捷豹正在將其暢銷車型XF的鋼制車身更換成鋁制硬殼式架構(gòu)，并用在新款XE和XJ身上。這是這家豪華車制造商為符合歐美排放標(biāo)準(zhǔn)所作出的最新努力之一。這輛預(yù)計(jì)今年冬季上市的新車已在2015年紐約車展上首次公開亮相。XF的尺寸為中大型，正好介于全尺寸XJ與中型XE之間。
XF的全白車身中含有75%的鋁，其中大部分鋁為RC5754，這是一種將報(bào)廢鋁重新加工制成的鋁，而新材料的成分非常低。這些來自于捷豹沖壓車間的再生鋁構(gòu)成了5000系列可鍛合金（鋁和鎂）的重要組成部分，捷豹將其用于XF，以提高車身和底座的堅(jiān)固程度。
鋼材被用于重量分配
鋼材的應(yīng)用位置包括車尾底座、行李箱蓋以及后座板，這樣不僅能滿足一些特殊的工程需求，而且還能平衡前后車身的重量。XF的設(shè)計(jì)重量分配為前半段51%，后半段49%。
鋼板與鋁制車身搭配顯然需要防止接觸腐蝕，而捷豹采用了一種基于航空加工技術(shù)的五步工藝。第一步是在鋼材上鍍鋅，接著用結(jié)構(gòu)粘合劑制作節(jié)點(diǎn)，并對整個(gè)車身實(shí)施電鍍，隨后進(jìn)行縫隙密封，最后完成車身噴涂。全車身沒有使用焊接，取而代之的是自鉆鉚接工藝。
車身側(cè)板由高強(qiáng)度6000系列鋁合金單片沖壓而成，這是一種內(nèi)含鎂和硅的可鍛合金。單塊側(cè)板的重量小于6公斤（13磅）。
捷豹將特定的高強(qiáng)度鋁合金用于前后防撞結(jié)構(gòu)與A柱和B柱。前部結(jié)構(gòu)與A柱的節(jié)點(diǎn)被設(shè)計(jì)成可分散撞擊能量的大塊形狀。此外，B柱也得到了超高強(qiáng)度（硼）鋼結(jié)構(gòu)的鞏固，且其中填充高密度泡沫。前懸掛塔由高壓壓鑄鋁制成，以提高該區(qū)域的堅(jiān)固程度。
橫跨車頭的儀表板橫梁，以及引擎蓋的防撞橫梁都由金屬鎂制成。
精準(zhǔn)鉚接，提升硬度
捷豹在其車身結(jié)構(gòu)上安裝側(cè)板的第一步是精確定位鉚接點(diǎn)，這樣最終呈現(xiàn)出的是一個(gè)具有一定扭轉(zhuǎn)度的堅(jiān)硬車身。捷豹聲稱2016款在上一款車型基礎(chǔ)上改進(jìn)了28%，每1度表面彎曲均有21.7千牛·米（16,000磅·英尺）扭矩。
安靜是捷豹素有的優(yōu)點(diǎn)，因此設(shè)計(jì)時(shí)必須盡可能排除噪音。比如說，捷豹用密封雙壁結(jié)構(gòu)制作車頭前隔壁后方的碰撞結(jié)構(gòu)。首先在盒狀鋁制結(jié)構(gòu)件中沖入泡沫填充物，當(dāng)車身進(jìn)入電鍍烤爐中加熱時(shí)，這些泡沫就會膨脹填滿結(jié)構(gòu)件內(nèi)部。在其他位置，捷豹使用泡沫噴涂的方法來減少噪音，這種工藝比膠泥板重量更輕，但同樣可以達(dá)到理想的降噪效果。
捷豹稱，新款XF比同級競品輕80公斤（176磅）左右，比鋼制車身的上一款XF輕190公斤（419磅）。后輪驅(qū)動款XF的整車重量為1770公斤（3902磅），全輪驅(qū)動款為1880公斤（4145磅）。
XF的阻力系數(shù)也從0.29降到了0.26。前保險(xiǎn)杠通風(fēng)口上的一個(gè)輔助部件可引導(dǎo)氣流，使其順暢地流經(jīng)前輪上方，而不必在車輪周圍形成紊流和阻力。
新款XF總長為4956毫米（195.1英寸），比上一款要短，其軸距為2962毫米（116.6英寸），比上一款長了51毫米（2.0英寸），但總長減少了84毫米（3.3英寸）。車輛后座的腿部空間增加了15毫米（0.6英寸），為951毫米（37.4英寸）。盡管XF的外形很像轎跑，但其頭部空間仍比上一款多出了28毫米（1.1英寸）。
在美國市場推出的XF配置了2個(gè)3.0L渦輪增壓汽油發(fā)動機(jī)，它們都采用同一款伊頓Roots渦輪增壓器。其中一臺的功率為254千瓦（340hp），扭矩為450牛·米（332磅·英尺），另一臺的數(shù)據(jù)為功率283千瓦（380hp），扭矩460牛·米（339磅·英尺）。這兩臺發(fā)動機(jī)都與八速自動變速箱連接，這是全輪驅(qū)動必要條件。
后輪驅(qū)動款計(jì)劃采用6速手動變速箱與340hp V6發(fā)動機(jī)，但在車輛發(fā)售時(shí)還不能馬上提供。上市的將是一款R型車，搭載一款功率為410千瓦（550hp），扭矩為681牛·米（磅·英尺）的5.0 L V8發(fā)動機(jī)。
新款車輛的電力轉(zhuǎn)向系統(tǒng)新添了傳感輸入，無論在不規(guī)則路面還是拱形路面上，都能更好地減緩轉(zhuǎn)向反應(yīng)。同時(shí)，新款車還安裝了采用鏈條傳動的全驅(qū)系統(tǒng)分動器，與老款的齒輪分動器相比，它的重量更輕，且扭矩傳動更為流暢。
可選的標(biāo)準(zhǔn)懸掛
