CORPORAT COMMUNICATIONS DPARTMNT P R S S F I L Lyon / March 2009 Renault Trucks Optifuel Lab vehicle registers 13 % lower consumption With the race for power that was the hallmark of the 2Oth Century now forgotten, today s focus has turned to energy savings and moderation. With the deployment of its laboratory vehicle, Optifuel Lab, Renault Trucks is showing that significant reductions in fuel consumption can indeed be achieved. Using a global approach and integrating highly refined aerodynamic features, Optifuel Lab is returning fuel savings of -13 %, which translates to 4.5l/100km or 120 g of CO 2 less per kilometre. This result, the culmination of thousands of kilometres travelled in realworld conditions, again demonstrates the lead that Renault Trucks has built in fuelefficiency technology. This is further proof that the brand is meeting head on the new demands of the emerging society. The solutions being tested today could well be integrated into the vehicles marketed in the medium and long term. Firmly focused on improving its products and fully meeting the needs of its customers, Renault Trucks has for a long time given top priority to manufacturing class-leading, fuelefficient vehicles. ven as the company conducts research to investigate and offer vehicles powered by alternative energy sources (hybrid and electric vehicles for example), Renault Trucks remains convinced that diesel-powered internal combustion engines will, for many more years to come, remain the predominant energy used for long-distance transport. This analysis is what prompted Renault Trucks to launch its Optifuel Lab research programme in 2007, with the primary objective of reducing the fuel consumption and exhaust emissions of a tractor-trailer unit. The first stage of the programme set out to prove that a significant drop in consumption could be achieved by reworking the aerodynamic characteristics of the tractor-trailer unit, by optimising the driveline and tyres and by utilising specific driving-aid systems. Today, after 4500 kilometres of general tests and measurements over a 2500-kilometre road circuit, the savings in fuel obtained from the project is -13%, or TR B50 1 15 99, route de Lyon 69806 Saint-Priest Cedex Fax : +33 (0)4 72 96 48 57 - www.renault-trucks.com RNAULT TRUCKS SAS Capital de 50 000 000 uros Siège social : 99, route de Lyon 69800 SAINT-PRIST siret : 954 506 077 00120 RCS Lyon B 954 506 077
4.5 l/100 km, converting to approximately 120 g of CO 2 per kilometre covered, in real operating conditions and compared to an equivalent vehicle on the market (Premium Route DXi 11 450ch). Nevertheless, this is a research vehicle that will not be brought to market; it is an invaluable tool used by Renault Trucks to validate different fuel-saving solutions that could, in the medium or long term, be integrated in commercially marketed ranges. At present, the vehicle remains a research vehicle that is not intended for the market. It does not satisfy road traffic standards which do not for example permit the use of deflectors behind the trailer. Renault Trucks hopes that its research and findings will enrich the debate on vehicle regulations and, in concert with other heavy vehicle constructors, encourage government authorities to reconsider their positions. What is Optifuel Lab? Optifuel Lab is a laboratory vehicle that was launched in 2007 and developed from a research programme. It is not intended to be marketed but is designed to test new fuel-saving technologies in real operating conditions. Optifuel Lab is part of a global research programme that brings together a range of vocations and fields of competence (aerodynamics, engine design, rolling resistance, drivingaids ). In its capacity as a research vehicle, it is able to test solutions that at times go beyond current regulatory authorisation applied to road transport as for example the use of deflectors in the front and rear of the tractor-trailer unit. With the aid of this lab vehicle, Renault Trucks is able to validate or invalidate certain research options or orientations so as to integrate them in its vehicle range in the medium term, on condition that they comply with technical and regulatory requirements. The development of road transport regulations is at the centre of on-going discussions between the constructor and public authorities. This research work helps Renault Trucks demonstrate that certain solutions can be directly adapted to production vehicles but that government involvement is crucial for that to happen.
Results surpassing initial objectives Whereas the objective at the start of the project was to achieve a reduction in consumption and emissions of about -10 %, Renault Trucks has since then measured savings of -13% in comparison with the Renault Premium Long Distance uro 5 Incentive, already established as a class leader in fuel consumption. These results were obtained by working simultaneously on all the different elements and units of the truck that play a role in fuel consumption. A global approach to enhance fuel efficiency The Optifuel Lab project brought together 23 working groups and was structured around four major themes: aerodynamics, driveline, rolling resistance and driving aid systems. Searching for the ideal design concept The first force that a moving truck has to deal with on the road is its natural resistance to air. The teams on the project worked on improving the aerodynamics, not only of the tractor, by incorporating a new design, but also of the entire tractor-trailer unit. Using the water droplet as its reference model (as its natural shape is the most aerodynamic known to exist), the Renault Trucks teams tested a number of solutions in order to minimise the vehicle s drag. Addressing the cab first of all: the wraparound bumper was lengthened 30 centimetres, the roof height reshaped and raised to 4.16 m, by the same token acting as an integrated deflector. The rearview mirrors were supplanted by a retro-vision system using cameras developed by Mekra. A global aerodynamic approach embracing tractor and trailer Beyond the design aspects, in-depth studies were done to investigate the overall aerodynamic characteristics of the tractor-trailer unit. The side deflectors behind the cab were optimised to better fuse it with the rest of the vehicle and obtain an almost complete fairing with side skirts encasing the wheels of the trailer. The fairing is transformed into air diffusers at the end, borrowing from the technique used in Formula 1. These diffusers are what guide air flow to offer the least possible resistance.
