Performance of Magnetic-Superconductor Non-Contact Harmonic Drive for Cryogenic Space Applications

Abstract

Abstract:Harmonic drives are profusely used in aerospace mainly because of their compactness and large reduction ratio. However, their use in cryogenic environments is still a challenge. Lubrication and fatigue are non-trivial issues under these conditions. The objective of the Magnetic-Superconductor Cryogenic Non-contact Harmonic Drive (MAGDRIVE) project, funded by the EU Space FP7, is to design, build, and test a new concept of MAGDRIVE. Non-contact interactions among magnets, soft magnetic materials, and superconductors are efficiently used to provide a high reduction ratio gear that smoothly and naturally operates at cryogenic environments. The limiting elements of conventional harmonic drives (teeth, flexspline, and ball bearings) are substituted by contactless mechanical components (magnetic gear and superconducting magnetic bearings). The absence of contact between moving parts prevents wear, lubricants are no longer required, and the operational lifetime is greatly increased. This is the first mechanical reducer in mechanical engineering history without any contact between moving parts. In this paper, the test results of a −1:20 inverse reduction ratio MAGDRIVE prototype are reported. In these tests, successful operation at 40 K and 10 −3 Pa was demonstrated for more than 1.5 million input cycles. A maximum torque of 3 N· m and an efficiency of 80% were demonstrated. The maximum tested input speed was 3000 rpm, six times the previous existing record for harmonic drives at cryogenic temperatures.

Z-Damper: A New Paradigm for Attenuation of Vibrations

“…Typical magnetic dampers are based in the induction of electrical eddy currents [11]. When a conductor is exposed to an alternating magnetic field, a power loss appears which is proportional to the square of the frequency of the oscillation.…”

The Development of Magnetic Gears for Transportation Applications

“…One such prototype is shown in Figure 18 [32]. Figure 18 Magnetic transmission in aerospace [13] A newer type of magnetic gears is magnetic cyclo gears. These gears, so far, are in the testing phase.…”

“…Linear, planetary, and even coaxial magnetic gears can be used in hybrid vehicles [11,12,13]. Figure 5 presents the model of a linear gear used in vehicles [23].…”

“…The examples of these gears in hybrid vehicles are given in [11,12,13]. The Magnomatics Company developed a combination of motor and gear, which was named Pseudo Direct Drive, as well as MAGSPLIT, which was applied in hybrid vehicles [14].…”

Aeronautical Magnetic Torque Limiter for Passive Protection against Overloads

“…It is easy to anticipate the major step forward that contactless technology can bring to common industrial applications. For instance, one of the most important breakthroughs would be the reduction of noise and vibration in aerospace applications [6][7][8].…”