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Renault : New Technology Developments

February 28, 1999 -- Notably, with the market introduction of the IDEdirect petrol injection engine Renault’s technical choices for the reduction of fuel consumption and CO2 emissions

During 1999, Renault will introduce for sale the first European engine with direct petrol injection (IDE - Injection Directe Essence) in the New Mégane Coupé and Cabriolet. This most recent example of Renault engine design illustrates the three main aspects of the manufacturer’s effort in the development of its powertrains: liveliness and ease of driving, control of emissions and reduction of fuel consumption. This last aspect is a major challenge from the point of view both of the customer, seeking reduced operating costs, and of the public authorities, demanding a greater respect for the environment through reduced CO2 emissions. Apart from IDE, Renault has followed other avenues of development to further reduce the fuel consumption of both its petrol and diesel vehicles.

Renault’s technical choices in terms of the development of powertrains are dictated by customer expectations. Engines must offer reduced fuel consumption and polluting emissions, but must also achieve ease and enjoyment of driving. The engine and the gearbox are not only units intended to provide vehicle propulsion, they also contribute, in the same way as dynamic behavior or ride comfort, to driving enjoyment, to the excitement, the feelings engendered by this wish to be at the wheel. In the same way as the design or the quality of life on board for example, the pleasure that one derives from driving one’s car is a defining element of choice when it comes to vehicle purchase.

Customer expectations are taken into account across international markets in order to further Renault’s strategy of profitable growth. An ambitious objective to produce four million units a year by 2010 will be achieved through the strong international development of the company. Its powertrains must therefore contribute fully to Renault’s strategy of internationalization with specific industrial installations and products, exemplified by the recent development of a 1.0-litre engine for the Brazilian market, and the future production in Brazil of an all-new 1.6 16V engine for the Scenic for sale in the Mercosur market.

Among all these aspects of development, the reduction of fuel consumption is a strong Renault tradition, part of a long-standing policy of respect for the environment, and respecting a double need. On the one hand, the customer demands cars with ever lower operating costs, while on the other, the public authorities want vehicles with ever greater respect for the environment by emitting less CO2. The emission of carbon dioxide, CO2, which for vehicles is expressed in g/km, is a direct measure of the fuel consumption of an engine for a given fuel. Although not yet subject to regulation, it nevertheless remains a subject of special attention.

Renault is thus committed to continuous progress in the reduction of fuel consumption and of emissions with the objective, by 2008, of respecting the ACEA undertaking to limit average CO2 emissions to 140g/km, representing a 25% reduction when compared with 1995.

Within the petrol engine range, progress in simulation, electronic engine management of ignition and fuel injection, work on the reduction of friction losses, and the move to 16-valve cylinder heads has resulted in better engine efficiency, leading to a reduction in both fuel consumption and polluting emissions. The new range of Renault low-friction 16V engines introduced in 1998 has thus permitted a 15% reduction in fuel consumption and CO2 emissions while further improving liveliness and driving pleasure and still meeting the Euro 96/Euro 2000 exhaust emission standards. This family now includes a total of four new engines, offered

within a 12-month period, on several models in the range: 140bhp 2.0 16V (Espace), 118bhp 1.8 16V (Laguna), 110bhp 1.6 16V (Clio, New Mégane, Scenic, Laguna) and the latest of all, the 95bhp 1.4 16V introduced in the New Mégane. These engines allow the various Renault models to return fuel consumption and CO2 emission figures among the lowest in their respective classes.

The diesel engines are generally notable for their extremely low fuel consumption, and consequently their low CO2 emissions. The addition of the direct-injection dTi (in the Mégane in 1997) resulted in a further reduction of 17% in the fuel consumption and CO2 emissions of this type of engine, while at the same time improving performance levels. The 100bhp 1.9 dTi engine in the Laguna will further evolve this year with the addition of a Common Rail fuel system. This will further increase its liveliness and driving enjoyment , with torque output rising to 250Nm. Towards the end of 1999, a 2.2 dTi 16V Common Rail engine equipped with a variable-nozzle turbocharger will be added to complete the range.

During 1999, Renault will also introduce the first European engine with direct petrol injection (IDE), offering a further reduction in fuel consumption.

This technology, already successfully applied in diesel engines, involves the direct injection of fuel into the combustion chamber under high pressure (100 bar). The main objective is to improve combustion and efficiency by reducing the "pumping losses" which arise from the low pressure existing in the inlet manifold, which the piston must overcome when drawing air into the combustion chamber. The solution adopted to reduce these losses is to increase pressure in the inlet manifold by adding more gas. The additional gas may be either an excess of fresh air or a massive introduction of exhaust gas via EGR (exhaust gas recirculation). These two strategies allow direct petrol injection to be employed, and Renault has worked on them both, in parallel. A third solution, also studied by the company, is that of direct air-assisted injection.

The first strategy, that of excess fresh air - as adopted by the Japanese manufacturers - leads to lean-mixture operation with stratified charge, creating a serious exhaust emission penalty because current catalytic converters cannot function during this type of operation. The technology will become viable in Europe from around 2002-2003, once sulphur-free petrol and new exhaust after-treatment systems become available.

