Flywheel containment with external touchdown rings at reduced diameter

Apparatus for containing a flywheel comprising:

• a flywheel;
• a shaft;
• a bearing arrangement for supporting the shaft;
• and
• a housing for housing the flywheel, the shaft and the bearing arrangement;
• wherein the flywheel is mounted on the shaft, the shaft is mounted to the bearing arrangement, and the bearing arrangement is mounted to the housing;
• wherein the flywheel has a rim formed by a circumferential face of the flywheel, and a hub formed on both axial sides of a radially central region of the flywheel, the hub being wider, axially, than the rim such that a circumferential contact surface is formed on both axial sides of the radially central region of the flywheel by the hub that is coaxial with the rim, the rim being between the axial sides of the radially central region of the flywheel;
• wherein the housing comprises an annular force transfer region that faces, and is concentric with, the contact surface, a diameter of the force transfer region being greater than a diameter of the contact surface;
• and
• wherein, in use, excessive radial movement of the flywheel results in the contact surface contacting the transfer region.

Apparatus for containing a flywheel comprising:

• a flywheel;
• a shaft;
• a bearing arrangement for supporting the shaft;
• and
• a housing for housing the flywheel, the shaft and the bearing arrangement;
• a lubricant system that is arranged to circulate lubricant to the bearing arrangement, wherein a distal edge of the contact surface comprises a lip for preventing lubricant from the bearing arrangement reaching the clearance;
• wherein the flywheel is mounted on the shaft, the shaft is mounted to the bearing arrangement, and the bearing arrangement is mounted to the housing;
• wherein the flywheel has a rim formed by a circumferential face of the flywheel, and a hub formed by a central region of the flywheel, the hub being wider, axially, than the rim such that a circumferential contact surface is formed by the hub that is coaxial with the rim;
• wherein the housing comprises an annular force transfer region that faces, and is concentric with, the contact surface, a diameter of the force transfer region being greater than a diameter of the contact surface;
• and
• wherein, in use, excessive radial movement of the flywheel results in the contact surface contacting the transfer region.