內(nèi)燃機(jī)照常轟鳴
????另一個方法是渦輪增壓。根據(jù)霍尼韋爾交通系統(tǒng)部門(Honeywell Transportation Systems)的調(diào)查顯示,,全球銷售的新車中有約25%配有渦輪增壓,,而且到2017年這個比例最終可能會達(dá)到40%。這種技術(shù)本身已有近100年的歷史了,,但汽車制造商正越來越多地采用這項(xiàng)技術(shù),。目前市場上有幾款渦輪增壓發(fā)動機(jī)就包括:福特的EcoBoost、馬自達(dá)的Skyactiv,、寶馬的EfficientDynamics,。渦輪增壓利用汽車自身產(chǎn)生的廢氣來驅(qū)動泵輪,迫使更多空氣進(jìn)入氣缸,。壓縮后的空氣可以和更多壓縮后的燃油(這里可以采用直噴技術(shù))相混合,,從而加大發(fā)動機(jī)的輸出動力。 ????機(jī)械增壓是一個成本更加昂貴,、但與渦輪增壓相類似的技術(shù)選擇,。機(jī)械增壓器的作用基本上與渦輪增壓器相同,但它不是借助汽車廢氣來驅(qū)動泵輪,,而通常是由發(fā)動機(jī)的風(fēng)扇皮帶來帶動,。機(jī)械增壓器的優(yōu)勢是,,不必等待汽車排出廢氣來開始增壓。機(jī)械增壓更常用于提高汽車性能,,而不是提高燃油經(jīng)濟(jì)性,。 ????很大程度上,包括福特(除了一款高性能的野馬汽車)在內(nèi)的美國汽車制造商認(rèn)為,,機(jī)械增壓技術(shù)過于昂貴,,相對于在發(fā)動機(jī)輸出功率方面實(shí)現(xiàn)的提高而言并不合算。這些公司大多轉(zhuǎn)而選擇渦輪增壓技術(shù),。然而,,一些汽車——比如大眾1.4升TSI Twincharger 四缸發(fā)動機(jī)既有機(jī)械增壓器,也有渦輪增壓器,。大眾及其海外合資企業(yè)是在發(fā)動機(jī)里結(jié)合包括柴油動力在內(nèi)的諸多節(jié)能技術(shù)的早期倡導(dǎo)者,,以此來節(jié)能意識格外強(qiáng)烈的歐洲客戶的需求。 ????其他越來越常見的做法包括(但不限于):在有任何移動部件的地方減少摩擦,。十年前還非常罕見的可變氣門正時技術(shù)現(xiàn)在幾乎是普遍存在。本田(Honda)在推出VTEC系統(tǒng)時首創(chuàng)了這項(xiàng)技術(shù),,VTEC系統(tǒng)甚至形成了自己的技術(shù)基因,。而寶馬在這方面也取得了很大的進(jìn)展,推出了Valvetronic系統(tǒng),。在配有Valvetronic系統(tǒng)的汽車?yán)?,一臺電腦智能地精確校準(zhǔn)進(jìn)氣孔與排氣閥的開關(guān)時間,以此與車輛的速度和負(fù)載相匹配,。 ????思邁汽車咨詢公司(IHS Automotive)全球汽車動力總成系統(tǒng)與部件預(yù)測部門負(fù)責(zé)人埃里克?費(fèi)德瓦表示,,預(yù)計(jì)未來可變氣門正時系統(tǒng)所帶來的巨大收益會變得越來越精確。而且,,預(yù)計(jì)還將會出現(xiàn)更多的混合動力電動發(fā)動機(jī),,支持傳統(tǒng)內(nèi)燃機(jī)。同時,,汽車變速器將獲得更多速度設(shè)置,,以便發(fā)動機(jī)在最高效的情況下運(yùn)作。費(fèi)德瓦說,,10年后:“發(fā)動機(jī)尺寸必須會大幅縮小,,而同時輸出功率很可能與目前相同、甚至更大,?!边^去,發(fā)動機(jī)技術(shù)改進(jìn)的收益一直集中在輸出功率方面,。費(fèi)德瓦在提到如今的汽車時說:“基本上等于是讓消費(fèi)者駕駛賽車發(fā)動機(jī),?!蔽磥恚l(fā)動機(jī)技術(shù)改進(jìn)的重點(diǎn)將集中在提高燃油經(jīng)濟(jì)性方面,。 ????所有這些創(chuàng)新所造成的影響是巨大的,。根據(jù)密歇根大學(xué)交通研究所(the University of Michigan Transportation Research Institute)進(jìn)行的分析顯示,自2007年以來,,輕型車輛的燃油經(jīng)濟(jì)性已提高了18%,,達(dá)到23.8英里/加侖。燃油經(jīng)濟(jì)性的改善部分歸功于發(fā)動機(jī)更加智能化,,以及在汽車節(jié)能方面的一系列其他增量型改善,。這個增長的實(shí)質(zhì)幅度并不巨大,但與1923年至2007年期間所有汽車的燃油經(jīng)濟(jì)性僅提高區(qū)區(qū)23%相比,,這可謂是一個巨大的飛躍,。 ????當(dāng)然,世界各國在打破依賴汽油的習(xí)慣方面還有很長的一段路要走,,而內(nèi)燃機(jī)并不會改變這一點(diǎn),。《國際汽車工程》雜志(Automotive Engineering International)高級編輯林賽?布魯克稱,,汽車制造商在研制仍能給汽車提供強(qiáng)大動力的小型發(fā)動機(jī)方面面臨一個物理極限,,而我們在大中型汽車方面已經(jīng)達(dá)到這種極限,在其他類型汽車方面也非常接近這個極限了,。在此之后,,要想減少燃料消耗,美國將需要建造更多面向電動汽車的公共充電站,,開發(fā)性能更加優(yōu)良的電池,,甚至或許要對內(nèi)燃機(jī)產(chǎn)生一個新的看法(幾家初創(chuàng)公司目前正在這方面努力。)但現(xiàn)在,,似乎老式的內(nèi)燃發(fā)動機(jī)還將會伴隨我們很長一段時間——而這件事也許并不是那么糟糕,。 ????譯者:iDo98 |
????Another method is turbocharging. According to Honeywell Transportation Systems, turbochargers were in about 25% of new cars sold globally, and could end up in 40% of cars as soon as 2017. The technology itself is nearly a century old, but automakers are increasingly embracing it. A few turbocharged engines: Ford's EcoBoost, Mazda's Skyactiv, BMW's EfficientDynamics. Turbocharging uses a car's own exhaust to power a pump that forces more air into the cylinders. That compressed air can mix with more compressed fuel (hello, direct injection), resulting in more power. ????Supercharging is a more expensive, but similar option. Superchargers do essentially the same thing as turbochargers, but instead of being powered by a vehicle's