Kenji Matsunuma

Development of Diesel Particulate Filter Made of Porous Metal

Pollution is worsening in cities. The exhaust gas from vehicles is the main cause of air pollution in cities. The major drawback of the diesel engine is the Particulate Matter (PM) contained in the exhaust fumes which is also said to lead to cancer. For about 20 years many tests have been conducted in order to reduce PM in diesel exhaust gas. However the exhaust gas in present diesel engines contains a significant amount of PM. This is because there is no practical material for the Diesel Particulate Filter (DPF). Conventional ceramic materials have problems such as cracking and melting during regeneration and conventional metal materials lack adequate corrosion resistance for practical use. The authors present a new type of DPF made of metal porous matter (Celmet) which is designed with a thermal construction and simple control system in order to solve the problem of diesel exhaust gas. As metal porous matter has low pressure loss per unit filter area during filtering, two-cylinder filters have similar trapping performance to the honeycomb type filter such as pressure loss and trapping efficiency, In this paper, 2,800--3,400cc diesel engines were used. Then a cycle of collection and regeneration with an electric heater andmorexa0» 12V battery was performed under several conditions on the engine bench and trapping efficiency and pressure loss were measured. It was confirmed that this new type DPF has good practical use in automobiles. Tests on forklifts were also performed. In a simple control system, this DPF can be applied to practical use. It is trouble-free for 6 months. The total performance of DPF for vehicles such as forklifts and heavy duty vehicles and the possibilities for other practical uses was mainly discussed.«xa0less

Study on Electrolytic Re-Insulation Grinding of Soft Magnetic Powder Cores

Soft magnetic powder cores are used for electromagnetic conversion coils, which are essential parts in automotive, home appliance, and other electronics industries. These cores are manufactured through the process of compacting pure iron powder covered with an insulation layer, and are distinguished by high electromagnetic conversion efficiencies. However, soft magnetic powder cores suffer from one problem: their electromagnetic conversion efficiencies drastically decrease when they are subjected to conventional finishing processes. This is directly attributable to the formation of conductive layers on finished surfaces, which significantly reduce the electrical resistance of material surfaces. As a solution to this problem, we developed an electrolytic re-insulation grinding method that finishes materials while applying a current between the material and the grinding wheel. This method regenerates the insulation properties of soft magnetic powder cores through the electrolytic removal of conductive layers formed during finishing, thereby improving electrical resistance. This development enables the finishing of soft magnetic powder cores without compromising their electromagnetic conversion efficiencies.

Development of a high-strength Si3N4 sintered body☆

Due to its heat-, wear- and corrosion-resistant properties, Si3N4 ceramic is a promising material for cutting tools and other wear-resistant products, and for automotive engines, gas turbines, and other structural items. Sumitomo Electric has successfully developed sintered bodies (σ1 = 130 to 150 kg/mm2 at room temperature) with high strength by controlling grain shapes grain diameter and aspect ratio. The high strength Si3N4 materials have fracture toughnesses of KIC = 5–7 MPa/m, thermal shock resistance of ΔT = 9000°C, good acid-resistant properties, and other properties all superior to those of conventional Si3N4 materials. Highly reliable Si3N4 materials with high Weibull modulus (m > 20) have also been developed by reducing metal inclusions that would cause defect factors leading to breakup. The high strength Si3N4 is already in practical use for plastic machining tools for non-ferrous metals (Al, Cu alloys), forging tools, and other wear-resistant products and structures of steel facilities. It is also being used for automotive parts and other items requiring high reliability. The high strength Si3N4 sintered bodies fully satisfy the requirements of these products.

Study on the High-Efficiency Smoothness Grinding of Soft Magnetic Powder Cores

Soft magnetic powder cores are materials manufactured by pressing pure iron powder covered with insulating film into shape. These are widely known soft magnetic materials which are used as essential electromagnetic conversion parts in automobiles and household appliances. In recent years, demand for higher magnetic properties and dimensional precision has been growing with respect to soft magnetic powder cores. It has therefore become necessary to develop a high-efficiency, high-precision finishing method. The issues to be addressed with regard to this kind of method are: (1) the pure iron used in these materials displays ductility resulting in burring and cohesion to machining tools, (2) these materials are green compacts with low binding forces between powder particles and high tendencies towards cracking and gouging, and (3) these materials possess residual pores at levels of several percent thus resulting in microscopically intermittent processing which causes heavy machining tool wear. We have solved these issues through the development of a super-smooth finishing method designed for soft magnetic powder cores.