Variable compression ratio system using a free piston
-A new mechanism that enables the Atkinson cycle-

Tomoaki Sato (Kanagawa Institute of Technology)･Tatsuro Kitahara (Shonan Institute of Technology)

This study proposes a novel internal combustion engine system that enables variable compression ratios even during engine operation by employing a free piston installed inside the cylinder. The proposed system realizes the Atkinson cycle without requiring a complex mechanical structure, enables optimal control according to operating conditions, and demonstrates the potential for creating a new thermodynamic cycle.

Research on a Small Two-Stroke Uniflow-Scavenged Opposed-Piston Engine

Ryoma Otsuki･Kai Araoka･Takumi Okuyama･Ikumi Okawara･Yoshiaki Yamazaki･Akira Iijima (Nihon University)

In recent years, while the proliferation of electric vehicles (EVs) has advanced in tandem with decarbonization initiatives, internal combustion engines have garnered renewed attention due to lingering challenges such as driving range limitations and charging infrastructure deficits. Under these circumstances, there is a growing demand for high-efficiency engines that depart from conventional design paradigms. To address this need, this study focuses on power-generation engines and investigates a two-stroke opposed-piston engine.

Comparative Study of Measurement Methods for Engine Efficiency Benchmarking in Hybrid Vehicles

Sukjoo Kim･Youngkuk An･Byungsoon Min (Tenergy)

Engine efficiency is a critical factor in determining fuel economy performance of hybrid vehicles, making accurate benchmarking of competitor vehicles essential for guiding development decisions. Three evaluation methods were investigated: a simplified estimation approach using engine torque acquired via CAN communication, a calculation method based on fuel flow meter and combustion pressure data, and a direct measurement approach with a torque sensor installed between the engine and transmission while connected to the vehicle. The measurement accuracy and practical applicability of each method were evaluated through mutual comparison of the engine efficiency results obtained.