal "fixed point" or vibration constraint boundary. When the weak position determined in step S121 is located within the second preset area of ​​the battery pack, it means that there is a rigid structure available for use near the weak position, namely the battery pack frame. At this time, the weak floor plate (i.e., the chassis wind noise contributing plate) can be elastically connected to the battery pack frame by elastic support members, thereby obtaining effective rigidity compensation with a small structural modification cost. When the weak position is far from the battery pack and not within the second preset area, there is no available external rigid support point. The cross-sectional rigidity of the plate itself can only be improved by adding reinforcing ribs or reinforcing plates. Therefore, distinguishing whether different treatments are applied within the second preset area of ​​the battery pack is essentially to make full use of existing structural conditions and select physically feasible and engineering-economical stiffness enhancement methods.

[0066] Regarding step S1221, in this embodiment, when the weak point is within the second preset area of ​​the battery pack, the filling method of the elastic support is as follows: First, determine the location of the battery pack frame crossbeam or longitudinal beam closest to the weak point; second, fill the gap between the battery pack frame and the vehicle floor sheet metal with the elastic support, so that one side of the elastic support contacts the upper surface of the battery pack frame and the other side contacts the lower surface of the floor sheet metal; finally, adjust the compression of the elastic support to form a stable elastic support relationship between the battery pack frame and the floor. After filling, the battery pack frame applies an additional elastic boundary constraint to the floor panel through the elastic support, which is equivalent to shortening the support span of the floor panel, thereby increasing the bending natural frequency of the panel. By adapting and adjusting the parameters of the elastic support, the modal frequency of the panel reaches or exceeds 1.2 times the frequency corresponding to the peak value of chassis wind noise energy. Under this frequency ratio condition, there is a sufficient frequency interval between the natural frequency of the panel and the wind noise excitation frequency, which can effectively avoid resonance coupling between the two.

[0067] Regarding step S1222, in this embodiment, when the weak point is not within the second preset area of ​​the battery pack, it indicates that there is no available external rigid support structure nearby. Therefore, it is necessary to add a reinforcing member at the weak point of the chassis wind noise contributing plate. The reinforcing member includes, but is not limited to, reinforcing ribs and reinforcing plates. The reinforcing ribs increase the moment of inertia of the plate section by forming a raised ridge structure on the plate surface, while the reinforcing plates increase the local thickness of the plate by lamination welding or bolt connection. The structure after adding the reinforcing member is equivalent to improving the bending stiffness of the plate section, so that the vibration displacement response of the plate under the same airflow excitation force is significantly reduced. By adapting and adjusting the size, quantity, and arrangement direction of the reinforcing member, the modal frequency of the plate reaches or exceeds 1.2 times the frequency corresponding to the peak value of chassis wind noise energy. Under this frequency ratio condition, even if there is still wind noise pressure pulsation with frequency f in the chassis cavity, there is a sufficient frequency difference between the natural frequency of the plate and the excitation frequency, and the phenomenon of structural resonance amplification will not be caused by frequency overlap.

[0068] Furthermore, if the weak point is located within the second preset area of ​​the battery pack of the target vehicle, after the mode of the chassis wind noise contributing plate is greater than or equal to 1.2 times the wind noise frequency corresponding to the energy peak, the method further includes: reducing at least one parameter of the number, area, and thickness of the elastic support members by a first preset step size until the energy peak of the chassis wind noise of the target vehicle is again greater than or equal to a preset energy threshold, and then using the actual number, actual area, and actual thickness of the elastic support members before the energy peak is again greater than or equal to the preset energy threshold as the target parameters of the elastic support members.

[0069] In this embodiment, after the initial installation of the elastic support member and achieving a plate mode frequency of 1.2 times the target frequency, a parameter optimization process is further performed. Specifically, at least one parameter among the number, area, and thickness of the elastic support member is gradually reduced according to a first preset step size. The number refers to the number of support points, the area refers to the contact area between the elastic support member and the floor or battery pack frame, and the thickness refers to the initial thickness of the elastic support member in its natural state. After each parameter reduction operation, the target vehicle is subjected to chassis wind noise testing again according to step S11, and it is determined whether the energy peak value is still less than the preset energy threshold. If the energy peak value is still less than the threshold after reducing the parameters, the parameters are further reduced according to the step size. If the energy peak value is found to be greater than or equal to the threshold again after reducing the parameters, it indicates that the current parameters are critically insufficient. At this time, the last parameter combination that met the requirements before the energy peak value exceeded the standard again is determined as the final target parameters.

