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A particulate trap with combined regeneration has been developed for use in light duty vehicles with diesel engines. This new system was tested first on an engine test rig. On-road vehicle tests are going on since August 1998. The results obtained clearly demonstrate the feasibility of this system. With this system trap regeneration has to be ensured under worst case conditions (exhaust gas temperature<400° C). To meet this requirement electrical heating in combination with a fuel-borne catalyst is applied. Different filter materials such as cordierite wall flow and silicon carbide monoliths were tested on the engine test rig. The paper reports on results from the engine test rig as well as from on-road vehicle testing. An overview about pre-heating and regeneration examples are given and energy balances are presented.

Metallic substrates for catalysts constitute a supporting technology to meet the various emission legislations world wide for passenger cars as well as for 2- and 3-wheelers. Hot tubes offer additional advantages, especially for 2- and 3-wheelers in combination with metallic substrates or as independent systems. Low thermal capacity data indicates an early light off. High thermal conductivity assists the catalyst under engine misfiring conditions. The wall thickness of the foil material used is responsible for low back pressure and high engine performance. The greater geometrical surface area of metallic substrates and hot tubes in combination with structured surfaces offers the automotive industry an opportunity to reduce catalyst volume. Simple, economical canning methods are a field of special interest in the automotive industry. These advantages combined allow metallic substrates a significant market share in automotive applications.

From SAE-Papers and several publications, the easy, effective function and management of an EHC-System is well known. The direction of the development is now to reduce the electrical energy consumption and to show the mechanical durability of the heating structure. This paper shows that it is possible to minimize the energy consumption and that the required service life can be in principle achieved with the introduction of these developments. The physical characteristics such as mass, geometrical surface area, cell density and electrical resistance of the EHC construction could be optimized to save energy. This, in conjunction with the operating parameters of the engine, the controlling of the secondary air and the catalyst configuration, will enable the goals to be met. The design of the converter, the physical characteristics and the results of the tests are shown with the Porsche 944 S2 and 968 applications.

Metal supported catalysts, whose early development actually started in the sixties, are used today in a few isolated cases as starter catalysts, retrofit and underfloor catalysts of small dimensions. The new Porsche Carrera 4 is the first production car to use a large main catalytic converter with metal supports. This paper describes the design of this catalyst and the advantages of using the metal supports, especially the increase in power output due to the reduction of exhaust back pressure. Also benefits in catalytic performance could be determined. The major requirement in using large metal supports in production is mechanical sturdiness. In extensive vehicle, test bench and laboratory tests and according to the theoretical calculations, the support with S-design described here has met this requirement.