標(biāo)準(zhǔn)減震器中的第二道閥門可提供基于速度和頻率的減震效果。中速駕駛時(shí)，該閥門處于敞開狀態(tài)，好讓一些液壓油通過。這一額外的流道可降低減震效果，使行駛效果更流暢。高速駕駛時(shí)閥門關(guān)閉，所有液體流經(jīng)活塞閥，閥門緊閉的狀態(tài)使車輛更容易控制。
此外，捷豹還提供了一個(gè)可選配的主動減震系統(tǒng)，該系統(tǒng)能夠分別以100次/秒和500次/秒的頻率感知車身和車輪的運(yùn)動狀況。這一電子系統(tǒng)已經(jīng)過改良，可在所有速度下更好地控制減震，此外搭配的路面質(zhì)地偵測算法也能提供更好的牽引力。與F型車一樣，這一功能現(xiàn)在可以由駕駛員在中控觸屏上進(jìn)行操控了。
XF內(nèi)置一個(gè)標(biāo)準(zhǔn)的高級牽引控制系統(tǒng)（全路面行進(jìn)控制系統(tǒng)），用以改進(jìn)后輪驅(qū)動款和全輪驅(qū)動款車型在冰雪環(huán)境中的行駛質(zhì)量。此外全輪驅(qū)動款還配備了一個(gè)制動扭矩定向裝置，從而使車輛的電子穩(wěn)定控制裝置可根據(jù)各種天氣條件與駕駛員的要求調(diào)整扭矩。
除主動減震系統(tǒng)外，全輪驅(qū)動款中還內(nèi)置了一個(gè)捷豹的適應(yīng)性表面反應(yīng)系統(tǒng)（ASR）。ASR采用路面質(zhì)地偵測算法，根據(jù)采集到的路面信息調(diào)整轉(zhuǎn)向反應(yīng)、換擋、油門反應(yīng)和穩(wěn)定性控制等操作。
前懸掛是F車型雙叉骨設(shè)計(jì)的改進(jìn)版本，改進(jìn)后車輛轉(zhuǎn)彎性能更優(yōu)秀。后懸掛系統(tǒng)中，雙叉骨與多連桿設(shè)計(jì)相互搭配，其中一個(gè)內(nèi)嵌連桿將前束連桿與控制臂相連。這一設(shè)計(jì)可將垂直力與水平力分離，使其能夠分別得到調(diào)節(jié)，從而提升行駛效果。
XF還提供一系列可選配的安全配置，其中包括自動應(yīng)急制動。在數(shù)據(jù)連接方面，XF可提供10.2英寸電容式觸屏，搭配智能手機(jī)的Incontrol應(yīng)用軟件。該觸屏與12.3英寸的可調(diào)節(jié)TFT（薄膜晶體管）設(shè)備，在L車型和路虎攬勝車型上也可以見到。
New XF moves to Jaguar's aluminum architecture
Jaguar's best-selling model, the XF, is moving from a steel body to the aluminum-intensive monocoque architecture used on the XE and XJ. It's one of the latest steps the luxury car maker has taken to meet regulatory and emissions demands in Europe and the U.S. The new car, scheduled for introduction in winter, was debuted to the public at the 2015 New York Auto Show. It's a midsize-plus model, fitting between the full-size XJ and the mid-size XE.
The car has a body-in-white that is some 75% aluminum, and much of that aluminum is RC5754, which is primarily scrap recycled with a small percent of new material. The recycled aluminum, which comes from Jaguar's press shops, constitutes much of the 5000 series wrought alloy (aluminum and magnesium) that is used on the XF, where specified to add stiffness (as for underbody reinforcements).
Steel used for weight distribution
Where steel is used, such as for the rear underbody, in the decklid, and rear-seat-area pan, it serves a number of specific engineering requirements, and it also contributes to a balanced front-rear weight distribution. The end result is a projected 51% front, 49% rear balance.
