Electric motor with modular stator ring and improved heat dissipation

• US 20040160141A1
• Filed: 06/14/2002
• Published: 08/19/2004
• Est. Priority Date: 06/14/2002
• Status: Active Grant

• Current Assignee: Bionx Canada, Inc.
• Original Assignee: Jean-Yves Dube
• Inventors: Dube, Jean-Yves
• Granted Patent: US 6,836,036 B2
• Time in Patent Office: Days
• US Class Current: 310/218
• CPC Class Codes: H02K 1/148 Sectional cores H02K1/141 takes precedence
• CPC Class Codes: H02K 1/187 to inner stators
• CPC Class Codes: H02K 11/00 Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection casings, enclosures or supports H02K5/00
• CPC Class Codes: H02K 9/227 Heat sinks
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction

Abstract

A stator ring for an electric motor, the stator ring comprising plural stator ring sections being molded of insulated ferromagnetic powder. The stator ring sections each have an arcuate shoe having a plurality of teeth projecting radially therefrom. The teeth are adapted for receiving coil windings. The stator ring sections are adapted for being retained end to end by a stator core to form a complete stator ring. The arcuate shoes of the stator ring sections create expansion gaps between opposite ends thereof when the stator core and the stator ring sections are subjected to heat expansion, to prevent damage of the stator ring due to the heat expansion. The stator core is also constituted with improved heat dissipation and adapted to mount an electronic circuit board with some of its components in direct heat conductivity with the core. Heat is dissipated by radiation, convection and ventilation.

Claims

1. A stator ring for an electric motor, said stator ring comprising at least two stator ring sections being molded of electrically insulated ferromagnetic powder, said stator ring sections each having an arcuate shoe having at least two teeth projecting radially therefrom, said teeth being adapted for receiving coil windings, said stator ring sections adapted for being retained end to end by a stator core to form a complete stator ring, said arcuate shoes of said at least two stator ring sections creating expansion gaps between opposite ends thereof when said stator core and said stator ring sections are subjected to heat expansion, to prevent damage of said stator ring due to said heat expansion.

2. The stator ring according to claim 1, wherein said stator ring sections are guidingly retained around said stator core by guide means so as to move about said stator core in a guided manner.

3. The stator ring according to claim 2, wherein said guide means include a flange such that the stator ring sections can slide in a guided manner thereon.

4. The stator ring according to claim 3, wherein said stator ring sections each have an arcuate peripheral groove in a side edge of said arcuate shoe, and said flange of said stator core has a corresponding arcuate peripheral rib for receiving said peripheral groove in sliding engagement thereon.

5. The stator ring according to claim 4, wherein said stator ring sections each have an arcuate peripheral rib on an opposed side edge of said arcuate shoe to receive an arcuate peripheral groove of another stator ring section juxtaposed thereon, whereby said stator ring sections may be coupled side by side to increase the size of said stator ring.

6. The stator ring according to claim 1, wherein said stator ring sections consist of a material different than said stator core.

7. The stator ring according to claim 1, wherein said teeth adapted for receiving coil windings each have at least opposed rounded edge surfaces for improving the winding of said coil windings on said teeth.

8. The stator ring according to claim 1, wherein said arcuate shoes are substantially wider than said teeth for enhancing heat dissipation of said stator ring.

9. The stator ring according to claim 1, wherein each said teeth comprises an outer plate at an outer end thereof, said outer plate being substantially wider than said teeth for enhancing magnetic flux of said stator ring.

10. The stator ring according to claim 1, wherein said arcuate shoes are provided with mating formations in opposed end walls thereof.

11. The stator ring according to claim 10, wherein said mating formations comprise a mating rib in one of said end walls and a mating slot in the other of said end walls.

12. The stator ring according to claim 1, wherein said stator core has a hub portion with a support surface adapted for receiving a circuit board of said stator ring.

13. The stator ring according to claim 12, wherein said hub portion has through bores for allowing air circulation toward said circuit board for at least one of cooling and dissipating heat of said circuit board.

