Wind turbine generator rotor arrangement

1 . A rotor arrangement for a wind turbine generator, the rotor arrangement comprising a cylindrical ring structure arranged to rotate around a rotational axis, the cylindrical ring structure comprising:

a plurality of ring-shaped permanent magnet packages arranged coaxially around the rotational axis,

a plurality of tie rods extending axially through the plurality of permanent magnet packages to join the plurality of permanent magnet packages together; and

one or more spacer components located between at least one axially adjacent pair of the plurality of permanent magnet packages to space the respective pair of permanent magnet packages apart,

wherein at least one of the one or more spacer components includes an impeller element that extends radially outward from a leading edge to a trailing edge, the leading edge of the impeller element being configured to meet oncoming air as the rotor rotates and to guide the oncoming air in a radial direction to flow from the leading edge to the trailing edge between the at least one axially adjacent pair of permanent magnet packages, and

wherein the impeller element is shaped so that the leading edge protrudes radially inward, beyond an inner circumferential edge of the adjacent permanent magnet package, to meet the oncoming air as the rotor arrangement rotates.

2 . The rotor arrangement according to claim 1 , further comprising one or more spacer components, located adjacent to an axially outer end package of the plurality of ring-shaped permanent magnet packages, against which one or more retaining elements of the rotor arrangement bear to retain the permanent magnet packages on the plurality of tie rods, the one or more spacer components at the end packages being configured to act as an impeller as the rotor rotates, in use, thereby to cause air to flow in a radial direction across the adjacent end package.

3 . The rotor arrangement according to claim 1 , wherein each spacer component is arranged for retaining one or more permanent magnets of the adjacent permanent magnet package in one or more respective axial cavities of that permanent magnet package.

4 . The rotor arrangement according to claim 1 , wherein the at least one of the one or more spacer components is arranged on a respective one of the plurality of tie rods.

5 . The rotor arrangement according to claim 4 , wherein each of the one or more spacer components includes the impeller element for causing the radial flow of air.

6 . The rotor arrangement according to claim 5 , wherein each impeller element is elongate and defines a longitudinal axis between the leading and trailing edges.

7 . The rotor arrangement according to claim 6 , wherein each impeller element is asymmetric.

8 . The rotor arrangement according to claim 7 , wherein each impeller element comprises:

a first air guiding surface extending between the leading and trailing edges on a first side of the impeller element, facing the oncoming air as the rotor arrangement rotates; and

a second air guiding surface extending between the leading and trailing edges on an opposing second side of the impeller element;

wherein the first air guiding surface is, at least partially, concave, and the second air guiding surface is, at least partially, convex.

9 . The rotor arrangement according to claim 8 , wherein the first air guiding surface is curved in a concave manner in a first portion that extends from the leading edge towards a point of maximum camber and, beyond the point of maximum camber, the first air guiding surface is convexly curved towards the trailing edge.

10 . The rotor arrangement according to claim 6 , wherein the longitudinal axis of each impeller element is backwardly inclined relative to the direction of rotation of the rotor arrangement, in use, to cause air to flow in a radially outward direction.

11 . The rotor arrangement according to claim 10 , wherein the longitudinal axis is inclined to the radial direction by more than 30 degrees.

12 . The rotor arrangement according to claim 10 , wherein the longitudinal axis is inclined to the radial direction by less than 60 degrees.

13 . The rotor arrangement according to claim 1 , wherein the at least one of the one or more spacer components include a circumferentially extending spacer plate comprising a plurality of radially extending channels recessed from a radial surface of the spacer plate, the plurality of channels being shaped to define a respective one of the one or more impeller elements between each pair of adjacent channels for causing the radial flow of air and directing the radial airflow through the respective pair of adjacent channels.

14 . The rotor arrangement according to claim 1 , wherein the one or more spacer components are joined by an adhesive to the adjacent permanent magnet package.

15 . The rotor arrangement according to claim 1 , wherein each of the one or more spacer components includes one or more axial locking formations for engaging one or more complementary formations on the adjacent permanent magnet package to retain the one or more spacer components in position, adjacent to that permanent magnet package.

