Low Viscosity EV Gear Oil Lubricant Technologies

Abstract Electric vehicle (EV) technology has matured over time, improving in some performance areas against traditional internal combustion engine (ICE) vehicles. Despite advancement, there is considerable opportunities for further improvements, particularly in the broader field of lubrication, including areas like grease. As in any mechanical system, greases and lubricants play a significant role in the component life of EV power plants and drivetrains. Moreover, they can significantly contribute to vehicle efficiency, energy savings, and overall driving experience. Since the lubricants in EVs work under harsh thermal and electrical environments, designing an ideal high performance and stable lubricant can be challenging. This paper evaluates the industry's progress on EV lubrication including analyzing existing lithium-based lubricants and spotlighting advanced material additives such as graphene, boron nitride, or cutting-edge ionic liquids. It also discusses optimizing base stock selection, with a focus on Polyalphaolefin (PAO) molecules and designing various additives to enhanc... Read More

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Modified oil-soluble polyalkylene glycols (PAGs) with low kinematic viscosity at 100° C, low volatility, and high viscosity index, suitable as base oils for lubricants. The PAGs comprise an aryl-polyalkylene glycol monoester compound with a specific molecular structure, providing improved performance characteristics compared to conventional PAGs.

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A lubricating fluid for electric motor systems in hybrid and electric vehicles, comprising a base oil of lubricating viscosity, a high molecular weight succinimide dispersant, an amine salt of a phosphoric acid ester, an ashless dialkyl dithiophosphate, and a sulfur-providing additive. The fluid has a kinematic viscosity of 4.5 cSt or less, 150-250 ppm total phosphorus, and an electrical conductivity of 37 nS/m or less. The succinimide dispersant is derived from a polyisobutylene with a number average molecular weight of 2000 or greater, and is post-treated with a phosphorus and boron containing compound.

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A lubricant composition for electric and hybrid vehicle motors, comprising a base oil blend of polyalkylene glycol (PAG), poly-alpha-olefin (PAO), and ester, with an additive package including a sulfur-based extreme pressure agent. The PAG provides thermal stability and low viscosity, while the PAO and ester enhance solubility and compatibility with the extreme pressure agent. The composition is optimized for electric motor applications, avoiding additives typically used in conventional lubricants that can degrade performance.

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Base oil for automotive transmission and gear systems that provides superior traction and thermal management properties in electric vehicles. The base oil comprises a unique blend of compounds optimized for electric vehicle powertrains, featuring improved oxidation stability, thermal conductivity, and viscosity characteristics. The formulation enables enhanced traction performance in electric vehicles, particularly in the high-temperature regions of the powertrain, while maintaining reliable low-friction operation in the low-temperature conditions of the battery pack and other components.

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A lubricating oil composition for electric vehicle cooling systems, comprising a base oil and a fluorine compound, where the base oil is a mineral oil with a 40°C kinematic viscosity of 1-25 mm²/s, and the fluorine compound content is 3-30% by weight. The composition provides both lubricity and cooling performance, enabling efficient heat management in electric vehicle systems.

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A lubricating fluid for electric motor systems in hybrid and electric vehicles, comprising a lubricating oil and additives, including a succinimide dispersant, a sulfur-providing additive, and a detergent system, that provides improved wear protection, oxidative stability, and electrical conductivity while maintaining low viscosity. The fluid is formulated with a specific combination of additives that balance antiwear, friction, and corrosion performance while minimizing electrical conductivity.

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A transmission fluid composition for hybrid and fully electric vehicles that provides lubrication, cooling, and electrical insulation. The composition comprises a major amount of a lubricating oil basestock and a minor amount of an additive package containing a phosphorus-containing compound, a calcium salicylate detergent, and a non-calcium-salicylate detergent. The additive package enables the fluid to balance competing demands of electrical insulation, wear protection, and low viscosity, while also providing cooling and energy efficiency benefits.

