Compact high power alternator

• US 8,207,642 B2
• Filed: 08/02/2010
• Issued: 06/26/2012
• Est. Priority Date: 07/10/2003
• Status: Expired due to Fees

• Current Assignee: Magnetic Applications, Inc.
• Original Assignee: Magnetic Applications, Inc.
• Inventors: Lafontaine, Charles Y., Scott, Harold C.
• Primary Examiner(s): LE, DANG D
• Application Number:
  US12/848,972
• Publication Number:
  US 20110025152A1
• Time in Patent Office: 694 Days
• Field of Search: 310/90, 310/67.R
• US Class Current: 310/90
• CPC Class Codes: H02K 1/187 to inner stators
• CPC Class Codes: H02K 1/2791 Surface mounted magnets; Inset magnets
• CPC Class Codes: H02K 1/30 using intermediate parts, e.g. spiders
• CPC Class Codes: H02K 11/05 Rectifiers associated with casings, enclosures or brackets
• CPC Class Codes: H02K 21/22 with magnets rotating around the armatures, e.g. flywheel magnetos
• CPC Class Codes: H02K 2201/03 Machines characterised by aspects of the air-gap between rotor and stator
• CPC Class Codes: H02K 7/088 radially supporting the rotor directly
• CPC Class Codes: H02K 7/09 with magnetic bearings
• CPC Class Codes: H02K 9/06 with fans or impellers driven by the machine shaft
• CPC Class Codes: H02K 9/10 by gaseous cooling medium flowing in closed circuit, a part of which is external to the machine casing
• CPC Class Codes: H02K 9/19 for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil

Abstract

An apparatus for converting between mechanical and electrical energy, particularly suited for use as a compact high power alternator for automotive use and “remove and replace” retrofitting of existing vehicles. The apparatus comprises a rotor with permanent magnets, a stator with a winding, and a cooling system. Mechanisms to prevent the rotor magnets from clashing with the stator by minimizing rotor displacement, and absorbing unacceptable rotor displacement are disclosed. The cooling system directs coolant flow into thermal contact with at least one of the winding and magnets, and includes at least one passageway through the stator core. Various open and closed cooling systems are described. Cooling is facilitated by, for example, loosely wrapping the winding end turns, use of an asynchronous airflow source, and/or directing coolant through conduits extending through the stator into thermal contact with the windings.

Claims

1. Power conversion apparatus comprising a shaft, a stator, and a rotor, the shaft, stator, and rotor being coaxially disposed with the rotor mounted on the shaft, the stator including at least one winding, and the rotor including a plurality of permanent magnets disposed proximate to the stator, separated from the stator by a predetermined gap distance, such that relative motion of the rotor and stator causes magnetic flux from the magnets to magnetically interact with the stator winding, wherein:

the shaft has a diameter and includes a tapered portion disposed between the ends of the shaft at a predetermined position relative to the stator, the diameter of the tapered portion varying in accordance with a predetermined taper from a minimum diameter greater than the diameter of the shaft to a maximum diameter greater than the diameter of the shaft;

the rotor includes a central through-bore having a predetermined taper corresponding to that of the tapered portion of the shaft; and

the shaft is journaled through the rotor tapered bore, such that shaft tapered portion is received in the rotor bore, cooperation of the tapered rotor bore and tapered shaft portion positioning the rotor with respect to the shaft and the stator.

2. The apparatus of claim 1 wherein the predetermined taper is in the range of 1 in. diameter per 7 inches of length to 1 in. diameter per 16 inches of length.

3. The apparatus of claim 1 wherein the predetermined taper is on the order of 1 in. per foot.

4. The apparatus of claim 1 further including first and second endplates, an outer casing and a plurality of tie rods, cooperating to maintain alignment of the shaft, rotor, and stator, wherein:

the shaft is rotatably held by the endplates in axial alignment with the endplates;

the stator is affixed to one of the endplates and maintained in predetermined disposition with respect thereto; and

the outer casing is disposed between the front and rear endplates with tie rods disposed to compress the front and rear endplates against the outer casing.

5. The apparatus of claim 1 wherein:

the rotor comprises an endcap and a cylindrical casing, the magnets being disposed on the interior of the casing; and

the stator is disposed within the rotor casing.

6. The apparatus of claim 5 wherein the rotor endcap comprises a peripheral portion connecting to the casing, a central hub having the tapered bore and a connecting portion connecting the peripheral portion to the central hub and including at least one air passageway therethrough.

7. The apparatus of claim 5 wherein the rotor endcap is contoured such that when the shaft tapered portion is received in the rotor bore, the shaft tapered portion is within the interior of the rotor casing.

8. The apparatus of claim 5 wherein at least a portion of rotor endcap is disposed an angle other than 90°

relative to the rotor casing, whereby the axial distance between the point of connection of the rotor to the shaft and the magnets is less than the axial length of the rotor casing.

9. The apparatus of claim 1 wherein:

the stator comprises a core including front and back side-faces and a generally cylindrical outer peripheral surface with a predetermined number of slots formed therein; and

the stator winding is wound around the core, such that with respect to at least one end face, the winding passes through a first slot, forms an end turn extending outwardly beyond the core side face, providing a space between the end turn and end face, then passes back through another slot.

10. The apparatus of claim 9 further including a fan and respective air passageways disposed to circulate air moved by the fan over the winding end turns.

11. The apparatus of claim 10 wherein the fan is electrically driven.

12. The apparatus of claim 1 further including a front endplate, a rear endplate, an outer casing, cooperating to maintain alignment of the shaft, rotor, and stator;

and

at least one air passageway through the rear end plate, at least one air passageway through the stator core, at least one air passageway through the rotor endcap, and at least one air passageway through the front end plate.

13. The apparatus of claim 12 wherein the stator core and rotor endcap are substantially open.

14. The apparatus of claim 6 wherein the connecting portion comprises a plurality of crossarms.

15. The apparatus of claim 14 wherein the rotor includes a casing, and the plurality of crossarms are disposed at a non-perpendicular angle relative to the axis of the rotor casing such that the axial length of the rotor casing interior is greater in proximity to the casing than in proximity to the shaft.

16. The apparatus of claim 15 wherein the rotor endcap connecting portion is contoured such that the central hub is disposed within the interior of the rotor casing.

17. The apparatus of claim 1 wherein:

the rotor is adapted to rotate over a predetermined operational range of rotational speeds;

the rotor and stator are configured such that rotation of the rotor at and above a predetermined speed within the range of speeds causes magnetic flux from the magnets to induce a predetermined level of current in the stator windings, such current tending to generate heat that, if not dissipated, would raise the temperature of the magnets above a predetermined destructive level; and

wherein the power conversion apparatus further includes;

a cooling system for directing coolant along a predetermined flow path into thermal contact with at least one of the winding and magnets, the cooling system generating sufficient coolant flow through the predetermined flow path at and above the predetermined speed to dissipate heat generated and maintain the temperature of the magnets below the predetermined destructive level.

18. The apparatus of claim 1 wherein the rotor is adapted to rotate over a predetermined operational range of rotational speeds, operation at and above a predetermined speed within the range of speeds tending to generate heat that, if not dissipated, would raise the temperature of the magnets above a predetermined destructive level;

And the apparatus further includes cooling means for dissipating heat and maintaining the temperature of the magnets below the predetermined destructive level over the predetermined operational range of rotational speeds.