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When a vehicle is in motion, noise is generated in the cabin that is composed of noise in multiple narrow-frequency bands and caused by input from the road surface. This type of noise is termed low-frequency-band road noise, and its reduction is sought in order to increase occupant comfort. The research discussed in this paper used feedback control technology as the basis for the development of an active noise control technology able to simultaneously reduce noise in multiple narrow-frequency bands. Methods of connecting multiple single-frequency adaptive notch filters, a type of adaptive filter, were investigated. Based on the results, a method of connecting multiple filters that would mitigate mutual interference caused by different controller transmission characteristics was proposed.

This paper introduces a minivan with a newly developed hybrid system known as THS-C (The Hybrid System - CVT). This hybrid system employs a highly efficient engine, a high performance exhaust emission control system, a high efficiency metal belt CVT, and a super efficient motor. System control of the engine, motor and CVT optimizes the operation of both the motor and the engine. With these improvements, this new vehicle achieves over 80% better fuel economy than a comparable conventional vehicle. Exhaust emissions are dramatically reduced using precision control during the engine starts and stops.

In order to satisfy future demands of low exhaust emission vehicles (LEV), a new fuel injection control system has been developed for SI engines with three-way catalytic converters. An universal exhaust gas oxygen sensor (UEGO) is mounted on the exhaust manifold upstream of the catalytic converter to rapidly feedback the UEGO output signal and a heated exhaust gas oxygen sensor (HEGO) is mounted on the outlet of the converter to achieve an exact air fuel ratio control at stoichiometry. The control law is derived from mathematical models of dynamic air flow, fuel flow and exhaust oxygen sensors (HEGO and UEGO). Experimental results on FTP (Federal Test Procedure) exhaust emissions show a dramatic reduction of HC, CO and NOx emissions and a possibility of practical low emission vehicles at low cost.