Behind the cab, the 70 cm-long deflectors help to minimise the zone of turbulence which builds up inevitably behind a moving truck and tends to slow it down. By restricting this zone of turbulence, the power needed to move the truck is reduced and so is the consumption. Special attention was also paid to the roof of the semi-trailer. Still in the spirit of recreating a drop of water, aerodynamic specialists raised the roof section also to reduce drag. As such, the roof is no longer flat but oblong in shape so as to be as aerodynamic as possible. In addition, engineers positioned a special fairing under the chassis of the semitrailer. All these elements combine to give Optifuel Lab an excellent (Cx) drag coefficient. Improving drag is in itself a good thing, but rolling resistance remains a considerable source of consumption. With this in mind, Renault Trucks entered into an agreement with Michelin to improve tyre performance and uses nergy SaverGreen tyres for Optifuel Lab. Optimising every component of the driveline Apart from work that was done on the engine itself, every driveline component was isolated and optimised with a view to cutting consumption. One essential principle was to better manage the operation of each element. For example, a two-speed water pump is used: the water flow in the cooling circuit is therefore controlled and functions at full speed only when needed. A similar system was used for the variable flow oil pump as well as for the disengageable air compressor, which will often shut itself off on the highway, where the need for air is limited and discontinuous. The result is a drop in consumption since the compressor is not operating permanently. The other mechanical units were improved so as to enhance performance. ngineers increased the oil temperature in the engine to minimise friction and energy loss. They also raised the maximum pressure in the combustion chamber to enhance combustion performance. Varying enhancements were also made to the prop shaft and the alternator, for which the conversion performance was improved. Driving-aid systems to achieve even lower consumption Because the driver has a crucial role to play to help reduce consumption, Optifuel Lab is equipped with driving aid systems to help improve fuel efficiency. Recognised for the performance of its Optidriver gearbox, and calling on the depth of its experience and
expertise, Renault Trucks has succeeded in further enhancing its operation. The gearbox now permits gear changes at even lower speeds than customary to give a more «torquey» driving experience. It is mated first of all to the improved coroll function which automatically disengages the engine and shifts to neutral when driving conditions allow it, as when negotiating a slight incline or at the start of a downhill run, and it is also connected to a cruise-control function that is programmed for fuel efficiency. The ASL, Adaptive Speed Limiter, has also been optimised. Using its GPS function, the speed limiter is able to analyse the truck position, the road profile (uphill or downhill), detect imposed speed limits and automatically set the appropriate gear. As an example, the system can slow down gradually when the vehicle is approaching a toll station. In the end, the combined savings from each component helps to give a significant drop in the overall consumption. Measuring results Validating the results obtained from a project such as Optifuel Lab does not make room for guesswork, and it is only after completing a battery of very stringent tests, validated by simulation, bench tests then by real-world testing that Renault Trucks validates the results. From a clean sheet to the verdict on the road The first phase of tests obviously took the form of computerised and purely virtual simulations. Once the proposed solutions are validated by computer, the Optifuel Lab teams can physically outfit the truck and position it on a test bench to perform static roller tests. Without having to leave the plant, engineers can then obtain a concrete view of the results of the expected solutions. Nevertheless, nothing replaces real-world conditions to validate a particular system and it is for this reason that the last phase is performed on the open road. ach trip is done in a convoy (at intervals of about five minutes) by Optifuel Lab and the reference vehicle, a Premium Long Distance DXi 11 450ch uro 5 Incentive, the classleading truck in terms of fuel consumption.
A circuit to give an accurate and representative measurement of consumption COMMUNIQU Geographical representation of the circuit The test circuit is a 400-kilometre loop section frequently used by the professional media to do test drives. The circuit links Chambéry, Geneva, Bourg-en-Bresse and Villefranche-sur-Saône, and presents all the operational situations met by hauliers and a number of undulating segments with a maximum altitude of just above 500 metres between kilometres 80 and 300 (see map above). It is divided into two sections: from the toll area in North Macon to the Fontanelle rest area and back. Data showing altitude, gradient, speed limit and journey stoppage times.
Minimising the impact of driver changes and weather conditions In order to obtain results with the highest level of pertinence, the Optifuel Lab teams tried to minimise the impact of any outside influence. Accordingly, in order to limit the impact of any particular driving style, drivers were changed at midway along the test route. The route was covered using the speed limiter as often as possible, with uphill and downhill sections done at speed using this technique and limited to 85 kph. The route was run six times in two weeks using this procedure so as not to be affected by changing weather conditions. It is noteworthy that the final result of -13 % against the reference vehicle was not the best measurement obtained over the six test runs but the overall average of all the runs. In all, some 5000 kilometres of testing was done. Measuring consumption The method used to determine consumption is called «full to full» and measures the amount of diesel oil used on each test run from Macon to Macon. The cumulated consumption reading taken at certain predefined points along the circuit is done by an AIC flowmeter (Automotive Information and Control Systems). All important remarks are logged when a reading is done (wind, rain, untimely stops ). Conclusion With the deployment of Optifuel Lab, Renault Trucks now has the resources to be the industry leader in fuel efficiency and low CO 2 emissions. The results obtained (-13%) have exceeded the initial objectives and are very promising for our future research efforts. They will give Renault Trucks the opportunity to validate solutions to help reduce fuel consumption so that they can be integrated in production vehicles in the medium term. Further information is available from www.renault-trucks.com/press Julien Berthet Tel : + 33 (0)4 72 96 39 86 - julien.berthet@renault-trucks.com Fabrice Piombo Tel : + 33 (0)4 72 96 12 20 - fabrice.piombo@renault-trucks.com