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.
譯：根據(jù)政府機(jī)構(gòu)、研究院所和汽車工業(yè)界的聲明，已經(jīng)為電動(dòng)汽車開啟了綠燈。然而技術(shù)的成熟度在很多方面還沒有得到一個(gè)可接受的程度，除過廣泛討論的續(xù)航里程，關(guān)注的焦點(diǎn)來到了汽車異響上。至少目前為止，在電動(dòng)化和傳統(tǒng)動(dòng)力噪音消失的大環(huán)境下，對于異響沒有投入足夠的研究。某些開發(fā)服務(wù)供應(yīng)商在設(shè)計(jì)開發(fā)前期結(jié)合虛擬仿真和物理試驗(yàn)的方法來分析和消除這些異響。



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.
譯：客戶對產(chǎn)品的質(zhì)量有著很高的標(biāo)準(zhǔn)，然后，這些標(biāo)準(zhǔn)又因人而異。不管是低端緊湊型還是高端車型，客戶都會根據(jù)他們自己的定義來判斷其舒適性和質(zhì)量。駕駛過程中的噪聲要根據(jù)客戶個(gè)人的感知來與車輛匹配。以下這三種行駛過程中的噪聲有一個(gè)基本的區(qū)別：滾動(dòng)噪聲、動(dòng)力總成和風(fēng)噪，駕駛員會欣然接受這些噪音，因?yàn)樗麄兎从沉塑囕v的一個(gè)實(shí)際技術(shù)狀況。甚至是指示燈的滴答聲 – 一種功能性提示音，也會出現(xiàn)在車內(nèi)。但是，只要是讓人感覺驚訝或或者是未知的噪音，這種噪音就會被認(rèn)為是不愉悅的和令人煩惱的，這就會給客戶留下產(chǎn)品質(zhì)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.
譯：在最初的汽車上，異響通常被動(dòng)力總成、滾動(dòng)噪聲和風(fēng)噪所掩蓋。經(jīng)過進(jìn)一步的開發(fā)和優(yōu)化，汽車異響更容易在車內(nèi)被聽到。如今，無噪音駕駛是汽車開發(fā)的一個(gè)中心點(diǎn)。然而，最新的汽車設(shè)計(jì)不僅注重減少讓人煩惱的噪音，還應(yīng)減少可能發(fā)生的維修費(fèi)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.
譯：下圖顯示了近30年來與開發(fā)相關(guān)的汽車噪音的表現(xiàn)。動(dòng)力總成、滾動(dòng)噪音和風(fēng)噪（藍(lán)色曲線）與異響（綠色曲線）進(jìn)行比較，這表明要避免車內(nèi)異響或保持目前的一個(gè)差距水平（見虛線）需要付出很大的努力。由于電動(dòng)汽車的引入和發(fā)展，如何避免異響又成為汽車開發(fā)商關(guān)注的一個(gè)焦點(diǎn)。

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.
譯：電動(dòng)汽車的電機(jī)不會產(chǎn)生任何燃燒噪音，乘客對讓人煩惱的噪音的感覺更加強(qiáng)烈，除此之外，它產(chǎn)生的直接影響車內(nèi)噪聲表現(xiàn)的機(jī)械噪聲也要小的多。因此，工程師們不得不面對這樣的一個(gè)挑戰(zhàn)：控制由于更敏感的客戶感知所帶來的保養(yǎng)成本的增加。下圖顯示是一款現(xiàn)代化的中級轎車在50km/h時(shí)速下的車內(nèi)整體和部分系統(tǒng)的噪聲水平。很明顯地看出，動(dòng)力總成的噪聲在很寬的頻段內(nèi)為主要的噪聲源。滾動(dòng)噪聲（100Hz以下）和行駛在路面上時(shí)的胎噪（大約1-2KHz）會在較小的頻段內(nèi)貢獻(xiàn)噪聲。當(dāng)車速大于50km/h時(shí)，車內(nèi)噪聲感覺變?yōu)橐环N由滾動(dòng)噪聲和風(fēng)噪引起的隨機(jī)噪聲。

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.
譯：車速低于50km/h對于城市內(nèi)典型的惡劣路面是非常重要的，因此是無噪音駕駛的一個(gè)重要的評判標(biāo)準(zhǔn)。這就是為什么很多主機(jī)廠對異響預(yù)防進(jìn)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.
譯：電動(dòng)汽車內(nèi)飾通常展現(xiàn)出來的是新材料的組合，未來的設(shè)計(jì)風(fēng)格和創(chuàng)新的概念。另一個(gè)顯著的特點(diǎn)就是電動(dòng)汽車內(nèi)部配置的簡化。這樣的設(shè)計(jì)一方面是使得最具創(chuàng)新性和惹人注目的外觀設(shè)計(jì)相得益彰，另一方面也有助于重量的減輕。新的連接概念或界面接口以及現(xiàn)代化的材料組合使用使得豐富的虛擬開發(fā)手段變得越來越重要。

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.
譯：異響的預(yù)防已經(jīng)成為開發(fā)過程中一個(gè)既定的部分，即使在概念設(shè)計(jì)階段也需要考慮可能的風(fēng)險(xiǎn)和應(yīng)對措施。在設(shè)計(jì)的開發(fā)前期，需要異響專家檢查和評估那些可能的異響源并采取相應(yīng)的措施。隨著開發(fā)周期變得越來越短，成本壓力越來越大，虛擬設(shè)計(jì)階段的異響就會被忽視。這時(shí)就需要專業(yè)的知識、豐富的經(jīng)驗(yàn)和權(quán)威性。直至目前為止，幾乎沒有客觀的評價(jià)方法（如，被動(dòng)聲學(xué)領(lǐng)域的聲壓級水平）可用于車內(nèi)異響的評價(jià)，區(qū)分異響以及異響與接觸點(diǎn)的相關(guān)性取決于專家。

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.
譯：目前，虛擬分析的方法在產(chǎn)品的設(shè)計(jì)開發(fā)前期對判斷、評估和最終避免異響提供了最有效的可能性。計(jì)算機(jī)輔助設(shè)計(jì)（CAD,如Catia軟件）正應(yīng)用于確定部件之間（如儀表板系統(tǒng)的安裝組件）的連接以及相鄰部件之間的搭接方式（如儀表板與A柱內(nèi)飾件）。相關(guān)部件之間不得小于規(guī)定的最小距離，該距離由多個(gè)參數(shù)來決定的，如連接方式、材料和部件的剛度。如果小于規(guī)定值和存在任何間隙、接觸或不兼容的情況都會導(dǎo)致異響。
（To be continued）