如今，人們對(duì)于非公路用車(chē)和卡車(chē)的需求已變得愈發(fā)復(fù)雜。車(chē)輛必須更環(huán)保，能在更苛刻的工況下運(yùn)行，行駛時(shí)長(zhǎng)更久，還需運(yùn)用最新的材料和科技技術(shù)，達(dá)到最佳性能，滿(mǎn)足市場(chǎng)需求。而為了更好地滿(mǎn)足未來(lái)全球范圍的減排需求，就需要將已有的技術(shù)更廣泛地投入應(yīng)用，同時(shí)也需要性?xún)r(jià)比更高的新技術(shù)研發(fā)有所突破。作為密封裝置、蓄能器和高性能材料的領(lǐng)先制造商，Freudenberg密封技術(shù)公司正積極致力于現(xiàn)有和待開(kāi)發(fā)的各類(lèi)動(dòng)力系統(tǒng)，以滿(mǎn)足世界各地不同的客戶(hù)需求。
在討論排放的測(cè)量時(shí)，議題的中心往往是法規(guī)要求，但總的來(lái)說(shuō)，提高能效是節(jié)能減排最直接有效的途經(jīng)。像發(fā)動(dòng)機(jī)小型化、燃油直噴、廢氣再循環(huán)、減小摩擦以及減少使用不必要的催化劑等手段，都會(huì)影響發(fā)動(dòng)機(jī)的能效，從而改變排放量。
系統(tǒng)最優(yōu)化
要實(shí)現(xiàn)系統(tǒng)最優(yōu)化并延長(zhǎng)車(chē)輛壽命，先進(jìn)的密封技術(shù)起著至關(guān)重要的作用。舉例來(lái)說(shuō)，密封技術(shù)決定著自動(dòng)變速傳動(dòng)系統(tǒng)中近1/4的機(jī)械能損耗，所以，自動(dòng)變速系統(tǒng)制造商十分渴望能進(jìn)一步減少系統(tǒng)摩擦，從而將機(jī)械能損耗降到最低。而如今，全新的密封材料和密封設(shè)計(jì)將會(huì)有效減輕系統(tǒng)重量，減少摩擦，并降低油耗。
而在發(fā)動(dòng)機(jī)方面，我們面臨的挑戰(zhàn)很多，包括要能匹配更加輕量化的發(fā)動(dòng)機(jī)，并且能適應(yīng)發(fā)動(dòng)機(jī)更極端的高溫/低溫工況要求。而隨著更先進(jìn)的燃料和潤(rùn)滑油的應(yīng)用，以及更加苛刻的駕駛工況出現(xiàn)，由此帶來(lái)的一系列挑戰(zhàn)也是我們必須面對(duì)的。為此，F(xiàn)reudenberg公司和客戶(hù)之間密切合作，制定出應(yīng)對(duì)這些挑戰(zhàn)的各種方案，同時(shí)針對(duì)各種不同的動(dòng)力系統(tǒng)，進(jìn)行節(jié)能減排性能的優(yōu)化。目前，公司已經(jīng)研發(fā)出了新的密封技術(shù)，能夠承受超過(guò)18,000小時(shí)的高負(fù)荷運(yùn)轉(zhuǎn)，并計(jì)劃將這一數(shù)字翻倍。
而在密封系統(tǒng)優(yōu)化的研發(fā)中，明確各種應(yīng)用需求至關(guān)重要。有時(shí)客戶(hù)往往會(huì)提出一些極具挑戰(zhàn)性的要求，時(shí)常同污染排放或溫度設(shè)定有關(guān)。而密封技術(shù)是摩擦學(xué)的一部分，所以如果沒(méi)有把所有性能參數(shù)都仔細(xì)分析過(guò)，就無(wú)法實(shí)現(xiàn)系統(tǒng)的正常運(yùn)轉(zhuǎn)。在很多時(shí)候需要同時(shí)采用多種密封技術(shù)，但是只有全面分析過(guò)速度、溫度、用途、環(huán)境、壓力、尺寸（也被稱(chēng)為S.T.A.M.P.S.）等各項(xiàng)參數(shù)，才能確定最優(yōu)的解決方案。
Freudenberg公司同時(shí)也在不遺余力地進(jìn)行低排放密封技術(shù)（LESS）產(chǎn)品的研發(fā)。LESS部件在制造和實(shí)測(cè)時(shí)，都會(huì)首先考慮S.T.A.M.P.S.參數(shù)，以實(shí)現(xiàn)各種運(yùn)輸機(jī)械和卡車(chē)的節(jié)能減排。這些產(chǎn)品包括：用于柴油發(fā)動(dòng)機(jī)的改進(jìn)款閥桿（有助于機(jī)油計(jì)量和漏氣控制）、新一代曲軸密封技術(shù)（摩擦降幅可達(dá)90%）、更先進(jìn)的密封材料及加工技術(shù)（以便改善機(jī)油的流動(dòng)和壓力，實(shí)現(xiàn)功率損失的最小化，提高傳動(dòng)系能效）、改良的密封墊（能適應(yīng)承受度更強(qiáng)的塑料罩）、兼容排氣系統(tǒng)和尿素添加劑的密封墊，以及耐高溫的車(chē)用尿素（AdBlue）接觸材料等。
車(chē)輛電氣化和其他全球主要趨勢(shì)
