Французская компания готовит к домашней выставке концепт С4 Cactus Airflow, расход топлива которого заявлен на уровне в 2 л на 100 км пути. Этого производитель добился, не только активно используя сверхлегкие материалы, но и применив свою фирменную разработку – пневмогибрид.
Citroen утверждает, что серийная версия кроссовера Cactus и без того на 200 кг легче стандартного хэтчбека С4, но вес концепта Airflow удалось снизить еще на 100 кг. Концепт получил целый ряд деталей из композитных материалов, включая панели кузова, элементы подвески, задние и боковые двери. Часть силовой структуры кузова выполнена из алюминия и высокопрочных сталей, а панорамное остекление – из поликарбоната. Утверждается, что этот материал имеет те же свойства, что и многослойное стекло, но при этом заметно легче.
На концепте применен ряд активных аэродинамических элементов. Например, менять свое положение могут воздухозаборники в переднем бампере, боковые дефлекторы и лопасти, установленные на колесные колпаки. Помимо них, С4 Cactus Airflow снабжен шинами размерностью 155/70/R19 с "ультра-ультра"-низким сопротивлением качению, компактными камерами вместо боковых зеркал заднего вида, особым задним спойлером и технологией Air Curtain. Аэродинамические накладки под названием "воздушная завеса" по бокам переднего бампера оптимизируют потоки воздуха в районе колесных арок.
В Citroen отмечают, что даже полностью светодиодная оптика вносит свой вклад в общую экономию топлива, так как потребляет значительно меньше энергии.
В состав гибридной силовой установки C4 Cactus Airflow 2L входит 82-сильный трехцилиндровый бензиновый мотор 1.2, два бака для сжатого воздуха, гидравлические помпа и двигатель, а также специальная автоматическая трансмиссия с планетарной передачей. Прототип имеет три режима езды: на бензине, на воздухе, а также при совместной работе обоих агрегатов.
Автомобиль использует вариант системы рекуперации энергии при торможении, однако накапливает не электричество, а воздух. Во время замедления подключенный к планетарной трансмиссии насос перекачивает жидкость через гидравлический мотор, сжимая воздушную пружину и накапливая воздух в баллоне. При разгоне происходит обратный процесс, а гидравлический мотор работает вместе с ДВС.
Инженерам удалось понизить потери на трение у ДВС на 20 процентов. В конструкции машины использовали специальные полимерные втулки и моторное масло пониженной вязкости.
Детальных технических характеристик концепта в Citroen предпочли не раскрывать, но заявили, что всерьез рассматривают перспективу применения задействованных технологий на серийных автомобилях.
The Citroën C4 Cactus AIRFLOW 2L Concept
With its smooth design lines, efficient engines and technologies selected to reduce vehicle weight, the production Citroën C4 Cactus already boasts a range of features designed to reduce fuel consumption.
With the C4 Cactus AIRFLOW 2L concept, Citroën is taking this approach even further.
1. A body optimised for aerodynamic performance
On the C4 Cactus AIRFLOW 2L, some styling features have been modified and others created in order to optimise vehicle aerodynamics.
Variable-geometry components:
The new front bumper features three air intakes that continuously adjust in accordance with vehicle use, both for engine cooling and to regulate air flow
Mobile side deflectors have been added to effectively guide the air flow around the vehicle
The wheels feature mobile shutters activated and controlled by centrifugal force
Fixed-geometry components:
New generation 19-inch "ultra ultra" low rolling resistance "tall & narrow" tyres. Their design improves both energy efficiency and aerodynamics. The large diameter also means they are better able to soak up bumps and dips in the road surface
The wheel arches feature an "Air Curtain". This is achieved with small aerodynamic slats on either end of the front bumper to channel the air along the wheels
The spoiler has been lengthened and an air extractor has been added on the rear bumper in order to reduce the turbulence that can increase drag
The conventional door mirrors have been replaced by smaller, slimmer rearview cameras to reduce the impact on air flow
The vehicle sub-structure has been entirely streamlined so the air flows smoothly underneath the car
LED light modules at the front and rear replace the existing lights. Consuming little power, these new modules save energy and benefit fuel economy
The changes can be identified by the colour of the components and by the materials used. The colour orange identifies all the aerodynamic features and underlines the high-tech character of the C4 Cactus AIRFLOW 2L concept.
