Renault reveals ultra fuel-efficient EOLAB concept
Renault has released details of its EOLAB concept which features 100 technical innovations to return fuel consumption of just 1.0L/100km, saying a production version will be ready in 10 years.
RENAULT HAS RELEASED details of its EOLAB concept which is designed to return fuel consumption of just 1.0L/100km while “maintaining established B-segment levels of performance, practicality and affordability”. Indeed, it weighs 400kg less than the equivalent Renault Clio.
EOLAB will get its world debut at the 2014 Paris Motor Show, but Renault has announced that the 100 technical innovations the prototype showcases will be introduced into production Renaults from now until 2020. Renault says its aim is that a production version of the EOLAB, able to return 1.0L/100km, will be available within 10 years.
EOLAB takes its name from combining the name of ‘Aeolous’ God and Ruler of the Winds in Greek mythology, and ‘Laboratory’.
According to Renault, its boffins focused their efforts on three main areas: minimising weight, refining aerodynamics and using hybrid technology:
- The car’s shape was designed to slice through air efficiently, while movable devices such as an active spoiler and lateral vanes perform the same way as ailerons;
- A weight saving programme brought the car’s mass down 400kg, thanks in particular to a multi-material body shell combining steel, aluminium and composites, as well as a magnesium roof that weighs just 4kg;
- Z.E. Hybrid technology: this new, compact and affordable hybrid power unit combines ultra-low fuel consumption with zero-emission travel for journeys of less than 60km and at speeds of up to 120km/h. (This is a similar approach to Mitsubishi’s Outlander PHEV.)
Renault says the design of the EOLAB concept was just as important as was the technical side, “With its sloping roof and breathtakingly slender rear end, the concept car’s true purpose is well masked: beneath its seductively designed shell, everything is geared towards frugality. It demonstrates that Renault is able to add a touch of dream-like magic to a prototype whose fundamental mission is to achieve ultra-low fuel consumption”.
EOLAB: A Summary
Aerodynamics of 0.235 Cd (30% less than equivalent Clio):
- Active ride height: Access mode, Urban mode and Extra-Urban mode;
- Active wheels – react to brake temperature to maximise Cd;
- Active front spoiler;
- Active rear flaps.
Weight savings across the entire vehicle (400kg less than equivalent Clio):
- Asymmetric 3-door layout;
- Compact revised brakes – no master cylinder and all systems integrated into one small lightweight unit;
- Narrow 145/45R17 Michelin ultra-low consumption tyres;
- Ultra-thin windscreen glass (3mm) – saves 2.6kg;
- Thinner interior trim & lighter plastics containing air bubbles;
- Optimised seat structures – save 12kg and 30mm in car length;
- Lightweight dashboard cross member;
- Lighter running gear – steel to aluminium;
- Magnesium roof weighs just 4.5kg;
- Brakes are 14.5kg lighter but retain the same braking efficiency;
- Fixed bonnet gains 2.5kg;
- LED front lights;
- Lithium –ion battery;
- Compact centre-exit exhaust system to save weight.
100% Renault Z.E. Hybrid powertrain:
- 1.0-litre three-cylinder 75hp SCe petrol engine;
- 400V, 6.7kWh battery with 66km range;
- Clutchless three-gear transmission;
EOLAB: The importance of aerodynamics…
Renault says it EOLAB concept paid attention to airflow underneath, and around the vehicle to make it as slippery as possible. Indeed, EOLAB’s CdA (drag coefficient) is 0.470m2 (A = 2.00m2 / Cd = 0.235) which represents an overall reduction of 0.200m² (around 30% when compared with a Renault Clio). This lower drag coefficient results in a significant fuel consumption reduction at higher speeds, for instance,at a stable speed of 130km/h, for example, it accounts for a fuel consumption saving of 1.2 litres/100km in comparison with the benchmark vehicle.
Variable ride height EOLAB’s ride height is variable via active air suspension; the four dampers can be raised or lowered by 25mm in relation to the default setting. When the car is parked, the suspension switches to its highest position in order to facilitate entry. As the vehicle begins to move, the suspension resumes its default setting (i.e. it lowers by 25mm) at speeds of between 5 and 70km/h in order to limit the amount of air that passes underneath it. For the same reason, the ride height is lowered by a further 25mm at speeds in excess of 70km/h.
Active spoiler At the same time, the boffins looked at EOLAB’s front bumper which is, for example, equipped with an active spoiler that lowers by 10cm at speeds in excess of 70km/h in order to restrict airflow beneath the car.
Aerodynamic flaps These 40cm x 10cm vertically-positioned flaps are visible on the rear bumper, rearward of the rear wheels. At speeds in excess of 70km/h, these flaps open by 6cm in order to ensure that as much of the airflow as possible stays attached to the vehicle as it moves forward. Without this solution, passing air has a tendency to become detached from the vehicle’s sides too early after passing the rear wheels and this has a negative effect on drag. In the open position, airflow remains attached to the car as far rearward as possible, right to the trailing edge of the bumper. “These flaps tauten the airflow and prevent turbulence which otherwise acts as a sort of aerodynamic brake,” explains William Becamel, the aerodynamics expert who worked on the project.
Active wheels While the boffins would argue that the most efficient wheel design is flat and smooth, they also understand that this would have a negative effect on brake cooling. So, Renault developed a system that covers the wheels whenever the brakes don’t need to be cooled, thereby reconciling design and aerodynamic efficiency considerations. The system is controlled by a temperature sensor built into the rims.
Tyres that slice through air To further perfect the EOLAB concept’s aerodynamic performance, it is fitted with narrow (145mm-wide) tyres. That’s 40mm narrower than the smallest tyres available for the Clio IV. Michelin and Renault’s designers worked on the tread pattern to give a visual impression of width, while the sidewalls were designed to exude an impression of light weight. At the same time, tyre supplier Michelin optimised the casing and tread to minimise rolling resistance while maintaining safety and performance. The tyres’ rolling resistance is 15% lower than those of the Clio IV.
To develop and build the technologies required for the EOLAB concept, Renault says it established the Cooperative Innovation Laboratory (LCI) – a company within a company. LCI sees engineering, product and design stuff all working in the same space.
Made up of around 40 people, “LCI is a bit like a start-up inside a major company. Conditions are ideal for developing innovations and breakthrough concepts,” explains Patrick Lecharpy.
Each project has four key ingredients: design, technology, economic constraints and customer surveys. LCI develops a wide range of projects and enjoys considerable leeway in its work: one-third of projects are the result of discussions with external players such as parts suppliers and specialist schools, the aim being to step outside the framework of conventional programs and create a fertile ground for completely original ideas. Renault Twizy was based on the work of LCI.