除了動(dòng)力系統(tǒng)優(yōu)化之外，其他一些全球主流趨勢(shì)也都著眼于未來(lái)的發(fā)動(dòng)機(jī)減排戰(zhàn)略?？傮w而言，所有歐洲和美國(guó)的新出廠設(shè)備，都嚴(yán)格遵循StageIV（四階段）排放標(biāo)準(zhǔn)。所以當(dāng)務(wù)之急是，需要了解其他國(guó)家或地區(qū)會(huì)以何種速度跟上這一減排步伐？比如，對(duì)于亟待解決空氣污染問(wèn)題的中國(guó)而言，其排放標(biāo)準(zhǔn)很可能會(huì)逐步向StageIV靠攏。然而，像印度或伊朗這些國(guó)家的情況就很難預(yù)測(cè)了。為此，全球的車(chē)輛制造商都必須盡可能地掌握尖端技術(shù)，以符合更嚴(yán)苛的法規(guī)和標(biāo)準(zhǔn)要求，同時(shí)，這也是為了更好地控制“總體擁有成本”（即TCO），延長(zhǎng)現(xiàn)有設(shè)備的使用壽命。
車(chē)輛電氣化也是一種主流趨勢(shì)，但具體發(fā)展因市場(chǎng)而異。對(duì)于物料搬運(yùn)設(shè)備而言，這一技術(shù)就被用在了工業(yè)用卡車(chē)上。卡車(chē)在封閉的環(huán)境里作業(yè)，并且需要額外配重以防止其翻倒?？ㄜ?chē)的電池就充當(dāng)了配重的角色，而一些客戶(hù)也正想方設(shè)法用燃料電池組件取代原來(lái)的電池，這樣就不再需要充電站了。這也被視為是節(jié)能減排的終極解決方案。不過(guò)，不同市場(chǎng)對(duì)設(shè)備電氣化的需求也不盡相同。例如，農(nóng)業(yè)用機(jī)械往往需要以一個(gè)恒定的速度作業(yè)相當(dāng)長(zhǎng)的時(shí)間，并且周?chē)r有充電和加氫基礎(chǔ)設(shè)施。在這一情況下，使用高效的柴油發(fā)動(dòng)機(jī)就是最佳方案了，因?yàn)橹灰m時(shí)加油，設(shè)備就可以進(jìn)行全天候的作業(yè)。
而對(duì)于城市的小型建筑工程機(jī)械而言，柴油混合動(dòng)力車(chē)技術(shù)然效果更佳。柴油發(fā)動(dòng)機(jī)以一個(gè)恒定的速度旋轉(zhuǎn)，類(lèi)似于一臺(tái)發(fā)電機(jī)，可以大大降低噪音，而設(shè)備作業(yè)則完全依靠電動(dòng)系統(tǒng)。但是，在某些情況下——比如對(duì)于挖掘機(jī)而言，用電動(dòng)系統(tǒng)替代液壓系統(tǒng)并不可行，而液壓輔助儲(chǔ)能系統(tǒng)則更管用。這樣，液壓系統(tǒng)產(chǎn)生的壓力就能儲(chǔ)存在蓄能器中，而不會(huì)再釋放回液壓系統(tǒng)。而在下一步作業(yè)啟動(dòng)時(shí)，就可以充分使用這部分能量，而不必耗費(fèi)新的能源。而如果多項(xiàng)低負(fù)荷作業(yè)都能使用蓄能器中儲(chǔ)備的能量，那么整體的能效平衡便能大大改善。
過(guò)去10年中，發(fā)動(dòng)機(jī)和傳輸密封系統(tǒng)的能效提升了近50%。而通過(guò)應(yīng)用和改良已有的新技術(shù)，在現(xiàn)有基礎(chǔ)上再提升50%的能效也不無(wú)可能。目前，汽車(chē)行業(yè)正在使用已有技術(shù)對(duì)設(shè)計(jì)進(jìn)行優(yōu)化，客戶(hù)將能夠以一種更加經(jīng)濟(jì)的方式步入節(jié)能減排的新紀(jì)元。
本文作者系Freudenberg-NOK密封技術(shù)公司運(yùn)輸機(jī)械工程部全球副總裁Joel Johnson，屬于《卡車(chē)與非公路設(shè)備工程》“高管視角（Executive Viewpoints）”年度系列報(bào)道的一部分。
Demands on off-highway vehicles and trucks today are exceedingly complex. Equipment must be more environmentally friendly, work in a more aggressive environment, run longer hours and rely upon the latest material and product technology to meet market demands for peak performance. To satisfy future global emissions-reduction demands, a wider application of existing technologies and the development of innovative yet cost-effective technologies is required. As a leading manufacturer of seals, accumulators and high-performance materials, Freudenberg Sealing Technologies is dedicated to addressing the existing and future system requirements of customers throughout the world.
