540 352履帶拖拉機(jī)－滑動齒輪變速箱設(shè)計（有cad圖+中英文翻譯）

540 352履帶拖拉機(jī)－滑動齒輪變速箱設(shè)計（有cad圖+中英文翻譯）,540,352履帶拖拉機(jī)－滑動齒輪變速箱設(shè)計（有cad圖+中英文翻譯）,履帶,拖拉機(jī),滑動,齒輪,變速箱,設(shè)計,cad,中英文,翻譯 更快、更順暢的變速器 變速箱通常不得不在舒適性和效率之間做出選擇，但一種新型的“犬牙嚙合式”（dog engagement）變速箱可以同時改善這兩種性能 隨著排放法規(guī)的日趨嚴(yán)格，汽車制造商為降低排放的努力已不再局限于改善燃燒過程和后期處理。許多公司認(rèn)為，現(xiàn)代發(fā)動機(jī)技術(shù)已經(jīng)發(fā)展到這樣一個階段：與投入巨額開發(fā)成本相比，技術(shù)進(jìn)步帶來的收效卻很小。 因此為了改善排放,最重要的是要著眼于整車的性能。作為車上第二昂貴的部件，變速箱理所當(dāng)然地成為第二步改善的目標(biāo)。 所有變速箱技術(shù)中，手動變速箱的效率最高，輸出功率可達(dá)輸入功率的96％。但并不是所有人都能駕馭手動變速箱，也不是所有人都愿意用它。因為用手動變速箱需要踩離合器，這在交通繁忙的時候很不舒服。駕駛員容易疲勞。而由扭矩中斷導(dǎo)致的“點頭”效應(yīng)也會使乘客很難受。 由于駕駛員操縱離合器而產(chǎn)生的扭矩中斷是手動變速箱的主要缺點。在換檔加速時，每升高一檔，駕駛員都必須通過松開油門并踩下離合器來使扭矩暫時中斷。完成整個過程大概只需一秒鐘，但在這段時間里車輛會暫時停止加速，速度也會降低。 與此截然相反的是傳統(tǒng)的自動變速箱。由于采用了變矩器，這種變速箱的換檔質(zhì)量不錯但效率相對較差——即使最近有所改進(jìn)。因此，最近進(jìn)行了許多研究，試圖發(fā)現(xiàn)傳統(tǒng)自動變速箱的有效替代方案。 主要的技術(shù)仍是無級變速（CVT）、雙離合器變速（DCT）和手自一體（AMT）變速器。它們在不同的方面優(yōu)于傳統(tǒng)的行星齒輪式自動變速器。 無級變速器采用帶鏈或錐盤滾輪來產(chǎn)生無限多種變速比。與傳統(tǒng)自動變速器相比，其效率和成本都有所改善。之所以有這些優(yōu)點，是因為它結(jié)構(gòu)簡單。這種變速器的零部件很少，通常只有一根橡膠或金屬傳動帶、一個液壓作用的驅(qū)動帶輪、一個機(jī)械扭矩感應(yīng)式驅(qū)動帶輪、一些微處理器和傳感器等。 這種變速器的工作原理是改變兩個帶輪表面之間的距離。帶輪上掛傳動帶的地方開了V形的槽。一側(cè)的帶輪沿軸向固定，另一側(cè)的帶輪可在液壓的作用下移動。 在驅(qū)動后，液壓缸可增加或減少帶輪兩側(cè)之間的距離。這樣會使傳動帶在帶輪側(cè)壁上的位置上下變動，變動的方式取決于駕駛情況。這樣會使變速比發(fā)生變化。錐盤滾輪型變速箱的工作原理與此類似但用的是驅(qū)動盤和動力滾輪。 CVT變速器“無級”的特點對技術(shù)人員最有吸引力。因為沒有檔位，CVT可以使發(fā)動機(jī)保持在最佳的功率范圍內(nèi)，這樣可以使效率提高并在相同的油耗下增加行駛里程。CVT可將發(fā)動機(jī)工作曲線上的每一點轉(zhuǎn)換為其本身工作曲線上相應(yīng)的點。 這種變速器最受日本汽車制造商的青睞，并且日本變速器生產(chǎn)商JATCO是主要的生產(chǎn)者。但在歐美國家，情況有所不同。盡管奧迪和其他一些制造商在一些車型上推出了CVT，但在這方面他們追趕的步伐仍然很緩慢。 DCT實際上是將兩臺手動變速箱合在一起。換檔過程是通過在兩臺變速箱的離合器之間相互切換實現(xiàn)的。這種變速器的換檔質(zhì)量和傳統(tǒng)自動變速箱相同，但由于系統(tǒng)會發(fā)生滑動、流體阻力和液壓損失，其效率和加速性能只比傳統(tǒng)行星齒輪自動變速器稍有提高。開發(fā)控制系統(tǒng)的成本也很高。 “最近在傳統(tǒng)自動變速器技術(shù)上取得的進(jìn)展，使開發(fā)和生產(chǎn)CVT或DCT的呼聲有所降低?！弊兯傧渖a(chǎn)企業(yè)Zeroshift公司的執(zhí)行總裁Bill Martin說?！坝捎诔杀具^高，有些汽車廠已經(jīng)取消了DCT項目。” AMT是成本最低的自動變速器技術(shù)。AMT用執(zhí)行器來代替?zhèn)鹘y(tǒng)的離合器跳板和換檔桿。這種變速器保留了手動變速器的高效率和加速性能，但某些型號的變速器的換檔質(zhì)量不高。扭矩中斷和“點頭”效應(yīng)仍是主要的缺點。 那么什么是最好的替代方案？變速器方面的新技術(shù)是曾出不窮的，但Zeroshift公司聲稱其變速器的效率優(yōu)于手動變速器，能提高市區(qū)駕駛的燃油經(jīng)濟(jì)性。同時，其換檔效率可以和改進(jìn)后的自動變速器相媲美。 Zerosift公司采用的是一種改進(jìn)版的AMT技術(shù)。這種技術(shù)用先進(jìn)的犬牙嚙合（dog engagement）系統(tǒng)代替同步器。 犬牙嚙合技術(shù)許多年前就已在賽車運動中采用，目的是為了加快換檔速度。傳統(tǒng)的犬牙式變速箱并不適合用在公路上，因為驅(qū)動環(huán)或犬牙之間的空間很大，會產(chǎn)生后坐——由扭矩突然變向而產(chǎn)生的一種不舒適的竄動。 Zeroshift公司通過增加第二套驅(qū)動犬牙來解決這一問題。這種技術(shù)還使每組犬牙只能傳遞兩種相反方向扭矩中的一種?！巴ㄟ^對兩套犬牙的嚙合和分離，可在上一個檔位沒有分離的情況下?lián)Q入新的檔位?！盡artin說。“換檔質(zhì)量超過采用現(xiàn)代化的6檔變速器的豪華轎車?！? 換檔可在瞬間完成，而扭矩不會發(fā)生中斷。而且這種方法既可用于升檔也可用于降檔。 “在使用傳統(tǒng)的AMT變速器時，由于需要關(guān)閉并重新打開油門，換檔過程中排放會達(dá)到高峰，而通過這種無過渡的換檔方式則可以消除這種現(xiàn)象?！盡artin說，“這樣還能降低燃油消耗?！? 盡管該技術(shù)在變速器領(lǐng)域還比較新，但該公司稱已經(jīng)引起了歐美各大汽車制造商的注意。最大的吸引力在于其成本比DCT低，Martin說。 由于可以保留大部分手動變速箱的結(jié)構(gòu)，這種變速箱的成本和復(fù)雜性都不會高于傳統(tǒng)的AMT變速箱?？刂葡到y(tǒng)的開發(fā)成本也會大大降低。這對試圖減少排放和削減成本的工程師來說是個好消息。 “大部分汽車制造商都來參觀過?！盡artin說。“有些公司馬上就和我們簽合同，另一些未作決定，拒絕的一個都沒有。”這再清楚不過地表明了汽車制造商現(xiàn)在正在將動力系統(tǒng)開發(fā)的重點轉(zhuǎn)移到變速箱上。 