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Lubricating oil composition for electric vehicles comprising a lubricating oil base oil, an extreme pressure agent, and a nitrogen-containing ashless dispersant, suitable for lubricating both electric motors and gear mechanisms in integrated electric vehicle powertrains.

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<div class="section abstract"><div class="htmlview paragraph">Advent of EV powertrain has considerable effect on transmission development activities as competed to regular ICE transmission. Conventional ICE transmission and the transmission for an e-powertrain differ on fundamental level. The conventional transmission has number of gear ratios, shift mechanism which enables the transmission to deliver a smooth power output as per demand from the driver. Whereas the e-powertrain transmission is mostly a single gear ratio transmission (reducer) which primarily depends on speed and torque variation from the motor to cater the driver requirement. Hence, the operating speeds of such e-transmissions can vary from 0 to 20000 rpm in both forward and reverse directions. Such a large speed variation as compared with conventional transmission calls for special attention towards the lubrication of internal components. High speeds and lower oil viscosities tend to disrupt the oil films in between contact surfaces causing metal to metal contact. This situation aggravates the wear and t... Read More

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A lubricating fluid composition for electric drives that prevents corrosion of electrical components while maintaining high efficiency in transmissions. The composition comprises 10-88% by weight of a low-viscosity synthetic oil, 0.1-5% by weight of a borated succinimide dispersant, 0.1-5% by weight of a 2,5-alkyl-thiadiazole compound, and 0.1-5% by weight of a phosphorus-containing additive. The composition has a dynamic viscosity of 0.8-4.0 mm2/s at 100°C and is suitable for use in electric motors, transmissions, and battery-operated vehicles.

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Electric vehicles (EVs) have gained increased attention in recent years owing to their excellent performance and emission of less hazardous products to the surroundings. The varied design of EVs compared to the internal combustion engine vehicles has created new requirements in lubricants and fluids for their operation. The increasing electrification of vehicle drivetrains has led to lubricants being in contact with more electrical components, such as motors, sensors, battery modules, and power electronics. This has led to different operating conditions, such as being subjected to an electric field, higher rpm, and higher thermal stress, affecting the electrical properties of lubricants, especially for electrified transmission fluid. The electrical properties of lubricants play a vital role in preventing corona discharge and arc absorbance, which can cause premature failure and electromagnetic interference problems in motors, leading to bearing instability, excessive vibrations, and noise. Understanding the interactions of lubricants with the electric field is crucial for optimizing ... Read More

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EV transmissions operate at high speeds, upto 30,000 rpm. High speed operation puts higher demands on bearings, seals, and gears. Bearings in EV transmissions are prone to electrically induced bearing damage and may exhibit signs of pitting and fluting. Surface-initiated rolling contact fatigue is another common problem gaining increased attention lately. Most EV transmissions require a coupling between an oil-lubricated gearbox to an electrical motor that runs with minimal lubrication at very high rpm. High mechanical and thermal stresses the seals are exposed to under starved lubrication conditions have a detrimental impact on their service life. Hence, proper lubrication is critical. In general, EV transmission fluids call for a somewhat different spectrum of properties compared to conventional ATF. Gear tribology simulations open new ways to the design and optimization of lubrication for EV transmissions. Additionally, such simulations can also provide valuable insights into the effects of different oil properties on cooling and lubrication efficiencies, thereby helping in matchi... Read More

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Extending the driving range of battery-based electric vehicles is one of the many challenges that need to be overcome before mass adaptation by the public. One of the ways to improve the driving range is to make the power unit more efficient. Currently, ultralow viscosity lubricant is used in power units. The fluid was developed for automatic transmissions and, therefore, not optimized for power unit applications. Before developing an optimized fluid, it is critical to understand the lubrication regimes in power units and quantify the amount of boundary, mixed, and hydrodynamic regimes. Once the relative proportions of boundary, mixed, and hydrodynamic regimes are known, lubricant formulators can select appropriate additive components for the reduction of power losses in those regimes while maintaining component durability (mechanical wear, corrosion, material compatibility, etc.) and lubricant life (oxidation). Understanding the lubrication regimes required an evaluation of power unit efficiency using a production unit under a broad range of speeds and torques. The efficiency data w... Read More