14. The stator ring according to claim 12-, wherein an insulating layer is sandwiched between said support surface and said circuit board for thermally and electrically insulating said circuit board.

15. An electric motor stator assembly comprising a stator core having an internal housing defined between an outer cylindrical wall and an inner central hub, support means for supporting a stator ring having coil windings about said outer cylindrical wall, passage means formed between said central hub and said outer cylindrical wall for dissipating heat from said internal housing, securing means for securing an electronic circuit board having heat generating electronic components in said housing, and conduction means to conduct heat directly from said housing, to a support shaft assembly of a wheel of a vehicle being motorized by an electric motor incorporating said stator assembly.

16. An electric motor stator assembly as claimed in claim 15 wherein there is further provided additional passage means and radiating ribs to constitute a heat sink in said inner central hub surrounding a shaft receiving bore, said central hub having a flat top wall to which is secured said electronic circuit board.

17. An electric motor stator assembly as claimed in claim 16 wherein said passage means and additional passage means are through bores extending through said stator core.

18. An electric motor stator assembly as claimed in claim 16 wherein said securing means are threaded bores provided in said flat top wall of said inner central hub for receiving fasteners to secure said circuit board thereto, said circuit board being a circular circuit board projecting from said hub in free space to enhance heat dissipation.

19. An electric motor stator assembly as claimed in claim 15 wherein said conduction means is a through bore in said hub in contact with said support shaft assembly of a wheel of a vehicle.

20. An electric motor stator assembly as claimed in claim 15 wherein there is further provided heat sink means secured through said circuit board and in contact with some of said electronic circuit components to conduct heat directly from said some of said components to said central hub on which said circuit board is secured, and electrically insulating thermal conductive insulating material between said heat sink means and said central hub.

21. An electric motor stator assembly as claimed in claim 20 wherein said some of said electronic circuit components are mosfets, said heat sink means being metal components in contact with an outer metal casing of said mosfets and a flat top surface of said central hub.

22. An electric motor stator assembly as claimed in claim 15 wherein said stator core is secured in a casing having opposed spaced apart housing walls having inner surfaces coated with a black paint to absorb heat from the stator core assembly, said housing walls having outer surfaces of light color to reflect heat.

23. An electric motor stator assembly as claimed in claim 22 wherein said housing walls are further provided with circumferential ribbed sections whereby to absorb heat and to facilitate the dissipation of said absorbed heat through said housing walls.

24. An electric motor stator assembly comprising a stator core having an internal housing defined between an outer cylindrical wall and an inner central hub, a stator ring having coil windings supported about said outer cylindrical wall, passage means formed between said central hub and said outer cylindrical wall for dissipating heat from said internal housing, securing means for securing an electronic circuit board having heat generating electronic components in said housing, and heat sink means secured through said circuit board and in contact with some of said electronic circuit components to conduct heat directly from said some of said components to said stator core through non-electrically conductive insulating means.

25. An electric motor stator assembly as claimed in claim 24 wherein said electronic circuit board is secured to a flat top wall of said inner central hub by fastener means, said some of said electronic circuit components being mosfets, said heat sink means being metal components in contact with an outer metal casing of said mostets and said flat top wall of said central hub through said non-electrically conductive insulating means.

26. An electric motor stator assembly as claimed in claim 25 wherein a heat conducting tab is secured to said metal casing of said mosfets, said circuit board having through bores therein, said metal components including a conductive element having opposed top and bottom flat conductive surfaces disposed on a respective one of opposed surfaces of said circuit board and a conductive intermediate core extending through an associated one of said through bores, said top flat conductive surface being in contact with said flat tab, said bottom flat conductive surface being in contact with said non-electrically conductive insulating means disposed on said flat top wall of said central hub.

27. An electric motor stator assembly as claimed in claim 26 wherein said metal components further includes a tin foil disposed between said tab and said top flat conductive surface, said conductive element being a copper conductive element.

28. An electric motor stator assembly as claimed in claim 26 wherein said circuit board is a circular disc-shaped circuit board, said through bores being spaced apart on a circumferential axis disposed over and about said flat top wall of said central hub.