Hydrodynamic bearing system for a brushless DC motor

Abstract

A hydrodynamic bearing system for a motor. The motor is illustrated and described as driving a pump for an artificial heart. The motor stator has a cylindrical bore which is closed at one end. The rotor is slidable and rotatable in the bore. The rotor has affixed to its shaft an impeller with its outside diameter concentric to the rotor outside diameter. Both rotor and impeller are supported hydrodynamically such that the tendency is for the entire rotor/impeller assembly (the only moving element) to be completely suspended by fluid. The rotor can be rapidly reversed to provide heart pumping action or can be driven unidirectionally for artificial heart pumping action of another type. The fluid cannot easily escape from the closed end of the stator, thereby providing a dashpot effect which tends to keep the rotor from changing position. In moving away from the closed end, the rotor brings fluid between the end of the rotor and the closed end of the bore to act as a buffer or bearing fluid when reversal moves the rotor toward the closed end.

Dependencies are inferred from the claim text.