Vibration motor

Patent metadata

Field	Value
Publication number	US-9800115-B2
Application number	US-201414557610-A
Country	US
Kind code	B2
Filing date	Dec 2, 2014
Priority date	Apr 4, 2014
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

A vibration motor includes an eccentric weight whose center of gravity is positioned outside a shaft and a holder made of resin and holding a ring-shaped back yoke and the eccentric weight. The back yoke includes an overhang portion which extends farther inward in a radial direction than an inner side edge of the opening of a rotor magnet. The holder includes a penetrated portion which is a tube-shaped portion positioned at an axially inner side of the rotor magnet and extends in the axial direction surrounding the shaft, an upper surface portion which expands radially outwardly from an upper side of the penetrated portion to cover an upper surface of the eccentric weight, and a lower surface portion which expands radially outwardly from the lower side of the penetrated portion to cover a lower surface of the overhang portion.

First claim

What is claimed is:

1. A vibration motor, comprising: a plate-shaped base; a case including a cylindrical circumferential surface portion, and a top surface portion closing an axially upper end side of the circumferential surface portion, the cylindrical circumferential surface portion being fixed to the base; a shaft including a lower axial end fixed to the base, and an upper axial end fixed to the top surface portion; a ring-shaped rotor magnet that surrounds the shaft and includes an opening at a center thereof; an armature that is disposed on the base and faces the rotor magnet with a gap in an axial direction; a ring-shaped back yoke that is in contact with an upper surface of the rotor magnet, expands in a radial direction, and includes an opening at a center thereof; an eccentric weight has a center of gravity that is located radially outside the shaft; and a holder that is a member made of resin and holds the ring-shaped back yoke and the eccentric weight; wherein the back yoke includes an overhang portion that extends inwardly in the radial direction farther than an inner side edge of the opening of the rotor magnet; the holder includes a penetrated portion that is a tube-shaped portion positioned at an axially inner side of the rotor magnet and that extends in the axial direction surrounding the shaft, an upper surface portion that expands radially outwardly from an upper side of the penetrated portion to cover at least a portion of an upper surface of the eccentric weight, and a lower surface portion that expands radially outwardly from the lower side of the penetrated portion to cover at least a portion of a lower surface of the overhang portion; and the shaft rotatably supports the holder that includes the penetrated portion.

2. The vibration motor according to claim 1 , wherein an inner edge of the back yoke includes a first concave portion spaced by a distance from a center axis of the shaft farther than an adjacent region on left and right sides in the circumferential direction; and resin that defines the penetrated portion contacts an inner side of the first concave portion.

3. The vibration motor according to claim 2 , wherein the eccentric weight includes a support opening that surrounds the shaft; and the support opening surrounds the shaft in a range greater than 180.degree.

4. The vibration motor according to claim 3 , wherein the support opening surrounds an entire circumference of the shaft.

5. The vibration motor according to claim 1 , wherein the eccentric weight includes a support opening that supports the shaft; and the support opening surrounds the shaft in a range greater than 180.degree.

6. The vibration motor according to claim 5 , wherein the support opening surrounds an entire circumference of the shaft.

7. The vibration motor according to claim 1 , wherein a portion of the eccentric weight covers an inner circumferential edge of the back yoke.

8. The vibration motor according to claim 5 , wherein a portion of the eccentric weight covers an inner circumferential edge of the back yoke.

9. The vibration motor according to claim 2 , wherein the eccentric weight includes a second concave portion at the upper surface thereof; and resin that defines the holder contacts an inner side of the second concave portion.

10. The vibration motor according to claim 1 , wherein the eccentric weight includes a second concave portion at the upper surface thereof; and resin that defines the holder contacts an inner side of the second concave portion.

11. The vibration motor according to claim 6 , wherein the eccentric weight includes a second concave portion at the upper surface thereof; and resin that defines the holder contacts an inner side of the second concave portion.

12. The vibration motor according to claim 2 , wherein an inner diameter of the penetrated portion is equal to or larger than an outer diameter of the shaft.

13. The vibration motor according to claim 8 , wherein an inner diameter of the penetrated portion is equal to or larger than an outer diameter of the shaft.

14. The vibration motor according to claim 2 , wherein the holder includes a sintered sleeve provided at an inner side.

15. The vibration motor according to claim 2 , wherein the upper surface portion of the holder includes a recess that is defined by a dented portion at a center side of the holder.

16. The vibration motor according to claim 15 , wherein an inner diameter of the recess is smaller than an outer diameter of the penetrated portion at the upper surface portion of the holder.

17. The vibration motor according to claim 2 , wherein a bottom of the recess is positioned at a lower side than an upper portion of the eccentric weight.

18. The vibration motor according to claim 2 , wherein the back yoke includes a flat plate.

19. The vibration motor according to claim 2 , wherein a portion of the eccentric weight covers an outer circumference of the rotor magnet.

Assignees

• Nidec Seimitsu Corp

Inventors

• Yamaguchi Tsuyoshi
• Aoi Takayuki
• Kiuchi Hiroyuki

Classifications

• H02K1/2793

  Rotors axially facing stators · CPC title

• H02K7/063 Primary

  integrally combined with motor parts, e.g. motors with eccentric rotors · CPC title

• H02K1/2795

  the rotor consisting of two or more circumferentially positioned magnets · CPC title