Rotor assembly and cooling arrangement for an electric machine

1. A rotor assembly for an electric machine comprising:

a rotor core having a rotatable shaft having hollow interior defining a coolant conduit and at least one post defining a winding pole;

a winding wound around the pole, and having axial segments that extend axially along the pole and end turn segments that extend axially beyond ends of the post;

a coolant manifold supported by the shaft and sealed from the winding but fluidly coupled to the coolant conduit wherein coolant can move between the coolant manifold and the coolant conduit, the coolant manifold having a thermally conductive face radially underlying at least a portion of the end turn segment and in thermal contact with the portion of an end turn segment, wherein heat from the end turn segment is transferred by conduction through the thermally conductive face of the coolant manifold to coolant in the coolant manifold; and

at least one coolant tube in fluid communication with the coolant manifold and extending axially along the post, wherein the coolant tube comprises a first thermally conductive face radially underlying, in thermal contact with, and at least partially supporting, an axial segment of a first winding and a second thermally conductive face radially underlying, in thermal contact with, and at least partially supporting, an axial segment of a second winding.

2. The rotor assembly of claim 1 further comprising a coolant manifold on opposite ends of the rotor core, with each of the coolant manifolds having a thermally conductive face in thermal contact with a corresponding one of the end turn segments.

3. The rotor assembly of claim 1 wherein heat from the axial segment is transferred by conduction through the thermally conductive face of the coolant tube to coolant in the coolant tube.

4. The rotor assembly of claim 1 further comprising a thermally conductive layer provided for separating the winding from the coolant tube.

5. The rotor assembly of claim 1 wherein the coolant manifold is in thermal contact with at least a portion of multiple end turn segments.

6. The rotor assembly of claim 1 further comprising a thermally conductive layer provided for separating the winding from the coolant manifold.

7. The rotor assembly of claim 6 wherein the thermally conductive layer is a coating applied to the winding.

8. The rotor assembly of claim 1 further comprising a cooling cage defined by opposing coolant manifolds on opposite ends of the rotor core, and at least one coolant tube fluidly coupling the manifolds adjacent an axial segment away from the pole, wherein the axial segment is in thermal contact with at least one coolant tube.

9. The rotor assembly of claim 8 further comprising four poles.

10. The rotor assembly of claim 9 further comprising four coolant tubes.

11. The rotor assembly of claim 10 wherein each coolant tube comprises a first thermally conductive face in thermal contact with a first winding and a second thermally conductive face in thermal contact with a second winding.

12. An electric motor comprising:

a cavity housing a rotor assembly and a stator;

the rotor assembly defining an axis of rotation and comprising:

a rotor core having a first post defining a first face of a first winding seat, and a second post defining a first face of a second winding seat;

a coolant tube at least partially defining a second face of the first and second winding seats;

at least one coolant manifold at least partially defining a second face of the first and second winding seats, and coupled with an axial end of the coolant tube; and

a first winding wound around the first post and at least partially supported by the first winding seat, wherein the first winding includes at least one first side segment extending axially along the post and at least one first end turn segment extending axially beyond the post;

a second winding wound around the second post and at least partially supported by the second winding seat, wherein the second winding includes at least one second side segment extending axially along the post and at least one second end turn segment extending axially beyond the post;

wherein a portion of the at least one coolant manifold is in thermal contact with at least a radially underlying a portion of the first and second end turn segments and the coolant tube is in thermal contact with at least a radially underlying a portion of the first and second side segments away from the posts.

13. The electric motor of claim 12 wherein the cavity is a dry cavity.