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Abstract A renewed interest in elastohydrodynamic lubrication (EHL) phenomena at high speeds, for which thermal effects strongly influence both traction and film thickness, has grown out of the challenges presented by high-speed geared transmissions in electric vehicles. This study uses a new ball-on-disc set-up employing the well-known ultra-thin-film interferometry technique to simultaneously measure EHL film thickness and traction at entrainment speeds up to 20 m/s and slide-roll ratios up to 100%. The effect of fluid composition is examined for Group I, II and III mineral oils, for two polyalphaolefins in Group IV, and for the traction fluid Santotrac 50. The effect of viscosity in the range 4180 mPa.s is investigated by varying bulk fluid temperature. At high speeds, both film thickness and traction are considerably lower than predicted by conventional EHL theory. The contact is seen to be fully-flooded for all conditions tested. The widely-used thermal EHL correction of Gupta is shown to overcorrect for the film thickness reduction even at modest SRRs. Finally, the influence o... Read More

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Lubricating oil composition for electric drive units, comprising a base oil, a phosphite compound, a metal detergent, a viscosity index improver, and an extreme pressure agent, wherein the base oil contains a branched alkyl group with 3-20 carbon atoms, the phosphite compound has a sulfur-containing group, and the extreme pressure agent is a thiadiazole compound. The composition provides balanced scuffing resistance and copper corrosion protection for electric drive units, particularly gearboxes and motors.

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Lubricating oil composition for transmissions that achieves both low viscosity and high gear protection while preventing copper corrosion and maintaining oxidation stability. The composition combines a sulfur-based extreme pressure agent with a phosphorus-based extreme pressure agent, both having specific molecular structures, to create a protective oil film on metal surfaces. This film suppresses metal-to-metal contact and solid phase fusion, preventing gear damage such as scuffing. The composition is suitable for use in transmissions where gear protection is critical, particularly in applications where low viscosity lubricants are required for fuel efficiency.

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<div class="section abstract"><div class="htmlview paragraph">In this study the main focus is on the low temperature behavior and mobility of lubricating greases; a characteristic that has always been challenging for grease formulators. A series of lab-scale polyurea grease samples are prepared, with three different types of low viscosity synthetic base oils (ISO VG 32), and are examined in terms of their low temperature behavior as potential lubricants for electric motor bearings of electric vehicles (EVs) and hybrid electric vehicles (HEVs). The cold flow properties are analyzed by utilizing a Low Temperature Flow Tester following the DIN 51805-2 (Determination of flow pressure of lubricating greases according to Kesternich method) standard. The test matrix includes the cold flow pressure assessment at various temperatures ranging from -0<sup>o</sup>C to -40<sup>o</sup>C, whereas those measurements are also repeated after various relaxation periods - at selected temperatures - from 4h up to 8h before the actual determination. By employing this mo... Read More

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The development of suitable fluids, including lubricants or coolants, for electric vehicles (EVs) requires large efforts on their formulation, characterization, and performance testing. An important property for these fluids is dielectric strength or breakdown voltage (BDV), which is expected to be as high as possible at wide temperature range. Short circuits and bearing currents are highly undesirable phenomena which are known to cause inefficiencies and potential failure or wear of electromechanical hardware if BDV magnitude is not adequate. In modern EVs, the typical fluids comprise lubricants (for bearings and gears in the driveline) such as automatic transmission fluids (ATFs) and low-viscosity gear oils, and coolants (for thermal management in the battery pack and power electronics), namely, ethylene-glycols and dielectric oils. Although these fluids are reported to have acceptable BDV at room temperature (according to ASTM D877 and/or D1816 standard methods) for electric equipment, BDV is likely to be altered when temperature changes occur. The information of BDV at room (20-3... Read More

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Lubricating oil composition for electric drive units, comprising a base oil, a phosphite with a sulfur-containing group, a thiadiazole compound, and a benzotriazole compound, with specific mass ratios of these components that balance scuffing resistance and copper corrosion protection.

