Method and apparatus for cooling a rotor assembly
A rotor assembly includes a rotor core having a rotatable shaft and defining at least one rotor post, a winding wound around the post that defines an end turn, and a coil support assembly including a coil support disc rotatably coupled to the rotatable shaft and comprising a radially inner portion and a radially outer portion coupled via a set of spokes. The radially outer portion overlies an end turn and defines a set of channels therethrough sized and disposed to receive a flow of fluid from the set of rotor windings.
1. A coil support assembly for a set of rotor windings of an electric machine, comprising:
a coil support disc comprising a radially inner portion and a radially outer portion, the radially inner portion rotatably coupled to a rotatable shaft of the electric machine, the radially outer portion comprising a set of arcuate segments respectively defining a set of channels therethrough in fluid communication with the rotor windings, the set of arcuate segments configured to overlie an end turn of the rotor windings relative to a rotational axis of the rotatable shaft; and
a retaining bracket surrounding the coil support disc and fastened to the set of arcuate segments.
2. The coil support assembly of claim 1 , wherein the retaining bracket is disposed outboard from the coil support disc with respect to the electric machine.
3. The coil support assembly of claim 1 , wherein the radially inner portion is coupled to the set of arcuate segments via a set of spokes.
4. The coil support assembly of claim 3 , wherein each respective spoke is disposed between a corresponding end turn of the set of rotor windings a rotor core of the electric machine.
5. The coil support assembly of claim 1 , wherein a number of arcuate segments corresponds to a number of poles of the electric machine.
6. A method of cooling rotor winding end turns of a rotor assembly of an electric machine, comprising:
receiving a fluid coolant flow at a coil support disc having a radially inner portion and a radially outer portion, the radially inner portion rotatably coupled to a rotatable shaft of the electric machine, and further coupled to the radially outer portion via a set of radially extending spokes, the radially outer portion comprising a set of arcuate segments respectively defining a set of channels therethrough, the set of arcuate segments configured to overlie a rotor winding end turn relative to a rotational axis of the rotor assembly, and a retaining bracket surrounding the coil support disc and fastened to the set of arcuate segments;
delivering the fluid coolant flow through a set of passages extending radially through the rotor winding end turns and in a thermally conductive relationship with the rotor winding end turns;
collecting, at a collection surface of the radially outer portion of the coil support disc, the fluid coolant flow from the set of passages; and
redirecting, by the collection surface, the fluid coolant flow radially outward from the rotor assembly.
7. The method of claim 6 , further comprising expelling, by the radially outer portion, the fluid coolant flow toward a set of stator windings.
8. A rotor assembly for an electric machine comprising:
a rotatable shaft having a rotational axis and defining a first coolant conduit fluidly connected with a source of coolant;
a rotor core fixed relative to the rotatable shaft and defining at least one rotor post;
a set of rotor windings wound around the rotor post and defining a corresponding set of rotor winding end turns extending axially beyond the rotor core; and
a coil support assembly fixed to the rotatable shaft, the coil support assembly including:
a coil support disc comprising a radially inner portion and a radially outer portion, the radially inner portion rotatably coupled to a rotatable shaft of the electric machine, and further coupled to the radially outer portion via a set of radially extending spokes; and the radially outer portion comprising a set of arcuate segments respectively configured to overlie the set of rotor winding end turns relative to the rotational axis, the set of arcuate segments defining a set of channels therethrough in fluid communication with the rotor winding end turn; and
a retaining bracket surrounding the coil support disc and fastened to the set of arcuate segments.
9. The rotor assembly of claim 8 , wherein the retaining bracket is disposed outboard from the coil support disc with respect to the electric machine.
10. The rotor assembly of claim 8 , wherein each respective spoke is disposed between a corresponding end turn of the set of rotor windings and the rotor core.
11. The rotor assembly of claim 8 , further comprising a coolant spray ring fixed relative to the rotatable shaft and arranged to receive a flow of coolant therefrom.
12. The rotor assembly of claim 11 , wherein the coolant spray ring defines a set of channels therethrough in fluid communication with the set of rotor winding end turns.
13. The rotor assembly of claim 11 , wherein each arcuate segment corresponds to a respective pole of the electric machine.
14. The rotor assembly of claim 8 , wherein the set of channels respectively define a set of collection surfaces angled to redirect a flow of coolant.
15. The rotor assembly of claim 8 , wherein the rotor winding end turns include end turn passages extending radially through the rotor winding end turns and in a thermally conductive relationship with the rotor winding end turns.
16. The rotor assembly of claim 15 , wherein a rotation of the rotatable shaft about the rotational axis radially expels a flow of coolant past the rotor winding end turns and radially outward from the rotor assembly.