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Due to its better fuel efficiency and low CO2 emissions, the number of diesel engine vehicles is increasing worldwide. Since they have high Particulate Matter (PM) emissions, tighter emission regulations will be enforced in Europe, the US, and Japan over the coming years. The Diesel Particulate Filter (DPF) has made it possible to meet the tighter regulations and Silicon Carbide and Cordierite DPF's have been applied to various vehicles from passenger cars to heavy-duty trucks. However, it has been reported that nano-size PM has a harmful effect on human health. Therefore, it is desirable that PM regulations should be tightened. This paper will describe the influence of the DPF material characteristics on PM filtration efficiency and emissions levels, in addition to pressure drop.

This paper is Part-1 of two papers discussing the filtration behavior of diesel particulate filters. Results of the fundamental study are presented in Part-1, and test results for real size DPFs are reported in the supplement, Part-2. In this paper, a fundamental experimental study was performed on the effect of pore size and pore size distribution on the PM filtration efficiency of the ceramic, wall-flow Diesel Particulate Filter (DPF). Small round plates of various average mean pore sizes (4.6, 9.4, 11.7, 17.7 micro-meters) with a narrow pore size distribution were manufactured for the tests. During the DPF filtration efficiency tests, ZnCl2 particles in the range of 10 nm to 500 nm were used instead of PM from actual diesel engine exhaust. ZnCl2 particles were made using an infrared furnace and separated into monodisperse particles by DMA (Differential Mobility Analyzer).

Modern filter systems allow a significant reduction of diesel particulate emissions. The new silicon bonded silicon carbide particulate filters (Si-SiC filters) play an important role in this application, because they provide flexibility in terms of mean pore size and porosity and also have a high thermal shock capability to meet both engineering targets and emission limits for 2005 and beyond. Particulate filters are exposed to high temperatures and a harsh chemical environment in the exhaust gas of diesel vehicles. This paper will present further durability evaluation results of the new Si bonded SiC particulate filters which have been collected in engine bench tests and vehicle durability runs. The Si-SiC filters passed both 100 and 200 regeneration cycles under severe ageing conditions and without any problems. The used filters were subjected to a variety of analytical tests. The back pressure and ash distribution were determined. The filter material was also analysed.

The future emission limits for gasoline fuelled passenger cars require more and more efficient exhaust gas aftertreatment devices - the catalytic converter being one essential part of the complex system design. The present paper summarizes the results of several basic research programs putting major emphasis on the application of highly sophisticated three-way catalyst technologies being taylored for the utilization on ultra thin-wall ceramic substrates. In the first part of the investigation the following effects were examined in detail: Different washcoat loadings at constant PGM-loadings Different volumes of catalysts for constant amounts of PGM and washcoat Similar washcoat technologies at different ratios of WC-loading to precious metal concentration in the washcoat.

The application of Diesel Particulate Filters (DPF's) is expanding in the European, Japanese and US markets to comply with the tighter PM regulations. SiC DPF's, featuring greater robustness, have been applied extensively to passenger cars and are expanding into larger sizes for Light Duty Trucks applications. The SiC-DPF has higher mechanical strength when compared to other materials, such as Cordierite. However, SiC's thermal expansion ratio is greater. Therefore, the SiC-DPF is designed with 35 X 35mm segments and cement bonded construction, both of which function to relieve thermal stress. The appearance of the SiC-DPF with the segment design is shown in Figure 1. In this paper, the thermal stress mechanism of the segmented joint during soot regeneration and the influence of the cement properties on the thermal shock resistance was investigated by using the soot regeneration model and thermal stress analysis in addition to the engine test.