Flexible shaft construction for a high inertia centrifuge

Claim 1

In a centrifuge that includes a motor secured on an elastomeric mount, a rotor vertically spaced above the motor, and a flexible shaft connected at its upper end to a rotor adapter that replaceably supports the rotor and at its lower end to the motor to transmit rotational energy from the motor to the rotor, the shaft having a relatively long, thin flexible portion intermediate said connections, wherein the improvement comprises a shaft construction comprising, a first tubular member connected to and extending vertically from the motor toward the rotor, a second tubular member connected to and extending vertically from said rotor adapter toward said motor, said first and second tubular members each surrounding said shaft and defining first and second annular clearances between said shaft and one another, said first and second tubular members each being substantially vertically coextensive with said shaft, and said shaft being structured and vertically positioned with respect to said motor and said rotor to produce self-balancing of said rotor through a flexure in said flexible portion of said shaft during rotation at the first and at least the second critical speeds, the lengths of said first and second tubular members and the dimensions of said first and second clearances being selected to limit the lateral deflection of said shaft due to a deformation at any point along its length so that said shaft is not permanently deformed, said deformation including deformation characteristic of the first and at least the second critical speeds.