Electric motor with field assemblies having core pieces with mating features

• US 20050099087A1
• Filed: 09/03/2004
• Published: 05/12/2005
• Est. Priority Date: 09/05/2003
• Status: Active Grant

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Du, Hung T., Verbrugge, Brandon L., Smith, David J., Zemlok, Michael A., Ortt, Earl M., Kusmierski, Robert G., Agnes, Michael J.
• Granted Patent: US 7,233,091 B2
• Time in Patent Office: Days
• US Class Current: 310/216.091
• CPC Class Codes: H02K 1/148 Sectional cores H02K1/141 takes precedence
• CPC Class Codes: H02K 1/18 Means for mounting or fastening magnetic stationary parts on to, or to, the stator structures
• CPC Class Codes: H02K 15/0435 Wound windings
• CPC Class Codes: H02K 15/10 Applying solid insulation to windings, stators or rotors
• CPC Class Codes: H02K 15/12 Impregnating, heating or drying of windings, stators, rotors or machines
• CPC Class Codes: H02K 3/325 for windings on salient poles, such as claw-shaped poles
• CPC Class Codes: H02K 3/522 for generally annular cores with salient poles
• CPC Class Codes: Y10T 29/49009 Dynamoelectric machine
• CPC Class Codes: Y10T 29/49012 Rotor
• CPC Class Codes: Y10T 29/49071 by winding or coiling
• CPC Class Codes: Y10T 29/49073 by assembling coil and core
• CPC Class Codes: Y10T 29/53143 Motor or generator

Abstract

An electric motor has a field assembly, such as a stator, has field coils that are wound to a net shape. Lead wires are brought out from the ends of each field coil. The field coils are insulated. The field coils are assembled with stator core pieces, such as pole pieces and return path pieces, into the stator. The stator core pieces are formed prior to being assembled with the field coils. In an aspect of the invention, the pole pieces and return path pieces are separately formed and then assembled together with the field coils, which have also been separately formed. The pole pieces and return path pieces are formed with mating features that are mated to hold the pole pieces and return path pieces together.

Claims

1. An electric motor, comprising:

a. a multi-piece stator having a plurality of pole pieces, a plurality of field coils and a plurality of return path pieces, a plurality of the return path pieces mated to each of the pole pieces;

i. each return path piece having opposed ends with a projection extending from each end;

ii. each pole piece having a neck with opposed receiving pockets therein between opposed outer fingers of a radial outer end of the neck and opposite sides of a radially outer section of a pole tip section of the pole piece, each opposed receiving pocket having one of the projections of one of the return path pieces that is mated to the pole piece received therein, the pole piece secured to the return path pieces that are mated to it by deformation of the opposed outer fingers of the radial outer end of the neck of the pole piece against the projections of those return path pieces;

iii. at least one of the field coils disposed around each pole piece between the pole tip section of the pole piece and the return path pieces mated to the pole piece; and

b. an armature received in the stator.

2. The electric motor of claim 1 wherein the fingers of the radial outer end of the neck of each pole piece have radially inwardly extending projections and the return path pieces have recesses at junctions of the projections and the ends of the return path pieces in which the projections of the fingers are received when the fingers are deformed against the projections of the return path pieces that are received in the opposed receiving pockets of the pole piece to form mating detents that mechanically lock the pole piece and those return path pieces together.

3. The electric motor of claim 2 wherein each return path piece is also welded to each pole piece to which it is mated.

4. The electric motor of claim 1 wherein the fingers of the radial outer end of the neck of each pole piece have radially inwardly extending projections and the projections of the return path pieces have recesses that are distally spaced from junctions of the projections and the ends of the return path pieces in which the projections of the fingers are received when the fingers are deformed against the projections of the return path pieces that are received in the opposed receiving pockets of the pole pieces to form mating detents that mechanically lock the pole piece and those return path pieces together, the mating detents distally spaced from the junctions of the ends of the return path pieces and their projections to increase the critical length of the pole piece and return path pieces mated to it.

5. The electric motor of claim 4 wherein each return path piece is also welded to each pole piece to which it is mated.

6. The electric motor of claim 1 wherein the pole tip section of each pole piece has circumferentially and radially outer edges that are recessed and have a radius to facilitate placement of the field coils on the pole pieces.

7. The electric motor of claim 6 wherein a radially extending outer surface of the radially outer section of the pole tip portion of each pole piece is smooth.

8. The electric motor of claim 6 wherein the circumferentially and radially outer edges of the pole tip section of each pole piece project outward to provide lips that provide retention of the field coils disposed on the pole pieces.

