Commutator

Patent metadata

Field	Value
Publication number	US-9502849-B2
Application number	US-201213550996-A
Country	US
Kind code	B2
Filing date	Jul 17, 2012
Priority date	Jul 18, 2011
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

A commutator includes a first body and a second body which are separately made of electrically insulating material, a plurality of commutator segments fixed on an outer surface of the first body and a plurality of commutator terminals. The first body is a hollow cylinder with two opposite ends. Each terminal has a contact area for contacting a corresponding one of the commutator segments. The second body has a base and a ring wall extending from the base, and one end of the first body is received in a space defined by the base and the ring wall, with the contact area of each terminal being in tight contact with the corresponding commutator segment at the inner side of the ring wall.

First claim

The invention claimed is:

1. A commutator, comprising:
a first body and a second body which are separately made of electrically insulating material, the first body being a hollow cylinder with first and second axial ends;
a plurality of commutator segments disposed on an outer surface of the first body, each commutator segment having a commutator surface for making slide contact with brushes of a brush motor, the commutator surface being exposed to air and axially extending a majority of the distance between the first and second axial ends of the first body; and
a plurality of commutator terminals, each commutator terminal having a contact area for contacting a corresponding one of the commutator segments;
wherein the second body has a base and a ring wall extending from the base, and the first end of the first body is received in a space defined by the base and the ring wall, with the contact area of each commutator terminal being in tight contact with the corresponding commutator segment at the radially inner side of the ring wall, the ring wall being parallel to the commutator surface.

2. The commutator of claim 1 , wherein each commutator terminal has a U- shaped end with two opposing branches, the ring wall being tightly inserted between the two branches with inner and outer surfaces of the ring wall being in contact with opposing surfaces of the two branches, respectively.

3. The commutator of claim 1 , wherein each commutator terminal is circumferentially positioned in a slot formed in the ring wall.

4. The commutator of claim 1 , further comprising a ring varistor having electrodes, each commutator terminal and a corresponding one of the electrodes being electrically connected to each other by a solder connection connecting a surface of the terminal to a surface of the electrode which face each other.

5. The commutator of claim 1 , further comprising a ring varistor having electrodes, each commutator terminal and a corresponding one of the electrodes being electrically connected to each other by a solder connection connecting a surface of the terminal to a surface of the electrode which are perpendicular to each other.

6. The commutator of claim 1 , wherein at least two projections are formed on one end surface of the ring wall remote from the base, and the commutator further has a ring varistor with an inner surface that is pressed onto outer surfaces of the at least two projections.

7. The commutator of claim 1 , wherein the base has a first surface contacting an end surface of the first end of the first body, one of the first surface and said end surface having a groove and the other one having a matching rib.

8. The commutator of claim 1 , wherein a plurality of fins are formed on the outer surface of the first body, each commutator segment being positioned between two adjacent fins.

9. An electric motor, comprising a rotor and a stator, the rotor having a shaft, a rotor core fixed on the shaft, a commutator fixed on the shaft adjacent to the rotor core, and rotor windings wound on the rotor core and electrically connected to the commutator, the commutator comprising a first body, a second body, a plurality of commutator segments, and a plurality of commutator terminals, the first body and the second body being separately made of electrically insulating material, the first body being a hollow cylinder with first and second axial ends, the commutator segments being disposed on an outer surface of the first body, each commutator segment having a commutator surface for making slide contact with brushes of a brush motor, the commutator surface axially extending a majority of the distance between the first and second axial ends of the first body, and each commutator terminal having a contact area for contacting a corresponding one of the commutator segments,
wherein the second body has a base and a ring wall extending from the base, and the first axial end of the first body is received in a space defined by the base and the ring wall, with the contact area of each commutator terminal being in tight contact with the corresponding commutator segment at the radially inner side of the ring wall.

10. The motor of claim 9 , wherein the stator has an oil-impregnated bearing adjacent to the commutator, and the commutator further has an oil stopper integrally extending from the second axial end of the first body adjacent to the bearing.

11. The motor of claim 10 , wherein the oil stopper has an annular tip, the outer diameter of which is greater than the diameter of an imaginary cylinder defined by outer surfaces of the commutator segments.

12. The motor of claim 11 , wherein the annular tip extends into a bearing holder that holds the bearing.

13. The motor of claim 10 , wherein the oil stopper has at least one axially extending portion extending from a surface of the oil stopper facing the second body, the commutator segments being radially positioned between the first body and the at least one axial extending portion.

14. The motor of claim 10 , wherein the base has a first surface contacting an end surface of the first end of the first body, one of the first surface and said end surface having a groove and the other one having a matching rib.

15. The motor of claim 14 , wherein the second body further has at least one protrusion projecting into at least one receiving hole formed on the rotor core, and the oil stopper further has a marker circumferentially aligned with the protrusion.

16. A method of forming a commutator, comprising:
disposing a plurality of commutator segments on an outer surface of a first body made of electrically insulating material;
assembling a plurality of commutator terminals which are separately formed with the plurality of commutator segments to a second body made of electrically insulating material and separately formed with the first body; and
assembling the first body with the commutator segments to the second body with the commutator terminals after the parts are formed in advance so that each commutator terminal is in tight contact with a corresponding one of the commutator segments.

17. The method of claim 16 , further comprising a step of electrically connecting a varistor to the commutator terminals before assembling the first body with the second body.

18. The method of claim 16 , further comprising a step of electrically connecting rotor windings of an electric motor to the commutator terminals before assembling the first body with the second body.

19. The commutator of claim 1 , wherein each commutator terminal is in contact with the corresponding commutator segment only at the radially inner side of the ring wall.

20. The commutator of claim 1 , further comprising an oil stopper integrally extending from the first body.

Assignees

• Cheung Chun Kit
• Wong Duncan Yiu Lung
• Lau James Ching Sik
• Gorlt Wilfried
• Johnson Electric Sa

Inventors

• Cheung Chun Kit
• Wong Duncan Yiu Lung
• Lau James Ching Sik
• Gorlt Wilfried

Classifications

• H02K7/083

  radially supporting the rotary shaft at both ends of the rotor (H02K7/086, H02K7/09 take precedence) · CPC title

• H02K13/04

  Connections between commutator segments and windings · CPC title

• Y10T29/49011

  Commutator or slip ring assembly · CPC title

• H01R39/32

  Connections of conductor to commutator segment · CPC title

• H02K11/028

  Suppressors associated with the rotor · CPC title