exhaust, they're mechanically driven, usually by the engine's fan belt. The supercharger's advantage is that there's no need to wait for exhaust to come out for the boost to kick in. The supercharger is more commonly used for performance rather than fuel economy. ????This has been largely deemed too pricey to justify the extra power by U.S. automakers, Ford included (except for one high-performance Mustang variant). These firms have largely opted for turbochargers instead. However, some vehicles -- like the Volkswagen 1.4-liter TSI Twincharger four-cylinder engine -- have both. Volkswagen and its overseas counterparts were early pioneers of combining efficiency technologies, including diesel power, in engines for hyper-fuel conscious European customers. ????Other increasingly common tactics include, but aren't limited to, reducing friction wherever there are moving parts. And variable valve timing, which was rare a decade ago and is now almost ubiquitous. Honda (HMC) pioneered the technology, with its VTEC system, which even got its own meme. And BMW has also made strides with its Valvetronic system. In cars equipped with the system, a computer intelligently times the opening and closing of air intake and exhaust valves to match a vehicle's speed and load. ????In the future, expect big gains from variable valve timing systems becoming more precise, says Eric Fedewa, director of IHS Inc.'s global powertrain and component forecasting. Also expect more hybrid electric engines to work as a support to traditional engines. At the same time, transmissions will get more speeds, in an effort to make engines operate at their most efficient. In 10 years: "engines will necessarily be a lot smaller and probably as powerful or more powerful than they are now," Fedewa says. In the past, gains have focused on power. "You've essentially got consumers driving race car engines," Fedewa says of today's cars. In the future, gains will focus on efficiency. ????The impact of all these innovations is substantial. According to analysis by the University of Michigan Transportation Research Institute, fuel economy for light-duty vehicles has improved 18% since 2007, to 23.8 miles per gallon. Part of the credit for those gains goes to smarter engines, along with a host of other incremental improvements in vehicle efficiency. The increase isn't huge in real terms, but it's a giant leap compared with the scant 23% gain in the fuel economy of all vehicles between 1923 and 2007. ????Of course, the world is still a long way from breaking its gasoline habit, and internal combustion won't change that. There's a physical limit to how small an automaker can make an engine and have it still power a car, and we've already hit it in large and midrange vehicles, says Automotive Engineering International senior editor Lindsay Brooke, and we're close in other classes. After that, to reduce fuel consumption the country will need more public chargers for electric cars, better batteries, and maybe even a new take on internal combustion. (Several startups are working on it.) But for now, it looks like the old-fashioned engine will be with us for a long time still -- and that might not be so bad. |