Carrier for a flywheel
The present invention relates to a flywheel apparatus for energy storage and recovery including a housing within which there is a chamber in which a flywheel on a shaft rotates. The chamber is evacuated to at or near vacuum pressure, so that air resistance-related energy losses of the flywheel as it rotates are reduced. Maintaining near-vacuum pressure within the chamber requires an effective seal between the housing and the shaft. The effective seal must be maintained despite any relative movement (in particular translational movement) of the flywheel and the housing. To this end, the shaft is mounted via a bearing arrangement on a carrier on which is also mounted a sealing arrangement. The carrier is mounted on the housing such that the carrier, the bearing arrangement and the sealing arrangement move substantially together relative to the housing.
1. An apparatus comprising:
a high speed flywheel mounted on a shaft;
a housing for housing the flywheel, the housing arranged to hold at least a partial vacuum;
a first carrier;
a bearing arrangement; and
a sealing arrangement, including two seals and a cavity defined in part between the seals, wherein the cavity extends circumferentially around the shaft, and wherein the cavity is at least partially filled with a sealing fluid and the seals are configured to retain the sealing fluid within the cavity whereby the sealing arrangement is arranged to enable at least a partial vacuum to be maintained within the housing;
wherein the bearing arrangement and the sealing arrangement are mounted on the first carrier; the shaft is mounted on the first carrier via the bearing arrangement; and the first carrier is mounted on the housing; wherein the carrier, the sealing arrangement and the bearing arrangement are arranged to move substantially together, relative to the housing, in a radial direction and/or in a direction parallel to the axis of the shaft.
2. An apparatus as claimed in claim 1 , wherein the first carrier, the bearing arrangement and the sealing arrangement are arranged to move substantially together with the shaft.
3. An apparatus as claimed in claim 1 , wherein the apparatus is arranged such that relative movement of the housing and the flywheel causes the movement of the first carrier, the bearing arrangement and the sealing arrangement.
4. An apparatus as claimed in claim 1 , wherein the apparatus is arranged to allow movement of the first carrier, the bearing arrangement and the sealing arrangement relative to the housing in a direction along a radial line of the shaft.
5. An apparatus as claimed in claim 1 , wherein the apparatus is arranged to allow movement of the first carrier, the bearing arrangement and the sealing arrangement relative to the housing in a direction substantially parallel to a longitudinal axis of the shaft.
6. An apparatus as claimed in claim 1 , additionally comprising a first damper for damping relative movement of the housing and the flywheel, wherein the first carrier is mounted on the housing via the first damper, and the first damper is arranged to damp relative movement of the housing and the first carrier, the bearing arrangement and the sealing arrangement.
7. An apparatus as claimed in claim 6 , wherein the first damper is arranged to damp relative movement, in a direction along a radial line of the shaft, of the housing and the flywheel.
8. An apparatus as claimed in claim 6 , wherein the first damper is arranged to damp relative movement in a direction substantially parallel to a longitudinal axis of the shaft of the housing and the flywheel.
9. An apparatus as claimed in claim 6 , wherein the first damper comprises an elastomeric damper.
10. An apparatus as claimed in claim 6 , wherein the first damper comprises a ring.
11. An apparatus as claimed in claim 10 , wherein the axis of the ring is substantially parallel to the axis of the shaft.
12. An apparatus as claimed in claim 6 , additionally comprising a second damper for damping relative movement of the flywheel and the housing.
13. An apparatus as claimed in claim 1 , additionally comprising a second carrier, the second carrier being separated axially from the first carrier, on an opposite side of the flywheel.
14. An apparatus as claimed in claim 13 , wherein the first carrier and the second carrier are each provided with at least one damper for damping relative movement of the flywheel and the housing in a direction along a radial line of the shaft, and wherein the second carrier is additionally provided with at least one damper for damping relative movement of the flywheel and the housing in a direction substantially parallel to the axis of the shaft.
15. An apparatus as claimed in claim 1 , wherein a further sealing arrangement is provided between the carrier and the housing and is arranged to damp relative movement of the flywheel and the housing.
16. An apparatus as claimed in claim 15 , wherein the further sealing arrangement is a static sealing arrangement.
17. An apparatus as claimed in claim 1 , wherein the sealing arrangement is arranged to maintain a pressure difference of approximately 1 atmosphere between its two sides.
18. An apparatus as claimed in claim 1 , wherein a seal is provided or formed between the carrier and an outer surface of the sealing arrangement.
19. An apparatus as claimed in claim 1 further comprising at least one flywheel contact surface and at least one housing contact surface, wherein the allowable movement of the carrier relative to the housing in a radial direction with respect to the shaft axis is less than the radial clearance between the flywheel contact surface and the housing contact surface.
20. An apparatus as claimed in claim 1 further comprising at least one flywheel contact surface and at least one housing contact surface, wherein the allowable movement of the carrier relative to the housing in an axial direction with respect to the shaft axis is less than the axial clearance between the flywheel contact surface and the housing contact surface.