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<div class="section abstract"><div class="htmlview paragraph">In electric vehicles (EVs), drivetrain lubricants are often utilized not only as a lubricating oil for the drivetrains but also for motor cooling. As such, they are required to both improve the efficiency of the drivetrains and to have a high cooling performance. Both requirements can be met by lowering the viscosity of the fluid, which effectively improves the heat transfer coefficient, reduces churning loss, and improves efficiency. However, low viscosity may adversely affect the fatigue life of gears and bearings. To address these issues, we used a high-performance base oil and optimized additives (e.g., anti-wear agents) to develop a fluid with higher lubricity than conventional automatic transmission fluid (ATF), even though its viscosity is lower. The 100,000-kilometer (WLTC mode) endurance test on an actual vehicle confirmed that there was no damage in the reduction gear unit parts. We also evaluated the torque loss on the reduction gear unit and fuel consumption and confirmed a higher performance in eac... Read More

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<div class="section abstract"><div class="htmlview paragraph">The purpose of this study is to investigate how the kinematic viscosity of lubricating oil used in hybrid electric vehicle (HEV) and electric vehicles (EV) transaxles affects thermal conductivity and gear seizure resistance. This study investigated the relationship between viscosity, thermal conductivity and gear seizure resistance in detail and found that thermal conductivity tends to decrease with decreasing viscosity. It was also found that the thermal conductivity decreases significantly after a certain viscosity. The relationship between viscosity and gear seizure resistance was also investigated and it was found that too low a viscosity causes a significant deterioration in gear seizure resistance.</div></div>

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We present an experimental investigation into the influence of oil viscosity on gear churning losses in splash lubricated transmission systems. The inertia rundown method was used to perform tests on a single gear within a cylindrical housing with several oils of different viscosities at several immersion depths. A complex and non-monotonic relationship between churning torque and viscosity was observed which was highly influenced by the rotational speed, with higher viscosity oils resulting in lower churning torque at higher speeds in some cases. This was attributed to a reduction in effective immersion depth due to oil being centrifugally distributed around the casing by the rotating gear, an effect that was observed to be more pronounced with higher viscosity oils. An effective immersion depth parameter, dependent on the rotational speed of the gear and the lubricant viscosity, was defined to account for this phenomenon. Gear churning losses could be better predicted using an existing empirical model when this parameter was used instead of the nominal immersion depth as is usually... Read More

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A low-traction, high-pressure viscosity fluid formulation for electric vehicle drive units and drivelines, comprising a base oil selected from API groups II-V and an additive, optimized for motor cooling, oxidation stability, and evaporation resistance while maintaining gearbox protection and efficiency.

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A lubricating base oil and lubricating oil composition for cooling equipment in electric vehicles, characterized by a base oil with a kinematic viscosity of 3 mm^2/s at 40°C and a flash point of 90°C or higher, while maintaining a pour point of -45°C or lower. The base oil is preferably an isoparaffinic base oil with a %CP of 60 or more. The lubricating oil composition contains the base oil as the primary component, with optional additives, and is particularly suited for cooling applications in electric vehicles.

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Lubricating oil composition, lubricating method, and transmission for improving fuel efficiency, wear resistance, low temperature fluidity, and usability of lubricating oils used in transmissions, while reducing traction coefficient. The composition contains a base oil, a friction modifier ester, and an antiwear ester. The base oil has a low viscosity index and low kinematic viscosity at 40°C, but high kinematic viscosity at 100°C. The friction modifier ester improves wear resistance and reduces traction coefficient. The antiwear ester has a high flash point for safety. The composition has good low temperature fluidity and wear resistance while meeting fuel economy and safety requirements.

