Gear Ratio Combination Analysis and Optimization for High Torque Density of Dual Magnetic Gear

When gearboxes have the same torque density, a higher gear ratio raises the overall system torque density of geared motors. Coaxial magnetic gears (CMGs) have a high torque density, which exceeds 100 kNm/m3, and are therefore expected to improve the overall torque density of the system. However, because the gear ratio and torque density are inversely proportional to those of a conventional CMG, conventional CMGs are not suitable for a gearbox. This study proposes a new CMG structure, which more than doubles the torque density compared with that of a conventional CMG. In addition, this structure improves the system efficiency.