Development of Ultra-Low-Friction and Zero-Leakage Mechanical Seal for High-Speed e-Mobility Shaft Sealing Applications 2020-01-1090
By the year 2020, EU legislation limits CO2 emissions for new passenger cars to a maximum of 95 g/km, and further reductions to 68 g/km are expected. An electric motor (e-motor) with high power density often requires shaft cooling in combination with increased rotational speeds to boost efficiency. Especially, low friction and durability of sealing faces are essential to overcome severe friction under high-speed rotation. This challenge can be resolved by using the revolutionary GlideXTM sealing technologies, featuring advanced surface-texturing that enables microscopic flow control in dynamic sealing faces. The surface-textured mechanical seal can reduce leakage to the level of insignificance and up to 90% less friction, compared to a non-textured seal. The advanced texturing produces a thin liquid-sealing film between sealing faces, and liquid-lubrication becomes dominant at low speeds; at high speeds, gas-lubrication becomes dominant by manipulating liquid ingress into sliding surfaces. As a result, the textured seal can maintain low friction even at very high-speed rotations, taking advantage of air as less viscous lubricant. Low friction promotes less wear, more service life, and less power/fuel consumption. Less power consumption helps higher battery range; lower friction leads to a reduction in CO2 emissions compared to ICE (Internal Combustion Engine) and hybrid vehicles. The proposed sealing technologies can be used for applications like ORC (Organic Rankine Cycle) compressors, water pumps, e-motor shaft cooling, reduction gear sealing, fuel cell compressors, and more. Herein, development of ultra-low-friction and zero-leakage mechanical seal for high-speed e-motor shaft is explained. Both numerical calculations and experiments are performed to confirm fluid film thickness, friction coefficient, and amount of leakage. Furthermore, application examples for e-motor shaft cooling system, reduction gearbox, and electric water pumps are introduced.
Citation: Tokunaga, Y., Nakahara, N., and Itadani, M., "Development of Ultra-Low-Friction and Zero-Leakage Mechanical Seal for High-Speed e-Mobility Shaft Sealing Applications," SAE Technical Paper 2020-01-1090, 2020, https://doi.org/10.4271/2020-01-1090. Download Citation