Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-08-30
2004-03-02
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S090000, C310S043000
Reexamination Certificate
active
06700262
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a rotary electric machine such as a fan motor or the like, and more particularly to a coupling structure between an insulator of a stator and a bearing holder.
A conventional fan motor which has been known in the art is generally constructed in such a manner that a rotor including a plurality of permanent magnets is rotated about a revolving shaft with respect to a stator including a plurality of salient poles. In the conventional fan motor thus constructed, the stator is mounted on a bearing holder in which at least one bearing for supporting the revolving shaft is fitted. Also, an insulator which is made of a synthetic resin material is arranged so as to cover a part of an outer surface of a stator core of the stator. Further, a coupling structure is provided so as to couple the insulator and bearing holder to each other to prevent relative movement between the bearing holder and the stator in both an axial direction of the revolving shaft and a peripheral direction thereof. For example, a motor disclosed in Japanese Patent No. 2,778,894 and U.S. Pat. No. 5,650,678 corresponding thereto is so configured that a bearing holder is deformed at a forward end thereof toward an insulator by heating, to thereby prevent relative movement between the bearing holder and a stator in an axial direction of a revolving shaft. Also, in the conventional fan motor described above, the bearing holder is provided on an outer periphery thereof with a projection and correspondingly the insulator is provided with a fitted section in which the projection of the bearing holder is fitted. Such construction effectively prevents relative movement between the bearing holder and the stator in the peripheral direction of the revolving shaft.
However, the bearing holder is often substantially varied in thickness during formation of the bearing holder by injection molding of a synthetic resin material or the like. Such a variation in thickness of the bearing holder leads to a so-called resin escaping or receding phenomenon which causes escaping or receding of the synthetic resin material during curing of the synthetic resin. When such a resin receding phenomenon substantially occurs at a portion of the bearing holder on which the bearing is held, the bearing holder is deteriorated in accuracy of an inner diameter thereof or varied in inner diameter. This causes deviation between a center of rotation of the bearing and that of the bearing holder to be increased, leading to vibration of the fan motor, so that it is deteriorated in durability.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing disadvantage of the prior art.
Accordingly, it is an object of the present invention to provide a rotary electric machine or machinery which is capable of permitting coupling between a bearing holder and an insulator to be carried out without causing a deterioration in accuracy of an inner diameter of a portion of the bearing holder on which the bearing is held.
It is another object of the present invention to provide a fan motor which is capable of permitting coupling between a bearing holder and an insulator to be carried out without deteriorating accuracy of an inner diameter of a portion of the bearing holder on which the bearing is held.
It is a further object of the present invention to provide a rotary electric machine which is capable of ensuring reliable coupling between a bearing holder and an insulator.
It is still another object of the present invention to provide a rotary electric machine which is capable of facilitating coupling between a bearing holder and an insulator due to deformation by heating.
It is yet another object of the present invention to provide a rotary electric machine which is capable of permitting application of any unnecessary stress from an insulator to a bearing holder to be effectively prevented by deformation of a plurality of projections provided on the insulator.
In accordance with the present invention, a rotary electric machine is provided. The rotary electric machine includes a rotor rotated about a revolving shaft arranged so as to extend in an axial direction thereof. Also, the rotary electric machine includes a bearing holder made of a synthetic resin material and constructed into a hollow structure. The bearing holder has a forward end positioned on one of both sides defined along an axis of the revolving shaft (hereinafter referred to as “one axial side”) and a rearward end positioned on the other of both sides defined along the axis of the revolving shaft and opposite to the one axial side (hereinafter referred to as “the other axial side”). Also, the bearing holder is coupled at the rearward end thereof to a casing and has at least one bearing for supporting the revolving shaft fitted therein. The rotary electric machine also includes a stator including a stator core, an insulator and a plurality of windings. The stator core is formed at a central portion thereof with a through-hole via which the bearing holder extends and includes a plurality of salient poles arranged on an outer periphery thereof so as to be spaced from each other at predetermined intervals in a peripheral direction of the revolving shaft. The insulator is made of a synthetic resin material exhibiting electrical insulating properties and arranged so as to cover a part of an outer surface of the stator core while keeping a magnetic pole surface of each of the salient poles of the stator core and an inner surface of the through-hole exposed. The windings each are formed by winding a conductive wire on each of the salient poles through the insulator. The rotary electric machine further includes a coupling structure for coupling the bearing holder and insulator to each other to prevent relative movement between the bearing holder and the stator in the axial direction of the revolving shaft and relative movement between the stator and the bearing holder in the peripheral direction of the revolving shaft. The coupling structure is constituted by at least one recess formed on the forward end of the bearing holder projecting through the through-hole of the stator core so as to be open on the one axial side and in a radial direction of the revolving shaft, as well as at least one projection provided on the insulator and tightly fitted in the recess of the bearing holder while keeping the bearing holder fully fitted in the through-hole of the stator core. The term “tightly fitted” or “tight fitting” as used herein is intended to mean fitting which is not readily released due to vibration or the like or which prevents the projection and recess fitted together from being readily disengaged from each other due to vibration or the like. Alternatively, the projection of the insulator may be press-fitted in the recess of the bearing holder. The term “press-fitted” or “press fitting” as used herein is intended to mean fitting carried out by forcibly fitting the projection in the recess by means of force at an increased magnitude, to thereby couple both to each other while deforming the projection and recess. However, tight fitting or press fitting is not necessarily employed when the projection and recess are deformed at a periphery thereof by heating, to thereby be coupled to each other as described hereinafter.
In the rotary electric machine of the present invention, it is merely required that the bearing holder is formed on the forward end thereof with the recess. This eliminates a necessity of substantially varying a thickness of the end of the bearing holder, resulting in effectively preventing a synthetic resin material of the bearing holder from escaping or receding which occurs at or near the forward end of the bearing holder when the bearing holder is made of the synthetic resin material. Thus, the present invention effectively prevents a deterioration in accuracy of a diameter of an inner periphery of the forward end of the bearing holder.
Also, in the present invention, the projection of the insulator is arranged in corr
Kobayashi Ryuji
Osawa Honami
Ouchi Yukio
Takakuwa Munenori
Nguyen Tran
Rankin, Hill Porter & Clark LLP
Sanyo Denki Co. Ltd.
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