2012

Implementation of a Non-Metallic Barrier in an Electric Motor

Electric motors that run in pure oxygen must be sealed, or “canned,” for safety reasons to prevent the oxygen from entering into the electrical portion of the motor. The current canning process involves designing a metallic barrier around the rotor to provide the separation. This metallic barrier reduces the motor efficiency as speed is increased. In higher-speed electric motors, efficiency is greatly improved if a very thin, non-metallic barrier can be utilized. The barrier thickness needs to be approximately 0.025-in. (≈0.6-mm) thick and can be made of a brittle material such as glass. The motors, however, designed for space applications are typically subject to high-vibration environments.

A fragile, non-metallic barrier can be utilized in a motor assembly if held in place by a set of standard rubber Oring seals. The O-rings provide the necessary sealing to keep oxygen away from the electrical portion of the motor and also isolate the fragile barrier from the harsh motor vibration environment. The compliance of the rubber O-rings gently constrains the fragile barrier and isolates it from the harsh external motor environment. The use of a non-metallic barrier greatly improves motor performance, especially at higher speeds, while isolating the electronics from the working fluid with an inert liner.

This work was done by George M’Sadoques, Michael Carra, and Woody Beringer of Hamilton Sundstrand for Johnson Space Center. For further information, contact the JSC Innovation Partnerships Office at (281)483-3809.

Title to this invention has been waived under the provisions of the National Aeronautics and Space Act {42 U.S.C. 2457(f)} to Hamilton Sundstrand. Inquiries concerning licenses for its commercial development should be addressed to:

Hamilton Sundstrand
Space Systems International, Inc.
One Hamilton Road
Windsor Locks, CT 06096-1010
Phone No.: (860) 654-6000

MSC-24876-1