Automatic Transmission and Driveline Fluids

Newcomb, T P; Tipton, Craig D.; Jao, Tze‐Chi

doi:10.4271/2007-01-3988

Cited by 9 publications

(4 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Most hybrid and electric vehicle transmissions operate with current lubricants developed for non-electrified automatic transmissions that are formulated to meet a variety of requirements including clutch friction durability, low temperature fluidity, anti-wear protection, and high resistance to oxidation. These lubricants must act to smoothly transfer torque, in both torque converters and at clutch interfaces, act as a hydraulic control medium to actuate the valve body and clutch systems, provide lubrication to protect the gears, bushings, bearings and seals, and be the transfer medium for the removal of excess heat generated by the transmission operation [1]. The critical characteristics are defined in various lubricant specifications.…”

Section: New Lubricant Characteristicsmentioning

confidence: 99%

“…Viscosity however can be varied dramatically, and the industry has been very active in pursuing lower viscosity lubricants in order to gain improvements in mechanical efficiency. In the 1990s, it was not uncommon for ATFs to require > 7 cSt viscosity at 100°C [1] and yet today there are reports of ATFs designed for specific transmissions with viscosities of ~ 3 cSt at 100°C [13]. Such reduction of viscosity can also provide a significant impact for heat transfer as illustrated in Fig.…”

Section: Heat Transfer Characteristicsmentioning

confidence: 99%

See 1 more Smart Citation

Lubricant Concepts for Electrified Vehicle Transmissions and Axles

Beyer¹,

Brown²,

Gahagan³

et al. 2019

Tribology Online

Self Cite

View full text Add to dashboard Cite

It is anticipated that many future electrified vehicle transmissions and axles will incorporate the electric motor within the unit housing. In such an arrangement, the lubricant will be in direct contact with powered motor windings, which raises new concerns regarding its electrical conductivity and its propensity to corrode copper. The heat produced at the motor windings will challenge the lubricant's heat transfer ability and its thermal stability. Expected high temperature excursions warrant the use of new plastics, which may give rise to new compatibility concerns. In this paper we share our learnings regarding the electrical properties of lubricants and discuss new methods to characterize copper corrosion. We review the factors that affect the heat transfer characteristics of lubricants and illustrate how improving heat transfer will favor the use of lower viscosity lubricants. We also share our early efforts to quantify lubricant compatibility with higher temperature plastics using tensile strength measurements. Finally, we discuss how these new concerns will shift the perception of what is required for lubricants used in different types of electrified transmission hardware.

show abstract

Section: New Lubricant Characteristicsmentioning

confidence: 99%

Section: Heat Transfer Characteristicsmentioning

confidence: 99%

Lubricant Concepts for Electrified Vehicle Transmissions and Axles

Beyer¹,

Brown²,

Gahagan³

et al. 2019

Tribology Online

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, it soon became apparent that this was not the best approach and specialized fluids began to emerge. In 1949, General Motors introduced the first specification, Type A, for mineral oils used in automatic transmissions (Newcomb et al, 2007). Since that time, transmission hardware continued to evolve, driving a stream of ever advancing fluid specifications.…”

Section: Introductionmentioning

confidence: 99%

“…From the late 1950s through the mid-1970s, improvements were made to enhance ATF resistance to oxidation and to improve low temperature fluidity through the reduction of low temperature viscosity. The focus on reducing low temperature viscosity continued through to the 1990s, along with some further improvements in wear and oxidation resistance, and the optimization of friction characteristics (Newcomb et al, 2007). Starting in the mid-1990s, the desire to improve corporate average fuel economy (CAFÉ) led to the use of new hardware capable of using low viscosity fluids.…”

Section: Introductionmentioning

confidence: 99%

A brief review of the rapid transformation of driveline lubricants for hybrid electric and electric vehicles

Newcomb

2023

Front. Mech. Eng.

View full text Add to dashboard Cite

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 corrosion in these applications is not always properly assessed by current specification tests. In this paper we will begin with a brief history of electric vehicles, highlight how driveline lubricants, specifically ATFs, have evolved over the years to meet new hardware requirements and then describe the performance requirements expected of lubricants specifically designed for vehicles with electric drive units (EDUs). Our primary goal, however, is to summarize the recent literature that illustrates the changing importance of various lubricant performance properties, new proposed test methods and offer some insight into future e-lubricant evolution.

show abstract