Zeroshift變速系統(tǒng)的工作原理 硬件部分包括兩套犬牙，安裝在兩個獨立的犬牙環(huán)上并受其驅(qū)動。兩套犬牙有一個共同的轂蓋，轂蓋和一個帶花鍵的軸相連。 每個犬牙具有特殊的輪廓。在一側(cè)是用于嚙合的直角面。這些直角面是沿對角線相對的，這樣犬牙在對某一個檔位具有驅(qū)動功能的同時，對另一個檔位具有超越傳動（overrun)功能。嚙合面有輕微的后向錐度，以保證犬牙能在加載時鎖定在嚙合的齒輪上。 相對角上有一個斜坡，可在新檔位接合后將犬牙從前一個檔位上推離。 在空檔時，兩個犬牙環(huán)處于變速比的中間位置。選一檔時，犬牙會發(fā)生移動并和犬牙嚙合面發(fā)生嚙合。犬牙通過與換檔執(zhí)行器相邊的換檔拔叉驅(qū)動。 驅(qū)動犬牙將一檔齒輪與輸出軸鎖定在一起，將扭矩從齒輪傳遞到輸出軸。一檔的超越傳動犬牙也會移動并將齒輪以相反的方向和輸出軸鎖定。這樣可在油門關(guān)閉且發(fā)動機(jī)倒拖時將扭矩從齒輪傳遞到輸出軸。這樣就消除了犬牙嚙合式變速箱常見的后坐現(xiàn)象。 在加大油門換高檔時，一檔齒輪的超越傳動犬牙卸載后和二檔齒輪嚙合。然后在換入二檔時，前一個驅(qū)動環(huán)卸載。 如果犬牙之間不能完全嚙合，即實現(xiàn)兩個犬牙面之間的嚙合，由于相對速度差的存在，二檔嚙合會打開一個嚙合缺口。在犬牙抵住犬牙嚙合面后，在撥叉和執(zhí)行器的共同作用下，儲存的能量會將犬牙送入缺口內(nèi)。 此時一檔超載傳動犬牙成為二檔的驅(qū)動犬牙。在換入二檔后，一檔的驅(qū)動犬牙隨即卸載。這時候，這些犬牙不再受其固定面的固定，可以被執(zhí)行器或犬牙上的斜面推離檔位。 然后一檔齒輪的驅(qū)動犬牙會移動到和二檔齒輪發(fā)生嚙合的位置。在二檔時，犬牙的作用正好相反。 中文譯文： 奧迪 Roadjet 在2006年1月的底特律車展上首次亮相的Roadjet概念車向我們展示了奧迪公司下一年的技術(shù)方向。該公司把重點放在內(nèi)飾設(shè)計、動力系統(tǒng)、底盤、電子系統(tǒng)和安全系統(tǒng)方面的技術(shù)創(chuàng)新上。 這些新的發(fā)展方向?qū)⑦M(jìn)一步鞏固奧迪公司在準(zhǔn)豪華車市場的地位。為了在美國市場吸引新的消費者，奧迪公司采取了兩種市場戰(zhàn)術(shù)。一方面，該公司正在努力進(jìn)入運動型多用途車輛（SUV）和緊湊型多用途車輛（CUV）的市場。 另一方面，該公司在美國市場引進(jìn)了新的豪華車和生活用車，以鞏固其在美國的市場地位。目前，該公司在美國的銷售額仍落后于BMW、Lexus和Mercedes-Benz；不久前剛推出的豪華型越野車Q7也未能趕上SUV潮流。 在歐洲，奧迪公司在鋁制車身、四輪驅(qū)動和新型動力系統(tǒng)方面的技術(shù)創(chuàng)新相當(dāng)成功。然而，如果它想要在美國增加市場份額，就必須在美國顧客所重視的領(lǐng)域有所創(chuàng)新，那就是：舒適性、豪華性和實用性。 奧迪公司的設(shè)計師在進(jìn)行內(nèi)飾設(shè)計時對這些方面予以了重視。他們發(fā)明了新型環(huán)繞式儀表板來代替現(xiàn)有車型偏于功能化的設(shè)計。他們對用于巡航控制、懸掛、環(huán)境控制和娛樂設(shè)施設(shè)定的多媒體界面（MMI）控制系統(tǒng)進(jìn)行了改進(jìn)，使乘客和駕駛員可以分別進(jìn)行控制。將這種技術(shù)與改進(jìn)的環(huán)境控制系統(tǒng)相結(jié)合，乘員可以各自進(jìn)行個性化的設(shè)定。 Roadjet采用柔和的暖色調(diào)－－土黃色作為內(nèi)飾的基色，以制造一種舒適的氛圍。該概念車采用了優(yōu)質(zhì)的功能性材料；內(nèi)飾采用優(yōu)質(zhì)的真皮，地板則采用氯丁橡膠材料。后座之間可安裝各種行裝設(shè)備：比如參展車上附帶的“espresso”咖啡機(jī)，或更實際一些的儲藏箱、嬰兒搖籃等。 為了增加實用性，后座椅的前后移動是斜向的，這樣可以增加肩部、腰部、腿部的空間和后部的載貨空間。當(dāng)后排座椅被推至最前方位置時，就可以使用斜放在后面的嬰兒座椅。 Roadjet的貨箱帶有電動伸縮的貨箱板，使裝載更方便、上面還有許多系結(jié)點，可用來固定行李。這種滑動的座椅和可伸出的貨箱板很可能將在奧迪Q5和A4車上采用。 為了增加豪華感，該概念車上還采用了昂貴的14喇叭Bang&Olufsen音響系統(tǒng)，功率高達(dá)1000W。音響系統(tǒng)還加入了“數(shù)字語音支持”功能，即用麥克風(fēng)和車上的揚聲器記錄并放大乘客的說話聲，以保證即使是在高速行駛時也能清楚地進(jìn)行交談。 為了改善道路安全性、便利性和交通管理，汽車制造商正在制定統(tǒng)一的標(biāo)準(zhǔn)，以開發(fā)新型的、能與其它車輛和路邊的本地?zé)o線通信網(wǎng)絡(luò)建立聯(lián)系的車內(nèi)系統(tǒng)。這種車輛能在發(fā)生交通堵塞、或遭遇惡劣天氣和事故等情況時向緊急服務(wù)部門、其它車輛或交通電腦發(fā)出信號。在Roadjet概念車上，你可以看到這種先進(jìn)系統(tǒng)的雛形。 各種新電子設(shè)備和豪華裝備的增加使車體重量不斷增大，再加上顧客對功率的要求不斷增加，這些都給豪華車排放和燃油消耗控制帶來了負(fù)面的影響。奧迪正在研究更先進(jìn)的技術(shù)，以實現(xiàn)豪華性和排放性的平衡。 Roadjet車的3.2升汽油直噴發(fā)動機(jī)基本上沿用了已有的尋機(jī)，不過為了增加功率輸出，采用了新型的、帶整體式真空罐的固定進(jìn)氣歧管。這種進(jìn)氣管設(shè)計結(jié)合了兩級凸輪作用的可變氣門升程技術(shù)，增大了發(fā)動機(jī)的功率。 盡管具有運動型轎車的性能，Roadjet的總體燃油消耗比現(xiàn)有的A4 Quattro車上的3.2升FSI發(fā)動機(jī)略低一些，這種將于2006年下半年投入生產(chǎn)的氣門機(jī)構(gòu)技術(shù)能使發(fā)動機(jī)在正常駕駛情況下滿足省油和平順性的要求，并能按照駕駛員的要求自動切換為高反應(yīng)速度和大功率狀態(tài)。 Roadjet概念車是第一款安裝了受車速控制的可變轉(zhuǎn)向比動態(tài)轉(zhuǎn)向系統(tǒng)。該系統(tǒng)既可實現(xiàn)高速公路駕駛的平順性，又能增加在野外彎道行駛時的操縱性。電子控制的可變彈性減震器可自動將轉(zhuǎn)向系統(tǒng)由柔軟舒適型轉(zhuǎn)變?yōu)檫\動型，以增加安全性和操縱性。 奧迪的工程師將所有這些系統(tǒng)通過電子技術(shù)連接在一起，為駕駛員提供了3種可選擇的模式：動態(tài)、舒適和運動。每種模式都對減震器、轉(zhuǎn)向系、變速箱和發(fā)動機(jī)的電子裝置進(jìn)行調(diào)整，以提供不同的駕駛體驗。 