Electric motor having brush holder with axial movement limiting armature contact member protector

• US 6,800,982 B2
• Filed: 05/08/2002
• Issued: 10/05/2004
• Est. Priority Date: 05/29/2001
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Ebihara, Yoshio
• Primary Examiner(s): Waks, Joseph
• Assistant Examiner(s): Cuevas, Pedro J
• Application Number:
  US10/140,206
• Publication Number:
  US 20020180301A1
• Time in Patent Office: 881 Days
• Field of Search: 310/219, 310/233, 310/237-239, 310/40.R
• US Class Current: 310/239
• CPC Class Codes: H01R 39/06 other than with external cylindrical contact surface, e.g. flat commutators
• CPC Class Codes: H01R 39/14 Fastenings of commutators or slip-rings to shafts
• CPC Class Codes: H02K 13/006 Structural associations of commutators
• CPC Class Codes: H02K 5/148 Slidably supported brushes

Abstract

An electric motor provides a carbon contact member of a commutator from colliding with a brush holder. A projection is formed in the brush holder so that it projects toward an end face of a resin mold of an armature. An end face of this projection, which is opposed to the end face of the resin mold of the armature, is positioned in the axial direction so as to form a clearance between the contact members and the brush holder when the armature is moved toward the brush holder by an external force and the end face comes in contact with the end face. As a result, if shock is applied to the fuel pump and the armature moves toward the brush holder, the contact members of the commutator are prevented from colliding with the brush holder. It thereby becomes possible to prevent the carbon contact members from being damaged.

Claims

1. An electric motor comprising:

a commutator having a plurality of contact members made of carbon and electrically isolated from each other and a supporting member for supporting said plurality of contact members;

an armature having a rotary shaft, wherein said commutator is coaxially fixed at one end thereof, said armature being molded in a resin;

a pair of brushes biased along said rotary shaft by a resilient member on said plurality of contact members of said commutator; and

a brush holder axially opposed to said commutator of said armature, for rotatably holding said rotary shaft and holding said brushes movably along the axial direction, wherein a limiter structure limiting movement of said armature toward said brush holder in the axial direction is formed in at least either of said brush holder or said armature to provide a clearance between said contact members and said brush holder when the movement of said armature is stopped by said limiter structure,

an axial direction of said brushes and an axial direction of said rotary shaft being substantially parallel, and

the limiter structure projecting in a direction parallel to the axial direction of the rotary shaft.

2. The electric motor according to claim 1, wherein said limiter structure is a projection formed on said brush holder so as to project toward said armature.

3. The electric motor according to claim 2, wherein said projection is opposed to an outer periphery of a resin mold of said armature.

4. The electric motor according to claim 2, wherein said projection is opposed to said supporting member of said commutator.

5. The electric motor according to claim 2, wherein said limiter structure is formed by projecting either whole or part of an outer periphery of a resin mold of said armature toward said brush holder.

17. The electric motor according to 1, wherein the limiter structure limits movement of the commutator in a direction parallel to the axial direction of the shaft.

6. An electric motor comprising:

a planar commutator having a plurality of contact members that are made of carbon and electrically isolated from each other;

a supporting member for supporting said plurality of contact members;

an armature having a rotary shaft and said commutator coaxially fixed at one end thereof, said armature being molded in a resin;

a pair of brushes biased along said rotary shaft by a resilient member on said plurality of contact members of said commutator; and

a brush holder axially opposed to said commutator of said armature, for rotatably holding said rotary shaft and holding said brushes movably along the axial direction, wherein a limiter structure limiting movement of said armatur toward said brush holder in the axial direction is formed in at least either of said brush holder or said armature to meet a condition, L1<

L2, where L1 is a distance between said limiter structure and the opposing contact face and L2 is a distance between the contact member of said commutator and the opposing face of said brush holder,

an axial direction of said brushes and an axial direction of said rotary shaft being substantially parallel, and

the limiter structure projecting in a direction parallel to the axial direction of the rotary shaft.

18. The electric motor according to 6, wherein the limiter structure limits movement of the commutator in a direction parallel to the axial direction of the shaft.

7. An electric motor comprising:

a commutator having a plurality of contact members;

a supporting member for supporting said plurality of contact members;

an armature having a rotary shaft, wherein said commutator is coaxially fixed at a first end of the rotary shaft;

a pair of brushes adjacent to said first end of said rotary shaft and biased by a resilient member at one end of said plurality of contact members of said commutator; and

a brush holder axially opposed to said commutator of said armature, for rotatably supporting said rotary shaft and movably supporting said brushes parallel to the rotary shaft; and

a limiter structure which limits movement of said armature in the armature'"'"'s axial direction so that said contact members do not make contact with said brush holder when said armature moves toward said brush holder,

an axial direction of said brushes and an axial direction of said rotary shaft being substantially parallel, and

the limiter structure projecting in a direction parallel to the axial direction of the rotary shaft.

8. The electric motor according to claim 7, wherein said contact members are made of carbon and are electrically isolated from each other.

9. The electric motor according to claim 8, wherein said armature is molded in a resin.

10. The electric motor according to claim 9, wherein said limiter structure is formed on said brush holder.

11. The electric motor according to claim 9, wherein said limiter structure is formed on said armature.

12. The electric motor according to claim 7, wherein said limiter structure is formed by a protruding portion on an end face of said brush holder and protrudes toward said commutator of said armature.

13. The electric motor according to claim 7, wherein said limiter is a continuous protruding portion of said armature.

14. The electric motor according to claim 7, wherein said projection is opposed to an outer periphery of a resin mold of said armature.

15. The electric motor according to claim 7, wherein said projection is opposed to said supporting member of said commutator.

16. The electric motor according to claim 7, wherein said limiter structure is formed by projecting either whole or part of an outer periphery of a resin mold of said armature toward said brush holder.

19. The electric motor according to 7, wherein the limiter structure limits movement of the commutator in a direction parallel to the axial direction of the shaft.