The changes reflect how styling and design can contribute to vehicle aerodynamics, reducing vehicle drag for an overall improvement of 20% in terms of aerodynamic performance compared with the production model.
2. Innovative materials for lighter weight
The production C4 Cactus is already 200kg lighter than the Citroën C4 hatchback, yet the C4 Cactus AIRFLOW 2L concept shaves off a further 100kg. This means Citroën's designers have reduced the weight of the concept by 11% compared with the production vehicle.
To achieve this, the brand has reduced the weight of many structural components, with the body sub-structure featuring new materials:
Aluminium, for the upper cowl panel, inner side members and rear floor pan
High-yield steels, for the front side rails and heel board
Composite materials for the front of the vehicle floor
These new materials are structural and help to soak up energy in the event of an impact. They also meet the highest standards in terms of mechanical strength.
This multi-material sub-structure made it necessary to develop special assembly techniques never used before in the automotive industry. Composite structural parts are a promising development area and will be essential to make cars lighter in the future. The large-scale production of these parts is one of the high-tech, industrial challenges to be addressed by the automotive sector.
Looking beyond the structural components, extensive studies were conducted on all vehicle parts to reduce weight.
Emphasis was placed on lightweight, high-performance materials:
Carbon-based composite materials have been used for the suspension springs, tailgate, rear bench, side panels, roof, roof cross-members, wings and doors. On the lower side sill, wheel arches and the lower part of the front bumper, the "textured" look of the carbon brings out the matt appearance of these parts, providing an attractive contrast with the pearlescent appearance of the surrounding features
Aluminium is used for the engine cradle. The bonnet specification is the same as for the production C4 Cactus, which already uses aluminium
Owing to their significantly lower bulk and density (around 2,700kg/m3 for aluminium and around 1,200 kg/m3 for carbon, compared with 7,800kg/m3 for steel), these materials contribute significantly to reducing overall vehicle weight
Given that every gram is important, Citroën also decided to use:
New processes to reduce the thickness of the tubes and cups in the exhaust system
Translucent polycarbonate, for the panoramic sunroof. This material is even lighter than multi-layer glass, but has the same properties in terms of thermal and acoustic insulation and ultra-violet filtering capability
Carbon fibre on the Airbump® panels to make the material lighter, while maintaining its technical properties
Hybrid Air technology for breakthrough fuel consumption
With the brand's latest-generation Euro 6 engines, the production C4 Cactus already ranks among the best in its segment with CO2 emissions from 82g/km and fuel consumption starting at just 91.1mpg.
The C4 Cactus AIRFLOW 2L concept goes even further by adopting the Hybrid Air drivetrain. Presented by the PSA Peugeot Citroën Group in January 2013, and featured on a Citroën C3 at the 2013 Geneva Motor Show, this technology combines a range of proven sub-systems and technologies. This includes a 3-cylinder PureTech petrol engine, a compressed air energy storage unit, a hydraulic pump/motor unit and an automatic transmission with an epicyclic gear train. An intelligent electronic management system manages input from the driver to optimise energy efficiency.
Three operating modes are available:
Air power (zero emissions) where the compressed air motor takes over from the petrol engine
Petrol power, using only the combustion engine
Combined power, drawing upon both the combustion engine and the compressed air
On the C4 Cactus AIRFLOW 2L concept, the two compressed air storage tanks are made of composite materials and are positioned at the rear of the vehicle.
The PureTech 82 engine, already available on the production model, has been optimised for this new hybrid drivetrain. Friction losses, which account for 20% of the power consumed by the engine, have been reduced in several ways. This includes using a Diamond-like carbon coating, making moving parts lighter and using bearings to guide rotating parts. Further improvements were made by adopting new polymer pads and using very low viscosity oil. Combined with efforts to optimise combustion, overall engine efficiency has been improved by 5%.
Combining the PureTech 82 engine with Hybrid Air technology for this concept reduces fuel consumption by 30% and contributes significantly to achieving a vehicle capable of 2l/100 km, while approaching the PureTech 110 in terms of dynamic performance.