[0070] The basic principle of this process is that the stiffness contribution of elastic supports is positively correlated with their number, contact area, and thickness. Provided the modal frequencies sufficiently avoid the excitation frequencies, the stiffness compensation provided by the elastic supports actually has a certain margin. By gradually reducing relevant parameters, the number of elastic supports can be reduced to the minimum necessary level while maintaining the suppression effect, thereby avoiding redundancy from over-design.

[0071] In this embodiment, the following objectives can be achieved through the optimization method of gradually decreasing the above parameters: First, it avoids unnecessary cost increases and material consumption caused by setting too many or too large elastic supports, ensuring that the amount of elastic supports used in each location accurately corresponds to the actual needs; Second, it reduces the impact of excessive filling of elastic supports on the original assembly gap and installation process between the battery pack and the floor, and avoids additional stress or assembly interference in surrounding components due to excessive compression of elastic supports; Third, by using "critical reproduction" as the reverse judgment endpoint, it ensures that the final determined target parameters are exactly at the boundary state of "just able to suppress chassis wind noise", providing a clear process reference benchmark for consistency control in subsequent mass production, so that other vehicles of the same type can achieve the most simplified design while ensuring the suppression effect after installing elastic supports according to the target parameters.

[0072] Furthermore, if the weak point is not located within the second preset area of ​​the target vehicle's battery pack, after the mode of the chassis wind noise contributing plate is greater than or equal to 1.2 times the wind noise frequency corresponding to the energy peak, the method further includes: reducing at least one parameter of the size and quantity of the reinforcing member by a second preset step size until the energy peak of the target vehicle's chassis wind noise is again greater than or equal to a preset energy threshold, and then using the actual size and actual quantity of the reinforcing member before the energy peak is again greater than or equal to the preset energy threshold as the target parameters of the reinforcing member.

[0073] In this embodiment, after the initial addition of the reinforcing member to achieve a plate mode frequency of 1.2 times the target frequency, a further parameter optimization process is performed. Specifically, at least one parameter among the size and quantity of the reinforcing member is gradually reduced according to a second preset step size. The size refers to the cross-sectional height and width of the reinforcing rib or the thickness and area of ​​the reinforcing plate, and the quantity refers to the number of reinforcing members added at the weak location. After each parameter reduction operation, the target vehicle is subjected to a chassis wind noise test again according to step S11, and it is determined whether the energy peak value is still less than the preset energy threshold. If the energy peak value is still less than the threshold after reducing the parameters, the parameters are further reduced according to the step size. If the energy peak value is found to be greater than or equal to the threshold again after reducing the parameters, it indicates that the current parameters are critically insufficient. At this time, the last parameter combination that met the requirements before the energy peak value exceeded the standard again is determined as the final target parameter.

[0074] The basic principle of this process is as follows: the cross-sectional dimensions and quantity of the reinforcing members are positively correlated with the increase in local stiffness of the plate. The larger the dimensions or the greater the quantity, the more significant the increase in the flexural section modulus of the plate, and the greater the increase in modal frequency. However, when adding reinforcing members for the first time, in order to ensure that the requirement of modal frequency being greater than or equal to 1.2 times the target frequency can be met in one go, an appropriate margin is usually left in the design values, that is, the actual stiffness compensation value provided will be greater than the theoretical minimum value required. By gradually reducing the size or quantity according to the step size and verifying whether wind noise recurs each time, the minimum amount of reinforcing members can be found under the premise of ensuring the suppression effect, avoiding engineering waste caused by excessive reinforcement.

[0075] In this embodiment, the following objectives can be achieved through the optimization method of gradually reducing the above parameters: First, it avoids excessive increase in local body mass due to excessive size or quantity of reinforcing parts, which is beneficial to controlling the overall vehicle weight reduction level. Especially for areas far from the battery pack, any increase in additional mass will directly affect the dynamic response characteristics of the panel at that location. Controlling the amount of reinforcing parts to the minimum necessary level can maintain the original body mass distribution state to the maximum extent. Second, it avoids adverse effects on the assembly space and installation process of surrounding components due to excessively dense or large reinforcing parts. For example, excessively large reinforcing ribs may interfere with adjacent pipelines or brackets, and too many weld points or bolt connections may increase the complexity of the manufacturing process. Third, by using "critical reproduction" as the reverse judgment endpoint, the final determined target parameters have clear boundary meaning. That is, the parameter combination is exactly in the critical state of "just able to suppress chassis wind noise", providing a clear process benchmark for consistency control in subsequent mass production.