16 . The rotor arrangement according to claim 15 ,

wherein each of the one or more spacer components is arranged for retaining one or more permanent magnets of the adjacent permanent magnet package in one or more respective axial cavities of that permanent magnet package, and

wherein at least one of said complementary formations on the adjacent permanent magnet package is defined by one of the one or more axial cavities of that permanent magnet package.

17 . The rotor arrangement according to claim 1 , further comprising one or more impeller vanes extending radially inward from an inner circumferential edge of the cylindrical ring structure, for causing the radial flow of air as the rotor arrangement rotates.

18 . The rotor arrangement according to claim 17 , wherein each impeller vane is arranged in a complementary manner to a respective one of the impeller elements of the one or more spacer components so that, collectively, the impeller vane and the impeller element cause the radial flow of air as the rotor arrangement rotates.

19 . The rotor arrangement according to claim 18 , wherein each impeller vane is connected to a respective one of the impeller elements of the one or more spacer components.

20 . The rotor arrangement according to claim 17 , wherein each impeller vane extends axially along the length of the cylindrical ring structure.

21 . The rotor arrangement according to claim 1 , wherein the cylindrical ring structure defines a central hollow portion.

22 . The rotor arrangement according to claim 21 , further comprising one or more impeller vanes extending radially inward from an inner circumferential edge of the cylindrical ring structure, for causing the radial flow of air as the rotor arrangement rotates,

wherein each impeller vane defines a leading edge within the central hollow portion of the cylindrical ring structure, the leading edge being configured to meet oncoming air as the rotor arrangement rotates, and thereby to cause a flow of air in a radial direction.

23 . A generator for a wind turbine comprising a rotor arrangement according to claim 1 .

24 . The generator according to claim 23 , comprising a stator arrangement defining a central hollow portion within which the rotor arrangement rotates.

25 . A rotor arrangement for a wind turbine generator, the rotor arrangement comprising:

a cylindrical ring structure, defining a central hollow portion, arranged to rotate around a rotational axis, the cylindrical ring structure comprising:

a plurality of ring-shaped permanent magnet packages arranged coaxially around the rotational axis,

a plurality of tie rods extending axially through the plurality of permanent magnet packages to join the plurality of permanent magnet packages together; and between at least one axially adjacent pair of the plurality of permanent magnet packages, a plurality of circumferentially arranged spacer components, each of the plurality of spacer components being arranged on a respective one of the plurality of tie rods and being configured to hold that pair of permanent magnet packages apart to define a pair of radial channels that extend between the pair of permanent magnet packages, and

a plurality of impeller vanes, each impeller vane extending radially inward from an inner circumferential edge of the cylindrical ring structure to define a leading edge within the central hollow portion of the cylindrical ring structure, the leading edge being configured to meet oncoming air as the rotor arrangement rotates, in use, and thereby to cause a flow of air in a radial direction through the respective pair of radial channels.

26 . The rotor arrangement according to claim 25 , wherein each impeller vane extends axially along the length of the cylindrical ring structure.

27 . A rotor arrangement for a wind turbine generator, the rotor arrangement comprising a cylindrical ring structure arranged to rotate around a rotational axis, the cylindrical ring structure comprising:

a plurality of ring-shaped permanent magnet packages arranged coaxially around the rotational axis, at least one ring-shaped permanent magnet package of the plurality of packages defining an inner circumferential edge,

a plurality of tie rods extending axially through the plurality of permanent magnet packages to join the plurality of permanent magnet packages together; and

one or more spacer components, located adjacent to an axially outer end package of the plurality of ring-shaped permanent magnet packages, against which one or more retaining elements of the rotor arrangement bear to retain the permanent magnet packages on the plurality of tie rods,

wherein at least one of the one or more spacer components includes an impeller element that extends radially outward from a leading edge to a trailing edge, the leading edge of the impeller element protruding radially inward beyond the inner circumferential edge and being configured to meet oncoming air as the rotor rotates and to guide the oncoming air in a radial direction to flow from the leading edge to the trailing edge across the axially outer end package.