Roadjet車的車身造型體現(xiàn)了奧迪公司新的設(shè)計方向。這款高1.55米、軸距4.7米、寬2.85米的概念車的車內(nèi)空間相當(dāng)寬敞。該公司采用棱角分明的輪廓線和精心設(shè)計的下陷的車門來掩蓋車身的高度。概念車上標(biāo)志性的LED尾燈很可能會保持原樣，而LED大燈可能在正式生產(chǎn)時換成可旋轉(zhuǎn)的氙氣放電燈。 大約在2007年底，奧迪公司將在下一代A4平臺的基礎(chǔ)上推出Q5型CUV。該車比Q7更輕更小，在利潤很高的美國CUV市場上將很有競爭力。Roadjet體現(xiàn)了該車的一些內(nèi)飾和外部造型方面的特點。 Q5必須更為結(jié)實，以符合CUV類車的室外生活方式的形象。同時，對于歐洲市場，Roadjet醒目的造型為下一代A4系列車型提供了樣板，該系列將于2007年推出一款新的兩箱轎車，以加入傳統(tǒng)轎車和Avant車系的市場。儀表板和其它內(nèi)飾方面的改進(jìn)將在24個月內(nèi)推廣到奧迪公司的其它車型系列。 Faster, smoother transmissions Transmissions have to compromise on either ride comfort or efficiency, but a new approach to the dog engagement gearbox could improve both. With tightening emissions regulations, carmakers are not just confining their efforts to improving combustion and after-treatment. Many are finding that modern engines are so advanced that the benefits of some engine technologies are small compared to the huge development costs involved. It's important to look at the whole vehicle in order to improve emissions. As the second most expensive piece of kit in the car, the transmission is the logical next place to look. Of all transmission technologies, the manual gearbox is the most efficient; around 96percent of the energy that is put in comes out of the other end. But not everyone can drive one or wants to. Because you have to dip the clutch pedal, it's less comfortable to drive in heavy traffic. It makes the driver tired and the torque interruptions' head-nod effect on passengers can be wearing. The driver's clutch control and corresponding torque interruptions are also the manual's weak point. When accelerating up through the gearbox, each up-shift requires the driver to cut the torque momentarily by lifting the gas pedal and dipping the clutch. It may just take a second to complete the operation, but during this time the vehicle is losing speed and acceleration. At the opposite and of the spectrum is the traditional automatic. Its shift quality is good thanks to its torque converter, but efficiency is relatively poor despite recent advances. Because of this ,a lot of the current research is trying to find an efficient alternative to the conventional automatic. The main technologies are continuously variable transmissions (CVTs); dual clutch transmissions(DCTs) and automated manual transmissions(AMTs).They all offer different benefits over the conventional planetary automatic. The CVT uses a belt chain or toroidal shaped dish drive to vary an infinite number of gear ratios. It has improved efficiency and cost when compared to conventional automatics.Its advantage comes from its simplicitu. It consists of very few components; usually a rubber or metal-link belt; a hydraulically operated driving pulley, a mechanical torque-sensing driving pulley, microprocessors and some sensors. The transmissions works by varying the distance between the faces of the two main pulleys.The pulleys have V-shaped grooves in which the connecting belt rides. One side of the pulley is