9. An electric motor, comprising:

a. a multi-piece stator having a plurality of pole pieces, a plurality of field coils and a plurality of return path pieces, a plurality of the return path pieces mated to each of the pole pieces;

i. each return path piece having opposed ends with a projection extending from each end and a recess in the projection distally spaced from a junction of each projection and the end from which it extends;

ii. each pole piece having a neck with opposed receiving pockets therein between opposed outer fingers of a radial outer end of the neck and opposite sides of a radially outer section of a pole tip section of the pole piece, the fingers having radially inwardly extending projections, each opposed receiving pocket having one of the projections of one of the return path pieces -that is mated to the pole piece received therein, the pole piece secured to the return path pieces that are mated to it by deformation of the opposed outer fingers of the radial outer end of the neck of the pole piece into the recesses of the projections of those return path pieces to form mating detents that lock the pole piece and those return path pieces together, the mating detents distally spaced from the junctions of the ends of those return path pieces and their projections to increase the critical length of the pole piece and the return path pieces mated to it;

iii. each return path piece also welded to each pole piece to which it is mated;

iv. at least one of the field coils disposed around each pole piece between the pole tip section of the pole piece and the return path pieces mated to the pole piece; and

b. an armature received in the stator.

10. An electric motor, comprising:

a. a multi-piece stator having a plurality of pole pieces, a plurality of field coils and a plurality of return path pieces, a plurality of the return path pieces mated to each of the pole pieces;

i. each return path piece having opposed ends with a projection extending from each end;

ii. each pole piece having opposed receiving pockets therein in which the projections of the return path pieces mated to the pole piece are received;

iii. each return path piece welded to each pole piece to which it is mated;

iv. at least one of the field coils disposed around each pole piece between the pole tip section of the pole piece and the return path pieces mated to the pole piece; and

b. an armature received in the stator.

11. The electric motor of claim 10 wherein a pole tip section of each pole piece has circumferentially and radially outer edges that are recessed and have a radius to facilitate placement of the field coils on the pole pieces.

12. The electric motor of claim 11 wherein a radially extending outer surface of the radially outer section of the pole tip portion of each pole piece is smooth.

13. A hand-held power tool, comprising:

a. a housing surrounding an electric motor, the electric motor including;

i. a multi-piece stator having a plurality of pole pieces, a plurality of field coils and a plurality of return path pieces, a plurality of the return path pieces mated to each of the pole pieces;

each return path piece having opposed ends with a projection extending from each end;

each pole piece having a neck with opposed receiving pockets therein between opposed outer fingers of a radial outer end of the neck and opposite sides of a radially outer section of a pole tip section of the pole piece, each opposed receiving pocket having one of the projections of one of the return path pieces that is mated to the pole piece received therein, the pole piece secured to the return path pieces that are mated to it by deformation of the opposed outer fingers of the radial outer end of the neck of the pole piece against the projections of those return path pieces;

at least one of the field coils disposed around each pole piece between the pole tip section of the pole piece and the return path pieces mated to the pole piece;

ii. an armature received in the stator; and

b. a drive train coupled to the motor.

14. The power tool of claim 13 wherein the fingers of the radial outer end of the neck of each pole piece have radially inwardly extending projections and the return path pieces have recesses at junctions of the projections and the ends of the return path pieces in which the projections of the fingers are received when the fingers are deformed against the projections of the return path pieces that are received in the opposed receiving pockets of the pole piece to form mating detents that mechanically lock the pole piece and those return path pieces together.

15. The power tool of claim 14 wherein each return path piece is also welded to each pole piece to which it is mated.

16. The power tool of claim 13 wherein the fingers of the radial outer end of the neck of each pole piece have radially inwardly extending projections and the projections of the return path pieces have recesses that are distally spaced from junctions of the projections and the ends of the return path pieces in which the projections of the fingers are received when the fingers are deformed against the projections of the return path pieces that are received in the opposed receiving pockets of the pole pieces to form mating detents that mechanically lock the pole piece and those return path pieces together, the mating detents distally spaced from the junctions of the ends of the return path pieces and their projections to increase the critical length of the pole piece and return path pieces mated to it.

17. The power tool of claim 16 wherein each return path piece is also welded to each pole piece to which it is mated.

18. The power tool of claim 16 wherein the pole tip section of each pole piece has circumferentially and radially outer edges that are recessed and have a radius to facilitate placement of the field coils on the pole pieces.

19. The power tool of claim 18 wherein a radially extending outer surface of the radially outer section of the pole tip portion of each pole piece is smooth.

20. A power tool, comprising a housing surrounding an electric motor, the electric motor including:

a. a multi-piece stator having a plurality of pole pieces, a plurality of field coils and a plurality of return path pieces, a plurality of the return path pieces mated to each of the pole pieces;

each pole piece having opposed receiving pockets therein in which the projections of the return path pieces mated to the pole piece are received;

each return path piece welded to each pole piece to which it is mated;

at least one of the field coils disposed around each pole piece between the pole tip section of the pole piece and the return path pieces mated to the pole piece; and

b. an armature received in the stator.

21. The power tool of claim 20 wherein a pole tip section of each pole piece has circumferentially and radially outer edges that are recessed and have a radius to facilitate placement of the field coils on the pole pieces.

22. The power tool of claim 21 wherein a radially extending outer surface of the radially outer section of the pole tip portion of each pole piece is smooth.