28 . A rotor arrangement for a wind turbine generator, the rotor arrangement comprising a cylindrical ring structure arranged to rotate around a rotational axis, the cylindrical ring structure comprising:

a plurality of ring-shaped permanent magnet packages arranged coaxially around the rotational axis, at least one pair of adjacent ring-shaped permanent magnet packages being spaced apart from one another,

a plurality of tie rods extending axially through the plurality of permanent magnet packages to join the plurality of permanent magnet packages together; and

one or more impeller vanes extending radially inward from an inner circumferential edge of the cylindrical ring structure, for causing radial flow of air between the at least one pair of adjacent, spaced apart ring-shaped permanent magnet packages as the rotor arrangement rotates.

29 . A rotor arrangement for a wind turbine generator, the rotor arrangement comprising a cylindrical ring structure arranged to rotate around a rotational axis, the cylindrical ring structure comprising:

a plurality of ring-shaped permanent magnet packages arranged coaxially around the rotational axis,

a plurality of tie rods extending axially through the plurality of permanent magnet packages to join the plurality of permanent magnet packages together; and

one or more spacer components located between at least one axially adjacent pair of the plurality of permanent magnet packages to space the respective pair of permanent magnet packages apart,

wherein the one or more spacer components are configured to act as an impeller as the rotor rotates, in use, thereby to cause air to flow in a radial direction, with respect to the rotational axis of the rotor arrangement, between the at least one axially adjacent pair of permanent magnet packages,

wherein the one or more spacer components comprise a plurality of circumferentially arranged spacer components, each of the plurality of spacer components being arranged on a respective one of the plurality of tie rods,

wherein each of the plurality of circumferentially arranged spacer components is shaped to define an impeller element for causing the radial flow of air,

wherein each impeller element is elongate and extends from a leading edge to a radially outer trailing edge, defining a longitudinal axis between the leading and trailing edges, and

wherein each impeller element is shaped so that the leading edge protrudes radially inward, beyond an inner circumferential edge of the adjacent permanent magnet package, to meet oncoming air as the rotor arrangement rotates.

30 . A rotor arrangement for a wind turbine generator, the rotor arrangement comprising a cylindrical ring structure arranged to rotate around a rotational axis, the cylindrical ring structure comprising:

a plurality of ring-shaped permanent magnet packages arranged coaxially around the rotational axis,

a plurality of tie rods extending axially through the plurality of permanent magnet packages to join the plurality of permanent magnet packages together;

one or more spacer components located between at least one axially adjacent pair of the plurality of permanent magnet packages to space the respective pair of permanent magnet packages apart; and

one or more impeller vanes extending radially inward from an inner circumferential edge of the cylindrical ring structure, for causing the radial flow of air as the rotor arrangement rotates,

wherein at least one of the one or more spacer components includes an impeller element that extends radially outward from a leading edge to a trailing edge, the leading edge of the impeller element being configured to meet oncoming air as the rotor rotates and to guide the oncoming air in a radial direction to flow from the leading edge to the trailing edge between the at least one axially adjacent pair of permanent magnet packages, and

wherein each impeller vane is arranged in a complementary manner to a respective one of the impeller elements of the one or more spacer components so that, collectively, the impeller vane and the impeller element cause the radial flow of air as the rotor arrangement rotates.

31 . A rotor arrangement for a wind turbine generator, the rotor arrangement comprising a cylindrical ring structure arranged to rotate around a rotational axis, the cylindrical ring structure comprising:

a plurality of ring-shaped permanent magnet packages arranged coaxially around the rotational axis,

a plurality of tie rods extending axially through the plurality of permanent magnet packages to join the plurality of permanent magnet packages together;

one or more spacer components located between at least one axially adjacent pair of the plurality of permanent magnet packages to space the respective pair of permanent magnet packages apart; and

one or more impeller vanes extending radially inward from an inner circumferential edge of the cylindrical ring structure, for causing the radial flow of air as the rotor arrangement rotates,

wherein at least one of the one or more spacer components includes an impeller element that extends radially outward from a leading edge to a trailing edge, the leading edge of the impeller element being configured to meet oncoming air as the rotor rotates and to guide the oncoming air in a radial direction to flow from the leading edge to the trailing edge between the at least one axially adjacent pair of permanent magnet packages, and

wherein each impeller vane extends axially along the length of the cylindrical ring structure.