Discussions regarding regulations often center around measuring emissions but, in general, improving efficiency is a direct input to improving emissions. Actions such as downsizing, direct injection, exhaust gas recirculation, friction reduction and selective catalytic reduction all affect engine efficiency and thus emissions.
Systems optimization
Advanced sealing solutions play a critical role in systems optimization and extending the overall life of the machine. For example, seals are responsible for nearly one-quarter of all lost mechanical energy in today’s automatic transmissions, so transmission manufacturers are keen to lower system friction to minimize this loss. New seal designs and materials available today can help lower system weight, reduce friction and lower fuel consumption.
In engines, we are challenged to support lightweight designs, accommodate extended temperature ranges and address challenges posed by advanced fuels, lubricants and aggressive media. Freudenberg works in close cooperation with customers to develop solutions that resolve these challenges, while also optimizing the efficiency and emissions performance of various powertrain systems. The company has developed seals that withstand more than 18,000 hours of hard operation with plans to double this.
In developing optimal sealing systems, it is essential to identify application conditions. In some cases, our customers have extreme requirements, perhaps relating to contaminant exclusion or temperature specifications. Seals are part of a tribological system and can’t function properly when all performance parameters are not carefully analyzed. In many cases, multiple sealing solutions can be considered, but the optimal solution becomes evident only through extensive analysis of factors like speed, temperature, application, media, pressure and size (S.T.A.M.P.S.)
Our company’s efforts have coalesced in the development of its Low Emission Sealing Solutions (LESS) portfolio of products. LESS components have been engineered and field-tested to address S.T.A.M.P.S. parameters that influence energy consumption, efficiency and emission challenges in mobile machinery and trucks. These products incorporate: valve stem modifications for diesel engines that facilitate oil metering and blow-by control; next generation crankshaft sealing technology that reduce friction up to 90%; material and process technologies that improve transmission efficiency through seals that use oil flow and oil pressure to minimize power loss; improved gaskets that accommodate the increased tolerance range of plastic covers; gaskets compatible with exhaust gas and urea additives; and AdBlue-resistant materials for high temperatures.
Electrification and other global trends
In addition to powertrain system optimization, other global trends also are driving future engine emission strategies. For the most part, all new equipment in Europe and in the United States conforms to Stage IV emission standards. A pressing question is where and to what degree will other regions follow suit? In China, for example, where air pollution is a major issue, we will likely see emission standards that converge with Stage IV limits. But what about in other markets like India and Iran? Global manufacturers must be able to incorporate new technologies that help meet stricter limits, while balancing a “total cost of ownership” approach that extends the life of existing equipment.
There’s also a trend toward electrification, but it varies by market. In material handling equipment, electrification certainly lends itself to industrial trucks. They are often operated in enclosed spaces and need additional weight so they don’t tip over. The battery supplies the counter weight and some customers are working to replace the battery with a fuel-cell assembly to eliminate the recharging station. This is the ultimate in emissions reduction. The view of the situation is different for each market though. Agricultural machines are often operated over long periods at a constant speed, far from any infrastructure. In this application, an efficient diesel engine is generally seen as the best choice because it can provide more of a 24/7 type performance only stopping for refueling.
For smaller construction machines used in an urban environment, a diesel-electric hybrid powertrain definitely makes sense. The diesel engine would run solely as a generator at a constant rotational speed, which reduces the noise level considerably, but the work is initiated via an electrical system. In some applications, such as a classic excavator, substitution of the hydraulic system with an electrical system is not practical, so hydraulic assist storage systems may make more sense. In these cases, the pressure generated by the hydraulic system is stored in an accumulator rather than being released back into the oil reservoir. This energy is then used to initiate the next machine movement rather than starting from scratch. If the phases with lower loads use the energy stored in the accumulator, the overall energy balance is improved.
During the past 10 years, the efficiency of engine and transmission sealing packages has been improved by nearly 50%. By applying and refining technologies available today, an absolute improvement of efficiency of the same magnitude can be achieved. By optimizing current designs with existing technology, customers are able to cost-effectively move the needle in emissions reduction.
Joel Johnson, Global Vice President, Mobile Machinery at Freudenberg-NOK Sealing Technologies, wrote this article for Truck & Off-Highway Engineering as part of our annual Executive Viewpoints series.
Author: Joel Johnson
Source: SAE Truck & Off-highway Engineering Magazine
Joel Johnson目前擔(dān)任Freudenberg-NOK密封技術(shù)公司運(yùn)輸機(jī)械工程部的全球副總裁。
過(guò)去10年中，發(fā)動(dòng)機(jī)和傳動(dòng)系密封系統(tǒng)的能效提升了近50%。Johnson相信，通過(guò)應(yīng)用和改良已有的新技術(shù)，在現(xiàn)有基礎(chǔ)上再提升50%的能效也不無(wú)可能。
圖為止推墊圈。