Liquid cooled stator for high efficiency machine

1. A method for building a stator assembly for a rotary electric machine, comprising the steps of:

providing a plurality of axially extending teeth spaced circumferentially from one another to define slots therebetween;

providing cooling structure in each slot;

winding stator windings around the teeth and the cooling structures such that each winding is at least partially disposed in each slot, the windings being electrically connected to form a plurality of phases, wherein the teeth, the cooling structures, and the windings cooperate to form a subassembly;

radially collapsing the subassembly with a fixture;

axially sliding an outer stator core over the collapsed subassembly to connect the teeth to the outer stator core; and

removing the collapsed subassembly from the fixture to allow the subassembly to automatically radially expand after the outer stator core is slid over the assembly.

2. The method recited in claim 1 , wherein each tooth includes a projection that mates with a corresponding recess in the outer stator core.

3. The method recited in claim 1 , wherein the stator windings are distributed windings around the teeth.

4. The method recited in claim 1 , wherein the stator windings are concentrated windings around the teeth.

5. A method for building a stator assembly for a rotary electric machine, comprising the steps of:

providing a plurality of axially extending teeth spaced circumferentially from one another to define slots therebetween;

providing cooling structure in each slot;

winding stator windings around the teeth and the cooling structures such that each winding is at least partially disposed in each slot, the windings being electrically connected to form a plurality of phases,

providing a compressible insulating layer between the cooling structures and the windings, wherein the teeth, the cooling structures, the compressible insulating layers, and the windings cooperate to form a subassembly;

radially collapsing the subassembly such that the compressible insulating layers are compressed;

axially sliding an outer stator core over the collapsed subassembly to connect the teeth to the outer stator core; and

radially expanding the subassembly after the outer stator core is slid over the assembly to automatically expand the compressible insulating layers.

6. A method for building a stator assembly for a rotary electric machine, comprising the steps of:

providing a plurality of axially extending teeth spaced circumferentially from one another to define slots therebetween;

providing cooling structure in each slot;

winding stator windings around the teeth and the cooling structures such that each winding is at least partially disposed in each slot, the windings being electrically connected to form a plurality of phases,

providing a compressible insulating layer between the windings and the teeth, wherein the teeth, the cooling structures, the compressible insulating layers, and the windings cooperate to form a subassembly;

radially collapsing the subassembly such that the compressible insulating layers are compressed when;

axially sliding an outer stator core over the collapsed subassembly to connect the teeth to the outer stator core; and

radially expanding the subassembly after the outer stator core is slid over the assembly to automatically expand the compressible insulating layers.

7. The method recited in claim 1 , further comprising enclosing the subassembly in resin after connecting the teeth to the outer stator core.

8. The method recited in claim 1 , wherein each cooling structure defines a plurality of coolant passageways radially aligned with one another.

9. The method recited in claim 1 , wherein the stator windings comprise rectangular wire formed in multiple turns with each turn having a width extending in a radial direction of the subassembly and a thickness greater than the width extending circumferentially.

10. The method recited in claim 1 , wherein the stator windings are wound such that the cooling structures in slots in one of the plurality of phases are not fluidly connected in series with the cooling structures in slots in another of the plurality of phases.