DC motor with a positive temperature coefficient thermistor

Patent metadata

Field	Value
Publication number	US-10873235-B2
Application number	US-201715715536-A
Country	US
Kind code	B2
Filing date	Sep 26, 2017
Priority date	Sep 29, 2016
Publication date	Dec 22, 2020
Grant date	Dec 22, 2020

Abstract

A DC motor includes: a brush configured to be connectable with the commutator; a first terminal attached to the brush; a second terminal disposed at a position away from the first terminal, the second terminal being configured to be connectable with an external terminal; a bracket to which the first terminal and the second terminal are attached; and a positive temperature coefficient (PTC) thermistor disposed between the first terminal and the second terminal, the PTC thermistor including a first electrode bonded to the first terminal and a second electrode bonded to the second terminal, wherein the PTC thermistor is a surface-mount type thermistor in which the first electrode and the second electrode are exposed on one surface side and wherein, on the one surface side of the PTC thermistor, the first electrode faces the first terminal and the second electrode faces the second terminal.

First claim

What is claimed is:

1. A DC motor comprising:
a brush configured to be connectable with a commutator;
a first terminal attached to the brush;
a second terminal disposed at a position away from the first terminal, the second terminal being configured to be connectable with an external terminal;
a bracket to which the first terminal and the second terminal are attached; and
a positive temperature coefficient (PTC) thermistor disposed between the first terminal and the second terminal, the PTC thermistor including a first electrode bonded to the first terminal and a second electrode bonded to the second terminal, the PTC thermistor further comprising a first major planar surface and an opposite second major planar surface,
wherein the PTC thermistor is a surface-mount type thermistor in which the first electrode and the second electrode are both disposed on the first major planar surface, and
wherein, on the first major planar surface of the PTC thermistor, the first electrode faces the first terminal and the second electrode faces the second terminal.

2. The DC motor according to claim 1 ,
wherein at least one of the first terminal and the second terminal has a surface which faces the PTC thermistor and includes a projection portion formed to protrude from the surface and being capable of positioning the PTC thermistor.

3. The DC motor according to claim 2 ,
wherein the projection portion comprises a claw portion.

4. The DC motor according to claim 1 ,
wherein the first terminal has a surface that faces the PTC thermistor and includes a first projection formed to protrude from the surface,
wherein the second terminal has a surface that faces the PTC thermistor and includes a second projection formed to protrude from the surface, and
wherein the PTC thermistor is disposed between the first projection and the second projection.

5. The DC motor according to claim 4 ,
wherein the first and second projections comprise claw portions.

6. The DC motor according to claim 1 ,
wherein, on the surface of at least one of the first terminal and the second terminal which faces the PTC thermistor, a flow suppressing portion protruding or being recessed from the surface to suppress a flow of a solder for bonding the PTC thermistor is provided at a position separated from a bonding portion bonded to the PTC thermistor.

7. The DC motor according to claim 1 ,
wherein the bracket has a positioning portion which is capable of positioning the PTC thermistor with respect to the first terminal and the second terminal.

8. The DC motor according to claim 7 ,
wherein the positioning portion has a surface which faces a surface opposite to the one surface of the PTC thermistor in a state where the one surface of the PTC thermistor faces the first terminal and the second terminal.

9. The DC motor according to claim 7 ,
wherein the positioning portion comprises a third projection.

10. The DC motor according to claim 9 ,
wherein the third projection has a columnar shape.

11. A motor comprising:
a motor frame;
a shaft rotatably supported by the motor frame and extended in an axial direction;
a bracket attached to the motor frame and including a penetration hole through which the shaft is passed and a groove;
a positive temperature coefficient (PTC) thermistor having a first major planar surface and a second major planar surface opposite to the first surface, a first electrode portion is disposed on the first major planar surface and a second electrode portion is disposed on the same first major planar surface;
a first terminal arranged in the groove and attached to a brush; and
a second terminal arranged in the groove and arranged at a position away from the first terminal, the second terminal being configured to be coupled with an external terminal,
wherein on the first major planar surface, the first electrode portion of the PTC thermistor is coupled to the first terminal and the second electrode portion of the PTC thermistor is coupled to the second terminal.

12. The motor according to claim 11 ,
wherein the first and second surfaces of the PTC thermistor are arranged at a plane parallel to the axial direction.

13. The motor according to claim 11 ,
wherein the first terminal has a third surface facing to the first surface and the second terminal has a fourth surface facing to the first surface, the third and fourth surfaces are arranged at a plane parallel to the axial direction.

14. The motor according to claim 11 ,
wherein the first and second terminals have a claw portion extending to a direction perpendicular to the axial direction and regulates movement of the PTC thermistor in a direction crossing to the axial direction.

15. The motor according to claim 11 ,
wherein the bracket has a protrusion extending to the axial direction and regulates movement of the PTC thermistor in a direction crossing to the axial direction.

16. A motor comprising:
a motor frame;
a shaft rotatably supported by the motor frame and extended in an axial direction; and
a bracket assembly attached to the motor frame,
wherein the bracket assembly comprises:
a bracket body having a penetration hole and a groove, the shaft is passed through the penetration hole;
a first terminal arranged in the groove;
a second terminal arranged in the groove; and
a positive temperature coefficient (PTC) thermistor having a first major planar surface and a second major planar surface opposite to the first surface and arranged in the groove so that the first and second major planar surfaces are arranged at a plane parallel to the axial direction, only one of the first and second major planar surfaces being faced to both of the first and second terminals.

17. The motor according to claim 16 ,
wherein the second terminal is arranged at a position away from the first terminal.

18. The motor according to claim 17 ,
wherein the first and second terminals have a claw portion extending to a direction perpendicular to the axial direction and regulates movement of the PTC thermistor in a direction crossing to the axial direction.

19. The motor according to claim 17 ,
wherein the bracket body has a protrusion extending to the axial direction and regulates movement of the PTC thermistor in a direction crossing to the axial direction.

Assignees

• Minebea Mitsumi Inc

Inventors

• Kuroda Minoru

Classifications

• H02K23/66 Primary

  Structural association with auxiliary electric devices influencing the characteristic of, or controlling, the machine, e.g. with impedances or switches · CPC title

• H02K13/10

  Arrangements of brushes or commutators specially adapted for improving commutation · CPC title

• H02K11/026

  Suppressors associated with brushes, brush holders or their supports · CPC title

• H02K5/145

  Fixedly supported brushes or brush holders, e.g. leaf or leaf-mounted brushes · CPC title

• H02K11/25

  Devices for sensing temperature, or actuated thereby · CPC title