2007-2008年，路虎推出了攬勝極光豪華版緊湊型SUV。當時該車型有三門轎跑版和五門版可供消費者選擇，并在市場上獲得巨大成功，但那時并未推出敞篷版。
2011年，路虎董事會決定在這款車型上采用難度極高的敞篷版設計。對于公司的設計師和工程師而言，這是一個巨大的挑戰(zhàn)。
路虎的首席外飾設計師Andy Wheel表示，“看起來敞篷版只是把轎跑版的車頂去掉了而已，但其實并沒有這么簡單！”
在結構剛度和扭轉剛度方面，敞篷版設計必須符合路虎的高標準嚴要求，也必須擁有與攬勝極光的金屬天窗版相同的各種地形駕駛性能。盡管具體數(shù)據尚未發(fā)布，但路虎表示，敞篷版 “與轎跑版相比，車身剛度僅下降了15%”。
路虎的敞篷版車型搭載的是柴油和汽油發(fā)動機，最高輸出功率可達177 kW（237 hp），綜合油耗符合歐洲最佳標準，為每100公里5.1 L （46.1 mpg），二氧化碳排量為每公里149g。
據預測，全球SUV市場將在未來五年內增長20%左右，同時，攬勝極光敞篷版也將占據引人注目的市場份額。路虎表示，在市場上所有的量產車型中，攬勝極光敞篷版的“Z”形折疊軟頂是最長最寬的。車頂開合速度很快，僅需18秒就可以完成開啟和關閉，在車速高達48 km/h（30 mph）時，21秒內就可以完成開合。
從概念到實車
由于市場上還沒有類似車型，因此路虎最初打造了一輛攬勝極光敞篷版概念車，并在2012年的日內瓦車展上正式發(fā)布，目的是測試市場對敞篷設計的反應，并決定是否量產該車型。
“市場反應非常好，”Wheel表示。所以，路虎決定對這款概念車進行量產。“具體怎樣實現(xiàn)該車型的量產是一個難題，我們最后決定從最基礎的工作開始做起。”
“我們對于概念車的后翼子板處凸起的流線型設計并不滿意，”Wheel解釋道。“當時我們已經認識到，我們需要設計一個更高效的車頂系統(tǒng)，不僅能優(yōu)化空間效率，減輕整備質量，也能兼顧車輛美學特征，所以要采用一體化的設計方式。我們最終決定采用‘Z’型折疊天窗，這種造型比概念車的‘K’型系統(tǒng)更加合適。‘Z’型折疊天窗可以優(yōu)化車內空間設計，有助于打造出流線型更優(yōu)美的后翼子板，讓車輛整體線條更加流暢。”
“Z”型折疊天窗也實現(xiàn)了汽車載荷空間的最大化，盡管后備箱開口相對較窄，但仍可以保證容積達到25L（0.88 ft³）。
由于路虎可以借鑒其姊妹品牌“捷豹”敞篷車的設計經驗和相關專業(yè)知識，因此所有的設計工作都可由路虎獨立完成，無需外部機構的參與。“盡管捷豹和路虎是（捷豹路虎旗下的）兩家獨立公司，但我們彼此非常了解，可以進行‘跨品牌’合作，對于攬勝極光敞篷版這樣需要大量專業(yè)知識支持的項目，這一點非常重要。”
但即便如此，路虎也用了三年時間才實現(xiàn)了攬勝極光敞篷版的量產。這是由于這款敞篷版豪華SUV在性能上絲毫沒有妥協(xié)，并且要求該車型的市場定位明確，銷量也必須有所保證。
在設計方面，工程師們面對的主要挑戰(zhàn)是打造出一個完整的無框車門系統(tǒng)。盡管敞篷版盡可能多地保留了轎跑版的部件，但車門必須徹底重新設計。路虎也為車窗玻璃的固定設計了特別的解決方案。
此外，設計團隊還需要為擋風玻璃設計全新的上框導軌，并加固A柱。Wheel表示，盡管敞篷版的擋風玻璃看起來傾斜度較大，但實際上其角度與轎跑版是相同的。
攬勝極光敞篷版的空氣阻力系數(shù)（Cd）為0.39，而轎跑版則為0.36。
后備箱蓋很難設計，因為箱蓋的非侵入型鉸接點在汽車外部，而這不符合美學規(guī)律。
最終采用的解決方案非常簡潔有效，擾流板在后備箱開啟處的位置設計得恰到好處，并與鉸接點進行了整合。風洞空氣動力實驗的結果顯示，這一設計可以在車頂開啟時讓后座乘員承受的風振降到最低，問題得到了順利解決。
Wheel表示：“這一解決方案可以說是一箭雙雕——在空氣動力學性能和美學特征上都獲得了最佳的效果！對設計師來說，如果某種設計方法能讓車輛的所有部件可以如有機整體般協(xié)調運行，那么這個設計一定是對的。而如果某個部件的設計必須做改變，那么其他部件就很可能受到影響。通過集成鉸接裝置和擾流板，我們就不必牽一發(fā)而動全身了。”
另外還有一個與美學相關的問題——擾流板尺寸很大，并且在一個非常明顯的位置，因而非常顯眼。這一問題也得到了有效解決。Wheel 說：“我們把擾流板分成了兩部分，上部是亮黑色，下部則與車身顏色一致。”
在設計和工程方面還有另一個成功之處。攬勝極光的轎跑版可選擇“動感”外觀，該款式車門下邊梁包含擴展部件，可用于遮擋敞篷版，以遮擋加固件。
敞篷版的整備質量比轎跑版重270 kg（595 lb）。
工程挑戰(zhàn)
Danella Bagnall是攬勝極光的汽車項目總監(jiān)，她詳細介紹了項目團隊在工程、技術、與測試方面遇到的主要挑戰(zhàn)。其中最大的難題是，量產敞篷版的設計并非基于概念車而進行的，而是必須進行大幅度的修改。
“轎跑版的車頂很大，而敞篷版沒有金屬車頂，因此也必須更換所有配套的抗扭剛度和硬度部件，框架車門也要一并更換。我們必須另辟蹊徑，解決敞篷版的剛度問題，并且不能損害內飾部件和越障性能等。我們與設計團隊通力合作，最終成功地解決了這些問題。”
A柱和半B柱結構需要額外加強，硼鋼和高強度鋼在這里得到了廣泛的應用。敞篷版的車門外部與轎跑版相同，但內部則用硼鋼和高強度鋼進行了特別加固。
車身支架水平置于車內和車身下方，這一點是很難做到的，原因是采用這種布局需要對排氣系統(tǒng)等其他系統(tǒng)部件進行調整，但敞篷版已經盡可能多的保留了轎跑版的原有部件。