For this first IDE engine, developed by the Powertrain Department in partnership with Renault Sport, Renault chose to work on the reduction of fuel consumption without compromising emissions performance. The chosen strategy is therefore that of re-injecting massive quantities of recirculated exhaust gas (high EGR ratio). This neutral gas in effect allows the partial vacuum within the inlet manifold - and hence the pumping losses - to be reduced, while retaining a homogeneous and stoichiometric air:fuel ratio which allows existing catalytic converters to operate with their normal efficiency.

With a capacity of 1,998cc, the new 140bhp 2.0 16V IDE engine (F5R series) will first be offered in the New Mégane Coupé and Cabriolet, replacing the old 2.0 16V engine (F7R series). It offers greater liveliness and better driving enjoyment with a wider range of useful torque and with maximum torque output increased to 200Nm, a high value for a 2-litre engine. A flexible and responsive engine at all speeds, its driving pleasure is complemented by a 16% reduction in fuel consumption (lower by 1.5 litres/100km) in the complete European test cycle.

Developed in little more than 24 months at a total cost of only FRF 250 million, the 2.0 16V IDE engine illustrates Renault’s new approach to the development of powertrains: a shorter development process and limited investment.

These are the results both of the intensive development of computer-aided engineering (CAE) which permits savings in both time and cost (3D design of the cylinder head covers, the combustion chamber, etc), and the installation of new flexible manufacturing processes. Until now, manufacturing lines have been dedicated to a single component or a family of similar components, with capacity fixed in advance. From now on, the flexible lines will allow any type of product to be made, and will therefore permit a faster response to changing patterns of demand. Two flexible lines, for cylinder heads and camshafts, were installed at the Cléon factory in 1998, able to deliver components for engines as different as the 1.8 16V, 2.0 16V, 1.9 dTi and soon the new 2.0 16V IDE. This concept has thus allowed the industrial investment requirement for IDE engine production to be held to only FRF 10 million. This flexible line principle will be extended to other engine components.

Other working approaches promising to benefit the fuel consumption of internal combustion engines have been identified and are in the process of development at Renault.

From 2000, the technology of the turbocharger for petrol engines will be developed for even greater driving enjoyment, but also in the interests of reducing fuel consumption. It will be a new development, far removed from the "previous generation" of turbo engines purely devoted to performance without concern for fuel consumption. This new petrol turbo development is equally different from the "low pressure" turbo solutions already offered in the market, which bring no significant gain in terms of reducing fuel consumption.

Based for example on a 2.0 16V engine, the turbo solution developed by Renault results in the achievement of the driving enjoyment of a naturally aspirated 2.5-litre engine - with a constant torque output of 250Nm from 1,750 to 3,500rpm - for a fuel consumption reduced by 15 to 20% when measured according to the complete European cycle. This reduction results from particular features, and especially from a strategy of mixture strength control intended to reduce the traditional very high consumption of turbo engines at full load. These special strategies are made possible among other things by a new generation of turbocharger with a double-intake turbine.

Envisaged for the early years of the next decade, the ADIVI (a French acronym for alternator-starter built into the flywheel) represents a major step forward in the electrical system and its relationship with the internal combustion engine. The conventional alternator, starter motor and flywheel are eliminated, and replaced by an electric motor interposed between the engine and the gearbox. This system has several functions: starter motor, generator of electrical power at several voltages, smoother of shocks and cyclic vibration of the engine, provider of additional power when needed . . . But it will also allow a reduction in fuel consumption and CO2 emissions, partly through greater efficiency when working in alternator mode, but above all by means of "stop and go" operation. This automatically stops the engine when it is idling after the car has come to rest, for example at a red light, with rapid and virtually silent restarting occurring as soon as the driver engages a gear and presses the accelerator.

The third avenue of development is that of "camless" engines, in other words engines without camshafts. Conventionally, in an internal combustion engine, the valves are operated from a camshaft, whose rotary movement is taken from the crankshaft and transmitted by the valve train toothed belt. In an engine with a "camless" valve train, each valve is operated by an electromagnetic actuator, independently of the other valves. Apart from eliminating the camshafts and reducing the number of moving parts which create friction, this approach also affords great freedom of choice in the timing of valve opening and closing according to engine speed and load, and the possibility of de-activating one valve or one cylinder. While allowing fuel consumption to be reduced, camless technology also contributes to an increase in torque and therefore in the liveliness of the engine.

While the techniques already described allow progress to be made in reducing the fuel consumption of all internal combustion engines, the ultimate desire still remains that of achieving the lowest possible fuel consumption, and this implies the use of dTi diesel engines of small capacity.

For the coming decade Renault is developing, alongside its 1.9dTi engine and the forthcoming 2.2 dTi, a new engine family consisting of a 4-cylinder 1.5 dTi and a 3-cylinder 1.1 dTi. This last engine will allow a small car to achieve CO2 emissions of less than 100g/km, while retaining liveliness and ease of driving.

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