Electric machine with stator cooling channels
An electric machine includes a housing, a rotor rotatably supported by the housing for rotation about a longitudinal axis and a stator assembly fixed secured to the housing spaced apart from a surface of the rotor and concentric with the rotor about the longitudinal axis. The stator assembly includes a stator winding comprising circumferentially spaced apart stator teeth about the longitudinal axis, the stator teeth having remote ends proximate the surface of the rotor. A plurality of sealed cooling channels extend parallel to the longitudinal axis and are disposed between remote ends of successive teeth. The cooling channels are formed in resin of the stator assembly, the cooling channels being fluidly connected to ports in a closed system to circulate cooling fluid to cool the stator assembly and configured to remove heat from the stator assembly proximate the rotor surface. Other aspects include methods of making such machines.
1. An electric machine comprising:
a housing;
a rotor rotatably supported by the housing for rotation about a longitudinal axis; and
a stator assembly fixedly secured to the housing spaced apart from a surface of the rotor and concentric with the rotor about the longitudinal axis, the stator assembly having a stator winding comprising circumferentially spaced apart stator teeth about the longitudinal axis, the stator teeth having remote ends proximate the surface of the rotor, wherein a plurality of longitudinal cooling channels extend parallel to the longitudinal axis are disposed between remote ends of successive teeth, and wherein each end of each longitudinal cooling channel is fluidly connected to radially extending channels formed in the stator assembly, the longitudinal sealed cooling channels being formed in resin of the stator assembly, the longitudinal sealed cooling channels and radially extending channels being fluidly connected to ports in a closed system and configured to circulate cooling fluid axially in the longitudinal cooling channels and radially in the radial extending channels to cool the stator assembly and remove heat from the stator assembly proximate the surface of the rotor.
2. The electric machine of claim 1 wherein the radially extending channels are disposed at each end of the stator assembly.
3. The electric machine of claim 2 wherein each of the longitudinal cooling channels and ends of the radially extending channels open to an annular space about the longitudinal axis at each end of the stator assembly.
4. The electric machine of claim 3 wherein at least a portion of each of the radially extending channels are formed in resin of the stator assembly.
5. The electric machine of claim 4 wherein at least some of the radially extending channels are bounded in part by conductors of end turns of the stator assembly.
6. The electric machine of claim 3 wherein each annular space is defined in part by an annular sealing device.
7. The electric machine of claim 6 wherein the stator assembly includes an inner sleeve concentrically disposed about the longitudinal axis radially inward from remote ends of the stator teeth.
8. The electric machine of claim 7 wherein portions of an inner surface of the inner sleeve define a portion of each longitudinal cooling channel.
9. The electric machine of claim 8 wherein the annular sealing device comprises a ring and a first o-ring sealing engaging the ring and a portion of the housing and a second o-ring sealing engaging the ring and a portion of the inner sleeve.
10. An electric machine comprising:
a housing;
a rotor rotatably supported by the housing for rotation about a longitudinal axis; and
a stator assembly fixedly secured to the housing spaced apart from a surface of the rotor and concentric with the rotor about the longitudinal axis, the stator assembly having a stator winding comprising circumferentially spaced apart stator teeth about the longitudinal axis, wherein radially extending channels are disposed at each end of the stator assembly, wherein at least a portion of each of the radially extending channels are formed in resin of the stator assembly and wherein at least some of the radial extending channels are bounded in part by conductors of end turns of the stator assembly, the radially extending channels being fluidly connected to ports and configured to direct cooling fluid radially with respect to the longitudinal axis in each radially extending channel.
11. The electric machine of claim 10 wherein ends of the radially extending channels open to an annular space about the longitudinal axis at each end of the stator assembly.
12. The electric machine of claim 11 wherein each annular space is defined in part by an annular sealing device.
13. The electric machine of claim 12 wherein the stator assembly includes an inner sleeve concentrically disposed about the longitudinal axis radially inward from remote ends of the stator teeth.
14. The electric machine of claim 13 wherein portions of an inner surface of the inner sleeve define a portion of cooling channels extending parallel to the longitudinal axis.
15. The electric machine of claim 14 wherein the annular sealing device comprises a ring and a first o-ring sealing engaging the ring and a portion of the housing and a second o-ring sealing engaging the ring and a portion of the inner sleeve.
16. The electric machine of claim 10 wherein the stator teeth have remote ends proximate the surface of the rotor, each tooth having a centerplane across a width extending radially, wherein a plurality of cooling channels extend parallel to the longitudinal axis are arranged on an outer periphery of the stator assembly such that a cooling channel is located on each centerplane, each cooling channel sealed by an inner surface of the housing along a longitudinal length thereof.
17. The electric machine of claim 16 wherein each of the cooling channels is open to the inner surface of the housing along each longitudinal length.
18. The electric machine of claim 16 wherein the stator teeth are comprised of laminations, each lamination having a plurality of notches, wherein each notch is aligned with a notch of an adjacent lamination to form each corresponding cooling channels.
19. The electric machine of claim 16 wherein each of the cooling channels opens to a common annular passageway on each end of the stator assembly.
20. The electric machine of claim 19 wherein each common annular passageway is fluidly coupled to the ports, wherein a first port receives fluid into its associated common annular passageway and a second port receives fluid from its associated common annular passageway.
21. The electric machine of claim 1 wherein at least a portion of each of the radially extending channels are formed in resin of the stator assembly and wherein at least some of the radial extending channels are bounded in part by conductors of end turns of the stator assembly.
22. The electric machine of claim 16 wherein a plurality of sealed rotor cooling channels extend parallel to the longitudinal axis and are disposed between remote ends of successive teeth, the rotor cooling channels being formed in resin of the stator assembly, the rotor cooling channels being fluidly connected to ports in a closed system to circulate cooling fluid to cool the stator assembly and configured to remove heat from the stator assembly proximate the surface of the rotor.
23. The electric machine of claim 10 wherein the stator teeth have remote ends proximate the surface of the rotor, each tooth having a portion of lowest flux density during operation at an outer periphery opposite an inner surface of the housing, and wherein a plurality of cooling channels extend parallel to the longitudinal axis are arranged on the outer periphery of the stator assembly such that a cooling channel is located at each of the portions of lowest flux density for each of the stator teeth.