Shingo Obara

New bearing units having lubricant supply structure were devised for realizing longer lifetime and better performance of rotation mechanisms of space machineries. The spacer sandwiched by two bearings was filled with grease and porous body was established between grease and the bearing for both preventing thickener transferred into bearings and supplying only oil for bearings. The oil supply function was verified by friction tests and bearing tests using fluorescent agent. The contribution for long lifetime of the oil supply system was confirmed by the lifetime tests under a vacuum which showed stable rotation for 2×10⁸ revolutions at a room temperature and 1×10⁹ revolutions at a temperature of 60℃. Moreover, large size bearing units with the oil supply structure were evaluated under high rotation speed for utilized in larger spacecraft requiring larger attitude control torque and observation systems requiring agile attitude control. Using larger size bearings and rotating with higher speed would cause to promote oil scattering by centrifugal force and oil evaporation by temperature rise, whereas the oil supply structure was conducted the feasibility to realize both larger size bearings, higher rotation speed, longer lifetime and low torque.