Search Results

The optimization on an engine-three way catalyst-vehicle system for best fuel economy under the constraints of emissions and driveability, has been studied for a smaller passenger car with 1.6 litter 4 cylinder engine. Full utilization of a computer was intended for the accumulation of basic data and a search for optimum calibration. An automatic Engine Test System ( AETS ) was developed. The optimum calibration was calculated for the engine-vehicle system with three-way catalyst based on the optimal control theory, and was implemented on an actual vehicle by an engine controller in which a 16 bits microprocessor was used. The results showed good agreement.

Four combustion chamber designs and three compression ratios (8:1, 9:1, and 10:1) were investigated for their emission, fuel economy, and octane number requirement characteristics using a 1.6 L (96.9 CID) 4-cyl engine. Time resolved measurement of hydrocarbon emissions was carried out to clarify the reason for differences in tail pipe emission between these combustion chambers. The “High Turbulence Type” combustion chambers, which included swirl (piston swirl) and/or squish, indicated better fuel economy under emission and octane number requirement constraints. The HC emission of the combustion chamber with squish and swirl was lower than that of the combustion chambers with squish alone. The time resolved measurement of HC emissions explained the difference in the exhaust process of these unburned hydrocarbons.

A reliability analysis was conducted by means of the failure mode effect analysis technique on the catalytic converter which has been adopted in the 1975 Toyota models. A series of vehicle tests was conducted to determine the failure modes criticality. The study was performed on a precious metal pelleted catalyst. Critical durability failure modes to the durability of the catalytic converter and their criticality were classified and substantiated through this study. The results are presented and discussed. The results obtained by this analysis are useful for improving the reliability of the catalytic converter.

The status of Toyota's development of low emission concept packages- 1. NOx and HC/CO Catalytic Converter and EGR, 2. Thermal Reactor, NOx and HC/CO Catalytic Converter and EGR and their components is described. Variations of thermal reactor design, performance and durability characteristics are discussed. Above the throttle valve entry EGR has been found to have desirable flow characteristics with a simple control system. EGR rate over 15% brings about unacceptably poor driveability and fuel economy with smaller vehicles. Many types of catalytic converters for pelleted catalysts have been designed and examined for their performance and durability. A down-flow type converter has relatively good flow distribution and warm-up characteristics. As for HC and CO, a few prototype vehicles have met the 1975 Federal Regulation at low mileage, but the 1976 regulation for NOx of 0.4 gm.