Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1992-04-21
1994-04-19
Stephan, Steven L.
Electrical generator or motor structure
Dynamoelectric
Rotary
310264, 310270, H02K 106
Patent
active
053048857
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an electric motor.
More particularly, the invention relates to a wound armature for an electric motor having a laminated stack and to an electric motor incorporating such an armature.
Such armatures are conventionally made from a stack of steel laminations which stack comprise a plurality of mushroom or T-shaped laminations with their stems extending radially out from a central hub which fits on a motor shaft. Each stem has arms which extend circumferentially of the rotational axis of the motor on each side of the stem. Wire is wrapped tightly around the stems of the stack to form armature windings. The wire used usually has a polymer coating to provide insulation between each of the wire turns and between the wire and stack.
It is necessary to wind the wire under a tension in order to ensure that the windings are tightly packed and avoid chaffing between the wire and stack. It has been found that when the wire is wound onto the stems, cuts may be formed into the layer of insulation coating the wire due to the tension under which the wire is wound. A simple "spider" comprising a spoked plastic disc may be placed against the outer surface of each end lamination to prevent damage to the wound wires of each coil.
BRIEF DESCRIPTION OF THE INVENTION
According to the invention there is provided an armature, for an electric motor, including a rotary shaft, the armature being supported on the shaft and having a lamination stack, the stack comprising a plurality of T-shaped steel laminations stacked one against another, each lamination having radially extending stems with arms which extend circumferentially with respect to the rotational axis of the shaft each side of the stems, armature windings wrapped around the stems of the stack, a spider at one end of the stack positioned inside the armature windings and formed of electrically insulating material and having a plurality of profiled spokes, the spokes each have one surface which fits against and covers a respective stem of the stack and an opposing arcuate surface to form a central upstanding profile extending to adjacent a radially remote end of the respective spoke, and arms extending circumferentially each side of the spoke at the end of the spoke to partly cover respective arms of the stack.
The spider may have a central boss which extends axially beyond a surface of each spoke and snugly fits over the shaft.
The spider is preferably profiled over the whole length of its spokes to provide a smooth curved base against which the wires of the armature windings are urged at each end of the stack when the windings are formed.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be further described by way of example with reference to the accompanying drawings, in which:
FIG. 1 is a plan view of a fractional horsepower universal motor embodying the invention;
FIG. 2 is an elevation of a spider for an armature of the motor showing, in part, armature windings and one end of an armature stack;
FIG. 3 is a part-sectional side view of the spider;
FIG. 4 is a sectional view along IV--IV of FIG. 2; and
FIG. 5 is an enlarged isometric view of a radially remote end of one spoke of the spider.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings in FIG. 1, a universal motor for a food mixer comprises a pressed steel frame in two parts 1, 2. The frame parts 1, 2 are joined to opposite sides of a U-shaped laminated stator 3. A rotor 4 of the motor comprises a shaft 5 having a worm 6 at one end and carrying an armature 7, with armature windings 8, and a commutator 9. The armature is formed as a laminated stack 3 of a plurality of T-shaped laminations and spiders 10A and 10B are mounted at each respective end of the stack 3. Brushgear 19 is mounted on the frame part 2 and supplies current to the commutator 9. The frame part 1 carries two implement holders 11, shown in dotted outline, for holding food beaters or the like, which mesh with the worm 6.
The frame part 1 comprises a bearing support part 12 for a bearing 13. The fr
REFERENCES:
patent: 3214621 (1965-10-01), Quear et al.
patent: 3315105 (1967-04-01), Moore, Jr.
patent: 3831268 (1974-08-01), Boyd et al.
patent: 3882336 (1975-05-01), Boyd et al.
Mok Kam-Shing
Wong Chi-Nung
Haszko D. R.
Johnson Electric S.A.
Stephan Steven L.
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