Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1998-04-13
2000-03-21
LaBalle, Clayton
Electrical generator or motor structure
Dynamoelectric
Rotary
310 59, 310227, H02K 900, H02K 902, H02K 904, H02K 928
Patent
active
060406453
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to electrical machines which convert mechanical energy into electrical energy, or vice versa, by an interaction between a magnetic field and an electric current. In particular, the present invention relates to a casing for such an electric machine, a rotor for such an electric machine, a conductive element of a rotor winding for such an electric machine, and a method of forming such a conductive element. Examples of such electric machines are electric motors, dynamos and alternators.
In known electric machines, the assembly of a rotor winding may be time consuming and therefore expensive. Moreover the rotor winding often comprises a large number of different parts, which increases the overall cost of the electric machine.
The performance of such electric machines may also be limited by the amount of heat generated in the rotor winding and in the region of the commutator. As a result of this limited performance, the range of applications of such electric machines, particularly in electrically powered vehicles, has been restricted.
BRIEF SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a conductive element of an armature for an electrical machine, comprising a metal strip having a pair of leg portions joined together at or about one end by a flat bridging portion, the first and second leg portions being bent in opposite directions perpendicularly to the plane of the bridging portion.
The armature may be easily constructed by arranging a number of such conductive elements with even circumferential spacing around a circle, to form the structure of the armature.
Preferably the first and second leg portions have a substantially equal width so that the assembled rotor consists of two winding planes of equal thickness, perpendicular to the axis of rotation.
However, in an alternative embodiment each conductive element may have three leg portions joined together at or about one end to a bridging portion, the two outer leg portions on either side of the bridging portion being bent in the same direction perpendicularly to the plane of bridging portion, and the middle leg portion being bent in an opposite direction.
In this alternative embodiment, the middle leg portion preferably has twice the width of each of the outer leg portions, so that the armature, when assembled, has three winding planes perpendicular to the axis of rotation, the middle winding plane having twice the thickness of each of the outer winding planes. This construction reduces shearing between the winding planes at high rotation speed and therefore reduces the risk of damage to the armature.
Preferably, each of the leg portions includes a radial portion, in which the current carried in the winding interacts with an applied magnetic field, and an outer portion which is bent towards the tangential direction of the armature so that it may be joined to another conductive element displaced around the circumference of the armature.
Preferably, the above-mentioned conductive element is stamped from metal sheet and the first and second leg portions are bent in opposite directions perpendicular to the metal sheet. In the method of forming the conductive element having three leg portions, the middle leg portion is bent in one direction perpendicular to the metal sheet, while the outer leg portions are bent in an opposite direction.
According to another aspect of the present invention, there is provided a conductive armature for an electrical machine, having a current-carrying winding formed from a plurality of integrally formed conductive elements circumferentially distributed around the armature, in which the radially outer portions of adjacent conductive elements have a gap between them to allow cooling fluid to flow through the radially outer portion of the armature. Each conductive element has a radially outer portion bent towards the tangential direction of the armature, the gap between adjacent conductive elements extending along a substantial por
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London Innovation Bulletin, Issue No. 5, 1990, p. 1.
LaBalle Clayton
London Innovation Ltd.
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