Energy Efficiency, Emissions, Tribological Challenges and Fluid Requirements of Electrified Passenger Car Vehicles

Abstract

The motivations for the move to electrified vehicles are discussed with reference to their improved energy efficiency, their potential for lower CO2 emissions (if the electricity system is decarbonized), their lower (or zero) NOx/particulate matter (PM) tailpipe emissions, and the lower overall costs for owners. Some of the assumptions made in life-cycle CO2 emissions calculations are discussed and the effect of these assumptions on the CO2 benefits of electric vehicles are made clear. A number of new tribological challenges have emerged, particularly for hybrid vehicles that have both a conventional internal combustion engine and a battery, such as the need to protect against the much greater number of stop-starts that the engine will have during its lifetime. In addition, new lubricants are required for electric vehicle transmissions systems. Although full battery electric vehicles (BEVs) will not require engine oils (as there is no engine), they will require a system to cool the batteries—alternative cooling systems are discussed, and where these are fluid-based, the specific fluid requirements are outlined.

Fuel-Lubricant Interactions: Critical Review of Recent Work

“…The second technology that will impact fuel dilution of lubricants is that of vehicle electrification [78]. There are increasing numbers of hybrid electric vehicles being manufactured that have both a conventional engine and a battery.…”

Perspectives of 2D MXene Tribology

“…[ 3 ] Due to its direct connection to energy and fuel efficiency, the significance of tribology becomes evident in light of global challenges such as decreasing earth resources, i.e., fossil fuel and minerals, as well as steadily rising CO 2 emissions contributing to global warming. [ 4,5 ] In this context, friction and wear have been identified as notably contributing toward a downgraded energy efficiency, inviting the development of greener, smarter, and more sustainable tribological processes and lubricants.…”

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efficiency, the significance of tribology becomes evident in light of global challenges such as decreasing earth resources, i.e., fossil fuel and minerals, as well as steadily rising CO 2 emissions contributing to global warming. [4,5] In this context, friction and wear have been identified as notably contributing toward a downgraded energy efficiency, inviting the development of greener, smarter, and more sustainable tribological processes and lubricants.Since ancient times, the most straightforward approach to reduce friction and wear was to place a liquid lubricant (oil or grease) between the rubbing surfaces. This greatly reduces or eliminates the solid-solid contact, thus enabling low-friction and lowwear conditions.

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“…Combined with more stringent regulations regarding the use of sulfur-and phosphorous-containing lubricant additives as well as efforts toward decarbonization to reduce CO 2 emissions and hazardous wastes, these factors propel the urgent development of alternative lubrication concepts. [4] In this context, nanomaterials used as additives in base oils or applied as solid lubricant coatings have gained notable…”

On-Line Feedback Control of Sliding Friction of Metals Lubricated by Adsorbed Boundary SDS Films

“…Especially with the development of electric vehicles and hybrid vehicles [3], there will be more frequent stop-starts than for conventional vehicles, potentially leading to higher levels of wear. How to actively control boundary lubrication is a very important subject among the current tribological challenges [4].…”