Competition with noise An Auchan NVH noise vibration test
[XCAR Technology Original]
Since the day when the automobile was invented, a "bad guy" who followed the vehicle along with it also appeared at the same time, and that was noise. In order to give users the best driving experience, in the past decades or even hundreds of years, car manufacturers have been fighting the "bad guy" of noise endlessly.
Now, automobile manufacturers will adjust their vehicles through strict noise control standards to ensure that each vehicle can achieve a good level of noise and vibration suppression when leaving the factory. Recently, the author was lucky enough to participate in and experience the NVH test of Changan Auchan. In the test, I experienced Changan Automobile’s emphasis on the development of Auchan’s NVH. So what "magic weapons" did Changan Automobile use to control Auchan’s NVH? Let’s continue to look down.
1. What is NVH?
NVH is the abbreviation of Noise, Vibration and Harshness. Noise and vibration are easy to understand. To put it bluntly, the roughness of acoustic vibration is those uncomfortable feelings, such as harsh, roaring sound and uneven vibration. NVH is the core index to measure the comfort and quality of a car, and the feeling it brings to users is also the most direct.
According to statistics, four of the top 10 complaints of consumers about automobiles are about NVH, namely, engine noise, tire noise, wind noise and body noise. About one-third of the complaints of the whole vehicle are related to the NVH problem of vehicles, and nearly 20% of the research and development expenses of major car companies are spent on solving the NVH problem of vehicles.
It can be seen that NVH is very important for both the vehicle itself and the brand, because it can give consumers the most intuitive impression and directly affect consumers’ perception of the "texture" of the vehicle, so it is an important task for all car companies to develop NVH well. At present, NVH is mainly determined by these points: government regulations, customer requirements, company needs and technical capabilities, competing models.
At present, automobile sound control has gone through three development stages:
1. Reduce noise: solve the error state of NVH and reduce noise.
2. Sound quality control: make the sound comfortable, meet the requirements of specific customer groups, and the sound of the vehicle model is personalized.
3, sound quality DNA: the model is personalized and the brand voice is differentiated.
Through the above three stages, the transition from noise control to sound design has been realized.
Second, the control of Auchan NVH
The vehicle noise that we can hear is usually generated by the noise source and transmitted through the channel to reach our ears. Generally, noise sources and transmission channels are controlled to reduce noise. Simply put, this is the transmission of sound in physics, and noise reduction should be suppressed from the source and propagation.
Generally speaking, vehicle noise is mainly divided intoAir soundandStructural sound：
Air sound sources: engine radiation noise, air inlet noise, air outlet noise, tire radiation noise, etc.
Structural sound sources: engine vibration, exhaust hook vibration, chassis vibration, transmission bearing vibration and so on.
Two kinds of sound sources are transmitted through the car body, and the air sound source reaches our ears through the car body barrier and car body sound absorption; The structural sound source reaches our ears through the body structure, bracket and vibration isolator. These two kinds of sound sources are transmitted and attenuated to form the interior noise together.
After understanding the generation of noise, let’s see what anti-noise and vibration capabilities Auchan has. Auchan, as an MPV model with high hopes from Chang ‘an, naturally invested a lot in NVH. We found many NVH development achievements on Auchan’s car body.
In the overall design, Auchan has optimized the acoustic vibration transmission structure such as modeling, powertrain, car body and chassis suspension, so as to reduce the noise source and isolate the transmission of vibration and noise outside the car.
The first is engine noise suppression. Auchan’s 1.5L naturally aspirated engine has done a number of treatments in silence, including valves, fuel injectors, air intake systems, silent pulleys, etc., which reduced the engine noise at the source. According to official data, the idle noise value of Auchan is only 39 decibels.
Auchan soundproofed the engine to reduce the noise from being transmitted into the cab through the front wall, fender, hood and other channels. The composite sound insulation and absorption material is pasted under the hood, which can absorb and reduce the noise of the engine and suppress the vibration of the hood.