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Since the engine noise of a small portable single cylinder 2 or 4 cycle gasoline engine exceeds 100 dB (A), making the reduction of noise levels is very important. Conventional noise reduction measures have been to expend the pulse flow energy of the exhaust gas even at some sacrifice of engine performance, that is, resistance is introduced to lower the flow rate. Recently, we have developed a carbon fiber felt from coal tar pitch, which shows high resistance to oxidation and physically and chemically stable properties, and used it in the exhaust muffler and in the bottom of the engine crankcase, enabling the reduction of noise emitted from the engine package by approximately 3 dB (A). Compared with rock wool and glass wool, this carbon felt has the superior characteristics of (a) lower mass and (b) larger surface area per unit weight (1)*.

The air cleaning device in this study consists of a stainless steel mesh used to negatively charge dust particles at the inlet and metal-coated fabric filters to collect the dust at 12, 24, and 48 volts. This device can replace the currently commercialized dust collector (which requires 6,000 volts for generating corona discharge), which could not be installed in motor vehicles due to its high voltage and generation of ozone. The test results show the device performs equally as well as the device with high voltage and could be comfortably applied to clean air in cars during their operation.

When a heavy duty truck with 2 rear axles is turning a curve at slow speed, a large side bending force to the chassis frame occurres as vehicle turning radius becomes smaller. In the past, the stress produced by side bending forces was little analyzed. By our research work of FEM, side bending stress of heavy duty truck could be analyzed accurately.

Automobile and motorcycle mufflers, installed in a restricted space, must effect noise reduction without interfering with engine efficiency. Experiments were performed in this study, using heat-resistant epoxide resin in place of expandable steel as the material for the muffler of a gasoline engine exhaust system. The findings show that use of heat-resistant epoxide resin as the material for a portion of a gasoline engine exhaust system i.e., : the muffler, results in noise reduction, even in a restricted space. This resin is also effective in bringing about weight reduction, vibration reduction and rust-proofing, and is expected to contribute to reduction of back pressure in exhaust piping systems.

Evidence has been obtained in this study to indicate that the hybrid muffler made up of heat-resistant thermosetting resin, ceramic paper, and carbon fiber felt used as a noise absorbing material, can reduce the noise without any compromise in engine performance. Further, it has been confirmed that a highly reliable muffler may be designed using this approach.

This study relates to the simultaneous reduction of NOx and soot exhausted from Direct Injection Diesel Engine. With use of the surface treated carbon fiber, NOx is significantly reduced through the adsorption and chemical conversion into N2 and CO2. With use of stainless steel nets connected with the cathode and electro conductive material composed of Cu coated cloth, carbon fiber and stainless steel net connected with anode of the car battery, soot is collected electrically and is easily removal and combustible into CO2. The test result operated with 500 ml D.I. Diesel Engine shows excellent performance of NOx and Soot at more than 50% reduction with the long recycle life of the used material.

EGR system is considered to be the most effective way of reducing the pollution, especially NOx, from diesel engine exhaust gas. However, EGR system is hampered by soot accumulation. In this study, a low-voltage soot removal device was installed at the air inlet in the EGR system. Measurements made with a Bosch smoke meter indicated that use of this device resulted in about a 50 - 84% reduction of soot, which would enable continuous use of EGR in diesel engines. The soot accumulated at the filter was easily removable and combustible into CO2.

In this study, the test results of commercialized 2 ton cargo truck on road for 6 months, are reported using the soot removal equipment at low voltage and with a short regeneration time. The equipment consists of using commercial truck battery, changing electrically neutral soot to negative charged soot. It adsorbs charged soot electrically with the metal mesh connected to positive pole and washes the soot with liquid detergent, during the cutting off of electric source. The removal of the accumulated soot was completed within two minutes, with 100% regeneration.