Flywheels for energy storage and methods of manufacture thereof

1. A flywheel assembly having a longitudinal axis and comprising an annular rotor and a rotor support for coupling the rotor to an axial shaft, wherein:

the rotor comprises fibres in a matrix material,

a ring comprising fibres in a matrix material is mounted on an outer circumferential surface of the rotor support and the rotor is mounted on an outer circumferential surface of the ring,

the rotor, rotor support and ring each having longitudinal axes which are coincident with the longitudinal axis of the assembly,

wherein the outer circumferential surface of the rotor support has a chamfer to assist fitting of the rotor support into the ring, and

further wherein the chamfer defines a lead in angle of 15° or less with respect to the longitudinal axis of the rotor support.

2. An assembly of claim 1 , wherein the ring has a greater elasticity than the rotor in a circumferential direction.

3. An assembly of claim 1 , wherein the ring has a greater elasticity than the rotor support in a circumferential direction.

4. An assembly of claim 1 , wherein the ring is mounted on an outermost circumferential surface of the rotor support.

5. An assembly of claim 1 , wherein the rotor support is press-fitted into the ring.

6. An assembly of claim 1 , wherein the ring is press-fitted into the rotor.

7. An assembly of claim 1 , wherein an interface between the rotor support and the ring intersects with a transverse plane that also intersects with an interface between the ring and the rotor.

8. An assembly of claim 1 , wherein the ring has a greater radial compressive strength than the rotor.

9. An assembly of claim 1 , wherein the ring has a lower radial compressive strength than the rotor support.

10. An assembly of claim 1 , wherein the fibres of the ring comprise glass fibres, basalt rock fibres and carbon fibres.

11. An assembly of claim 1 , wherein the ring has an interference fit around the rotor support.

12. An assembly of claim 1 , wherein the rotor has an interference fit around the ring.

13. An assembly of claim 1 , wherein the rotor support defines a frusto-conical inner surface, which is rotationally symmetrical about its longitudinal axis.

14. An assembly of claim 13 , wherein an angle defined by the frusto-conical inner surface of the rotor support with respect to a plane perpendicular to its longitudinal axis is selected so that elastic deformation of the rotor support during rotation matches that of the ring.

15. An assembly of claim 14 , wherein the angle is in a range from 17 to 26°.

16. An assembly of claim 13 , wherein the outer circumferential surface of the ring defines an outer cylindrical surface, and the rotor support and the ring are configured such that an imaginary surface defined by outwardly projecting the frusto-conical inner surface of the rotor support extends through the ring from its inner circumferential surface to meet the outer cylindrical surface of the ring.

17. An assembly of claim 1 , wherein the outer circumferential surface of the ring has a chamfer to assist fitting of the ring into the rotor.

18. An assembly of claim 17 , wherein the chamfer defines a lead in angle of 15° or less with respect to the longitudinal axis of the ring.

19. An assembly of claim 1 , wherein an inner circumferential surface of the ring has a chamfer to assist fitting of the rotor support into the ring.

20. An assembly of claim 1 , including an inner annulus mounted on an inwardly facing surface of the rotor.

21. An assembly of claim 20 , wherein the inner annulus includes particles of magnetic material.

22. An assembly of claim 20 , wherein an outer circumferential surface of the inner annulus has a chamfer to assist fitting of the inner annulus into the rotor.

23. An assembly of claim 22 , wherein the chamfer defines a lead in angle of 15° or less with respect to a longitudinal axis of the inner annulus.

24. An assembly of claim 22 , wherein a volume defined by an inner circumferential surface of the rotor, the chamfer of the rotor support and the chamfer of the inner annulus is filled with a bonding material.

25. An assembly of claim 24 , wherein the bonding material is a resin material.

26. An assembly of claim 20 , wherein an edge at each end of an inner circumferential surface of the inner annulus has a chamfer which defines an angle in the range from 20 to 60° with respect to the inner circumferential surface of the inner annulus.

27. An assembly of claim 26 , wherein the chamfer at each end of the inner circumferential surface of the inner annulus defines an angle in a range from 50 to 55° with respect to the inner circumferential surface of the inner annulus.

28. An assembly of claim 1 , wherein the rotor support is bonded to the ring using a resin material.

29. An assembly of claim 1 , wherein the rotor is bonded to the ring using a resin material.

30. A method of manufacturing a flywheel assembly, the assembly comprising an annular rotor, a rotor support for coupling the rotor to a support shaft, and a ring, wherein the rotor and the ring comprise fibres in a matrix material, the ring is mounted on an outer circumferential surface of the rotor support and the rotor is mounted on an outer circumferential surface of the ring, the method comprising:

press-fitting the rotor support into the ring.

31. A method of claim 30 , wherein the outer circumferential surface of the rotor support is press-fitted into the ring.

32. A method of claim 30 , including press-fitting the ring into the rotor.

33. A method of claim 32 , wherein the rotor support is press-fitted into the ring and then the ring is press-fitted into the rotor.

34. A method of claim 30 , wherein an interface between the rotor support and the ring intersects with a transverse plane that also intersects with an interface between the ring and the rotor.

35. A method of claim 30 , including press-fitting an inner annulus onto an inwardly facing surface of the rotor.

36. A method of claim 30 , including incorporating bonding material between the outer circumferential surface of the rotor support and the ring.

37. A flywheel assembly having a longitudinal axis and comprising an annular rotor and a rotor support for coupling the rotor to an axial shaft, wherein:

the rotor comprises fibres in a matrix material,

a ring comprising fibres in a matrix material is mounted on an outer circumferential surface of the rotor support and the rotor is mounted on an outer circumferential surface of the ring,

the rotor, rotor support and ring each having longitudinal axes which are coincident with the longitudinal axis of the assembly,

an inner annulus is mounted on an inwardly facing surface of the rotor, and

an outer circumferential surface of the inner annulus has a chamfer to assist fitting of the inner annulus into the rotor.

38. An assembly of claim 37 , wherein the chamfer defines a lead in angle of 15° or less with respect to the longitudinal axis of the inner annulus.

39. An assembly of claim 37 , wherein the outer circumferential surface of the rotor support has a chamfer to assist fitting of the rotor support into the ring, and

wherein a volume defined by an inner circumferential surface of the rotor, the chamfer of the rotor support and the chamfer of the inner annulus is filled with a bonding material.

40. An assembly of claim 39 , wherein the bonding material is a resin material.

41. A flywheel assembly having a longitudinal axis and comprising an annular rotor and a rotor support for coupling the rotor to an axial shaft, wherein:

the rotor comprises fibres in a matrix material,

a ring comprising fibres in a matrix material is mounted on an outer circumferential surface of the rotor support and the rotor is mounted on an outer circumferential surface of the ring,

the rotor, rotor support and ring each having longitudinal axes which are coincident with the longitudinal axis of the assembly, and

the rotor is bonded to the ring using a resin material.