To enhance the durability of an energy storage device without decreasing the efficiency of energy conversion.
In this energy storage device, upper and lower flywheels 9, 10 supported in such a way as to be rotatable about a common rotation axis K-K are stored in a housing 2. The upper and lower flywheels 9, 10 are rotated in opposite directions to store energy. Dynamic pressure type gas bearing mechanisms 16, 18 are formed between the upper flywheel 9 and the interior wall surface 2b of the housing, and a dynamic pressure type gas bearing mechanism 20 is formed between the lower flywheel 10 and the interior wall surface 2b of the housing, so that the upper and lower flywheels 9, 10 are supported by the housing 2. The upper and lower flywheels 9, 10 are placed adjacent to each other, and additional dynamic pressure type gas bearing mechanisms 22, 24 are formed between the upper and lower flywheels 9, 10, so that the flywheels 9, 10 are supported against each other.
OKAMURA HIROMASA
YONEDA OSAMU