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Lubricants with a functional water portion have demonstrated a drastic reduction in friction under elastohydrodynamic lubrication conditions. With water-containing polyalkylene glycols, superlubricity with coefficients of friction <0.01 have been measured in model and gear contacts. In addition to the low friction, their calorimetric properties make them particularly interesting for application in electrified vehicles because the liquid can simultaneously serve as lubricant for the gearbox and coolant for the electric motors and the power electronics. In this study, the influence of water content between 8 wt% and 40 wt% of water-soluble polyalkylene glycols on friction and film thickness in elastohydrodynamically lubricated rolling-sliding contacts such as in gears and bearings is investigated. A polyalphaolefine oil is used as a reference. Friction has been measured on a ball-on-disk tribometer and film thickness on an optical tribometer. For a water content of 40 wt%, superlubricity with coefficients of friction down to 0.004 are found. The decrease in friction is up to 95%... Read More

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Hybrid electric and electric vehicles have represented a small portion of the automotive market for many years and mainly use current lubricants, typically automatic transmission fluids (ATFs). However, regulatory compliance to limit greenhouse gases and increased consumer demand have resulted in a rapid global transition to electrified vehicles. This has prompted the need for new advances in vehicle technology to improve efficiency and thereby increase range. Enabling and optimizing such advances requires a new generation of driveline lubricants. Incorporating an electric motor in a transmission or axle, where the motor is exposed to the gear box lubricant, creates new challenges that focus attention on lubricant characteristics that were previously not differentiating features, for example, electrical and thermal properties. Additionally, lubricants must now also be compatible with the constituents used in electric motors which include new polymeric materials and, in some cases, exposed copper. Compatibility tests of these polymers vary within the industry and the risk of copper co... Read More

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Lubricating composition for gear oils, limited-slip applications, and power transmission fluids with improved extreme pressure, friction, and copper corrosion performance. The composition includes a unique blend of sulfur compounds, specifically organic sulfide reaction products with a specific sulfur moiety profile, and a phosphorus-containing friction modifier. The sulfur compounds are derived from a sulfur source substantially devoid of sulfur chlorides and hydrogen sulfides, and have a specific weight ratio of S3 to S4 moieties. The composition provides enhanced performance in extreme pressure and friction applications while minimizing copper corrosion.

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Ester compound for lubricating oil additive with improved biodegradability, oxidation stability, and friction reduction properties. The compound is prepared by reacting a fatty acid with a carboxylic acid or an ester, and can be used as a viscosity index improver, anti-wear agent, or friction property improver in lubricating oils. The compound exhibits enhanced biodegradability, oxidation stability, and friction reduction properties compared to conventional ester-based additives.

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Lubricant composition for driveline and industrial gears containing a hydrocarbon base stock and a combination of esters, including a carboxylic acid mono-ester and a dicarboxylic acid di-ester, to improve traction coefficient and reduce energy losses at low temperatures. The composition enables the use of lower-cost Group II and III base oils while achieving comparable performance to high-end Group IV oils.

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Abstract This study explores the rheological and tribological behavior of water-based lubricants (WBLs) as potential alternatives for electric vehicle (EV) applications. As the transportation sector increasingly shifts towards EVs to reduce carbon emissions, the demand for efficient lubricants becomes critical. WBLs here are defined as fluids containing a minimum of 50 wt% water mixed with glycerol, ethylene glycol (MEG), polyethylene glycol (PEG), or one of two polyalkylene glycols (PAGs). Rheological properties were investigated and compared with traditional lubricating oils. Results demonstrate distinctive rheological characteristics in WBLs, with viscositytemperature responses resembling traditional oils with lowered pressureviscosity coefficients. Nevertheless, WBLs exhibit promising film-forming capabilities in highly loaded contacts. Additionally, in sliding contacts, WBLs generally display lower friction coefficients compared to traditional oils, with PEG exhibiting the lowest value near 0.1. These findings suggest that WBLs may offer advantages in reducing friction and ene... Read More