[0076] For example, such as Figure 7The figure shows the comparison curves of in-vehicle noise and floor vibration before and after adding an elastic support between the battery pack frame and the floor in this embodiment of the application. The black solid line and the blue solid line are the sound pressure level curves of the noise around the driver's ear before and after optimization, respectively. The black dashed line and the blue dashed line are the Z-axis vibration acceleration curves of the passenger floor before and after optimization, respectively. From the overall trend of each curve in the figure, it can be seen that in the frequency range of 20Hz to 300Hz, the black noise curve before optimization has obvious energy bulges at multiple frequencies, which are particularly prominent in the 80Hz to 160Hz frequency band, with the peak amplitude significantly higher than the surrounding frequency bands. At the same time, the black dashed line of the passenger floor Z-axis vibration acceleration before optimization also shows an obvious peak in this frequency band, indicating that there is a strong correlation between the noise and the floor vibration in this frequency range. After adopting the stiffness-strengthening structure optimization scheme provided in this embodiment of the application, the peak amplitude of the blue noise curve in the 80Hz to 160Hz frequency band is significantly reduced compared with the black curve before optimization, and the Z-axis vibration acceleration of the floor represented by the blue dashed line also decreases synchronously. Furthermore, throughout the entire 20Hz to 300Hz analysis frequency band, both the blue noise curve and the blue vibration acceleration curve remained below their corresponding black curves, without generating new energy peaks at other frequencies. This indicates that the introduction of the elastic support effectively reduced the original chassis wind noise frequency peaks without introducing new structural resonance issues. The above comparative results verify the effectiveness of the technique of adding elastic supports between the battery pack frame and the floor to increase the floor modal frequency and suppress plate vibration response, and this optimization effect is consistent across a wide frequency band.

[0077] like Figure 8As shown, the graphs compare the in-vehicle noise and floor vibration before and after floor mode enhancement in this embodiment of the application. In the lower graph, the black curve and blue dashed line represent the in-vehicle noise sound pressure level before and after optimization, respectively. In the upper graph, the black curve and blue dashed line represent the floor Z-axis vibration acceleration before and after optimization, respectively. The comparison of the curves in the graph shows that within the frequency range of 20Hz to 300Hz, both the in-vehicle noise curve and the floor vibration acceleration curve before optimization exhibit significant energy peaks at specific frequencies, and the peak frequency positions of the two are highly consistent, indicating that the in-vehicle noise at this frequency mainly originates from the vibration response of the floor panel. After enhancing the local mode of the floor using the stiffness-reinforcing structural scheme provided in this embodiment of the application, both the blue noise curve and the blue vibration acceleration curve show a significant downward trend throughout the entire analysis frequency band. Near the original peak frequency, the optimized noise amplitude and vibration amplitude are significantly reduced compared to before optimization. Meanwhile, the optimized blue noise curve and blue vibration acceleration curve did not show any new energy spikes or peaks across the entire frequency range, indicating that the modal enhancement operation did not introduce additional structural resonance issues. The above comparison results verify that by increasing the modal frequency of the floor panel to avoid the chassis wind noise excitation frequency, the vibration response of the panel can be effectively suppressed and in-vehicle noise reduced.

[0078] In summary, for example, when a car is traveling at a constant speed above 110 km / h, a noticeable low-frequency rumbling sound is heard in the front seats, with a frequency of approximately 120 Hz. Wind noise testing of the chassis revealed that the noise is caused by air turbulence and resonance in the chassis cavity beneath the passenger side floor, leading to fluid pressure fluctuations that excite structural modal resonance in that area, resulting in interior noise. After installing an optimized deflector in front of this chassis cavity, the low-frequency rumbling sound to the driver's left ear decreased by 5 dB(A), and the sound disappeared. Adding five pieces of foam between the battery pack frame and the floor near the chassis cavity, such as... Figure 9 The positions of the five circles shown reduce the low-frequency booming sound in the driver's left ear by 4 dB(A); or as... Figure 10 As shown, a reinforcing plate was added. After the passenger-side floor mode was increased from 110Hz to 145Hz, the low-frequency booming sound in the driver's left ear decreased by 5dB(A), and the low-frequency booming sound disappeared.

