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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.

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.