Development of New Generation Hybrid Transaxle for Mid-Size SUV

Hirokazu Arai･Shinichiro Suenaga･Kohei Shimayabu･Junichiro Yasui･Yuji Yamaya･Keisuke Yuki･Hiroki Kato (Toyota Motor)

To achieve carbon neutral, we have developed a PHEV system for the new RAV4 as an electric vehicle option tailored to energy conditions and customer needs. By reconsidering the arrangement of high-voltage components, the system has been significantly downsized and lightened. In particular, this introduction focuses on the technologies behind the major improvements in the transaxle, including its miniaturization, weight reduction, and loss reduction.

Development of High-Performance e-Axle Oil

Kazunori Ishigami･Gou Kato･Makoto Maeda (JATCO)･Ryo Sasaki･Hitoshi Komatsubara (ENEOS)

The evolution of electric vehicles toward longer range and improved performance necessitates compact, high‑power, highly efficient e‑axles. Improving motor and gear performance, in turn, requires e‑axle lubricants that offer excellent heat dissipation and high lubricity. In this study, we developed an industry‑leading low‑viscosity oil that satisfies these requirements.

Consideration on Lubrication of High-Speed Rotating Gear (Fourth Report)
-Parametric Study using a Lubrication Device-

Kazuki Sakai･Tomoyuki Hara･Tetsuya Sato･Junji Yamada･Kensuke Suzuki･Naohiro Fujita･Masayoshi Ohno (Univance)

Based on our previous findings, we have developed an efficient lubrication system that utilizes the suction airflow generated at the end of meshing in high-speed rotating gears, and have reported its effectiveness. In this study, as part of an adaptability assessment aimed at future mass production, we conducted a parametric study to examine the design conditions of the lubrication device. This presentation introduces a portion of those results.

Influence of Lubrication Direction on Cooling Performance in High-Speed Traction Drives and Observation of Oil Film Behavior

Shunki Boku･Yuki Kawamoto･Shunichi Tajima･Masayuki Ochiai (Tokai University)

Traction drives at high peripheral speeds are attracting attention as reduction mechanisms for electric vehicles, but thermal cooling under high-speed operation remains a major issue. This study measured roller surface temperatures under different lubrication directions and confirmed that 'disengagement lubrication' provides superior cooling performance. Additionally, oil film flow was visualized to qualitatively investigate the mechanisms behind enhanced cooling in the 'disengagement lubrication' and to support a foundational understanding of the observed thermal behavior.

Method of Simultaneous Multi-Point Instantaneous Contact Pressure and Temperature Measurement on Gear Tooth Surfaces Using by Thin-Film Sensors

Yuji Mihara (Tokyo City University)･Michiyasu Owashi･Takumi Iwata (MOTORA)

Understanding the direct contact load and temperature distribution of gear units, which are essential for power transmission in drivetrains, is crucial. Therefore, we introduce application examples of thin-film sensors and previous measurement cases that enable these measurements using thin-film sensors.

Reducing Life Cycle CO₂ Emissions and Battery Cost in BEVs through Bearing Friction Loss Minimization

Franz Voelkel (Schaeffler Technologies)･Seiya Nishizawa･Ken Sakaguchi (Schaeffler Japan)･Volkhard Walther･Johannes Kerstiens (Schaeffler Technologies)

Bearing losses add up to a significant share of overall vehicle power losses. On the one side, this influences the downstream emissions, on the other side a BEV's upstream emissions are heavily affected well as a certain capacity of the battery is only needed to feed these losses. Every piece of energy which is not lost to friction doesn't have to be stored in a battery. This lecture discloses the hidden potentials in mechanical power loss reduction, especially for bearings, by means of power density increase, on-the-point optimization and drag loss minimization.