The acronym alone tells the whole story: Together with four universities and four industrial partners, the BMW Group has launched the CLEVER Project. The CLEVER (Compact Low Emission Vehicle for Urban Transport) project seeks to create a low-emission, highly practical city car.
The prototype combines the safety features of a microcar and the manoeuvrability of a motorcycle, with the added benefits of being more fuel efficient and less pollution than other vehicles. "Through the Project we wish to determine in technological terms to what extent one can combine the three core features — 'small, light, and safe' — in one and the same car," is how BMW Group project manager Peter Krams defines the project and the goals set.
The prototype of this revolutionary one-metre-wide vehicle designed to decongest city traffic is the result of a £1.5 million collaborative project which involved nine European partners from industry and research. The three-year international project involving German, French, British and Austrian organisations and funded by the European Union, took off in December 2002 and was completed in March this year.
NEW TECH AT WORK
Being CLEVER means accelerating with a low-emission natural gas power unit and sitting between three wheels. This means minimum air drag, low weight, and compact dimensions on the road: the research car is approximately three metres long, one metre wide, and 1.4 metres tall, weighs less than 400 kilograms, and has just one square metre frontal area facing the wind. It also means enjoying the driving pleasure of a motorcycle with all the safety of a passenger car, the driver and passenger sitting in a crash-optimised aluminium spaceframe leaning over with computer management into bends and offering the occupants the typical experience of a two-wheeled vehicle.
Concentrating on the absolutely essential in city traffic motoring, the development engineers have created new technologies and, accordingly, new solutions. Particularly the technology of leaning into bends, the way it is interpreted here, is brand-new: The single-cylinder power unit with its infinitely variable CVT transmission comes in a subframe holding the two rear wheels running on swingarms. This entire unit is then connected to the mainframe at the front by a central bolt with two hydraulic actuators allowing the driver and passenger to lean into a bend by up to 45 degrees, depending on driving conditions and individual requirements. This, in turn, enables the vehicle to take bends entirely free of lateral forces, the driving status being calculated at all times by a computer.
The University of Bath, UK, one of the partners in the project, focused on the design and simulation of the vehicle chassis and control of the hydraulic tilting system. "The CLEVER vehicle is a tremendous leap forward in the development of vehicles for the 21st century," says Dr Jos Darling, senior lecturer in Mechanical Engineering at the University of Bath, who is in charge of its part of the project, with Dr Geraint Owen. "Making our vehicles smaller is a good solution to the relentless increase in traffic in our towns and cities. The advent of microcars was a first step, but with its manoeuvrability and narrowness, the CLEVER vehicle is the ultimate in the search for a small vehicle to get around cities.
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"The fact that it has a stylish design, can carry a passenger, is not open to the weather and is as high as a conventional car, will mean it will be much more popular with motorists than previous novel city vehicles. It costs less to run, is quieter and is less polluting, and this will make it popular with environmentalists. Its strengthened safety frame makes it very safe for the driver in accidents, says Darling.
Developing the front-wheel steering running in an H-shaped swingarm, the research engineers responsible for the project have created a similarly exceptional solution: to save space and weight, on the one hand, while at the same time providing a firm structure to take up energy in head-on-collisions, they have developed a new kind of wheel hub steering. The pivot pin in the wheel turns around when steering is positioned within the hub, with the front axle being fastened to the swingarm booms on either side. When the driver turns the steering wheel — which incidentally comes from the BMW Z4 — a steering transmission with lever arm control transmits the driver's commands, not only turning the wheel in the desired direction, but also the entire passenger compartment leaning into the bend, depending on the speed of the vehicle. "But even so, the driver always has the feeling as if he were steering a car “, states BMW's Krams.
ECONOMICAL AND SAFE
An important objective in the CLEVER Project is to use a low-emission drive system. One of the main requirements on the agenda from the start, therefore, was to keep CO2 emissions to a minimum of roughly 60 grams/100 kilometres. Hence, the development engineers opted in favour of a proven single-cylinder power unit displacing 230 cubic centimetres and developing 17bhp, running on natural gas provided from two pressure cylinders.
Given this kind of power, the research car accelerates to 60kph in approximately seven seconds and has a top speed of about 100kph. The two gas cylinders with a capacity of 1.7 kilos of CNG (compressed natural gas) each offer a range of approximately 200km. This means that two persons are able to travel around 100km on just one euro (Rs 55). Right from the start, passive safety was also a fundamental requirement for the CLEVER project, together with ecological compatibility and superior economy.
Krams says: "Nobody will get into an innovative car like this if it is not safe." Like in a Formula 1 racing car, therefore, the mainframe weighing just under 60kg forms a survival cell, while the front wheel and wheel guide units provide approximately 35 centimetres or 13.8 inches deformation travel, thus adequately taking up energy in the event of an impact. Benefiting from special seatbelts and an airbag for the driver developed especially for the CLEVER car, the research vehicle has completed the Euro NCAP crash test with the same results as a modern compact car. So the three-wheel prototype offers a safe survival area even in a head-on collision at 56kph.
The CLEVER Project began in 2002 at the initiative of Berlin Technical University and was promoted in the Fifth Framework Programme of the EU Commission. Other scientific partners in the development process were the University of Bath in the UK, the French institute Français du Pétrole, and the University of Ground Culture in Vienna. The industrial partners participating in the project were Cooper-Avon Tyres, ARC Leichtmetall Kompetenzzentrum Ranshofen GmbH, TAKATA-PETRI AG, and WEH GmbH. The BMW Group acted as the technology leader in the project and was responsible for the design and construction of the chassis, interior and exterior.
A further responsibility of the BMW Group was to design and build the prototypes. Krams says: “Acting as a leader in technology in providing individual mobility, the BMW Group regularly examines innovative concepts – and, as a manufacturer of both cars and motorcycles, BMW also examines vehicles in between these categories. Our objective in this research project was not to build a vehicle ready for series production, but rather to develop new overall vehicle concepts and appropriate technical solutions. CLEVER presents the approach taken, but does not claim to be a universal solution."