Oil Free Bearings for APUs

Active magnetic bearings (AMBs) make potentially reveolutionary Auxiliary and Integrated power Units (APU/IPU) designs possible. However, their ability to sustain and operate through transient events, while remaining both small and lightweight is restricted. Since APU/IPU size, weight and reliability are crucial flight worthy design issues, a durable compact backup bearing system is needed. Moawk Innovative Technology, Inc. (MiTI) proposes development of a lightweight Zero Clearance Auxiliary Bearing (ZCAB) suitable for high-speed high-temperature rotor systems. MiTi has already demonstrated the ZCAB at speeds to 10,000 rpm, under simulated shock, under simulated AMB failure and has a patent pending for this backup bearing. Under this proposed program, MiTi will 1) refine he ZCAB design for high speed IPU operation; 2) conduct design tradeoff studies to optimize the total bearing package size and weight for the advanced IPU under development by Sundstrand; 3) select the ZCAB tribomaterials system needed to assure adequate life; and 4) prepare a preliminary design of a high speed simulator test rig of the Sundstrand IPU to verify ZCAB operation throughout the required operating envelope. The support of Sundstrand Aerospace has been enlisted for Phase I to provide guidance and review the preliminary integrated ZCAB system design. Under Phase II a prototype integrated AMB/ZCAB system will be fabricated and tested under both steady state and transient conditions to verify the integrity of the design for ultimate demonstration in the Sundstrand IPU during a Phase III activity.