Motor armature having distributed windings for reducing arcing

• US 6,930,429 B2
• Filed: 07/03/2003
• Issued: 08/16/2005
• Est. Priority Date: 06/14/2000
• Status: Expired due to Fees

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Wang, Ren Hong
• Primary Examiner(s): TAMAI, KARL I
• Application Number:
  US10/613,187
• Publication Number:
  US 20040017124A1
• Time in Patent Office: 775 Days
• Field of Search: 310/225, 310/206, 310/198, 310/184, 310/180, 310/179, 310/220, 310/222, 310/224, 310/234, 310/158, 295/98, 296/05, 296/06
• US Class Current: 310/225
• CPC Class Codes: H02K 23/30 having lap or loop windings
• CPC Class Codes: Y10T 29/49009 Dynamoelectric machine
• CPC Class Codes: Y10T 29/49011 Commutator or slip ring assembly
• 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

Abstract

An armature for a brush commutated electric motor having a distributed coil winding arrangement for reducing brush arcing and electromagnetic interference (EMI). The winding pattern involves segmenting each coil into first and second subcoil portions with differing pluralities of turns. Each subcoil portion is wound around separate pairs of spaced apart slots of a lamination stack. Adjacent coils are wound such that one subcoil portion of each is wound in a common slot to therefore form an overlapping arrangement of each pair of adjacently coils. The winding pattern serves to “shift” the resultant magnetic axes of each coil in such a manner so as to significantly reduce brush arcing and the EMI resulting therefrom. The reduction in EMI is sufficient to eliminate the need for EMI reducing components, such as chokes, which have typically been required to maintain EMI to acceptably low levels. Commutation efficiency is also improved by the distributed winding pattern described above because of the reduction in the unevenness of the magnetic coupling between adjacent coils.

Claims

1. An electric motor comprising:

an armature having a plurality of spaced-apart posts defining a plurality of winding slots therebetween;

a commutator having a plurality of commutator bars that number twice that of said winding slots;

at least one brush disposed adjacent said commutator;

a stator disposed coaxially with the armature, said stator having a plurality of spaced apart field coils;

said armature including;

a first coil having a first subcoil portion and a second subcoil portion having differing numbers of turns;

said first subcoil portion being wound in a first pair of spaced apart ones of said slots;

said second subcoil portion being wound in a second pair of spaced apart ones of said slots that are offset from said first pair of spaced apart slots;

a second coil having a first subcoil portion and a second subcoil portion having differing numbers of turns;

said first subcoil portion of said second coil being wound in said second pair of spaced apart slots so as to overlap said second subcoil portion of said first coil;

said second subcoil portion of said second coil being wound in a third pair of spaced apart ones of said slots offset from said second pair of spaced apart slots;

wherein both of said coils begin commutation at the same angular position relative to said brush; and

wherein both of said coils end commutation at the same angular position relative to said brush.

2. The electric motor of claim 1, wherein one of said first and second subcoil portions of said first coil has approximately three times a number of winding turns as the other.

3. The electric motor of claim 1, further comprising a third coil having first and second subcoil portions that are wound in the same said slots as said subcoil portions of said second coil.

4. An electric motor having an armature, the electric motor comprising:

a lamination stack having a plurality of radially extending posts, said posts forming a plurality of slots therebetween, said slots being arranged in a circumferential pattern;

a plurality of coils wound around said slots, said coils being arranged in pairs about said lamination stack;

each said coil being divided into first and second subcoil portions, with said first subcoil portion having a first plurality of winding turns and said second subcoil portion having a second plurality of winding turns, and wherein said first and second subcoil portions are wound in different, circumferentially offset pairs of said slots and coupled to designated pairs of commutator segments of a commutator;

wherein a first pair of said coils are wound in an overlapping fashion such that the first subcoil portion of a second one of said first pair of coils is wound in the same slots as said second subcoil portion of a first one of said first pair of coils, and said second subsoil portion of said second one of said first pair of coils is wound in a pair of slots offset by one slot position from said slots that said second subcoil portion of said first one of said first pair of coils is wound in; and

wherein a second pair of coils circumferentially offset from said first pair of coils is further wound such that a first subsoil portion of a first one of said second pair of coils is wound in the same slots as said first subcoil portion of said second coil of said first pair of coils, and said second subcoil portion of said first one of said second one of second pair of coils is wound in the same slots as said second subsoil portion of said second coil of said first pair of coils; and

wherein a resultant magnetic axis of each said coil is at the same angular position relative to the pair of commutator segments to which each said coil is secured; and

wherein said same angular position enables coincident commutation zones to be formed for each of said coils.

