Permanent magnet for motor, motor and magnetizing method

a permanent magnet and motor technology, applied in the field of motors, can solve the problem that the inherent ability of magnetic materials cannot be completely brought ou

Inactive Publication Date: 2005-08-11
SEIKO INSTR INC
View PDF5 Cites 34 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0021] The present invention provides, in order to attain the above-mentioned object, a permanent magnet for a motor, which is disposed in a rotor for the motor and has a cylindrical shape, including domains that are magnetized in a radial direction and are arranged at regular intervals in a circumferential direction, ch

Problems solved by technology

As a result, there is a problem that full magnetization (magnetic saturation) for the permanent magnet i

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Permanent magnet for motor, motor and magnetizing method
  • Permanent magnet for motor, motor and magnetizing method
  • Permanent magnet for motor, motor and magnetizing method

Examples

Experimental program
Comparison scheme
Effect test

embodiment

(1) Outline of Embodiment

[0040] If a motor is downsized, a permanent magnet (having a cylindrical shape and provided to a rotor) used therefor is reduced in size. This requires a compact magnetizing head for magnetizing the permanent magnet and makes is difficult to allow current to flow in large amounts at the time of magnetization. As a result of suppressing current to be supplied to the magnetizing head (hereinafter, referred to as magnetizing current) at the time of magnetization, the permanent magnet is hardly magnetized to its limit of the magnetizing force (full magnetization). Thus, it is difficult to bring out an ability of the magnetic material fully.

[0041] Among others, in the case of using an outer rotor type motor, a magnetizing head for allowing magnetizing current to flow should be arranged inside a cylindrical magnetic material in order to magnetize the magnetic material from inside the same. In addition, a multipolar permanent magnet has been under study. Hence, th...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

PUM

PropertyMeasurementUnit
Lengthaaaaaaaaaa
Magnetismaaaaaaaaaa
Login to view more

Abstract

The present invention relates to a cylindrical permanent magnet which is used in a micro DC brushless motor used in a compact hard disc etc. An Sm—Co based magnetic material is used as a magnetic material and the permanent magnet has domains magnetized in a radial direction and arranged at regular intervals in a circumferential direction. Provided that P represents a pitch corresponding to an average of an inner circumferential length and outer circumferential length in one of the domains, D denotes an inner diameter of the permanent magnet, t represents a thickness in the radial direction, N represents the number of domains, and M represents the number of AC phases for driving the motor, D is set to 20 (mm) or smaller and t is set to satisfy the relation of t≦πD/(NM−π).

Description

TECHNICAL FIELD [0001] The present invention relates to a motor, for example, a motor including a rotor provided with a permanent magnet. BACKGROUND ART [0002] In recent years, computers have been put in widespread use in a rapid pace. Disc-like storage media such as a hard disc and a magneto-optic disc are widely used for storage devices in most of those computers. Those storage media are rotated at a high speed by a small-sized motor provided to a disc drive and data is read or written from and to the media. [0003] The motor used for the disc drive is designed to generate a rotating magnetic field by means of a stator coil so as to act on a permanent magnet provided to a rotor, thereby rotating. [0004] The permanent magnet is magnetized radially (in a radial direction) and inverts polarities at a predetermined pitch along a circumferential direction. That is, the N pole and the S pole appear at regular intervals along an inner or outer circumference. The same polarity is attained ...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

Application Information

Patent Timeline
no application Login to view more
IPC IPC(8): H01F1/053H01F13/00H01F41/02H02K1/27H02K15/03H02K21/22
CPCH01F13/003H01F41/028H02K1/2786Y10T29/49075H02K21/222Y10T29/49009H02K15/03H02K1/2791H02K1/27H01F7/02H01F13/00
Inventor TAKEHARA, ISAMUKINOSHITA, SHINJIGOTOH, HIROMITSU
Owner SEIKO INSTR INC
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap