Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-11-02
2001-03-27
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S261100
Reexamination Certificate
active
06208059
ABSTRACT:
This invention relates to a rotor for an electric machine, a retainer for retaining a winding conductor in a slot in a rotor, and a method of manufacturing a rotor. The invention relates in particular, but not exclusively, to the retention of winding conductors in high speed rotors for aircraft generator applications.
FIG. 1
shows a known form of rotor for a rotary electric machine in which axially extending slots carrying rotor winding conductors
103
are partially closed to retain the conductors by retaining lugs
104
,
105
formed as integral parts of the rotor. The lugs
104
,
105
are relatively heavy and have been found to have a detrimental effect upon the magnetic properties of the machine. Furthermore, during manufacture of the rotor
101
, it is necessary to thread the winding conductors
103
axially through their respective slots
102
, which increases the time and effort required to produce the rotor and is potentially damaging to the winding conductors
103
and any insulating lining
106
used inside the slots
102
.
As shown in
FIG. 2
, rotors for electric machines are also known which have longitudinal slots
201
in which conductor bars
202
are held against centrifugal acceleration by dovetail wedges
203
of high strength metal alloy. However, the wedges
203
of rotor
204
shown in
FIG. 2
are relatively heavy, and have stress concentration points
205
,
206
at the edges of the wedge and in the body of the rotor, which tend to weaken the rotor.
The invention seeks to overcome or mitigate at least some of the above mentioned problems.
Accordingly the invention provides a rotor for an electric machine, the rotor comprising: a rotor body having axially extending, circumferentially spaced slots therein; at least one winding conductor disposed in each said slot; and a retainer located in each said slot radially outwardly of the or each said winding conductor for limiting radial outward movement of the or each winding conductor; wherein each retainer has a radially inwardly directed surface configured so as to locate the or each winding conductor in a predetermined position in its respective slot.
This predetermined position may be centred within the slot in the circumferential direction of the rotor.
Each retainer is conveniently substantially crescent-shaped, viewed in lateral cross-section through the rotor and the inwardly directed surface of the retainer is the concave surface of the crescent. The or each winding conductor may be substantially circular in cross-section.
Conveniently, the circumferential extent of each slot is such as to accommodate only one winding conductor.
The invention also includes a rotor for an electric machine, the rotor comprising: a rotor body having axially extending, circumferentially spaced slots therein; at least one winding conductor disposed in each said slot; and a retainer located in each said slot radially outwardly of the or each said winding conductor for limiting radial outward movement of the or each winding conductor; wherein the retainer presents no axially extending corners to the wall of the slot in which it is located.
Each slot may conveniently be defined by a continuous surface, which surface is curved where it mates with the retainer. Such a construction facilitates the avoidance of acute, stress inducing angles which tend to weaken the rotor.
The invention also includes a rotor for an electric machine, the rotor comprising: a rotor body having axially extending, circumferentially spaced slots therein; at least one winding conductor disposed in each said slot; and a retainer for limiting radial outward movement of the or each winding conductor; wherein said slots each have a radially outwardly directed mouth for permitting radial insertion of the or each winding conductor therethrough, the retainer and a surface of the respective slot each being configured so as to permit radial insertion of the retainer into the slot and secure location of the retainer in a position radially outwardly of the or each said winding conductor within the slot.
Preferably, the retainer is securely located in said position by rotation about its longitudinal axis following insertion into said slot. The retainer may be substantially kidney shaped in lateral cross-section and may be made from a substantially lighter material than the rotor body.
The invention also includes a retainer for retaining a winding conductor in a slot in a rotor, the retainer being elongate and substantially kidney shaped in lateral cross-section. The retainer may conveniently be made of plastics material.
The invention also includes a method of manufacturing a rotor for an electric machine, comprising the steps of: preforming a winding conductor; disposing the winding conductor in a slot in the rotor; and fitting a retainer in said slot in a position radially outwardly of the winding conductor.
Conveniently, the or each retainer is fitted by inserting it radially inwardly into its respective said slot, then securely locating it in said position, preferably by rotating it about its longitudinal axis.
REFERENCES:
patent: 2858462 (1958-10-01), Knaus
patent: 4147946 (1979-04-01), Linscott, Jr. et al.
patent: 4829206 (1989-05-01), Honshima et al.
patent: 4843271 (1989-06-01), Shah
patent: 4876469 (1989-10-01), Khutoretsky et al.
patent: 4896066 (1990-01-01), Tomite
patent: 6057624 (2000-05-01), Ohtake et al.
Lucas Industries Limited
Nguyen Tran
Ohlandt Greeley Ruggiero & Perle L.L.P.
LandOfFree
Rotor for an electric machine, retainer for retaining a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rotor for an electric machine, retainer for retaining a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rotor for an electric machine, retainer for retaining a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2503017