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Abstract The rheological and tribological properties of environmentally compatible lubricants of different bases (native oil, synthetic ester, polyalkylene glycolcontaining oil) compared to a conventional, mineral oilbased lubricant are investigated in order to develop toxicologically harmless and technically suitable lubricants for electromechanical drives. The aging of the oil is also considered. The results of this study reveal that the properties of polyalkylene glycolcontaining and synthetic esterbased lubricants have the potential to act as substitutes for lubricants containing mineral oil. By examining and improving the properties of sustainable lubricants, gear oils that are partially or totally nonmineral oil based will be highly attractive in the future.

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The increasing worldwide demand for hybrid and electric vehicle technology has brought new challenges for the global lubricant industry. The new lubricants for electric vehicles, also called E-fluids or EV-fluids, are expected to meet a new set of requirements including withstanding the much severe operating conditions of EV powertrains. High starting torques, high RPMs and uncontrollable shaft currents passing through the contact interfaces are some of the most challenging powertrain conditions that can impact the performance of these lubricants. Although there have been some papers already reporting on significant alteration of tribological properties of lubricants under electrification, so far there are no standard test protocols aimed at the fast and reliable screening of base oils, additives and formulated lubricants under such conditions. Thus, this research work focuses on exploring the popular four-ball ASTM-D4172 standard method to evaluate the tribological behavior of lubricants under electrified conditions. Specifically, a conventional four-ball tester was instrumented wit... Read More

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A lubricant composition for electric vehicle gearboxes that reduces energy losses by minimizing traction coefficient. The composition includes a base stock and a traction coefficient additive, which can be a polyhydroxyalkyl or polyhydroxyalkenyl carboxylic acid or a polyether compound. The additive is specifically designed to reduce friction between gear components, enabling improved energy efficiency and longer battery life in electric vehicles.

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A lubricating and cooling fluid for electric motor systems that provides wear protection, friction reduction, and cooling while maintaining low electrical conductivity and copper corrosion resistance. The fluid comprises a lubricating base oil, a sulfurized component, a dispersant system with two dispersants of different molecular weights, and a friction modifier system with multiple components. The dispersants are balanced to maintain low conductivity while providing wear protection, and the friction modifiers are selected to optimize friction reduction while minimizing electrical conductivity. The fluid is designed for use in electric motor systems operating at elevated temperatures, where conventional lubricants may fail to provide adequate performance.

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Lubricant composition for cooling electric vehicle engines and batteries. The composition contains polyalkylene glycols (PAGs) obtained by polymerizing alkylene oxides like ethylene oxide or copolymerizing ethylene oxide and propylene oxide. The PAGs cool the engine components and batteries by transferring heat more effectively than air or water. The composition can also lubricate engine parts like bearings and gears. It provides an alternative cooling method to air or water cooling for electric vehicles and hybrid vehicles.

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Purpose This paper aims to address the influence of lubrication methods on operational characteristics, power losses and temperature behavior of gears and bearings. It contributes to the improvement of resource and energy efficiency of geared transmissions. Design/methodology/approach Experimental investigations were performed at a gear and bearing power loss test rig. Thereby, dip lubrication, injection lubrication with injection volumes from 0.05 to 2.00 l/min and minimum quantity (MQ) lubrication with an injection volume as little as 28 ml/h were considered. Measurements were evaluated in terms of no-load and load-dependent power loss, bulk temperatures and mean gear coefficients of friction. Findings Results show strongly reduced no-load gear and bearing losses for lubrication methods with low lubricant quantities. Load-dependent losses are similar to conventional lubrication methods and tend to be lower at high speed. This is related to higher bulk temperatures, as the heat dissipation of lubrication methods with low oil quantities is limited. Limited thermal load limits were sh... Read More

