A Stator And A Rotor For An Electric Motor

Abstract

A stator and a rotor suitable for use in an electric motor or generator. The stator comprises a plurality of stator coils and a support for holding the coils around a rotor of the motor. A cylindrical sleeve is mounted radially inwardly on the support to form a barrier in use between cooling fluid passing over the coils and a rotor located within the stator. The rotor comprises a hub, a plurality of rotor segments, and a plurality of permanent magnets. The segments are arranged around the hub in a ring, with the permanent magnets disposed between the segments. A radially outwardly facing exposed surface of each magnet is spaced radially inwardly from an outer cylindrical profile defined by the segments.

What is claimed is: 
     
         1 . A stator for an electric motor, the stator comprising:
 a plurality of stator coils;   a support for holding the coils around a rotor of the motor; and   a cylindrical sleeve mounted radially inwardly of the support to form a barrier in use between cooling fluid passing over the coils and a rotor located within the stator.   
     
     
         2 . A stator of  claim 1 , wherein the sleeve is formed of a fibre-reinforced material. 
     
     
         3 . A stator of  claim 2 , wherein the sleeve is formed of a carbon fibre-reinforced material. 
     
     
         4 . A stator of  claim 2 , wherein the material includes fibres wound in opposed spirals in at least two adjacent layers. 
     
     
         5 . A stator of  claim 1 , including two sleeve end supports which are received inside respective ends of the sleeve. 
     
     
         6 . A stator of  claim 1 , wherein the sleeve is an interference fit within the stator. 
     
     
         7 . A stator of  claim 6 , wherein the sleeve is an interference fit with radially inwardly facing surfaces of the support. 
     
     
         8 . A stator of  claim 1 , wherein the support defines a plurality of inwardly facing channels along which windings of the coils extend, and the sleeve closes the inwardly facing open sides of the channels. 
     
     
         9 . A stator of  claim 1 , wherein inner windings of the coils are less densely packed than outer windings of the coils to assist circulation of the fluid over the coils. 
     
     
         10 . A stator of  claim 1 , wherein the coils include a thermally conductive covering material. 
     
     
         11 . A stator of  claim 1 , including a housing which extends around the stator, wherein a fluid path is defined between the support and the housing for receiving cooling fluid, the fluid path including a plurality of sections which extend in a substantially axial direction over the length of the support. 
     
     
         12 . A stator of  claim 11 , wherein the support defines holes for receiving axially extending rods that couple the support to a housing of a motor containing the stator, and the holes locate the rods in the assembled motor between adjacent axially extending sections of the fluid path. 
     
     
         13 . A stator of  claim 1  wherein the cooling fluid is a liquid. 
     
     
         14 . A stator for an electric motor, the stator comprising:
 a plurality of stator coils;   a support for holding the coils around a rotor of the motor rotatable about an axis of the motor; and   a housing which extends around the stator, wherein a fluid path is defined between the support and the housing for receiving cooling fluid, the fluid path including a plurality of sections which extend in an axial direction over the length of the support.   
     
     
         15 . A stator of  claim 3 , including a cylindrical sleeve mounted radially inwardly of the support to form a barrier in use between cooling fluid passing over the coils and a rotor located within the stator. 
     
     
         16 . An electric motor including a stator of  claim 14 . 
     
     
         17 . A motor of  claim 16  including a rotor, wherein a pump for pumping the fluid over the coils is located within the rotor. 
     
     
         18 . A motor of  claim 17 , wherein the pump is driven by the rotation of the rotor. 
     
     
         19 . A rotor for an electric motor, the rotor comprising:
 a hub;   a plurality of rotor segments; and   a plurality of permanent magnets,   wherein the segments are arranged around the hub in a ring, with the permanent magnets disposed between the segments, and a radially outwardly facing exposed surface of each magnet is spaced radially inwardly from an outer cylindrical profile defined by the segments.   
     
     
         20 . A rotor of  claim 19 , wherein the hub includes a radially extending flange having a contoured surface facing the rotor segments, the surface being contoured so as to draw cooling fluid adjacent to the flange radially outwards as the flange rotates with the rotor. 
     
     
         21 . A rotor of  claim 20 , wherein a plurality of radially extending grooves are defined by the contoured surface. 
     
     
         22 . A rotor of  claim 19 , wherein an axially extending groove is defined by the outwardly facing surface of each rotor segment. 
     
     
         23 . A rotor of  claim 22 , wherein the groove is located substantially centrally in the circumferential direction in the outwardly facing surface of each rotor segment. 
     
     
         24 . A rotor of  claim 19 , wherein a fan is provided within the rotor for circulating cooling fluid over the rotor. 
     
     
         25 . A rotor of  claim 24 , wherein the fan is driven by the rotation of the rotor. 
     
     
         26 . An electric motor including a rotor of  claim 19 . 
     
     
         27 . A motor of  claim 26 , wherein the motor is configured to be coupled to an external fan to circulate cooling fluid over the rotor. 
     
     
         28 . A combination of a motor of  claim 27  and a fan, wherein the fan and motor are coupled together such that the fan is operable to circulate cooling fluid over the rotor of the motor. 
     
     
         29 - 31 . (canceled) 
     
     
         32 . An electric motor including a stator of  claim 1 .