5. The electric motor of claim 4, wherein one of said first and second subcoil portions of each said coil has a greater number of winding turns that the other of said subcoil portions.

6. The electric motor of claim 4, wherein one of said first and second subcoil portions of each said coil has approximately three times the number of winding turns as the other of said subcoil portions.

7. An electric, rotating machine comprising:

a stator having a plurality of field coils, wherein said field coils are spaced apart to form gaps therebetween;

an armature having a plurality of coils wound thereon such that a magnetic axis of a first one of said coils is advanced, relative to a given pair of said field coils when said first coil is excited, and a magnetic axis of a second one of said coils is retarded, relative to said given pair of field coils when said second coil is excited; and

wherein said first and second coils complete commutation while passing through coincident angular regions relative to said brush.

8. The machine of claim 7, wherein each of said first and second coils is segmented into two subcoil portions coupled in series.

9. The machine of claim 8, wherein said subcoil portions of said first and second coils are wound such that at least one of said subcoil portions of each are wound in a common pair of slots of said armature.

10. An electric motor comprising:

an armature having a plurality of spaced apart posts defining a plurality of spaced apart winding slots;

a stator disposed coaxially with the armature, said stator having a plurality of spaced apart field coils defining an angular region between each adjacent pair of said field coils;

said armature including;

a first coil having a first subcoil portion and a second subcoil portion;

said first subcoil portion having a first plurality of winding turns and being wound in a first pair of spaced apart ones of said slots;

said second subcoil portion having a second plurality of winding turns and being wound in a second pair of spaced apart ones of said slots that are offset from said first pair of spaced apart slots;

a second coil having first and second subcoil portions wound in third and fourth pairs, respectively, of spaced apart ones of said slots;

wherein said subcoils of said first coil are wound with different numbers of winding turns to shift a resultant magnetic axis of said first coil so that said resultant magnetic axis lies at a first predetermined angular position relative to a first pair of commutator bar to which said first coil is secured;

wherein said subcoils of said second coil are wound with differing numbers of turns to align a resultant magnetic axis of said second coil at a second predetermined angular position to a second pair of commutator bars to which said second coil is secured; and

wherein said first and second predetermined angular positions define the same angular position, and wherein said coils have coincident commutation regions.

11. An electric motor of claim 10, wherein said subcoil portions of each said coil have differing numbers of winding turns.

12. An electric motor comprising:

an armature having a plurality of spaced apart posts defining a plurality of spaced apart winding slots;

a stator disposed coaxially with the armature, said stator having a plurality of spaced apart field coils defining an angular region between each adjacent pair of said field coils;

said armature including;

a first coil having a first subcoil portion and a second subcoil portion;

said first subcoil portion having a first plurality of winding turns and being wound in a first pair of spaced apart ones of said slots;

said second subcoil portion having a second plurality of winding turns and being wound in a second pair of spaced apart ones of said slots that are offset from said first pair of spaced apart slots;

a second coil having first and second subcoil portions wound in third and fourth pairs, respectively, of spaced apart ones of said slots;

wherein a resultant magnetic axis of said first coil is positioned at a first angular point relative to a pair of commutator bars to which said first coil is coupled;

wherein a resultant magnetic axis of said second coil is positioned at a second angular point relative to a pair of commutator bars to which said second coil is coupled, said first and second angular points defining the same angular point; and

wherein both of said coils begin and complete commutation within a predetermined, coincident angular commutation region relative to said given pair of field coils.

13. The electric motor of claim 12, wherein said first and second subcoil portions of each of said first and second coils are wound with differing numbers of winding turns.