The steel applications pose an obvious galvanic-corrosion-protection requirement and Jaguar employs a five layer process based on aerospace techniques. First a zinc coating is applied to the steel. Then the joints are made with structural adhesive. Next, the entire body is electrocoated. Following that, seam sealer is applied, and finally the body is painted. There are no body welds, although self-piercing rivets are used.
The bodyside panels are stamped from single sheets of high-strength 6000-series aluminum alloy, which is a wrought alloy that contains magnesium and silicon. A panel weighs less than 6 kg (13 lb).
Jaguar uses specific high-strength aluminum alloys for front and rear crash structures and the A- and B-pillars. The front structure joint with the A-pillar is a large section shaped to distribute crash energy. The B-pillar also gets an ultra-high-strength (boron) steel reinforcement and is filled with high-density foam. The front suspension towers are high-pressure die-cast aluminum for added stiffness in that area.
Both the dashboard's cross-car beam and the hood crush beam are made of magnesium.
Precise riveting boosts rigidity
Assembling the side panels to the remainder of the body structure starts with precise locating of the rivets, so the overall result is a more torsionally rigid package. Jaguar claims up to 28% improvement, with the 2016 model specification at 21.7 kN·m (16,000 lb·ft) per degree.
Naturally a Jaguar has to be quiet and the best way is to ensure that is to design noise out. The crash structure behind the front bulkhead, for example, consists of sealed double-wall sections. Foam fillers are placed inside boxed aluminum sections, and when the body goes through the electrocoating ovens, the foam expands to fill. In other locations, sound deadening is a spray-on type that can perform the needed sound reduction with less added weight than mastic sheeting.
The XF is some 80 kg (176 lb) lighter than comparable competition, Jaguar claims, and 190 kg (419 lb) below the previous model with the steel body. Vehicle weight is 3902 lb (1770 kg) for the rear wheel drive model, 4145 lb (1880 kg) for the AWD.
