Winding insulation arrangement for axial flux machines

Abstract

A stator 20 for an axial flux machine such as a motor or generator. The stator includes a stator core 32 having a back plane 24 which in use is disposed perpendicularly about a rotational axis of the machine. A plurality of teeth 26 extend axially from the back plane so as to form winding receiving slots 28 between adjacent teeth. The stator also includes an electrical winding 30 including a plurality of coils 32 , each coil being located about a tooth of the stator core and being electrically isolated from the stator tooth by means of an insulating former 34 having a shape which closely conforms to the shape of the stator tooth. The coils 32 are interconnected to form the winding 30 . A method of constructing a stator is also disclosed.

1 . A stator for an axial flux machine, the stator including:
 a stator core having a back plane which in use is disposed perpendicularly about a rotational axis of the machine, and a plurality of teeth extending axially from the back plane and including a free end opposite the backplane, wherein a plurality of winding receiving slots are defined between adjacent teeth; and   an electrical winding including a plurality of coils, each coil located about a stator tooth of the plurality of stator teeth and electrically isolated from the stator tooth by means of an insulating former having a shape which closely conforms to the shape of the stator tooth, the coils being interconnected to form the electrical winding.   
     
     
         2 . The stator of  claim 1  wherein each stator tooth has a substantially trapezoidal shape and each winding receiving slot has substantially parallel side walls. 
     
     
         3 . The stator of  claim 2  wherein each insulating former includes a sleeve having a tooth receiving opening therethrough and a pair of flanges extending outwardly from the sleeve with one flange being located at each end of the sleeve, and wherein the coil is wound between the flanges. 
     
     
         4 . The stator of  claim 3  wherein the tooth receiving opening of each sleeve has a substantially trapezoidal shape so as to closely conform to the shape of the stator tooth upon which it is located. 
     
     
         5 . The stator of  claim 1  wherein a length of each insulating former is substantially equal to a length of the stator teeth such that a free end of each insulating former substantially aligns with the free end of a stator tooth within a plane parallel to the back plane. 
     
     
         6 . The stator of  claim 1  wherein each insulating former includes, at an end facing the stator core back plane, a fastener arranged to secure the insulating former to the back plane. 
     
     
         7 . The stator of  claim 1  wherein each insulating former includes at least one wiring channel at a radially outer side thereof to facilitate interconnection of the coils. 
     
     
         8 . The stator of  claim 7  wherein the machine is a multiphase machine and each insulating former includes a plurality of wiring channels arranged so as to guide conductors between successive coils of the same phase and electrically isolate them from coils of other phases and from the stator core. 
     
     
         9 . The stator of  claim 2  wherein each insulating former includes side covers configured to at least partially enclose the coil and electrically isolate it from side walls of adjacent teeth and/or adjacent coils. 
     
     
         10 . The stator of  claim 9  wherein each side cover includes retaining clips which snap closed over the coil once wound. 
     
     
         11 . The stator of  claim 2  wherein the coils are provided on every second tooth of the stator core and insulating sleeves surround intervening teeth so as to electrically isolate the coils from side walls of the intervening teeth. 
     
     
         12 . (canceled) 
     
     
         13 . A method of constructing a stator for an axial flux machine, the method comprising:
 providing a stator core, the core having a back plane which in use is disposed perpendicularly about a rotational axis of the machine, and a plurality of teeth extending axially from the back plane so as to define winding receiving slots between adjacent teeth, wherein each of the plurality of teeth includes a first end at the back plane and a second end opposite the back plane;   providing a plurality of insulating formers, each former including an opening defined therein and configured to closely conform to the shape of the stator teeth;   winding a coil about each former;   sliding the second end of a tooth of the plurality of teeth into the opening of each former; and   connecting the coils together to form an electrical winding.   
     
     
         14 . The method of  claim 13  wherein each insulating former includes side covers configured to at least partially enclose the coil and electrically isolate it from side walls of adjacent teeth and/or from adjacent coils, the method further comprising coupling the side covers to the insulating formers before sliding the teeth into the openings. 
     
     
         15 . The method of  claim 13  wherein the insulating formers and associated coils are placed on every second tooth of the stator core, the method further comprising sliding insulating sleeves onto intervening teeth so as to electrically isolate the coils from the intervening teeth. 
     
     
         16 . The stator of  claim 1  wherein a cross section of each stator tooth, taken along a plane parallel to the back plane, is substantially uniform from the back plane to the free end of each stator tooth. 
     
     
         17 . The stator of  claim 3  wherein the free end of each stator tooth is configured to extend at least partially through the tooth receiving opening. 
     
     
         18 . The stator of  claim 1  wherein the coils wound around the insulating formers are inserted onto a one-piece stator core. 
     
     
         19 . The method of  claim 13  wherein each insulating former of the plurality of insulating formers includes a sleeve that defines the tooth receiving opening, a first flange at the first end of the sleeve and a second flange at the second end of the sleeve, wherein the first flange and the second flange provide structural support to the insulating former. 
     
     
         20 . The method of  claim 13  further comprising providing a stator core including a plurality of teeth extending axially from a backplane prior to sliding each former onto a tooth of the plurality of teeth.