Method for making an encapsulated coil structure
Magnet wires wound in slots in a lamination stack of a dynamoelectric machine are encapsulated, in whole or in part, with plastic. The plastic may be thermally conductive and have features molded therein that enhance heat transfer. The plastic may stiffen the armature and increase its critical speed. Characteristics of the plastic, its geometry and its distribution may be varied to adjust spinning inertia and resonant frequency of the armature. The magnet wires may be compressed into the slots, by application of iso-static pressure or by the pressure of the plastic being molded around them. Larger magnet wire can then be used which increases the power of the electric motor using the armature having the larger magnet wire. A two or three plate mold may be used to mold the plastic around the armature. Balancing features can be molded in place. The plastic can have a base polymer that is a blend of two or more polymers and various thermally conductive fillings.
1. A method for forming a given size armature to increase the power of an electric motor using that given size armature, comprising:
securing a lamination stack having slots therein on an armature shaft;
securing a commutator on one end of the armature shaft;
winding magnet wires in the slots in the lamination stack and securing ends of the magnet wires to the commutator;
molding plastic to at least partially encase the magnet wires in the plastic to hold them in place in the slots without using coil stays; and
winding the magnet wires in the slots includes winding them so that they also occupy portions of the slots that are occupied by coil stays in an armature where coil stays are used to hold the magnet wires in place in the slots and where the armature in which the coil stays are used has the same size as the given size armature.
2. The method of claim 1 and further including applying pressure to the magnet wires to compress them in the slots.
3. The method of claim 2 wherein applying pressure to the magnet wires includes applying the pressure with the plastic while it is being molded.
4. The method of claim 2 wherein applying pressure to the magnet wires includes applying the pressure by applying iso-static pressure to the magnet wires before the plastic is molded.
5. The method of claim 4 wherein applying iso-static pressure includes placing the armature with the magnet wires wound in the slots in the lamination stack in a cavity of a fluid bladder and pressurizing the fluid bladder.
6. A method for making an electric motor with a given size armature to increase the power of the electric motor using that given size armature, comprising:
securing a lamination stack having slots therein on an armature shaft;
securing a commutator on one end of the armature shaft;
winding magnet wires in the slots in the lamination stack and securing ends of the magnet wires to the commutator;
molding plastic to at least partially encase the magnet wires in the plastic to hold them in place without using coil stays;
winding the magnet wires in the slots includes winding them so that they also occupy portion of the slots that are occupied by coil stays in an armature where coil stays are used to hold the magnet wires in place in the slots and where the armature in which the coils stays are used has the same size as the given size armature; and
disposing the armature in a stator.
7. The method of claim 6 and further including applying pressure to the magnet wires to compress them in the slots.
8. The method of claim 7 wherein applying pressure to the magnet wires includes applying the pressure with the plastic while it is being molded and further including retaining the magnet wires in the slots with molded plastic.
9. A method for making a power tool having an electric motor with a given size armature to increase the power of the electric motor using that given size armature, comprising:
securing a lamination stack having slots therein on an armature shaft;
securing a commutator on one end of the armature shaft;
winding magnet wires in the slots in the lamination stack and securing ends of the magnet wires to the commutator;
molding plastic to at least partially encase the magnet wires in the plastic to hold them in place in the slots without using coil stays;
winding the magnet wires in the slots includes winding them so that they also occupy portion of the slots that are occupied by coil stays in an armature where coil stays are used to hold the magnet wires in place in the slots and where the armature in which the coil stays are used has the same size as the given size armature; and
disposing the armature in a stator to form the electric motor and disposing the electric motor in the power tool.
10. The method of claim 9 and further including applying pressure to the magnet wires to compress them in the slots.
11. The method of claim 10 wherein applying pressure to the magnet wires includes applying the pressure with the plastic while it is being molded and further including retaining the magnet wires in the slots with molded plastic.