fixed axially; the other side moves, actuated by hydraulics. When actuatec, the cylinder can increase or reduce the amount of space between the two sides of the pulley. This allows the belt to ride lower or higher along the walls of the pulley, depending on driving conditions. This changes the gear ratio. A torodial-type design works in a similar way but runs on discs and power-rollers. The "stepless" nature of its design is CVT's biggest draw for automotive engineers. Because of this, a CVT can work to keep the engine in its optimum power range, thereby increasing efficiency and mileage. A CVT can convert every point on the engine's operating curve to a corresponding point on its own operating curve. The transmission is most popular with Japanese carmakers and Japanese supplier JATCO is a major producer. But in the US and Europe driving styles are different. Uptake has been slow despite Audi and other manufacturers having offered CVT otions on their ranges. The DCT is, in effect, two manual gearboxes coupled together. Gear shifts are made by switching from one clutch on one gearbox to another clutch on the other. The shift quality is equal to a conventional automatic, but slip, fluid drag and lydraulic losses in the system result in only slightly improved efficiency and acceleration over the conventional planetary automatic. Developing the control strategy is costly too. "Recent advances in conventional automatic technology have weakened the argument to develop and set up production for CVT or DCT." says Bill Martin, managing director of transmission firm zeroshift. "Some carmakers have cancelled DCT projects because of the cost." The cheapest way to build an automatic is with an AMT. AMTs use actuators to replace the clutch pedal and gear stick of a conventional manual. They keep the high efficiency and acceleration of a manual gearbox, but the shift quality on some models is lacking. Torque interruptions and the head-nod effect are the most common complaint. so what is the alternative? There are always new ideas in transmissions, but Zeroshift says that its technology has efficiency benefits over a manual, delivering fuel economy improvements to city driving. Shift quality can also be equal to that of a refined automatic. Zeroshift's approach is an upgrade to the AMT. The synchromesh is replaced with an advanced dog enqaqement system. Dog engagement has been used for many years in motor sport to allow fast shifts. Conventional dog boxes are unsuitable for road use as the large spaces between the drive lugs or "dogs" create backlash, an uncomfortable shunt caused by the sudden change in torque direction. Zeroshift's technology solves this problem by adding a second set of drive dogs. It has also made each of the two sets of dogs only capable of transmitting torque in one or other opposing directions. "By controlling the engagement and disengagement of the two sets you can shift into the new gear befor disengaging the previous gear, "says Martin. "The shift quality is