电动汽车异响性能该如何设计开发

According to statements of politicians, research and industry, e-mobility has got the green light. However, the technical maturity is not yet on an acceptable level in all respects. Apart from the cruising range, which is widely discussed, the focus is on squeak and rattle (S&R). This has, by now, not sufficiently been studied in the context of e-mobility and the lapse of classical powertrain noise. Development service providers such as Bertrandt combine virtual simulation methods with physical test methods to analyse and eliminate annoying noises at an early stage.
译：根据政府机构、研究院所和汽车工业界的声明，已经为电动汽车开启了绿灯。然而技术的成熟度在很多方面还没有得到一个可接受的程度，除过广泛讨论的续航里程，关注的焦点来到了汽车异响上。至少目前为止，在电动化和传统动力噪音消失的大环境下，对于异响没有投入足够的研究。某些开发服务供应商在设计开发前期结合虚拟仿真和物理试验的方法来分析和消除这些异响。



ROLL MOTION, ACTUATION AND WIND SOUND AND THEIR INDIVIDUAL PERCEPTION
The end consumer sets high quality standards for the product. These standards, however, differ from individual to individual. No matter if sub compact or premium car – the customer will judge comfort and quality according to his own definitions. Driving noise has to match the car according to the customer’s individual perception. There is a basic distinction between three kinds of driving noise: roll motion, powertrain and wind sound. They are welcome, as they reflect the car’s actual technical condition to the driver. Even the indicator’s ticking sound – a so-called functional sound – is being expected inside the car. But as soon as surprising or unknown noise is perceived, this noise is considered unpleasant and disturbing and gives the customer the impression of inferior quality.
译：客户对产品的质量有着很高的标准，然后，这些标准又因人而异。不管是低端紧凑型还是高端车型，客户都会根据他们自己的定义来判断其舒适性和质量。驾驶过程中的噪声要根据客户个人的感知来与车辆匹配。以下这三种行驶过程中的噪声有一个基本的区别：滚动噪声、动力总成和风噪，驾驶员会欣然接受这些噪音，因为他们反映了车辆的一个实际技术状况。甚至是指示灯的滴答声 – 一种功能性提示音，也会出现在车内。但是，只要是让人感觉惊讶或或者是未知的噪音，这种噪音就会被认为是不愉悦的和令人烦恼的，这就会给客户留下产品质量低劣的印象。

E-MOBILITY AS A CHALLENGE
In the first automobiles, S&R was covered by powertrain, roll motion and wind sound. The further cars were developed and optimised, the easier S&R could be heard inside the car. Nowadays, the development of so-called noiseless driving is a central point. The most recent designs, however, do not only focus on reducing annoying noise – they also should reduce probably occurring warranty expenses.
译：在最初的汽车上，异响通常被动力总成、滚动噪声和风噪所掩盖。经过进一步的开发和优化，汽车异响更容易在车内被听到。如今，无噪音驾驶是汽车开发的一个中心点。然而，最新的汽车设计不仅注重减少让人烦恼的噪音，还应减少可能发生的维修费用。

Figure 1 shows the noise appearance related to the development over a period of approximately 30 years. The development of the powertrain, roll motion and wind sound (blue curve) is compared with the annoying noise (green curve). It shows that currently, considerable efforts have to be made to avoid S&R in the interior of the car or to keep them at the present Delta level (see dotted line), respectively. As a result of introducing and developing electric cars, S&R and how to avoid it are, again, at the centre of the developers’ attention.
译：下图显示了近30年来与开发相关的汽车噪音的表现。动力总成、滚动噪音和风噪（蓝色曲线）与异响（绿色曲线）进行比较，这表明要避免车内异响或保持目前的一个差距水平（见虚线）需要付出很大的努力。由于电动汽车的引入和发展，如何避免异响又成为汽车开发商关注的一个焦点。

