Reduced friction and wear of high-speed gears in e-mobility application – 30,000 rpm by using Triboconditioning® CG
THE CHALLENGE
Reach 30,000 rpm for an e-axle
Overheating of transmission gears due to starved lubrication and excessive friction
Gear teeth wear and component failure
In order to make electric mobility more affordable, the focus on developing drives for electric vehicles is increasingly shifting towards e-axles. By integrating electric motors, power electronics, and transmission into a compact unit on the front or rear axle of the vehicle, space is saved. This compact drive module can be easily integrated into various vehicle types without significant design changes. The cost savings come from the reduction of components and connecting cables, as well as simplified cooling, compared to the traditional distributed design.
A leading powertrain technology provider aimed to develop a high-speed e-axle for electric vehicles with the ambitious goal of achieving up to 30,000 revolutions per minute for the e-motors and a top speed of 240 km/h when installed in a Tesla Model 3 car. These objectives subjected the transmission to extreme loads and limited lubrication. Traditional transmission gears proved inadequate in tests due to excessive friction and overheating. Therefore, an optimized gear finishing solution was sought to enhance gear performance under these highly demanding conditions.
THE SOLUTION
After engaging in a thorough discussion with the client, experts from Tribonex recommended applying the Triboconditioning® CG treatment to the gear teeth of the high-speed e-axle. This treatment was carried out on both the input and output shaft gears using a standard mass-finishing treatment platform in combination with Tribonex's reactive process fluids. The outcome was enhanced surfaces with a better negatively skewed surface profile, the creation of a low-friction anti-wear tribofilm on the surface, and an increase in surface compressive stress. All of these improvements were achieved in a single integrated process step.
As a result of this innovative approach, the transmission was able to endure the full drive cycles even at the challenging operational speed of 30,000 rpm. Consequently, the Triboconditioning® treatment led to a notable enhancement in power and efficiency, broadening the EV's performance capabilities at a modest additional cost.
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