A Study on Predicting Backpressure in Mufflers with Exhaust Variable Valves

YUNJEONG SHIM･JAEYEON JO･YONGWOO MO (Hyundai Motor)･JEONGSU KOO･JINMAN SHIN (Sejong)

This study proposes an integrated methodology for predicting the backpressure performance of mufflers equipped with variable valves by combining experimental and analytical approaches. An airflow rig-based evaluation system was developed to replicate internal combustion engine (ICE) and hybrid electric vehicle (HEV) operating conditions. To enhance one-dimensional (1-D) simulation accuracy, a novel parameter extraction technique was introduced. Furthermore, the influence of thermal aging on valve spring torque was investigated, revealing its significant impact on backpressure characteristics. The proposed approach improves the correlation between simulation and experimental results, enabling more accurate backpressure predictions. This advancement supports optimized exhaust system design and reduces development time during the early stages of vehicle development.

Development of a Hydrocarbon Pyrolysis Model Considering Catalyst Deactivation Behavior

Akiko Miura･Toshiaki Sakima･Hirotsugu Matsuda･Yuji Harada (Mazda)

In the development of technologies for carbon recovery from hydrocarbon fuels, it is essential to construct a model that quantitatively represents the hydrocarbon pyrolysis reaction. During pyrolysis, H₂, CH₄, and carbon are generated, and carbon accumulates on the catalyst surface, leading to deactivation and eventually reaction termination. To reproduce this phenomenon, we developed a model that incorporates both pyrolysis rates and the progression of deactivation, based on experimental results.

Key technology of brand-new 1.5L 3 cylinder engine for 3rd generation series hybrid powertrain (1st report)
-Development of combustion design technologies-

Isei Matsuzaki･Yukiyo Yamada･Akihiro Shikata (Nissan Motor)

Development of a new 1.5L engine focused on improving thermal efficiency through high-speed combustion, extensive EGR, and a high compression ratio. The characteristics of 100% electric drive, which allow the engine operating range to be limited, were utilized to enable combustion technologies optimized for these conditions. This paper presents these technologies and their performance evaluation results.

Key technology of brand-new 1.5L 3 cylinder engine for 3rd generation series hybrid powertrain (2nd report)
-Fuel economy improvement-

Taichi Ando･Isei Matsuzaki･Akihiro Shikata･Yukiyo Yamada (Nissan Motor)

In developing a brand-new 1.5L engine, average thermal efficiency was introduced during on-vehicle driving as an index of fuel economy. This efficiency was improved through control that leverages characteristics of an electric power generation-dedicated engine to achieve optimal operating points considering an improved warm-up temperature profile.