Rotary electrical machines

Abstract

A rotary electrical machine ( 1 ) has at least one stator ( 23 ). The stator is provided with at least one radial channel ( 107 ) for ducting cooling air. The channel ( 107 ) extends between a first position ( 113 ) at or substantially near the rim ( 109 ) of a winding region of the stator ( 23 ) and a second position ( 119 ) at or substantially near the center ( 51 ) of the winding region. The machine ( 1 ) has cooling means ( 91-97 ) for causing cooling air to enter the radial channel ( 107 ) via the second position ( 119 ) and exit via the first portion ( 113 ). The stator may have electrical windings arranged as coil sectors ( 183-197 ) disposed substantially equi-angularly in a generally circular pattern. At least some of the coil sectors are wound in a generally spiral fashion when viewed axially. A rotor ( 13 ), for the machine may have a plurality of equi-angularly spaced magnets ( 127 ), which are generally circular but with a cut-away portion, when viewed axially.

What is claimed is:  
     
       1. A rotary electrical machine comprising at least one substantially disc-shaped stator and at least one substantially disc-shaped adjacent rotor, a space being provided between said stator and said rotor, the stator being provided with at least one set of at least two substantially parallel radial channels for ducting of cooling air, the set of radial channels extending between a first position at or substantially near the rim of a winding region of the stator and a second position at or substantially near the centre of the winding region, the electrical machine further comprising cooling means for causing cooling air to pass through the set of radial channels and to pass through said space between said stator and said rotor. 
     
     
       2. A machine according to  claim 1 , wherein said cooling air enters the radial set of channels via the first position and exits via the second position. 
     
     
       3. A machine according to  claim 2 , wherein said cooling air passes through the space between the stator and the rotor after exiting the set of radial channels. 
     
     
       4. A machine according to  claim 1 , wherein said cooling air enters the set of radial channels via the second position and exits via the first position. 
     
     
       5. A machine according to  claim 4 , wherein said cooling air passes through said space between the stator and the rotor before entering the set of radial channels. 
     
     
       6. A machine according to  claim 1 , wherein said cooling means is arranged to subject one position of the at least one set of radial channels to a reduced pressure to suck the cooling air through the set of radial channels from the other position. 
     
     
       7. A machine according to  claim 1 , wherein said cooling means is arranged to provide pressurised cooling air to the at least one set of radial channels at one position to blow the cooling air through the set of radial channels to the other position. 
     
     
       8. A machine according to  claim 1 , further comprising a drive shaft and the cooling means comprises an evacuation compressor actuable by the drive shaft. 
     
     
       9. A machine according to  claim 1 , wherein the cooling means comprises a pump. 
     
     
       10. A machine according to  claim 1 , wherein the cooling means comprises a cooling fan. 
     
     
       11. A machine according to  claim 1 , wherein the at least one stator comprises electrical windings. 
     
     
       12. A machine according to  claim 1 , wherein the at least one rotor has a plurality of substantially equi-angularly spaced magnets. 
     
     
       13. A machine according to  claim 1 , wherein the at least one set of radial channels follows a substantially straight path between the first and second positions. 
     
     
       14. A machine according to  claim 1 , wherein the at least one set of radial channels follows a curved or meandering path between the first and second positions, the general direction of the channels being radial. 
     
     
       15. A rotary electrical machine comprising at least one stator, the stator being provided with at least one set of radial channels for ducting of cooling air, said radial channels extending between a first position at or substantially near the rim of a winding region of the stator and a second position at or substantially near the centre of the winding region, the electrical machine further comprising cooling means for causing cooling air to enter the radial channels via the second position and exit via the first position each set of radial channels comprising at least two substantially parallel radial channels. 
     
     
       16. A machine according to  claim 15 , wherein the at least one stator comprises at least three electrical windings. 
     
     
       17. A machine according to  claim 16 , wherein at least one radial channel of a set of radial channels being disposed between adjacent windings.