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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.

DPF substrate is exposed to high temperature during regeneration and to acid components in exhaust gas. Therefore, DPF material needs to have an excellent thermal shock resistance, thermal and chemical stability to the sulfuric acid. This paper presents the durability test results of the Si-SiC DPF material. In particular, thermal shock resistance, oxidation resistance and acid resistance parameters have been evaluated by comparison with recrystallized-SiC and cordierite materials. As the results, the strength of Si-SiC decreased between ΔT=500 and 600deg.C, while that of recrystallized-SiC decreased between ΔT=300 and 400deg.C. The result is attributed to the difference in the elastic modulus. About oxidation resistance, material properties of Si-SiC, compared between pre- and post- oxidation, have greater stability than those of recrystallized SiC. And naturally, both SiC materials have superior acid resistance to cordierite.

It is well known that an EHC (Electrically Heated Catalyst) is very effective in reducing cold start HC emissions. However, the large electric power consumption of the EHC is a major technical issue. When installed in the exhaust manifold, the EHC can take advantage of exhaust heat to warm up faster, resulting in a reduced electric power demand. Therefore, a structurally durable EHC which can withstand the severe manifold conditions is desirable. Through the use of a extruded monolithic metal substrate, with a flexible hexagonal cell structure and a special canning method, we have succeeded in developing a structurally durable EHC. This new EHC installed in the exhaust manifold with a light-off catalyst directly behind it demonstrated a drastic reduction in FTP (Federal Test Procedure) Total HC emissions.

The electrically-heated catalyst ( EHC ) has been established as an effective technology for lower-emission regulations. High electrical power consumption was a major concern for the EHC system in the past. This issue was addressed through the development of the EHC design and the alternator-powered EHC system combined with a light-off ( L/O ) catalyst. The subsequent challenges have been to prove the EHC's reliability and durability. NGK has developed a durable, extruded EHC for very severe exhaust system installations. In addition, the EHC's electrical connector system is required to meet high performance and reliability objectives under extreme environmental conditions unique to this application. This report describes the design concept of NGK's EHC including our new electrical connector system and durability results. In summary, the NGK EHC design concept has been confirmed to have excellent durability performance.

This paper describes a newly-developed, high-performance RTD,(Resistive Temperature detector), which meets OBD-II monitoring requirements. The OBD-II catalyst monitoring requirements are high temperature durability, high accuracy, and narrow piece-to-piece variation. Catalyst monitoring methods have been reviewed and studied by checking the catalyst exotherm(1)(2). The preliminary test results of catalyst monitoring are also described herein.

Japan’s recent dominance of the international auto industry does not result from some major single factor, such as technological superiority or advanced automation. It derives from twenty years of building flexible, durable industrial systems integrating assemblers, suppliers, and related companies. Current competitive advantages result from combinations of seemingly unrelated company, government, and labor practices. Japan’s position of leadership will instigate major changes in international labor forces, corporate strategies, and government policies, as former auto powers adapt to new competition, and simultaneous shifts in energy and economics.

This paper describes the design and property of an electrically heated zirconia exhaust gas oxygen sensor having small-sized and sheet-shaped sensing element. Sensing element and sensor have been miniaturized by monolithic formation of sensing element and heater by means of thick-film techniques. The difference in response property according to the angle of the electrode to exhaust gas flow because of the sheet-shaped configuration of sensing element was minimized by proper design of protective cover. Similarity in λ control property and limit cycle frequency was demonstrated with heated zirconia oxygen sensor having test tube-shaped sensing element by engine dynamometer durability test over 120,000 equivalent miles.