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The most suggestive outlining between the vehicles powered by the electric motor (EVs) and hybrid electric vehicles (HEV) consists in the battery power supplied to the electric motor and unilaterally fulfilling the traction characteristic, while HEVs can only minimize dependence on fossil fuels. The main difference between electric motors and combustion engines in terms of emissions, carbon footprint, and sustainability is that electric motors eliminate the possibility of contamination of oil by soot. In addition, global insights about current Hybrid and EV lubrication involves new specialized lubricants to overcome challenges of electrical compatibility and the short persistence in the environment - known as biodegradability. Biogenic or recycled lubricants have fallen under the incidence of a very high cost for the automotive industry, in contrast to achieving tough performance and efficiency. Nowadays, eco-sustainability proposes future improvement trends. Lubricants from vegetable and animal sources are relevant, coupled with the numerous possibilities of formulating lubricants f... Read More

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Abstract The market of electric and hybrid vehicles (EVs and HEVs) is expanding exponentially in recent years. It serves as a greener solution in the transportation sector as compared to internal combustion engine vehicles (ICEVs). Conventional lubricants used for ICEVs are not suitable for the EVs and HEVs as the latter operates on electric motors instead of combustion engines. Performance characteristics such as the electrical conductivity, thermal conductivity and copper compatibility are not considered by the ICEVs lubricant but are important for the EVs and HEVs. In this research, computer-aided molecular design technique is used to design the lubricant that is compatible with the EVs and HEVs. The lubricant properties considered are thermal conductivity, specific heat capacity, viscosity, density, and flash point. Group contribution (GC) property prediction model is utilized to ensure that the desired properties are possessed by the generated lubricant. There are six possible solutions of lubricant being generated and discussed. Other properties such as the electrical conducti... Read More

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<div class="section abstract"><div class="htmlview paragraph">To achieve carbon neutrality by reducing carbon dioxide (CO<sub>2</sub>) emissions, vehicles with an internal combustion engine have started to be replaced by electrification vehicles such as hybrid electric vehicles (HEVs), plug-in HEVs (PHEVs), and battery EVs (BEVs) worldwide, which have motors in their transaxles (T/As). Reducing transmission torque loss in the transaxles is effective to reduce CO<sub>2</sub> emissions, and lowering the viscosity of lubrication fluids in T/As is a promising method for reducing churning and drag loss. However, lowering viscosity generally leads to thin oil films and makes the lubrication condition severe, resulting in worse anti-fatigue and anti-seizure performance. To deal with these issues, we made improvements on the additive formulation of fluid, such as the addition of an oil-film-forming polymer, chemical structure change of calcium detergents, and an increase of anti-wear additives including phosphorus and sulfur. As a result, we succeeded in d... Read More

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A gear oil composition for automobiles that balances high-load gear performance with fuel efficiency. The composition contains a base oil, a sulfur-based extreme pressure agent, and a phosphorus-based extreme pressure agent, with specific requirements for their combined performance. The gear oil composition provides excellent seizing resistance and wear resistance for high-load gears, while also achieving improved fuel efficiency through reduced viscosity.

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Lubricant fluid for electric vehicle transmissions that provides improved performance in electric vehicles operating at high torques, high speeds, and low temperatures. The lubricant composition contains specific base oils, additives, and viscosity modifiers that provide the required properties for electric vehicle transmissions. The composition has low electrical conductivity to insulate high voltage components and prevent dielectric breakdowns. It also has high electrical resistivity. The composition can be used in electric vehicle transmission applications to improve efficiency and reliability.

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A durable lubricating fluid for electric motors and hybrid-electric motors that maintains low electrical conductivity over its lifespan. The fluid comprises a lubricating oil, a thiadiazole or derivative providing sulfur and nitrogen, an amine salt of a phosphoric acid ester providing phosphorus and nitrogen, and a sulfur-to-phosphorus-to-nitrogen weight ratio of at least 2.3. This composition delivers wear protection while maintaining low electrical conductivity, making it suitable for electrified vehicles.