smoother than a typical modern six-speed automatic luxury car." The shift is instant and the torque is not interrupted.This philosophy is used for both up and down shifts. "In conventional AMT there is an emissions spike during a shift due to the need to back off and reintroduce throttle, this is eliminated by going seamless, "says Martin. "This also reduces fuel consumption." It is a relative newcomer to the transmission sector, but the firm says that it is already attracting the attention of major European and US carmakers. The big draw is as a low-cost alternative to DCT, says Martin. Because the manual gearbox architecture is largely maintained, production costs and complexity are not greater than for a conventional AMT. Development of the controls side is also considerably cheaper. Music to the ears of engineers trying to cut emissions and costs. "Most of the carmakers have seen the system at least once," says Martion. "Some signed us immediately. Some have said not yet. None have said no. "That may be the clearest sign yet that when it comes to powertrain developments, carmakers are starting to focus on the transmission. HOW ZWROSHIFT WORKS The hardware consists of two sets of bullets. mounted and actuated on two independent bullet rings. both sets of bullets run on the common hub, which is attached to the shaft with splines. Each bullet has a special profile. On one side they have an angled face for engagement. These are diagonally opposed, allowing the bullet to have a drive function for one gear and an overrun function for the other gear. The engagement faces taper backwards slightly to ensure the bullet latches onto the engaged gear under load. the opposite corners have a ramp, which pushes the bullet out of the previous gear once the new gear has been engaged. In neutral both bullet rings are positioned midway between the ratios. To select first gear, the bullets are moved into mesh with the engagement dogs.The bullets are actuated via shift forks conected to the shift actuators. The driving bullets lock first gear to the output shaft and transfer torque from the gearwheel onto the output shaft. The first gear overrun bullets are also moved into gear to lock the wheel to the output shaft in the opposite direction. This transfrs torque from the gearwheel onto the output shaft when the throttle closes and the engine overruns. This eliminates the backlash you'd expect from a dog engagement gearbox. To shift up with an open throttle, first gear's overrun bullets are unloaded and move in to engage second gear. This is followed by the previous driving ring which becomes unloaded when second gear is taken up. If the bullet is stopped from engaging fully-dog-face to dog-face-the second gear wheel opens an engagement window due to the relative speed difference. With the bullet pushed against the engagement dog compliance between the fork and actuator allows the stored energy to fire the bullet into the window. The first gear overrun bullets have now become the second gear