[0079] In summary, this application embodiment, by conducting chassis wind noise tests on the target vehicle, can accurately determine the peak energy of the chassis wind noise and the chassis wind noise contributing components, thereby precisely locating the in-vehicle noise phenomenon to a specific chassis cavity excitation source and the corresponding body panel transmission path, providing a clear target and quantitative basis for subsequent optimization. Furthermore, by comparing the determined peak energy with a preset energy threshold, objective criteria are provided for determining whether optimization is needed and whether the optimization meets the standard, avoiding the uncertainty and repeated verification costs associated with subjective experience. When the peak energy exceeds the standard, the method adds a deflector to the chassis cavity corresponding to the chassis wind noise contributing component, using the deflector to change the cavity's airflow... By considering the airflow direction and shear layer characteristics at the inlet, the excitation intensity of vortex-induced acoustic coupling is reduced from the source of the flow field. Alternatively, by adding stiffness reinforcement structures to the chassis wind noise contributing plates, the modal frequencies of these plates are increased to avoid the excitation frequencies, thus preventing resonance amplification through structural transmission paths. These two methods can be implemented independently or in synergy, allowing the optimization scheme to be flexibly selected and adapted according to the specific chassis layout and wind noise characteristics, effectively broadening the applicability of the method. Through the complete closed-loop process combining testing, judgment, and optimization, the peak energy of chassis wind noise is ultimately reduced to below a preset energy threshold, thereby systematically solving the chassis wind noise problem caused by the lack of engine noise masking in new energy vehicles and improving in-vehicle driving comfort.

[0080] Based on the same inventive concept, embodiments of this application provide a new energy vehicle, including: Chassis; The air deflectors and / or stiffness reinforcement structures installed on the chassis are installed based on the aforementioned vehicle chassis wind noise optimization method.

[0081] Since the electronic device described in this embodiment is an electronic device used to implement the information processing method in the embodiments of this application, those skilled in the art can understand the specific implementation methods and various variations of the electronic device in this embodiment based on the information processing method described in the embodiments of this application. Therefore, how the electronic device implements the method in the embodiments of this application will not be described in detail here. Any electronic device used by those skilled in the art to implement the information processing method in the embodiments of this application falls within the scope of protection of this application.

[0082] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0083] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for optimizing wind noise in a vehicle chassis, characterized in that, Applied to new energy vehicles, the method includes: Conduct chassis wind noise tests on the target vehicle to determine the peak energy of the chassis wind noise and the chassis wind noise contributing components. If the energy peak value is greater than or equal to a preset energy threshold, a guide vane is added to the chassis cavity corresponding to the chassis wind noise contributing plate, and / or a stiffness reinforcement structure is added to the chassis wind noise contributing plate to adjust the mode of the chassis wind noise contributing plate, so that the energy peak value of the chassis wind noise of the target vehicle is less than the preset energy threshold.

2. The vehicle chassis wind noise optimization method as described in claim 1, characterized in that, The target vehicle has three-dimensional acceleration sensors and chassis microphones installed in multiple chassis cavity areas, and an in-cabin microphone is installed at the target location in the passenger compartment of the target vehicle. The target vehicle undergoes chassis wind noise testing to determine the peak energy of the chassis wind noise and the contributing chassis wind noise components, including: The target vehicle is controlled to drive on a road with preset road surface characteristics at a preset speed and during the driving process, and the vehicle body vibration signal from each three-dimensional acceleration sensor, the chassis cavity noise signal from multiple chassis microphones, and the passenger compartment noise signal from the cabin microphone are acquired. Spectral analysis was performed on the vehicle body vibration signal, chassis cavity noise signal, and passenger compartment noise signal, and the passenger compartment noise signal was filtered and replayed to determine the peak energy of the chassis wind noise of the target vehicle and the chassis wind noise contributing components.

3. The vehicle chassis wind noise optimization method as described in claim 1, characterized in that, The chassis cavity includes a front wall and a top wall. The front wall refers to the side wall of the chassis cavity near the front of the target vehicle, and the top wall refers to the side wall of the chassis cavity near the passenger compartment of the target vehicle. The first edge of the guide plate is located at the bottom of the front wall of the chassis cavity; Along the width direction of the target vehicle, the projected width of the deflector on the plane where the front wall is located is greater than or equal to the width of the front wall; The projected length of the deflector along the front and rear directions of the target vehicle on the plane where the top wall is located is less than the vertical height of the front wall. The angle between the plane where the guide plate is located and the plane where the front wall is located is greater than 90°; The second edge of the guide plate is suspended and has a toothed shape.

