eJournals International Colloquium Tribology 23/1

International Colloquium Tribology
ict
expert verlag Tübingen
125
2022
231

Novel Defoamers for Use in Low Viscosity Elecric Vehicle Fluids

125
2022
Noriko Ayame
Akira Takagi
Go Tatsumi
ict2310157
23rd International Colloquium Tribology - January 2022 157 Novel Defoamers for Use in Low Viscosity Electric Vehicle Fluids Noriko Ayame ENEOS Corporation, Lubricants R&D Dept, Yokohama, Japan Corresponding author: ayame.noriko@eneos.com Akira Takagi ENEOS Corporation, Lubricants R&D Dept, Yokohama, Japan Go Tatsumi ENEOS Corporation, Lubricants R&D Dept, Yokohama, Japan 1. Introduction Lubricant foaming can cause problems such as lowering of cooling efficiency and breaking down of oil film which triggers wear or seizure [1]. Therefore, defoamers are critical additives in lubricants especially for electric and hybrid vehicles. Conventionally, polydimethylsiloxane (PDMS) have been used as defoamers for automotive lubricants [2]. Compared with other lubricant additives, PDMS is unique in terms of not dissolving in the lubricants and working as a defoamer when keeping a finely dispersed state. However, due to its high density, PDMS is prone to sedimentation during a long-term storage. Additionally, centrifugal force and filter adsorption make PDMS distribution uneven under use in mechanical devices. As a result, the defoaming performance of PDMS gradually disappears [2]. Furthermore, lower viscosity lubricants can improve energy efficiency and cooling performances of motors [3, 4], so the demand for super low viscosity lubricants is growing, but PDMS partially dissolves into the such super low viscosity lubricants, leading to the increase of foaming. To solve these problems, the improvement of PDMS defoamers has been needed. 2. Results and discussion In this study, the effect and mechanism of a novel defoamer, a highly dispersed PDMS (HD-PDMS) were investigated. The HD-PDMS was designed to improve its dispersibility in lubricants by a micellization technology which prevents the aggregation and adsorption of PDMS. The results of particle size measurements using the dynamic light scattering method showed that the particles of the HD-PDMS kept smaller sizes within lubricants than those of the conventional PDMS. In addition, the HD-PDMS also gave much better defoaming performances after the centrifugal separation or filtration which simulates the practical uses in automobiles, as shown in Fig.1. For use in super low viscosity lubricants, fluorinated PDMS defoamers have better defoaming performances than PDMS. On the other hand, the fluorinated PDMS has the higher density, leading a poorer dispersibility than PDMS. The micellization technology was also applied to improve the dispersibility of the fluorinated PDMS. The experimental results showed that this micellization technology was also effective for improving the fluorinated PDMS, suggesting that the fluorinated HD-PDMS can maintain the defoaming performance for a long period of time even in super low viscosity lubricants. Fig.1: defoaming performance of HD-PDMS 158 23rd International Colloquium Tribology - January 2022 Novel Defoamers for Use in Low Viscosity Electric Vehicle Fluids References [1] Tonća Ćaleta Prolić, Anđelko Lepušić, 2012, “EF- FECT OF FOAMING ON THE ANTIWEAR PROPERTIES OF LUBRICATING OILS,” goriva i maziva, 51, 1, 29-46. [2] Kalman Koczo, Mark D. Leatherman, Kevin Hughes, Don Knobloch, 2017, “Foaming Chemistry and Physics,” Lubricant Additives: Chemistry and Applications, Third Edition, 337-384. [3] Kurosawa, O., Matsui, S., Komiya, K., Morita, E. et al., 2003, “Development of the Fuel Saving Low Viscosity ATF,” SAE Technical Paper 2003-01- 3257. [4] Beyer, M., 2019, “Lubricant Concepts for Electrified Vehicle Transmissions and Axles,” Tribology Online, vol.14, No.5