Axially free flywheel system

Abstract

A flywheel energy storage system that allows high-speed operation with use of mechanical rolling element bearings for radial support of a vertical axis flywheel while they allow it to be mechanically free or unrestrained in the axial direction. Magnetic bearings are used to carry the flywheel weight axially. The axial unconstraint by the mechanical bearings allows the flywheel to freely grow or shrink in axial length from Poisson Effect contraction that occurs when rotating to very high speeds and stress levels as well as from thermal expansions from motor/generator heating or other sources, and also insures that the magnetic bearing carries all of the flywheel weight, thus greatly extending the life of the mechanical bearings. Radially compliant elements mechanically in series with the mechanical bearings provide for a lower radial stiffness, which allows the flywheel to traverse its rigid body resonance at a low speed. Above that speed, the flywheel spins about its mass center instead of the geometric center and radial loading on the bearing becomes much lower.

Dependencies are inferred from the claim text.