Effect of Engine Oil Containing Ultrafine bubbles on Reduction of Friction Loss in Piston-Cylinder System
-Influence of cylinder bore honing specifications and lubricant viscosity-

Kai Horiba (Graduate School of Tokyo City University)･Yuji Mihara (Research Center for High Hydrogen Engine Tribology HEET Tokyo City University)･Syusuke Hoshino･Takumi Iwata (Graduate School of Tokyo City University)･Masakuni Oikawa (Research Center for High Hydrogen Engine Tribology HEET Tokyo City University)

The effect of nanoscale ultrafine bubbles (UFB) generated in engine lubricating oil by the ultra-fine hole method on reducing friction between the piston and cylinder was investigated. Friction force measurements using a floating liner engine showed that UFB reduces FMEP due to the bubble density. In this study, the relationship between the friction reduction effect was verified by changing the cylinder honing specifications and oil viscosity.

Reduction of Engine Bearing Friction with Engine Oils Containing Ultrafine Bubbles
-Effect of generation density and oil viscosity-

Shusuke Hoshino･Kai Horiba･Takumi Iwata (Graduate school of Tokyo City University)･Masakuni Oikawa･Yuji Mihara (Research Center for High Efficiency Hydrogen Engine and Engine Tribology (HEET), Tokyo City University)

The effect of ultrafine bubbles generated in engine oil on the friction characteristics between the crank journal and plain bearing was verified using an engine bearing testing rig. In this study, the effect on friction reduction was investigated by changing the ultra-fine bubble density and oil viscosity in engine oil.

Influence of Piston Design Parameters on Oil Film Volume at Piston-Cylinder Interface

Yasuhiro Ishikawa･Ruka Matayoshi･Akemi Ito (Tokyo City University)･Kenichi Yamashita (Isuzu Advanced Engineering Center)

Understanding the lubrication oil supply mechanism to a piston-cylinder interface is crucial for predicting its lubrication performance through numerical analysis. This study aims to investigate the influence of piston design parameters on oil supply. Using a visualized single-cylinder engine, the oil film volume, which strongly correlates with the supplied oil quantity, was measured. The relationship between skirt geometry and oil film volume was clarified.

A Study on Water Evaporation Characteristics from Emulsified Oil in a Hydrogen Engine

Akemi Ito･Itsuki Motomiya･Daisuke Hiyama･Ryosuke Ichimura (Tokyo City University)

Hydrogen engines produce more water than conventional fossil fuel engines. It was shown in our previous report that oil emulsification occurred during vehicle operation in winter and the correlation between the water content in oil and the period when oil temperature exceeds the dew point. This paper will discuss the results of unit tests conducted to investigate the time and temperature required for water to evaporate from emulsified oil.

Study of Fuel-Efficient Engine Oil for Automobiles Using Re-Refined Base Oil (RRBO)

Yuta Watanobe･Takumaru Sagawa･Kiyoshi Hanyuda･Ayano Otsuka (Shell Lubricants Japan)

As a countermeasure against climate change, the automotive industry is required to reduce CO2 emissions; thus, introduction of low-viscosity, fuel-efficient engine oil is being promoted. Meanwhile, the use of re-refined base oils (RRBO) obtained by recycling the used lubricants are being adopted around the world. The performance of fuel-efficient engine oils for automobiles using RRBO would be reported in this presentation.

Development of the flat low viscosity engine oil JASO GLV-2 0W-16

Shunsuke Nara･Junichi Sudo･Kazuo Yamamori･Yuta Uematsu･Satoshi Hirano･Noriya Ishizaki･Atsuhisa Tamano (Toyota Motor)･Shogo Eryu･Yushi Kato (ENEOS Corporation)

Achieving carbon neutrality necessitates significant reductions in CO2 emissions and enhancements in fuel efficiency.
To address this challenge, we have developed a fuel-efficient flat viscosity oil by utilizing advanced low-viscosity base oils and viscosity index improvers.
Our formulation enhances fuel efficiency across low to medium temperature ranges while maintaining reliability at high temperatures.
Furthermore, this oil meets the new engine oil quality standard, JASO GLV-2, and is expected to effectively reduce CO2 emissions in both new and existing vehicles.

Relationship Between Degradation of Additives in EV Fluid and Friction Properties

Toshimitsu Numata･Sawa Araki･Yuriko Fujii･Kiyotaka Nakamura (Nissan ARC)

In this study, EV fluid was oxidatively degraded.
The degradation of the additives was analyzed by LC-MS, IR, and GC-MS.
In addition, friction properties were evaluated using a ball-on-disk type friction tester, and sliding surfaces were analyzed by TOF-SIMS and AES.