High performance composite flywheel

Abstract

A flywheel system for storing and delivering on demand electrical energy includes a flywheel supported for high speed rotation on bearings in a vacuum enclosure, and a motor-generator for spinning the flywheel up to speed and then for converting the rotational inertia in the flywheel back to electrical power. The flywheel includes a solid steel hub and a rim having only two rings press-fit on the hub with an interference fit. The rings are filament wound construction made primarily from standard modulus carbon fiber/epoxy. The steel hub stores between 40% and 60% of the energy in the flywheel. The press-fitting of the rings on the hub creates radial interference pressure between the hub and each of the composite rings that is greater than 5 ksi when at rest. The outer carbon fiber/epoxy ring is radially thinner than the inner ring, and both the hub outer diameter and the inner diameter of the assembled composite rim are tapered with the same angle. The inner composite ring and the inner diameter of the outer ring are also tapered with a matching taper. The ratio of steel hub mean diameter to flywheel outer diameter is between 0.50 and 0.70, and the ratio of inner carbon fiber/epoxy ring mean outer diameter to flywheel outer diameter is between 0.80 and 0.90. An epoxy resin is used for the manufacture of composite flywheels that is comprised primarily of Bisphenol A epoxy and a mixture of curing agents comprised between 20 and 70% of cycloaliphatic amine by weight. The remainder of the curing agent mixture is comprised primarily of an aliphatic amine or ether amine.

Dependencies are inferred from the claim text.