敞篷版的測試等級與攬勝極光的金屬車頂車型持平。Bagnall表示：“但我們必須專門增設一些新的測試標準，包括在陡峭越野路面上行駛時的車頂?shù)拈_合性能。這很有趣，但也很有挑戰(zhàn)性！”
工程團隊與供應商偉博思通（Webasto，該公司也是捷豹“F”車型折疊車頂?shù)墓蹋┖驮O計團隊通力合作，進行了大量工作，以確保車頂系統(tǒng)不會占據后備箱的空間。
控制天窗升起時的空氣動力噪聲也很重要，而密封性更是重中之重，Bagnall解釋道：“我們?yōu)槌ㄅ癜孳囆偷木脑O計完全可以保證這些方面的高性能，為此我們采用了特殊材料和密封結構，比如在A柱頂部周圍和車門玻璃之間的設計。”
工程師們之前設計“F”型車頂時積累了許多專業(yè)知識和技術工藝，得益于此，路虎現(xiàn)在可以打造出這款能在全路況中保持良好性能的車頂系統(tǒng)，甚至在北極地區(qū)也可以完全打開。
作者：Stuart Birch
來源：SAE《汽車工程雜志》
翻譯：SAE上海辦公室
How Land Rover took the lid off the Evoque
When Land Rover designed its highly successful Range Rover Evoque premium compact SUV in 2007-2008, it created 3-door coupe and 5-door versions. But a convertible was not on the alternative body style list.
So when the company’s Board decided in 2011 that such an arguably unlikely option should be added, it was a serious challenge for the company’s designers and engineers.
“Even though the car just looks as if the roof has been chopped off the Coupe, it wasn’t quite that simple!” said Andy Wheel, Land Rover’s Chief Exterior Designer.
It had to be engineered to meet Land Rover’s high level of structural rigidity and torsional stiffness requirements and to provide the same wide breadth of all-terrain capability of metal-roof Evoques. Although no specific figures have been released, Land Rover states that the convertible has “only a 15% reduction in body stiffness compared to that of the coupe.”
A choice of diesel and gasoline engines—with up to 177 kW (237 hp) and a best EU combined fuel consumption of 5.1 L/100 km (46.1 mpg) and CO2 emissions of 149 g/km—are offered.
In a global SUV market forecast to grow by some 20% over the next five years, the Evoque convertible will occupy an unusual niche, Land Rover reckoning its Z-fold fabric roof is the longest and widest currently fitted to any production car on sale today. The roof is also fast acting, with a stowage time of 18 sec, and raising—at speeds up to 48 km/h (30 mph)—in 21 sec.
From concept to reality
With nothing quite like it on the market, Land Rover initially pursued the idea of a convertible Evoque by building a concept and revealing it at the 2012 Geneva Motor Show, to test both public opinion of the design, and to help decide if there was a business case.
“It received a very positive public reaction,” said Wheel. So Land Rover elected to develop the concept for production. “The challenge was how we were going to do it in reality; we decided to go back to basics.