drive bullets. As second gear takes over, the load is removed from the first gear drive bullets. These bullets are now no longer held by their retention angie and can be either moved out of gear by actuators or pushed out of gear by contact with the ramp face of the bullet. The first gear drive bullets then move across into engagement with second gear. In second gear, the roles of the bullets are reversed. Audi Roadjet Audi plans to add comfort, luxury and practicality without increasing emissions The Roadjet concept, first shown at Detroit in January 2006,indicates a number of technical directions that Audi going to take in the coming year. The firm is focusing on interior design, powertrain, chassis, electronics and safety innovations. These new directions will help Audi strengthen its position in the sub-luxury market that it previously had to itself. Audi has two main tactics to attract new customers in the US. It is breaking into the sports utility vehicle(SUV)and compact utility vehicle(CUV)markets. It also introduces new luxury and lifestyle features to strengthen its position in the US; sales there still lag behind those of BMW, Lexus and Mercedes-Benz. The recently launched Q7 off-road luxury vehicle is a late bid to capitalise on the SUV boom. In Europe, the carmaker's technical innovations such as aluminium construction, four-wheel-drive, and novel powertrain technologies have been successful. But if Audi wants to increase its US market share, it needs to innovate in those areas valued by American customers: comfort, luxury and practicality. Audi's designers have focused on this in the interior. They have devised a new wrap-around instrument panel shape to replace the more functional design in existing models. They have expanded the vehicle's multi-media interface (MMI)control system, used for cruise control, suspension, climate and entertainment separate controls. Combined with an upgraded climate system, occupants can set their own individual climate settings. Soft, warm, earthy colours are used in the Roadjet to create a feeling of well-being. The concept uses high quality functional materials: the upholstery is fine leather; the floor is neoprene. The space between the rear seats can house a range of optional equipment: the show car featured an espresso coffee machine. Storage boxes and baby carriers are more realistic alternatives. To enhance practicality, the rear seats slide backwards and forwards diagonally to increase shoulder and leg-room or rear load space. When the rear seats are in their most forward position, an oblique-facing child seat can be used behind the seats. Roadjet's load bay features an eletrically extending load floor to ease loading, offering unmerous lashing points to secure luggage items. The sliding seats and extending load floor are very likely to enter production on Audi's Q5 and A4 models. To heighten the sense of luxury, the concept uses a costly 1,000W Bang & Olufsen sound system with 14-speakers.This incorporates a "digital