New Evaluation Solution Provided for High-Speed Rotation of EV Drive Units

JFE Techno Research (Headquarters: Chiyoda-ku, Tokyo; President and CEO: Kazuhiro Seto), leveraging its specialized motor evaluation technology developed based on material evaluation and measurement technologies cultivated in the steel industry, is collaborating with Technical Support Inc. (Headquarters: Hamamatsu City, Shizuoka Prefecture; President and CEO: Masazumi Yamamoto) and their high-speed dynamometer testing technology for motors. This collaboration enables the provision of a new solution to address the increasing rotational speeds of EV drive units. This technology evaluates the actual behavior of cooling and lubricating oil supplied to gears under high-speed rotation environments of up to 24,000 rpm by capturing high-speed imagery and combining the data with numerical analysis (fluid dynamics analysis). It is expected to provide new insights for cooling and lubrication design under high-speed conditions, which are seeing accelerated development.

【Background and Technical Features】 In recent years, driven by the trend towards miniaturization of units to enhance vehicle body design flexibility, there has been rapid progress in increasing the output density and reducing the size of motors, inverters, and reduction gears that constitute e-Axles. Since motor output is a product of torque and rotational speed, the industry as a whole is accelerating the trend towards higher motor rotational speeds with the aim of reducing weight and improving efficiency. On the other hand, higher rotational speeds create numerous technical challenges such as heat generation, vibration, insulation, and strength, making the optimization of gear cooling and lubrication a critical theme. The most significant feature of the new solution being offered is its ability to visualize and improve the accuracy of analysis for gear cooling and lubrication mechanisms. This is achieved by combining Technical Support Inc.'s high-speed dynamometer testing technology with JFE Techno Research's specialized measurement using high-speed cameras and fluid dynamics analysis technology. This allows for detailed observation of how cooling oil, supplied to the gears via a drip method, adheres and scatters during high-speed rotation, and to what extent it is supplied to the gear teeth. In the experiments, ATF was used as the test oil, employing a drip method with controlled droplet size and supply volume. The oil temperature was maintained at room temperature (temperature variations can also be accommodated). Measurement of cooling oil behavior using a high-speed bench and high-speed camera

Test Gear

Gearbox

【Test Configuration】 ●Test Specimen Gear: Gear for e-Axle ●Test Oil: ATF ●Maximum Rotational Speed: 24,000 rpm ●Cooling Lubrication