Liquid cooled electric motor

• US 8,970,075 B2
• Filed: 08/08/2012
• Issued: 03/03/2015
• Est. Priority Date: 08/08/2012
• Status: Active Grant

• Current Assignee: AC Propulsion, Inc.
• Original Assignee: AC Propulsion, Inc.
• Inventors: Rippel, Wally E., Moore, Christopher C., Carosa, Paul F.
• Primary Examiner(s): NGUYEN, TRAN N
• Application Number:
  US13/570,169
• Publication Number:
  US 20140042841A1
• Time in Patent Office: 937 Days
• Field of Search: None
• US Class Current: 310/54
• CPC Class Codes: H02K 1/20 with channels or ducts for flow of cooling medium
• CPC Class Codes: H02K 1/32 with channels or ducts for flow of cooling medium
• CPC Class Codes: H02K 5/203 specially adapted for liquids, e.g. cooling jackets
• CPC Class Codes: H02K 9/19 for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil
• CPC Class Codes: H02K 9/193 with provision for replenishing the cooling medium; with means for preventing leakage of the cooling medium

Abstract

A liquid-cooled, radial air gap electric motor includes a stator, a rotor, a rotor shaft, two end bells, a housing, a coolant manifold system, and a coolant sump. The rotor includes a plurality of axially directed slots located near its periphery. The coolant manifold system directs a first portion of liquid coolant to flow past some portion of the stator and a second portion of liquid coolant to flow through the rotor slots. Some or all of the liquid coolant is received by the coolant sump from which the coolant may be recirculated.

Claims

1. A liquid-cooled, radial air gap electric motor comprising:

a stator having motor windings;

a rotor having an at least partially hollow rotor shaft configured to rotate about a longitudinal axis of rotation;

a housing;

a coolant sump disposed at the bottom of the housing;

a first and a second end-bell, the first end-bell disposed at a first end of the motor housing and the second end-bell disposed at a second end of the motor housing, the first and second end-bells carrying rotor shaft bearings supporting the at least partially hollow rotor shaft; and

a coolant manifold coupled to the first end-bell and configured to receive a liquid coolant through a coolant inlet port from a liquid coolant source and to distribute the liquid in at least a the first path into the at least partially hollow rotor shaft, wherein from the at least partially hollow rotor shaft the liquid coolant may flow radially outward in operation through one or more shaft radial holes in the at least partially hollow rotor shaft and then longitudinally into a rotor coolant passage formed in the rotor, and then into the sump, the second path radially outward in operation through one or more inlet radial holes in the coolant inlet port and then longitudinally into a peripheral coolant passage formed in a gap disposed between the housing and the stator, and then into the sump.

2. The electric motor of claim 1, wherein

the coolant manifold includes a first circular coolant baffle that forms a first annular region bounded by the stator and the first coolant baffle and an inner surface of the housing.

3. The electric motor of claim 2, wherein

the first coolant baffle includes at least one radially directed hole configured so that a portion of the second path of coolant flow is directed away from the first coolant baffle.

4. The electric motor of claim 2, wherein

the motor is configured so that a portion of the second path of coolant flow is directed through a longitudinal passage within a stator core of the stator.

5. The electric motor of claim 2, wherein

the peripheral surface of the stator is equipped with at least one radially directed cooling fin.

6. The electric motor of claim 2, further comprising:

a second circular coolant baffle that forms a second annular region bounded by the stator and the second coolant baffle and an inner surface of the housing, the second annular region configured so that some coolant flow along the second path is directed from the peripheral coolant passage through at least one radially directed hole in the second coolant baffle away from the second coolant baffle.

7. The electric motor of claim 1, wherein the rotor further includes a plurality of rotor bars, a front end-ring and a rear end-ring.

8. The electric motor of claim 1, wherein the rotor is a wound rotor that includes a winding and at least one slip ring and brush.

9. The electric motor of claim 1, wherein the rotor contains at least one permanent magnet.

10. The electric motor of claim 1, wherein the rotor includes at least one rotor endplate that includes at least one axially directed, tapped hole configured so that a screw can be screwed into the tapped hole in order to adjust the mass balance of the rotor.

11. The electric motor of claim 10 wherein the endplate and an end-ring are mutually attached with at least one pair of corresponding keyed elements.

12. The electric motor of claim 1, wherein the stator is electrically insulated from the housing.

13. The electric motor of claim 1, wherein the rotor is electrically insulated from the housing.

14. The electric motor of claim 1, wherein the rotor and the stator are electrically insulated from the housing.

15. The electric motor of claim 1, further comprising:

a rotor speed sensor.

16. The electric motor of claim 1, further comprising:

a rotor position sensor.

17. The electric motor of claim 1, further comprising:

a front shaft liquid seal.

18. The electric motor of claim 1, wherein the quantity of coolant is limited so that a gap between the rotor and stator is not flooded with coolant during operation.

19. The electric motor of claim 1, wherein the coolant comprises a low viscosity oil.

20. The electric motor of claim 1, wherein the coolant is a liquid other than oil.

21. The electric motor of claim 2, wherein the first end-bell and the first coolant baffle are formed as a single part.

22. The electric motor of claim 21, wherein the second end-bell and the second coolant baffle are formed as a single part.

23. The electric motor of claim 1, further comprising a pump configured to pump coolant from the sump to the coolant inlet port.

24. The electric motor of claim 23, wherein the pump is disposed within the sump.