Stator with bar winding and fluid cooling for a rotary electric machine
Stator for a rotary electric machine and having: a magnetic core axially crossed by a plurality of slots; a stator winding comprising a plurality of bars which are arranged inside the slots; a plurality of cooling channels which, in use, are flown through by a cooling fluid and are obtained inside the slots between the bars of the stator winding; and a plurality of covering elements, each of which consists of an electrically insulating plastic material, engages, without clearance, a corresponding slot on all sides of the slot, and centrally has a cavity wherein a series of corresponding bars are arranged and wherein the cooling channels are obtained.
1 . A stator for a rotary electric machine and comprising:
a magnetic core axially crossed by a plurality of slots;
a stator winding comprising a plurality of bars, which are arranged inside the slots;
a plurality of cooling channels, which, in use, can be flown through by a cooling fluid and are obtained inside the slots between the bars of the stator winding; and
a plurality of covering elements, each of which is made of an electrically insulating plastic material, engages a corresponding slot, without clearance, on all sides of the slot and has, at the centre, a cavity where a series of corresponding bars are arranged and the cooling channels are obtained;
wherein each covering element has two major side walls that are opposed and radially oriented and two opposite minor head walls connect the two major side walls to each other and have an extension lower than an extension of the major side walls;
wherein each cooling channel is delimited by walls of a corresponding covering element and by at least one corresponding bar;
wherein each covering element has seats, each of which consists of two facing and opposite recesses cut into the two major side walls of the covering element and is configured to accommodate therein, without clearance, the ends of at least one corresponding bar;
wherein the cooling channels are arranged next to the seats where the bars are arranged;
wherein two annular cooling manifolds are provided which are arranged at opposite ends of the magnetic core and into which the cooling channels flow;
wherein two annular containing bodies are provided, each of which internally delimits a corresponding cooling manifold and is made of plastic material; and
wherein two annular connection bodies are provided, which are arranged at the two opposite ends of the magnetic core, are connected without interruptions to all the covering elements with which they form a single, indivisible assembly, and thus connect all the covering elements together, and form a support base for the containing bodies.
2 . The stator according to claim 1 , wherein each seat is shaped so as to accommodate at least two bars in contact with one another.
3 . The stator according to claim 1 , wherein each seat is shaped so as to accommodate exactly two bars in contact with one another.
4 . The stator according to claim 1 , wherein in each slot two end cooling channels are provided that are arranged on the sides of the bars and of the central cooling channels arranged between the bars.
5 . The stator according to claim 1 , wherein:
each slot has a through opening facing a central axis; and
each covering element has a protuberance engaging, without clearance, the through opening of the corresponding slot.
6 . The stator according to claim 1 , wherein each major side wall has axial ribs, each of which delimits a corresponding seat.
7 . The stator according to claim 1 and comprising a casing which contains the magnetic core and externally delimits the two cooling manifolds.
8 . The stator according to claim 7 , wherein the stator winding has two heads which are housed in the cooling manifolds.
9 . The stator according to claim 1 , wherein each connection body connects all the covering elements in the slots together.
10 . The stator according to claim 1 , wherein the containing bodies are welded to the respective annular connecting bodies.
11 . The stator according to claim 1 , wherein the covering elements are made of a plastic material having a thermal conductivity greater than 1 W/m K.
12 . A method for manufacturing the stator according to claim 1 and comprising the steps of:
injection moulding the plastic material into the slots of the magnetic core to manufacture the covering elements; and
inserting the bars into the covering elements internally lining the slots.