[Che Xunwang report] when cars, the smaller the noise inside the cabin, give people comfort is higher. It is self-evident. However, exactly what to do in order to effectively reduce the noise? Later laying and spraying is often too late. Only in the development stage, under more effort, will it be possible to come up with a vehicle with good NVH performance. For example, in August 2019 listed Roewe RX5 MAX, one of good reputation, especially the car is quiet, mute level even beyond the mainstream joint venture vehicle. To this end, I came to SAIC NVH lab, do a lot of site visits.
take a look at the majestic RX5 MAX mute performance.
midsize SUV Roewe is SAIC Roewe RX5 MAX 2019 heavy vehicle. At first, I focus on it, mainly in the beautiful appearance of the interior and a rich network functionality. When the test drive find that it’s muted performance was terrific on the road, the car is very quiet. According to the manufacturers data, the car idling 37.4 db noise, noise 60km per hour 57.2 db, 61 db noise one thousand meters 80k speed, speed of 120km 66.4 db noise. This achievement has surpassed the same level of the joint venture vehicle: Tiguan L.
| two car noise contrast | ||
|---|---|---|
| Roewe RX5 MAX | Tiguan L | |
| an idle | [ 123] 37.4 db | dB |
| 60 km / h | 57.2 dB | dB |
| km / h | dB 64.0 | [ 123] |
| 66.4 | dB 67.3 [ 123] dB | tabulation: Juxun Wang |
Although this is not a rigorous test, but because at the same time, consistent with the premise for each other than, or can explain some of the problems.
Well, good Roewe RX5 MAX muted performance come from? The answer
this question, depending on the NVH performance of the vehicle. Good NVH allows particularly low noise inside the car. But to do this, it is difficult. Because the car is a moving object, at least there will be an engine vibration, resonance phenomenon are theIt is inevitable. Furthermore, a car consists of thousands of parts, impossible and achieve seamless. So, deal with NVH, it is the embodiment of technology manufacturers. The so-called technical level, one of the factors is whether advanced laboratories. To this end, SAIC Technology Center built a series of laboratory, bear NVH performance development and validation SAIC own brand models. For example mdash; mdash;
anechoic chamber
: from 1.7 meters long wedge absorption composition, the sound absorbing material such as glass wool pack. Exposure to the lab, do not say if you do not move, could hear his heart beating. In such a quiet environment, you can test motors, speakers and other sound power automotive components, improve vehicle NVH performance.
reverberation chamber: 
radian wall an irregular configuration, thereby generating reverberant field experiment environment for components and acoustic barrier material sound, sound absorption performance test.
Drum vehicle semi-anechoic chamber: 
comprises four semi-anechoic chamber drum, drum two semi-anechoic chamber, by a vehicle noise, noise isolation, intake and exhaust noise, and other tests. Among them, four drum semi-anechoic chamber is the largest, most advanced laboratories, equipped with the most quiet of the drum. High speed, body noise less than 45 decibels, the noise level is equivalent to the residential area shortly after midnight. With it, simulate different road conditions, detect vehicle NVH issues, in order to optimize the engineers to make improvements.
Laboratory vehicle vibration abnormal noise: vibration and abnormal noise where 
When the simulated vehicle traveling road for the vehicle and the vibration transmission characteristic analysis abnormal sound problem solving provides advanced technology.
Transmission NVH Laboratory: dynamometer bench background noise of only 65 db, and is built in an anechoic chamber to protect a quiet test environment. It may be MT, AT, DCT, AMT, EDU NVH other experiments of various types of transmission.
Room Sound Quality Evaluation: comprisesSquare subjective quality evaluation system, PEQ V digital equalizer, HMS VI digital dummy head, hi playback system, the NVH data analysis system. Sound quality analysis and subjective evaluation, NVH data analysis and management, vehicle sound design initiative on the vehicle sound quality was evaluated by binaural data acquisition.
abnormal sound test bench: 
stage background noise less than 29 decibels, by X, Y, Z three directions noise excitation sequence to simulate the actual road conditions, and signal playback, locking abnormal sound source.
sealing Laboratory: into the vehicle by inflating a sealing manner testing apparatus, the test or analysis of the vehicle body structure and welding a cover assembly, comprising a front wing, a door, an engine hood, trunk lid airtight, using acoustic leak detection unit, determines the amount of leakage and leakage paths. Conducive to better debug engine high-frequency noise, tire noise, wind noise and so on.
In addition to the many laboratories, as well as advanced technology mdash; mdash; simulation. 
at the beginning of the Roewe RX5 MAX design, R & D personnel by simulation analysis can be found in advance of potential noise problems. That is, when the vehicle has not been created, noise and vibration problem has been resolved. Rather than wait until the vehicle is made out, by entities in the exploration, how to find the problem, and then one by one to solve.
In fact, NVH performance is a very boring topic. Simple appreciated that it mainly consists of components, each of the system, the vehicle three parts. Because many content using tabular form, you simply introduce a few of them. 
Roewe RX5 MAX part NVH project
| project | |
|---|---|
| wheelTire noise and vibration | |
| NVH performance of the fan | |
| seat NVH performance | |
| into the exhaust NVH performance | |
| Powertrain NVH performance | |
| The chassis structure dynamics | |
| Vehicle sealing performance | |
| vehicle wind noise properties | |
| tabulation: Chexun Wang | |
For example,Vehicle covers more than 50 key areas of the sound absorbing material, a sound absorbing pad including a hood, roof, the occupant sound absorbing mats, and the like.
The sound-absorbing cotton vehicle selection, but also through a stringent certification, PP (polypropylene) + PET (polyester) constituting the two-component material, can be realized up to 95 the percentage of sound absorption coefficient.
not even trim snap sloppy. The above rubber ring has a seemingly simple, but it can effectively reduce the noise.
within
door panel, the laying of a thick rubber sheet around the mounting hole also covering, thereby cut off the noise.
and some models in this regard process is relatively simple. Most commonly, this figure is lower plastic sheeting.
Glass insulation, the Roewe RX5 MAX windscreen and front side windows wide standard double-glazed glass. This increases the acoustic PVB glass film (lower panel), can effectively block external noise, enhance the interior of the quiet.
The results show a double glazed glass, art we conducted experiments to mdash; mdash; source noise from the vehicle exterior noise value of 71.9 db, the car fell to 35.3 db.
on the perforated seat also pay attention mdash; mdash; roewe RX5 MAX perforated leather seat design draws energy absorption of the wedge principle, the incident sound wave absorb dissipated, both beautiful and substantial absorption of high-frequency sound, to mute the purpose.
After the above ldquo; carefully selected rdquo; then, go through the vehicle under simulated conditions of 10 million km running test, to ensure that noise is not because long-term use increases.
A seemingly simple car noise, to go through such a variety of research and development programs. These can work, the vast majority of car buyers, it is difficult to understand. Although NVH engineering is very complicated, with the advanced laboratory, solid materials, stringent technical standards, Roewe RX5 MAX of NVH technology, or to achieve the ultimate mdash; mdash; texture comparable to mainstream hardcore joint venture vehicle.