Liquid-cooled rotary electric machine having axial end cooling

1. A liquid-cooled rotary electric machine comprising:

a coolant inlet and a coolant outlet;

a stator having a central axis;

a rotor surrounded by the stator and having rotation relative to the stator about the central axis;

a jacket defining a heat transfer surface in conductive thermal communication with the stator, the jacket having opposite axial ends, an interior volume in which the stator and rotor are located, and an axial end portion having walls, the interior volume partially enclosed by the jacket axial end portion;

a fluid channel traversing the jacket heat transfer surface between the jacket axial ends;

a fluid passage defined by jacket axial end portion walls and in fluid communication with the fluid channel, a flow path of liquid coolant through the machine defined by the fluid channel and the fluid passage between the coolant inlet and the coolant outlet; and

a heat source in conductive thermal communication with a jacket axial end portion wall, whereby at least a portion of heat transferable between the heat source and the fluid passage is convectively transferable between the jacket axial end portion walls and liquid coolant along the flow path;

wherein the fluid passage has first and second openings between which the flow path of liquid coolant through the machine extends, the fluid channel and the fluid passage fluidly connected to each other via one of the first and second openings; and

wherein the flow path is generally spiral-shaped and extends about the stator central axis with changing radial distance therefrom between the first and second openings.

2. The machine of claim 1 , wherein the other of the first and second openings is fluidly connected to one of the coolant inlet and the coolant outlet.

3. The machine of claim 2 , wherein the jacket axial end portion walls define a port isolated from the fluid passage and to which the fluid channel is fluidly connected, and the other of the coolant inlet and the coolant outlet is fluidly connected to the port.

4. The machine of claim 1 , wherein the first and second openings are located at opposite ends of the fluid passage along the flow path.

5. The machine of claim 1 , wherein the heat source is located axially adjacent to a jacket axial end portion wall relative to the central axis.

6. The machine of claim 1 , wherein the heat source is located radially adjacent to a jacket axial end portion wall relative to the central axis.

7. The machine of claim 1 , wherein the jacket axial end portion fully encloses the interior volume at one jacket axial end.

8. The machine of claim 1 , wherein the fluid passage and the heat source do not overlap axially.

9. The machine of claim 1 , wherein the machine comprises power electronics, and the heat source comprises the power electronics.

10. The machine of claim 9 wherein the machine comprises a cover disposed over the jacket axial end portion and defining the fluid passage, a jacket axial end portion wall disposed between the cover and the power electronics.

11. The machine of claim 1 , wherein the machine comprises a bearing supported by the jacket axial end portion, the rotor is supported within the jacket interior volume by the bearing, and the heat source comprises the bearing.

12. The machine of claim 1 , wherein the heat source is located axially between the rotor and the fluid passage.

13. The machine of claim 1 , wherein relative to the central axis, a portion of the fluid passage extends radially outward of the heat source.

14. The machine of claim 1 , further comprising a separable cover that defines the fluid passage, and wherein the fluid passage is located between the rotor and the cover in a direction parallel to the central axis.

15. The machine of claim 14 , wherein a jacket axial end portion wall is disposed axially between the cover and the heat source.

16. The machine of claim 1 , wherein the heat source is disposed axially between the rotor and the jacket axial end portion.

17. A method for liquid-cooling a rotary electric machine, comprising the steps of:

conveying liquid coolant along a fluid channel traversing a heat transfer surface of a jacket in conductive thermal communication with a stator surrounding a rotor, and along a fluid passage fluidly connected in series to the fluid channel and defined by a jacket axial end portion partially enclosing an interior volume in which the stator and rotor are located; and

convectively transferring heat from the stator through the heat transfer surface and from a heat source in conductive thermal communication with a wall of the jacket axial end portion, to liquid coolant along a flow path defined by the fluid channel and the fluid passage that extends between a coolant inlet and a coolant outlet of the machine;

wherein the fluid passage has first and second openings between which the flow path of liquid coolant through the machine extends, the fluid channel and the fluid passage fluidly connected to each other via one of the first and second openings; and

wherein the flow path is generally spiral-shaped and extends about a stator central axis with changing radial distance therefrom between the first and second openings.