➤ All along, the car’s NVH, or quietness is always a hot topic, is a comprehensive measure of automobile manufacturing quality problems, but also our sense of judgment is an important indicator of the car. In the case does not affect the driving, we hope that the more quiet as possible, and that the more quiet vehicles as they should be more expensive.
but the reality is, do not be difficult quietness seems, is the easiest way like stacking, many own brand vehicles will make efforts in this regard. From this perspective, quietness is not a thing of sophisticated technology.
This can not help but let us heart wondering why there are a lot of people say that cars quietness is metaphysics, requires a lot of manpower and resources? Quiet and good cars are not necessarily have advanced and expensive way. With these questions, rutting monarch today to have a conversation car quietness of this topic.
in the end what factors affect car quietness?
professional, used to be called the silent NVH engineering work, and we want to talk today quietness is a meaning. The purpose is to reduce NVH work noise and vibration inside the vehicle, the vehicle occupants auditory, tactile and visual experience a high comfort.
What factors will affect the quietness of the car, we can from the noise source, transmission path to divide.
There are common sources of noise automotive power system (such as the engine system, transmission system, and intake and exhaust systems), air conditioning systems, road noise and wind noise. Engine noise, tire noise and wind noise heard more of these, we focus here transmissions and air conditioning systems.
significant source of noise is the conventional braking system noise, the noise can be subdivided into the brake brake whistle, peristaltic noise, percussion, beep, sound five kinds of the brush disc. The following table rutting monarch for everyone finishing their own characteristics, all kinds of strange noises as occurred in the brake disc, will produce mutual restraint, you want to capture all very difficult.
The figure is the Mercedes-Benz GLC such as brake squeal problems raised by netizens, so that he himself and 4S shops are a headache.
Since the air-conditioning system is connected directly with the vehicle, it can be said about a NVH ofFor a move are exposed in front of everyone. Many people would have had a similar experience: when the outlet in the imminent closure at that point, a different sound prone; and prone to abnormal sound or switch hot and cold air, air volume to maximum and other circumstances.
The figure is someone such as users experience, really startled him.
These are common outlet abnormal noise problem. For this reason, vehicle noise test was designed to test a program called “whistle outlet abnormal sound” of. We Naji Li’s Q / JLY J7110245C-2018 standard, its test standards are as follows, that the purpose of this test is to look at different flow rates, at different temperatures, air conditioning air system is not in use will bring discomfort .
The main purpose of this test is to investigate ▲ blade vibration abnormal noise, abnormal noise of the blower is not. However, according to rut Jun know, Geely enforcement of this test is not strong enough. This problem is not auspicious one, some do not even have this test joint venture.
As for a transmission path, the maximum transfer body is a body in white.
We take the passenger to use more load bearing structure, this structure is not the body frame, an engine body and chassis of each mounting base assembly, the benefits of light weight, low chassis, the downside is the mechanism operating noise and vibration is more easily transmitted to the vehicle through the vehicle body.
In order to solve this problem, often use two routes to achieve noise reduction. A route is to strengthen and improve the rigidity of the body structure of the vehicle body; and a vibration isolation through sound insulation, sound absorption and vibration absorbing method of reducing or eliminating noise. After
A more familiar, the stack may be achieved by physically material. The former we usually hear is relatively small, but in fact a great impact.
For example, lack of rigidity of the vehicle body, can result in low frequency magnitude response is easy to generate resonance. Like the vehicle body floor, roof, side panel member such large, vibration is generated in a low frequency range when insufficient stiffness. We know that low-frequency resonance occurs at low speed, middle speed when it is our common condition, so also must pay attention to this problem.
▲ just aboveIntroduces traditional NVH control methods, modern philosophy, as well as ANC active noise reduction technology, but the penetration of this technology is not high, but the real effect is yet to be improved.
Or unreasonable design of the body structure and accessories, can also cause resonance problems. But because of many reasons, not easy to want to control better. For example, many people complain about the low-frequency resonance problems XC60 suspected that some parts of the interior of the trunk to form a resonant ,, low-frequency noise generated by the refraction to near the rear center console, the formation of standing waves, resulting in ear pressure (30Hz to sensitive populations low frequency noise under).
Based on the above description, we will find the car muted project is actually very complex, there are technical reasons, cost reasons, does not happen overnight can overcome the problem.
That is not to say that silence and good car more senior?
here, we may be more wondering, why we can achieve good acoustics by stacking other difficulties it did not seem so terrible ah.
On this, we need to think in two ways.
First, cotton insulation, brace plate, seal, double glazed glass and other physical means indeed very effective noise reduction means, especially for a new car, it is sufficient to cover this program many types noise, so if we can use more of course, it is good.
However, doing so would cause side effects, the biggest downside is the increased vehicle weight. We say that the car the whole car noise including the “four four fender + + + firewall + hood after the U-groove + + trunk floor” sound, depends on how much weight treatment, usually 30kg weight gain is not surprising.
such as sound insulation brands WEY before too much material (VV7 with nearly two tons of vehicle weight, insulation materials about 30kg weight), resulting in excessive vehicle weight problems it caused to the discussion. In fact, the vast majority of domestic models (including the joint venture vehicle) NVH research in other areas are not deep enough, the primary means of weight change quietness. Under
summary, although by way stacker will sacrifice some consumption, but performance is improved comfort, combined with the manufacturing cost of the vehicle is relatively controllable, can really make a relatively “inexpensive” Silent models.
As it is worthwhile, still have to see where we focus on. We say that noise control is not good enough Japanese cars, such as Honda has always been a bit of noise control flying self, but there is still a large number of fans recognized their product strength. Family cars in general, the more than 200,000 prices, taking into account the difficult aspects is understandable.
understand these, we need to use a dynamic look at quietness – with the car in two or three years, how its quietness performance.
At this time, the traditional physical methods are not well resolved noise suppression. Needs to be strengthened in all aspects of the above talk, which is why the use of luxury cars after five or six years has maintained a high level of quietness reasons.
For example, this body rigidity, the torsional rigidity of the vehicle body in a better long time after use and still be relatively good state, which makes the fitting accuracy of the fitting does not run away, not prone to interfere with iso ring.
take the torsional and bending rigidities of these two indicators, the economy of Car (with windshield) respectively 700 ~ 900 kNmiddot; m / rad, 8000 ~ 12000N / mm; class cars respectively in 900 ~ 1300 kNmiddot; m / rad, 10000 ~ 16000N / mm. This is why we feel more comfortable high-class cars, one of the reasons.
Or abnormal sound outlet, the incidence of new car will be lower, but because the next loose leaf senescence and more prone to abnormal sound. So if you buy a car muted concern, we recommend that owners of old listen to feedback, we will be very valuable.
written in the last
silence of the good car we will be advanced it? After the above description, I think we will have a steelyard own.
It automobiles noise roughly three ways:
1 start from structure analysis, optimization analysis BIW as the main body structure and accessories;
2. material from the start, a higher sound insulation materials, insulation materials, or increase the use of the area;
3. From the start of noise propagation characteristics, by using the reciprocity principle of superposition cancellation, noise reduction strength, i.e. ANC active noise reduction.
to remove the ANC active noise reduction techniques such penetration is not high, senior high quietness practice is by optimizing the structure, to ensure long-term quietness. However, this means because the processing complex and involves many aspects, cost and execution of manufacturing are demanding.
on Jun ruts come into contact with, a common practice in the industry or in the stacker, although it will gain weight, but through other parts of the lightweight come up may well be a way. At least we buy a car and a new car this time around, the positive feedback is very good.
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