voice support" function that uses microphones and the car's speakers to pick up and amplify passengers' voices to ensure clear conversation even at high speeds. In a bid to improve road safety, convenience and traffic management, carmakers are working to common standards to develop a new in-car system to talk to other cars and roadside wireless olcal area networks. In traffic jams, bad weather or accident situations, cars send information to emergency services, other cars and traffic computers. The Roadjet concept featres previews such a system. The weight of all the new electronics and luxury equipment in this segment, combined with customers' growing demand for power is having a negative effect on exhaust emissions and fuel consumption. Audi is looking at sophisticated technical solutions to balance the equation. Roadjet's 3.2-litre gasoline direct injection engine is based on an existing engine but features a new fixed intake manifold with an integral vacuum reservoir to increase its output. This is combined with a two-stage cam operated variable valve lit technology to increase output. Despite the sports car performance, the Roadjet's overall fuel consumption is slightly lower than the current A4 Quattro 3.2FSI.The valve train technology, due to enter production later in 2006,lets the engine perform economically and smoothly during normal driving, switching automatically to more responsive, more powerful characteristics when the driver demands. Roadjet also has the first Audi application of speeddependent variable ratio dynamic steering for a stable highspeed motorway ride but with enhanced control on twisty country roads. Electronically-controlled variable rate dampers automatically adjust from soft and comfortable to firm and sporty to enhance safety and handling. Audi's engineers have electronically linked all of these systems to create three driver-selectable programmes: dynamic, comfort and sport. Each programme adjusts the dampers, steering, gearbox and engine eletronics to give different driving experiences. Roadjet's body styling marks a new direction for the carmaker.At 1.55m high with a wheelbase 4.7m long and 2.85m wide, the concept is roomy. The firm has used a combination of sharp feature lines and careully-sculpted concave-section doors to disguise the height. While the trademark LED tail lights are likely to enter production unchanged, steerable xenon gas discharge lights will replace the LEDs in the headlamps. Around the end of 2007 Audi will launch the Q5 CUV, based on the next A4 platform. Smaller and lighter than the Q7,it will be well placed to compete in the profitable CUV segment in the US. The Roadjet previews elements of the interior and exterior styling of this model. The Q5 will need to be more rugged to match the outdoor lifestyle image of the CUV segment. At the same time, for the European market, the Roadjet's sharp style previews the next A4 model range, which may produce a new hatchback body in 2007 to join the conventional saloon and Ava