4. The vehicle chassis wind noise optimization method as described in claim 3, characterized in that, The projection of the guide plate on the plane of the front wall extends beyond both sides of the front wall, and the projection on each side extends beyond the front wall by a width of 5mm-10mm. The projected length of the guide plate on the plane where the top wall is located is 1 / 3 to 1 / 2 of the height of the front wall; The angle between the plane where the guide plate is located and the plane where the front wall is located is 105°-120°, or the angle between the plane where the guide plate is located and the plane where the top wall is located is 15°-30°. The second edge is arc-shaped or sawtooth-shaped, and the distance between two adjacent teeth is 30mm-50mm; The guide plate is made of modified PP plastic; The thickness of the guide plate is 2mm-3mm.

5. The vehicle chassis wind noise optimization method as described in claim 1, characterized in that, Multiple acceleration sensors are arranged within the first preset area of ​​the chassis wind noise contributing plate; Adding a stiffness-enhancing structure to the chassis wind noise contributing plate to adjust the modal characteristics of the chassis wind noise contributing plate includes: The chassis wind noise contributing plate is tapped to obtain acceleration data collected by each acceleration sensor, and the weak point of the chassis wind noise contributing plate is determined based on the acceleration data. A stiffness-enhancing structure is added to the weak points of the chassis wind noise contributing plate to adjust the mode of the chassis wind noise contributing plate.

6. The vehicle chassis wind noise optimization method as described in claim 5, characterized in that, Adding stiffness-reinforcing structures to the weak points of the chassis wind noise contributing plate to adjust the modal characteristics of the chassis wind noise contributing plate, including: If the weak point is located within the second preset area of ​​the battery pack of the target vehicle, then the elastic support is filled as a stiffness-enhancing structure between the battery pack frame closest to the weak point and the chassis wind noise contributing plate, so that the mode of the chassis wind noise contributing plate is greater than or equal to 1.2 times the wind noise frequency corresponding to the energy peak. If the weak point is not located within the second preset area of ​​the battery pack of the target vehicle, a reinforcing member is added as a stiffness-enhancing structure to the weak point of the chassis wind noise contributing plate, so that the mode of the chassis wind noise contributing plate is greater than or equal to 1.2 times the wind noise frequency corresponding to the peak energy.

7. The vehicle chassis wind noise optimization method as described in claim 6, characterized in that, If the weak point is located within the second preset area of ​​the battery pack of the target vehicle, then after ensuring that the mode of the chassis wind noise contributing plate is greater than or equal to 1.2 times the wind noise frequency corresponding to the energy peak, the method further includes: Decrease at least one parameter among the number, area, and thickness of the elastic support members according to the first preset step size until the energy peak of the chassis wind noise of the target vehicle is greater than or equal to the preset energy threshold again. Then, the actual number, actual area, and actual thickness of the elastic support members before the energy peak is greater than or equal to the preset energy threshold again are taken as the target parameters of the elastic support members.

8. The vehicle chassis wind noise optimization method as described in claim 6, characterized in that, If the weak point is not located within the second preset area of ​​the target vehicle's battery pack, then after ensuring that the mode of the chassis wind noise contributing plate is greater than or equal to 1.2 times the wind noise frequency corresponding to the energy peak, the method further includes: The size and quantity of the reinforcing member are reduced by a second preset step size until the energy peak of the chassis wind noise of the target vehicle is again greater than or equal to a preset energy threshold. Then, the actual size and quantity of the reinforcing member before the energy peak is again greater than or equal to the preset energy threshold are taken as the target parameters of the reinforcing member.

9. The vehicle chassis wind noise optimization method as described in claim 1, characterized in that, Adding a deflector to the chassis cavity corresponding to the chassis wind noise contributing plate and / or adding a stiffening reinforcement structure to the chassis wind noise contributing plate to adjust the mode of the chassis wind noise contributing plate, so that the peak energy of the chassis wind noise of the target vehicle is less than the preset energy threshold, including: First, a deflector is added to the chassis cavity corresponding to the chassis wind noise contributing plate. If the peak energy of the chassis wind noise of the target vehicle cannot be made less than the preset energy threshold, a stiffness reinforcement structure is added to the chassis wind noise contributing plate to adjust the mode of the chassis wind noise contributing plate so that the peak energy of the chassis wind noise of the target vehicle is less than the preset energy threshold.

10. A new energy vehicle, characterized in that, include: Chassis; The air deflector and / or stiffness reinforcement structure arranged on the chassis are arranged based on the vehicle chassis wind noise optimization method according to any one of claims 1 to 9.

Images