Flywheel systems

Abstract

A flywheel system comprises a flywheel rotor comprising a rotor disc and a rotor shaft and has a longitudinal axis extending centrally through the rotor disc and the rotor shaft. The system further comprises a journal assembly configured to facilitate rotation of the flywheel rotor. The journal assembly comprises a sleeve having an aperture extending therethrough from a first end to a second, opposite end, a rod at least partially disposed within the aperture of the sleeve, and a nut coupled to a portion of the rod. The rod has a length greater than the sleeve such that a portion of the rod extends axially beyond the first end of the sleeve. A method of forming the flywheel comprises coupling the rod to the rotor shaft and pulling the second end of the rod to tension the rod. The nut maintains the tension in the rod when coupled thereto.

What is claimed is: 
     
         1 . A flywheel system, comprising:
 a flywheel rotor comprising a rotor disc and a rotor shaft; and   a journal assembly adjacent to the flywheel rotor and comprising:
 a sleeve having an aperture extending therethrough from a first end to an opposite second end, the second end of the sleeve coupled to the rotor shaft; and 
 a rod at least partially disposed within the aperture of the sleeve, the rod comprising an elongated shaft at a first end thereof and a head at a second end thereof, the first end of the rod extending axially beyond the first end of the sleeve, and the head at the second end of the rod retained by mechanical interference within a recess in the rotor shaft, wherein longitudinal axes of the sleeve and the rod are coaxial with a longitudinal axis of the flywheel rotor. 
   
     
     
         2 . The flywheel system of  claim 1 , wherein the rod comprises an annular protrusion between the elongated shaft and the head, the annular protrusion extending circumferentially beyond outer surfaces of the elongated shaft and the head. 
     
     
         3 . The flywheel system of  claim 2 , wherein the annular protrusion of the rod intervenes between a portion of the sleeve and the rotor shaft. 
     
     
         4 . The flywheel system of  claim 2 , wherein the rotor shaft comprises protruding features adjacent to the rod, outer surfaces of the annular protrusion of the rod comprising one or more linear portions corresponding to the protruding features of the rotor shaft. 
     
     
         5 . The flywheel system of  claim 1 , wherein the rod has a longitudinal length relatively greater than a longitudinal length of the sleeve, the second end of the rod extending axially beyond the second end of the sleeve. 
     
     
         6 . The flywheel system of  claim 1 , wherein the second end of the sleeve encircles an end portion of the rotor shaft, the second end of the sleeve coupled to the end portion of the rotor shaft by mechanical interference. 
     
     
         7 . The flywheel system of  claim 1 , wherein the sleeve and the rod individually comprise a single, monolithic unit. 
     
     
         8 . A flywheel system, comprising:
 a flywheel rotor comprising a rotor disc and a rotor shaft;   a journal assembly adjacent to the flywheel rotor and comprising:
 a sleeve having an aperture extending therethrough from a first end to an opposite second end, the second end of the sleeve coupled to the rotor shaft; and 
 a rod at least partially disposed within the aperture of the sleeve, a first end of the rod extending axially beyond the first end of the sleeve and a second end of the rod coupled to the rotor shaft, and the rod having a longitudinal axis coaxial with longitudinal axes of the sleeve and the flywheel rotor; 
   a bearing assembly encircling the journal assembly, the bearing assembly comprising bearings disposed between an inner housing and an outer housing; and   an annular space extending radially between the inner housing and the outer housing about the bearings, the annular space sized and configured for formation of a squeeze film damper about the bearings.   
     
     
         9 . The flywheel system of  claim 8 , wherein the inner housing is movably disposed within the outer housing. 
     
     
         10 . The flywheel system of  claim 8 , wherein the outer housing substantially surrounds the inner housing, and the inner housing is coupled to the outer housing. 
     
     
         11 . The flywheel system of  claim 8 , wherein an exterior surface of the inner housing and an interior surface of the outer housing define at least one fluid path of the annular space extending radially between the inner housing and the outer housing. 
     
     
         12 . The flywheel system of  claim 11 , wherein at least one fluid path is in communication with the bearings of the bearing assembly. 
     
     
         13 . The flywheel system of  claim 8 , wherein the bearings comprise angular contact bearings configured to support one or more of radial loads and axial loads of the flywheel rotor. 
     
     
         14 . A flywheel system, comprising:
 a flywheel rotor comprising a rotor disc and a rotor shaft;   an upper journal assembly and a lower journal assembly coupled to the flywheel rotor, each of
 the upper journal assembly and the lower journal assembly comprising: 
 a sleeve having an aperture extending therethrough from a first end to an opposite second end; 
 a rod disposed within the aperture of the sleeve such that a portion the rod extends axially beyond the first end of the sleeve; 
   an upper bearing assembly disposed about the upper journal assembly;   a lower bearing assembly disposed about the lower journal assembly; and   an electromagnet adjacent to the rotor disc, the electromagnet configured to move the flywheel rotor axially toward the upper bearing assembly and away from the lower bearing assembly to apply an axially compressive force against a bearing disposed within the upper bearing assembly.   
     
     
         15 . The flywheel system of  claim 14 , further comprising a gear drive system adjacent to the lower bearing assembly, the gear drive system and the electromagnet configured to adjust a load applied to the bearing. 
     
     
         16 . The flywheel system of  claim 14 , wherein the upper bearing assembly comprises a first load cell adjacent to the upper journal assembly and the lower bearing assembly comprises a second load cell adjacent to the lower journal assembly. 
     
     
         17 . The flywheel system of  claim 14 , wherein the sleeve is coupled to the rotor shaft, the second end of the sleeve circumferentially enclosing an end of the rotor shaft. 
     
     
         18 . The flywheel system of  claim 14 , wherein the sleeve directly contacts the rotor shaft along at least two consecutive sides of the rotor shaft. 
     
     
         19 . The flywheel system of  claim 14 , wherein a longitudinal axis of the flywheel rotor extends centrally through the rotor disc and the rotor shaft, the longitudinal axis of the flywheel rotor substantially aligned with longitudinal axes of the sleeve and the rod. 
     
     
         20 . The flywheel system of  claim 14 , wherein:
 the upper bearing assembly comprises two or more bearing assemblies stacked axially adjacent to one another; and   the lower bearing assembly comprises two or more additional bearing assemblies stacked axially adjacent to one another.