“One aspect of the concept car with which we were not happy concerned the extra shut lines in the rear quarters where the tonneau panel fitted,” he explained. “We realized we needed a more efficient roof system in terms of space efficiency and mass but also regarding any compromises to the aesthetics of the vehicle. So it was a very holistic approach. We decided a Z-fold system made more sense than the concept’s K-fold. With Z-fold we could optimize interior space, produce an uninterrupted rear quarter panel, and make the whole thing look ‘effortless.’”
The roof Z-fold also maximizes load space, and although the trunk opening is relatively narrow, it gives access to 25 L (0.88 ft³) of space.
The work was all done in-house because Land Rover could borrow sister brandJaguar’s convertible design know-how and associated technology expertise: “Although Jaguar and Land Rover are separate (beneath the corporate umbrella of JLR) we all know each other and can ‘cross-brand,’ which is important in a project like this, where knowledge sharing is very important.”
Even so, it has taken three years to bring the Evoque Convertible to production, partly because a “no compromises” convertible premium SUV is so mechanically unusual but also to be absolutely sure of its sales and marketing positioning.
Creating an entire frameless door system was a major challenge. Although the Evoque Coupe’s components were used as much as possible for the convertible, the doors had to be entirely re-engineered and a different solution for holding the glass designed.
The windshield needed an entirely new header rail design, and the A-pillars strengthened. Although the windshield of the convertible looks exceptionally steeply raked, the angle is exactly that of the coupe, said Wheel.
Cd of the Evoque Convertible is 0.39; the coupe achieves 0.36.
The trunk lid was difficult because the required non-intrusive hinge points would be on the car’s exterior, which was aesthetically unacceptable.
A neat solution emerged; aerodynamic testing in a wind tunnel to minimize wind buffeting of rear-seat occupants when the roof was open resulted in a spoiler fitted immediately above the trunk opening. The hinge problem was solved by integrating them within the spoiler.
Said Wheel: “We had a two-for-one solution: improved aerodynamics and improved aesthetics! With design, you know you’ve got it right when everything acts together like a house of cards. But if you have to change one thing it upsets so many others; with the hinges and spoiler we didn’t have to do that.”
There was another associated aesthetic issue, but that, too, was solved simply. The spoiler was large and positioned in an area where it was very prominent: “So we effectively divided it in two; the top part is gloss black, the lower, body color,” he said.
Design and engineering had a further success. An option for the Coupe Evoque is “Dynamic” styling, which includes sill extensions. These are used on the convertible to hide strengthening components.
Overall, the convertible is 270 kg (595 lb) heavier than the coupe.
Engineering challenges
Danella Bagnall, Vehicle Programs’ Director for the Evoque, detailed some of the major engineering, technology, and testing challenges the convertible brought to her team, the most significant being that the convertible was not planned from model conception.
“The roof of the coupe is large and taking it off for the convertible meant we had to replace all of the torsional stiffness and rigidity that it, and the coupe’s framed doors, provided. We had to find that contribution to the convertible’s stiffness in other ways without compromising the interior package and off-road clearances, etc. But it has been great to solve it and to work closely with the design team.”
A lot of additional structure was needed for the A-pillars and the half B-pillars. Boron steel and high-strength steel (HSS) were used extensively. The outer door skin is the same as the coupe, but inside the door there is additional reinforcement, again using boron and HSS.
Bracings were placed under and within the car laterally, which was difficult to achieve because it required packaging items such as the exhaust system. Changing extant components from the coupe was kept to a minimum, however.
The car has been tested to the same level as the tin-top Evoque. Said Bagnall: “But we had to create some new test standards including operation of the roof while the car is at steep angles off-road. Quite fun but a bit challenging!”
Working with supplier Webasto (which also supplies the folding roof of the Jaguar F-type) and the design team, a lot of engineering effort went into ensuring that the roof did not encroach into the trunk space.
Controlling aerodynamic noise with the roof up was a priority, with particular attention to sealing, explained Bagnall: “We made refinement an ‘anchor’ for the convertible. We have delivered that via the materials we use and the sections of our seals—for example, around the top of the A-posts and between door glasses.”
Expertise and processes used by the F-type convertible engineers paid dividends in meeting the company’s criteria to ensure the roof will operate in all conditions that a Land Rover might experience, including open top in the Arctic, of course.
Author: Stuart Birch
Source: SAE Automotive Engineering Magazine
路虎并不是想把攬勝極光敞篷版造成一條船，但它需要保持與路虎傳統(tǒng)車型同等的性能。
路虎攬勝極光敞篷版的內飾。安全系統(tǒng)包括后座后方的兩個防滾架，可在90毫秒內彈出。
路虎的外部設計師Andy Wheel表示，攬勝極光敞篷版的設計工作“絕非易事”。
攬勝極光汽車項目總監(jiān)Danella Bagnall和她的團隊與設計師們緊密合作，實現(xiàn)了敞篷版的量產。該車型的生產流水線與轎跑版和五門版相同。
路虎與供應商偉博思通合作研發(fā)了攬勝極光敞篷版的車頂系統(tǒng)。
路虎攬勝極光敞篷版配置了一塊10.2英寸的觸摸屏。