Design and Analysis of a Novel, Low-Cost, High-Speed Cycloidal Magnetic Gear for Aerospace Servo Actuator Applications

Magnetic gears provide a noncontact alternative to mechanical gears for high precision applications requiring high reliability. In a single stage, at large gear ratios, cycloidal magnetic gears (CyMGs) can achieve higher torque densities than coaxial magnetic gears. This article compares consequent pole (CP) CyMGs against surface permanent magnet (SPM) CyMGs. Furthermore, the SPM CyMGs are subdivided into conventional (North-South) magnet array designs and Halbach array designs. An optimization analysis reveals that when realistic manufacturing constraints are imposed, as outer diameter decreases, the CP CyMG's maximum achievable volumetric torque density can surpass that of the SPM CyMG. The CP topology also significantly reduces part count, increases manufacturability, and allows for integration of rectangular commercial-off-the-shelf magnets to produce a low-cost, high-performance gearbox. The internal pins through which CyMGs transfer torque to the output shaft are analyzed over a full mechanical cycle for an example set of pins and a pin disc system with a 1 N center dot m load applied on the outer circumference. Furthermore, the operating point under which the maximum reaction force occurs is discussed in this article. This article also describes a CP CyMG prototype that was fabricated and tested at input speeds exceeding 8700 RPM. This is the highest speed test of a magnetic gear of any topology in the literature to date.

Automated summary

Magnetic gears offer a noncontact solution for high precision and high reliability applications. In this study, cycloidal magnetic gears (CyMGs) are compared to surface permanent magnet (SPM) CyMGs, with a focus on optimizing the design and reducing manufacturing costs. The results show that CyMGs with consequent pole (CP) topology have higher torque densities and can integrate commercial-off-the-shelf magnets for a low-cost, high-performance gearbox. Furthermore, a prototype of CP CyMG is fabricated and tested at extremely high input speeds, setting a record for magnetic gears.