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A diesel particulate filter (DPF) using porous metal for a filter, due to its high thermal conductivity, and a radiation heater for a regeneration device, due to its uniform distribution of temperature, has been developed. When high trapping efficiency is required, filter thickness should be increased. However, the thicker filter has a problem of low regeneration efficiency caused by the declination of temperature in the direction of thickness in the filter. In order to improve regeneration efficiency, a filter-heater structure which achieves uniform distribution of temperature was designed by using computer simulation and confirmed good regeneration efficiency of this structure in the experiment.

In order to reduce the amount of particulate matter (PM) in the exhaust gas of diesel engines, a dual flow type diesel particulate filter (DPF) system made of porous metal filters has been developed. In this paper, the development and the evaluation results will be discussed. The test results on the engine bench and the vehicle have revealed good performance of the DPF system and have practical application for urban buses.

We have developed a new type of system to prevent disc brake squealing. The rotor vibration radiates the squeal noise, therefore if the rotor vibration can be stopped electronically, no squeal is generated. Based on this concept, the Electronic Control Canceling System for a Disc Brake Noise ( ECCN ) was developed for the opposed type brake which has four brake pistons. The ECCN consists of four piezoelectric elements and one electronic control unit, and can stop the low-frequency squeal of 2∼4kHz by using a small amount of energy with the noise dynamometer and the test vehicle.

We have developed a new Carbon/Carbon composite (C/C) manufacturing process called the “Carbon Powder Sintering Method [1] (C.P.S.M.)”. This study was conducted to evaluate the friction characteristics of C/C manufactured by the C.P.S.M. as compared with C/C manufactured by conventional methods using a dynamometer. In general, C/C shows a high friction coefficient at a high temperature, but shows a low friction coefficient at room temperature. There is a transition temperature point between both friction coefficients. As a result of this study, it was found that the transition temperature of the C.P.S.M. C/C is lower than for any other conventional C/C.

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.