High efficiency linear motor

• US 5,519,266 A
• Filed: 06/01/1993
• Issued: 05/21/1996
• Est. Priority Date: 06/01/1993
• Status: Expired due to Term

• Current Assignee: Anorad Corporation (Rockwell Automation, Inc.)
• Original Assignee: Anorad Corporation (Rockwell Automation, Inc.)
• Inventors: Chitayat, Anwar
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US08/044,264
• Time in Patent Office: 1,085 Days
• Field of Search: 310/12, 310/179, 310/180, 310/154, 318/135
• US Class Current: 310/12.22
• CPC Class Codes: H02K 1/16 Stator cores with slots for windings
• CPC Class Codes: H02K 1/27 Rotor cores with permanent magnets
• CPC Class Codes: H02K 15/024 with slots
• CPC Class Codes: H02K 29/03 with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems
• CPC Class Codes: H02K 3/12 arranged in slots
• CPC Class Codes: H02K 3/28 Layout of windings or of connections between windings windings for pole-changing H02K17/06, H02K17/14, H02K19/12, H02K19/32
• CPC Class Codes: H02K 41/031 of the permanent magnet type

Abstract

A linear motor has coil assemblies driven by multiple phases mounted side by side on a base plate such that they do not overlap. The coil assemblies include conductors wound upon teeth such that voids in the coil assemblies are minimized along with path lengths and thermal resistances between windings and the base plate, thus maximizing heat dissipation and the power capacity of the motor. The linear motor may have coil assemblies with teeth composed of a first material having desirable magnetic properties and a base plate composed of an inexpensive second material minimizing costs of materials. The teeth may be of varying lengths in or to further minimize voids. The coil assemblies are compactly mounted with a longitudinal axis normal to an axis of movement. Permanent magnets are mounted upon a back iron plate with axis of symmetry normal to the axis of movement. The magnets have outline shapes such that a generally sinusoidal magnetic flux distribution is produced along said axis of movement so as to prevent cogging.

Claims

1. A linear motor having an armature comprising:

a plurality of coil assemblies;

a base plate;

said coil assemblies being next to each other upon said base plate in a non-overlapping and non-interleaving arrangement;

said coil assemblies including a coil composed of windings of a conductor;

a plurality of center tooth members;

said windings being tightly wound on the center tooth members so as to minimize air spaces between the windings, adjacent windings, and the center tooth members;

at least one outside tooth member on an outer side of each coil assembly and parallel with said center tooth members; and

means for insulating said windings from each other and from said center and outside tooth members.

2. A linear motor having an armature according to claim 1 wherein:

said conductor is one of square copper wire and copper foil.

3. A linear motor having an armature according to claim 1 wherein:

said center tooth members and said outside tooth members are integral with said base plate.

4. A linear motor having an armature according to claim 1 further comprising means for affixing said coil assemblies to said base plate.

5. A linear motor having an armature according to claim 4 wherein said means for affixing includes an epoxy for attaching said coil assemblies to said base plate.

6. A linear motor having an armature according to claim 4 wherein said means for affixing includes a tongue and groove means for interlocking said coil assemblies with said base plate.

7. A linear motor having an armature according to claim 6 wherein said tongue and groove means includes:

protruding teeth of said center tooth members and said outside tooth members protruding past said windings and out of bases of said coil assemblies;

grooves in said baseplate; and

said protruding teeth interlocking with said grooves so as to affix said coil assembly to said base plate.

8. A linear motor having an armature according to claim 6 wherein each coil assembly includes only one center tooth member and said tongue and groove means includes said center tooth member having an opening in its center for one of cooling purposes and clearance purposes for means for mounting said base plate.

9. A linear motor having a armature according to claim 4 wherein said means for affixing includes:

said center tooth members having a through aperture; and

threaded means for affixing passing through said through aperture so as to engage said coil assemblies with said base plate.

10. A linear motor having an armature according to claim 4 wherein:

said center tooth members and said outside tooth members are composed of a first magnetizing material; and

said base plate is composed of a second magnetizing material.

11. A coil assembly for use in linear motors comprising:

a coil composed of windings of a conductor;

a plurality of center tooth members;

said windings being tightly wound on the center tooth members so as to minimize air spaces between the windings, adjacent windings, and the center tooth members;

at least one outside tooth member on an outer side of said coil and parallel with said center tooth members; and

means for insulating said windings from each other and from said center and outside tooth members.

12. A coil assembly according to claim 11 wherein:

said conductor is one of square copper wire and copper foil.

13. A coil assembly according to claim 11 further comprising means for mounting said coil assemblies.

14. A coil assembly according to claim 13 wherein said means for mounting includes protruding teeth of said center tooth members and said outside tooth members protruding past said windings and out of bases of said coil assemblies.

15. A coil assembly according to claim 13 wherein each center tooth member has an opening in its center for one of cooling purposes and clearance purposes for said means for mounting.

16. A linear armature according to claim 13 wherein said means for mounting includes said center tooth members having a through aperture for a fastening means.

17. A coil assembly comprising:

concentric coils;

teeth inside a center of and interposed between the concentric coils;

the teeth being spaced apart along a first direction;

the concentric coils being substantially in the first direction and in a second direction perpendicular to the first direction;

the teeth having lengths increasing in the second direction as distances in the first direction from the teeth to the center of the concentric coils increase such that voids between the teeth and the concentric coils are minimized so as to facilitate heat transfer.

18. A coil assembly according to claim 17 wherein:

said teeth include a center tooth and a first set of teeth;

said concentric coils include a first coil and a second coil;

the first coil encircles the center tooth;

the first set of outside teeth has a length in the second direction greater than that of the center tooth and has end surfaces substantially even with end surfaces of the first coil;

the second coil encircles the first set of outside teeth and the first coil; and

the second coil encloses a volume composed of the first set of outside teeth, the first coil, and the center tooth wherein voids are substantially eliminated so as to maximize heat transfer therethrough.