For a quick reach to the operating temperatures, the three way catalytic converter is recently located closer to the engine and subjected to higher temperatures than before. At the same time, the three way catalytic converter has upper thermal limits. Therefore, the operating temperatures have to be estimated accurately in the early period of product development. In this research, the four analysis methods are linked with the one-dimensional engine cycle simulation to achieve the goals.
Firstly, for the estimation of gas temperatures at the exhaust port of the engine, the combustion analysis using the 3D-CFD was conducted to accurately simulate the way the heat was generated. Then, for the estimation of heat dissipation from the exhaust system to the atmosphere, the heat conduction analysis coupled with the air flow analysis around the vehicle body using the 3D-CFD was conducted. To take into considerations the heterogeneity of reactions in the three way catalytic converter, the gas flow in the exhaust pipe was also analyzed using the 3D-CFD. As the last step for estimation of temperatures in the 3-way catalysis, the reactions in the catalysis were analyzed to take into account the heat generated by the oxidation of unburnt hydrocarbons promoted by the catalysis.
The correlation between the estimation by this method and the actual measurement was taken in the five models having various engine configurations such as the number of cylinders and cooling methods, and vehicle configurations such as the scooter and the motorcycle. It has consequently been confirmed that this method allows estimation of temperatures in degrees Celsius inside the three way catalytic converter at higher temperatures as accurately as a maximum error of 5%. Thus, enabled is an accurate evaluation of parts layout to satisfy the heat resistance requirements of the three way catalytic converter at higher temperatures.