Takehisa Yaegashi

A Multi-Dimensional Numerical Method for Predicting Warm-Up Characteristic of Automobile Catalytic Converter Systems

A multi-dimensional numerical method for predicting the warm-up characteristic of automobile catalytic converter systems was developed to effectively design catalytic converter systems which achieve low tail pipe emissions with satisfactory package ability. The features of the method are: (1) consideration of the governing phenomena such as gas flow, heat transfer, and chemical reactions and (2) capability of predicting warm-up characteristic for not only the catalytic converters but also the system as a whole during emission test modes such as the USA LA-4 mode. The description of the method is presented. The experimental verifications of the method were conducted to assure the accuracy of it. The effect of design parameters such as electrically heated catalyst (EHC), high loading of noble metal and thin honeycomb wall on warm-up characteristic of the catalyst are analyzed in the paper.

Measurement of Flame Temperature Distribution in Engines by Using a Two-Color High Speed Shutter TV Camera System

A two-color high speed shutter TV camera system has been developed as a new sensing device for measuring the flame temperature in engines. The TV camera system can measure the radiant intensities of high temperature substances accurately and rapidly. And, the two-dimensional temperature distribution can be easily calculated from the radiant intensities by using an image processor. This system is applicable to measurement of flame temperature in diesel and gasoline engines. The relation between the progress of combustion phenomena and the measured temperature distribution is clearly explained. It is confirmed that the system is effective for measurement of the flame temperature distribution in engines.

Study of divided converter catalytic system satisfying quick warm up and high heat resistance

Catalyst specifications and converter layouts were studied to identify the high conversion performance under various in-use driving conditions, high mileage intervals and extended life cycle. The effects of volumes, configuration, selection and loading distribution of precious metals, additive components and substrate type for catalyst were studied on engine dynamometers and vehicle tests to optimize a catalyst converter system. Moreover, model gas experiments were conducted to analyze deterioration mechanisms and conversion characteristics of catalysts. As a result, the concept of a divided catalyst converter system, which provides separate functions for a close-coupled and an under-floor catalyst, was found to be effective for the future exhaust system. For reducing HC emissions, the close-coupled catalyst should warm up quickly and resist a high temperature. The under-floor catalyst, located at a rather low temperature position, is durable and maintains high NOx conversion.

Analysis of fuel and combustion behavior during cold starting of SI gasoline engine

Abstract In order to reduce hydrocarbon emission from spark ignition engines, it is important not only to improve catalyst conversion efficiency but also to reduce directly engine-out hydrocarbon emissions during cold starting and warming-up processes. This paper quantitatively analyzes the fuel behavior during the cold starting process of a modern production engine. Using a specially designed analytical method, cycle-by-cycle behavior of required fuel amount for stable startability and engine-out hydrocarbon were observed. Further, using a specially designed analytical engine with intake and exhaust values driven by hydraulic control, the fuel amount of intake port and cylinder wall-wetting, burned fuel and engine-out hydrocarbon emissions at the first cycle were measured. The effect of fuel properties and fuel atomization were analyzed and characteristics of engine-out hydrocarbon emissions during this process were observed.