Electric vehicle (EV) passengers perceive annoying noise significantly stronger, as an e-motor does not make any combustion noise. In addition to that, it causes way less mechanical sound which directly affects the noise appearance in the interior of the car. So, engineers have to live up to the challenge of thwarting warranty costs that are risen by a more sensitised customer perception. Figure 2 shows the total and partial noise in the interior of a modern middle class car at 50 km/h. It becomes clear that the powertrain sound dominates in wide frequency ranges. Rolling noise (below 100 Hz) and wheel noise on the street (approximately 1 to 2 kHz) add noise in smaller frequency bands. At a speed of more than 50 km/h, the perception inside of the car blurs to a random noise caused by the rolling and wind sound.
译：电动汽车的电机不会产生任何燃烧噪音，乘客对让人烦恼的噪音的感觉更加强烈，除此之外，它产生的直接影响车内噪声表现的机械噪声也要小的多。因此，工程师们不得不面对这样的一个挑战：控制由于更敏感的客户感知所带来的保养成本的增加。下图显示是一款现代化的中级轿车在50km/h时速下的车内整体和部分系统的噪声水平。很明显地看出，动力总成的噪声在很宽的频段内为主要的噪声源。滚动噪声（100Hz以下）和行驶在路面上时的胎噪（大约1-2KHz）会在较小的频段内贡献噪声。当车速大于50km/h时，车内噪声感觉变为一种由滚动噪声和风噪引起的随机噪声。

A speed below 50 km/h is of importance for typical bad road surfaces inside the city and is thus a significant criterion for noiseless driving. That is why many OEMs invest in S&R noise prevention.
译：车速低于50km/h对于城市内典型的恶劣路面是非常重要的，因此是无噪音驾驶的一个重要的评判标准。这就是为什么很多主机厂对异响预防进行投入的原因。



An EV’s interior often displays new material combinations,futuristic design and innovative concepts. Another vital feature of e-cars is the distinctively reduced interior equipment. On the one hand, this is to go harmonically with the mostly innovative and eye-catching exterior design; on the other hand, it contributes to the weight reduction. New connexion concepts or interfaces as well as modern material combinations make experienced virtual developing methods more and more important.
译：电动汽车内饰通常展现出来的是新材料的组合，未来的设计风格和创新的概念。另一个显著的特点就是电动汽车内部配置的简化。这样的设计一方面是使得最具创新性和惹人注目的外观设计相得益彰，另一方面也有助于重量的减轻。新的连接概念或界面接口以及现代化的材料组合使用使得丰富的虚拟开发手段变得越来越重要。

Preventing S&R is already an established part of the car developing process. Even during conceptioning, possible risks need to be considered and countermeasures have to be prepared. At an early stage of the development phase, the experts for disturbing noise then detect and evaluate possible error sources and take steps accordingly. As development periods become shorter and shorter and the cost pressure increases, often the virtual annoying noise is disregarded. This requires expertise, experience and authority as up to today, nearly no objective evaluations – for example, the noise pressure level in the field of passive acoustics – are available for the interior of cars. Distinguishing the S&R as well as correlation to the contact points are up to the experts.
译：异响的预防已经成为开发过程中一个既定的部分，即使在概念设计阶段也需要考虑可能的风险和应对措施。在设计的开发前期，需要异响专家检查和评估那些可能的异响源并采取相应的措施。随着开发周期变得越来越短，成本压力越来越大，虚拟设计阶段的异响就会被忽视。这时就需要专业的知识、丰富的经验和权威性。直至目前为止，几乎没有客观的评价方法（如，被动声学领域的声压级水平）可用于车内异响的评价，区分异响以及异响与接触点的相关性取决于专家。

VIRTUAL DEVELOPMENT STAGE
Presently, virtual analysis methods offer the most efficient possibility to determine, evaluate and finally avoid S&R at an early stage of product development. Computer aided design (CAD, for example the Catia software) is being applied to issue the junctions in a component (such as mounting parts of an instrument panel) as well as in interfaces to neighboured component parts (such as the instrument panel to the A-pillar cover). The relevant components may not come below a specified minimum distance which is defined by several parameters such as the connexion concept, the material and the stiffness of the component part. S&R occurs if the specified value is undercut and there is any clearance, contact or clash.
译：目前，虚拟分析的方法在产品的设计开发前期对判断、评估和最终避免异响提供了最有效的可能性。计算机辅助设计（CAD,如Catia软件）正应用于确定部件之间（如仪表板系统的安装组件）的连接以及相邻部件之间的搭接方式（如仪表板与A柱内饰件）。相关部件之间不得小于规定的最小距离，该距离由多个参数来决定的，如连接方式、材料和部件的刚度。如果小于规定值和存在任何间隙、接触或不兼容的情况都会导致异响。
（To be continued）