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April 02, 2003
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This Week:

• The All-New 2004 BMW 5 Series

• 3200 Deposits taken for the new Bentley Continental GT

• GM's New 3.6L V-6 VVT To Debut In 2004 Cadillac CTS

• Chrysler Group Reports U.S. March Sales

• PSA Peugeot Citroën Porto Real Plant in Brazil To Start Citroën C3 Production

• Renault presents new-generation particulate filter

• Toyota To Unveil Second Generation Prius And Camry Solara At The 2003 New York International Auto Show

• Volkswagen do Brasil celebrates its 50th anniversary

• GM Reports March Sales Of 391,752, Down 3 Percent

• BMW Group and Brilliance Sign Joint Venture Contract for Planned Production in China

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Renault presents new-generation particulate filter
 

The new Euro IV exhaust emission standards, which come into force from 2005, require better performance of various engine components including exhaust aftertreatment systems. In response to the fiscal incentives which already apply in some countries, Renault is introducing a 2.2 dCi engine which complies with these standards (IF Euro IV), equipped with a new-generation particulate filter. This filter/catalytic converter, of the socalled periodic regeneration type, works without any additive. The automatic regeneration is controlled by the fuel injection computer. During the second quarter of 2003, Renault will begin selling a version of Vel Satis 2.2 dCi equipped with a particulate filter and complying with the Euro IV fiscal incentive requirements.

To achieve this level of exhaust emissions, major work has been carried out on the engine's internal combustion (injectors, pistons) but also by increasing the size of the exhaust post-treatment components: catalytic converter, EGR (exhaust gas recirculation) system and particulate filter.

The new exhaust emission standards applicable to new-build vehicles in 2005 call for the halving of emissions of particulates and oxides of nitrogen (NOx).

Special features of the Renault filter

Renault developed its particulate filter system in collaboration with Engelhard, Ibiden and Eberspaecher. This catalysing filter, of the periodic regeneration type, works without any additive. It consists of a structure which incorporates channels, laid out in such a way as to force the exhaust gas to pass over its surfaces. This substrate of porous material, made of silicon carbide, is covered with a catalytic coating. Sensors which check the temperature and the pressure within the particulate filter inform the fuel injection computer which controls the regeneration of the filter and is also responsible for self-diagnosis of the system.

A new catalytic converter and EGR bypass intercooling are the other components which contribute to meeting the new standard.

Principle of operation

The particulate filter is installed in the exhaust run beneath the vehicle, in the place normally occupied by the catalytic converter.

The filter works on a two-phase principle:

First phase, the trapping of particulates

During this phase, the filter fills up with particulates.

Second phase, regeneration

Regeneration involves the periodic burning-off, every 300 to 500km according to the way in which the vehicle is used, of the particulates which have accumulated in the filter. In the presence of oxygen, the regeneration through combustion of the particulates takes place naturally whenever the temperature of the exhaust gas exceeds 570°. It is the fuel injection computer which, by altering the injection schedule, brings about this increase in temperature.

The oxidation catalyst

Now of greater volume, it is installed immediately downstream of the turbocharger exhaust. Its warm-up is faster and its larger size improves its efficiency.

The EGR system

This sophisticated system reduces NOx emissions from diesel engines. The EGR, controlled by the fuel injection computer, recycles part of the exhaust gas back into the inlet manifold. Mixed with fresh incoming air, it improves combustion within the engine and reduces the formation of NOx.

(March 04, 2003)