Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-01-13
2001-08-21
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S201000
Reexamination Certificate
active
06278213
ABSTRACT:
TECHNICAL FIELD
The present invention relates to the stator winding and core design of an electrical machine.
BACKGROUND OF THE INVENTION
Generators are found in virtually every motor vehicle manufactured today. These generators, such as the common Lundell generator, produce alternating current to meet the vehicle's electrical needs. While the engine of the vehicle is running, the generator produces sufficient electricity to supply the vehicle's electrical demands and to recharge the battery.
An important component of the generator is the stator. In most generators, the stator contains the main current-carrying winding in which electromotive force produced by magnetic flux is induced. Typically, the current-carrying winding consists of conducting wire, which is wound and inserted into the slots of the stator. Each slot is located between two teeth. The wire is wound and inserted into slots in the stator in bundles. The prior art teaches the winding and insertion of wire having a rounded profile. This rounded wire, however, has several disadvantages associated with its use in a conventional stator.
First, the bundles of rounded wire do not occupy the stator slots in an efficient manner. Typically, the ratio of copper wire area to total slot area is 50%. This conventional design produces a lower output current and is less efficient electrically than a design in which the wire occupies a higher ratio of the slot.
Second, in a conventional stator design, two features are used to retain the wire in the slot: tooth tips and wedges. The teeth of the conventional stator are widened at the bottom of the slot to make the slot correspondingly narrower. In addition, a paper wedge typically is inserted into the slot after the bundle of wire has been inserted. Insertion of the wedge is a significant problem in the manufacturing area, and the process of insertion raises cost by increasing equipment down time and maintenance.
Third, the conventional stator design does not permit efficient stamping of the stator core. The stamping of a conventional stator core lamination according to the prior art produces a significant amount of scrap. This low material utilization results because the conventional stator design uses widened tooth tips.
Fourth, the use of rounded wire in the conventional stator design results in poor heat conduction because the wire is loosely bundled in the slot. This poor heat conduction results in higher stator wire temperatures. In turn, this higher temperature decreases the reliability, performance, and efficiency of the wire.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a solution to the above mentioned problems. A stator constructed in accordance with the present invention is characterized by the features specified the section of Detailed Description of the Preferred Embodiments. The present invention is a high fill stator design. This new design is furthered by the fact that flattened magnet wire is now widely available for use in stators. Flattened magnet copper wire is now available with a height to width ratio of up to 4 to 1 with the ends of the wire rounded. Use of flattened magnet wire allows redesign of the stator to overcome the disadvantages of wire having a rounded profile.
The present invention uses flattened magnet wire that is wound and inserted into the stator slots. The flattened magnet wire is stacked into the stator slots. In addition, the slots of the present invention are angled so that the flattened wire fits loosely at the top of each slot but fits tightly at the bottom. This angling retains the wire in each slot.
The use of flattened magnet wire and the corresponding new core design overcome the disadvantages of the prior art. First, the stacked flattened wire utilizes nearly 80% of the slot area. The use of flattened wire also produces a correspondingly higher output current and is more efficient than the use of wire with a rounded profile. Second, the self-retaining nature of the invention eliminates the need for a paper wedge or tooth tips, reducing cost. Third, the geometry of the new core design produces less scrap during the stamping of the stator core lamination. Fourth, the flattened wire and core design improve heat conduction, resulting in lower wire temperatures and a corresponding increase in reliability, performance, and efficiency. The new core design has an additional advantage. The use of stacked flattened wire in the new design stiffens the stator teeth in the radial direction, reducing vibration and noise.
REFERENCES:
patent: 2407935 (1946-09-01), Perfetti et al.
patent: 3860744 (1975-01-01), Schuler
patent: 4613780 (1986-09-01), Fritzsche
patent: 5587619 (1996-12-01), Yumiyama et al.
Delphi Technologies Inc.
Dobrowitsky Margaret A.
Nguyen Tran
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