Coefficient of drag was reduced from 0.29 to 0.26. An assist comes from vents in the front bumper that direct airflow smoothly over the front wheels, instead of becoming turbulent around the wheels and creating drag.
The new model is shorter than its predecessor at 195.1 in (4956 mm) long overall, on a 116.6-in (2962-mm) wheelbase. The wheelbase actually is 2.0 in (51 mm) longer, but overall length is 3.3 in (84 mm) shorter. Rear legroom is slightly greater, up 15 mm (0.6 in) to 951 mm (37.4 in). Despite the coupe look, headroom is greater by 1.1 in (28 mm).
There are two 3.0-L supercharged gasoline engines for the U.S. market, both using the same Eaton Roots-type supercharger. One is rated at 340 hp (254 kW) and 332 lb·ft (450 N·m), the other at 380 hp (283 kW) and 339 lb·ft (460 N·m). Both are bolted to the eight-speed automatic, which is required for pairing with all-wheel drive.
A six-speed manual is listed for rear-wheel-drive models and the 340-hp V6, but is not available at launch. A supercharged version of the 5.0-L V8 rated at 550 hp (410 kW) and 502 lb·ft (681 N·m) will be available with a forthcoming Type R performance model.
The electric power steering has been upgraded with improved sensing inputs, better damping steering response to both road irregularities and road camber. The AWD system transfer case is new, with a chain drive for lighter weight and smoother torque transfer vs. the previous gear-drive type.
Standard, optional suspension variants
The standard shock absorbers contain a second valve to provide velocity- and frequency- dependent damping. During moderate driving conditions, that valve is open and some hydraulic fluid passes through. This additional flow path reduces damping for a smoother ride. At increasing speed, the valve closes and all the fluid has to go through the piston valve, which firms up the ride for better control.
In addition, there's Jaguar's optional active damping system, which senses body movements 100 times/s and wheel movement 500 times/s. This electronic system has been improved for better control of damping at all speeds, and incorporates advanced algorithms for road texture detection to provide better traction. Like the F-Type, it can now be driver-configured at the control stack touch-screen.
The XF incorporates a standard advanced traction control system (All Surface Progress Control) that improves drive away on both rear-drive and AWD models in ice and snow. Also included with AWD is torque vectoring by braking, for which the vehicle's electronic stability control modulates torque-on-demand for varying weather conditions.
Integrated with AWD and the active damping system is Jaguar's Adaptive Surface Response. ASR employs algorithms for road-surface-texture detection and uses the information to modify steering response, transmission shifting, throttle response, and stability control operation.
The front suspension is an upgraded double-wishbone design modeled after the F-Type to improve cornering. The rear suspension drops the double-wishbone for a multi-link with an integral link that connects the toe link to the control arm. This separates vertical from lateral forces, so each can be tuned separately, for a better ride.
The XF has a full suite of optional safety features, including automatic emergency braking. For connectivity, it offers the 10.2-in corporate capacitive touch screen with Incontrol Apps for a smartphone. This touch screen and the 12.3-in configurable TFT (thin film transistor) instrument cluster also are available on theLand Rover Range Rover.
捷豹XF采用鋁制車身，外貌酷似轎跑，但后座空間比舊款更大，頭部空間提高1.1英寸。
如圖所示，XF的引擎蓋防撞橫梁與儀表板跨車頭橫梁用鎂材料制作而成。
后座側(cè)板用鋼材料制作，以平衡整車重量。為實(shí)現(xiàn)這目標(biāo)，捷豹采用了多步驟的接合工藝，以防止側(cè)板與鋁制車身的接觸腐蝕。
XF前輪驅(qū)動款車型的分動器加入了流暢度更高的鏈?zhǔn)津?qū)動裝置，以替換齒輪驅(qū)動。
XF的前部結(jié)構(gòu)與進(jìn)行過加強(qiáng)的A柱相結(jié)合，以更好地分散沖撞能量。