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A lubricating oil composition for automatic transmissions and electric motors that combines the benefits of transmission oil and electric motor oil. The composition features a low-viscosity base oil with improved energy efficiency, electrical insulation, and oxidative stability. It contains a specific combination of polyisobutenyl succinic acid and alkyl/alkenyl succinic acid, along with calcium-based detergents, amine-based and phenol-based antioxidants, and phosphorus-containing compounds. This unique formulation enables the oil to simultaneously lubricate and cool both automatic transmissions and electric motors, while also providing improved fuel efficiency and energy saving properties.

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<div class="section abstract"><div class="htmlview paragraph">Decreasing fuel consumption in Internal Combustion Engines (ICE) is a key target for engine developers in order to achieve the CO<sub>2</sub> emissions limits during a standard cycle. In this context, reduction of engine friction could help meet those targets. The use of Low Viscosity Engine Oils (LVEOs), which is currently one of the avenues to achieve such reductions, was studied in this manuscript through a validated numerical simulation model that predicts the friction of the engines piston-cylinder unit, journal bearings and camshaft. These frictional power losses were obtained for four different lubricant formulations which differ in their viscosity grades and design. Results showed a maximum friction variation of up to 6% depending on the engine operating condition, where the major reductions came from hydrodynamic-dominated components such as journal bearings, despite an increase in friction in boundary-dominated components such as the piston-ring assembly. Also, an evaluation of the potent... Read More

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A lubricating fluid for electric motor systems that provides wear protection, copper corrosion inhibition, and high electrical resistivity. The fluid comprises a base oil and a phosphorylated succinimide dispersant with 2-3.5 wt% phosphorus, which delivers 650 ppm or less phosphorus to the fluid. The fluid has a kinematic viscosity of 3-6.5 cSt at 100°C and a resistivity of at least 50 MΩ·m after aging at 150°C.

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The development of specialized lubrication fluids for electric vehicle powertrains are providing greater performance, more efficiency, and component longevity. Selda Gunsel, vice president of global lubricants and fuels technology at Shell, explains how e-fluids are created and the challenges that must be overcome as we shift to an electrified world

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Synthetic lubricating oils have attracted more and more interests due to their unique advantages. There are main two synthetic lubricating oils, poly--olefins (PAOs) and synthetic esters, while they each have strengths and weaknesses due to their specific molecular structures. Here, linear polymer-based liquid lubricants were designed via a strategy of complementary advantages, by esterifying the hydrogenated hydroxyl-terminated polybutadiene (HO-HPB-OH), with different saturated fatty acids (acetic acid, butanoic acid, octanoic acid and lauric acid). As lubricant base oil via overcoming one's weaknesses by acquiring others' strong points, ultralow friction and excellent wear-reduction performance were obtained with the proposed linear polymer-based liquid lubricants in comparison with the commercial PAO base oils, especially the dilaurate with the longer hydrocarbon chain length.

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The effect of lubricant viscosity on dynamics of a high-precision spur gear pair with near-zero backlash is investigated under deterministic and uncertain conditions via a tribo-dynamic model. This model, for the first time, considers the backlash reduction induced by the lubricant film between meshing teeth. In general, increasing viscosity can mitigate vibration in off-line-of-action (OLOA) direction and decrease dynamic transmission error (DTE) but can hardly mitigate vibration in line-of-action (LOA) direction. Moreover, increasing viscosity can suppress the uncertainty of OLOA vibration caused by the uncertain backlash, supporting stiffness and meshing stiffness but cannot suppress the uncertainty of DTE. Therefore, gear dynamic performance can be improved by increasing lubricant viscosity. However, to what extent the gear dynamic performance can be improved depends on the operating condition and surface roughness.

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