Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-02-11
2001-05-22
Mullins, Burton (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S089000, C310S091000, C310S156030, C310S261100
Reexamination Certificate
active
06236126
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to electric motors and more particularly to brushless motors suitable for driving a blower used in an automotive air conditioning device.
2. Description of the Prior Art
In order to clarify the task of the present invention, one conventional brushless motor used for the above-mentioned field will be briefly described.
The brushless motor comprises a driving unit, a drive shaft powered by the driving unit and a parts protecting case. The parts protecting case houses therein the driving unit. The drive shaft projects upward from the case. A blower of the air conditioning device is fixed to the drive shaft. The driving unit comprises a yoke fixed to the drive shaft, a plurality of magnets circumferentially arranged and secured to an inner surface of the yoke having S- and N-poles thereof arranged alternately, a fixed housing for rotatably supporting the drive shaft and a stator mounted to the fixed housing. Upon energization of the driving unit, the yoke and thus the drive shaft is rotated at a high speed relative to the fixed housing.
However, in the brushless motor having the abovementioned structure, it is very difficult to smoothly rotate the drive shaft because of inevitable vibration of the yoke. If, due to the vibration of the yoke, the drive shaft fails to rotate smoothly, the parts protecting case tends to produce a marked noise caused by resonance.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a brushless motor, which assures a smoothed and noiseless operation.
It is another object of the present invention to provide a brushless motor which is simple, compact and economical.
According to a first aspect of the present invention, there is provided a brushless motor which comprises a parts protecting case; a drive shaft rotatable about its axis relative to the parts protecting case; a fixed housing for rotatably holding therein the drive shaft; a stator tightly held by the fixed housing; a shock absorbing unit interposed between the fixed housing and the parts protecting case to suppress transmission of vibration of the fixed housing to the parts protecting case; a yoke connected to the drive shaft to rotate therewith; a plurality of magnets held by the yoke; and a vibration damping structure provided by the yoke to suppress transmission of vibration of the yoke to the drive shaft.
According to a second aspect of the present invention, there is provided a brushless motor which comprises a parts protecting case; a drive shaft rotatable about its axis relative to the parts protecting case; a fixed housing for rotatable holding herein the drive shaft, the fixed housing having a flange portion; a stator tightly held by the fixed housing; a shock absorbing unit interposed between the flange portion of the fixed housing and an upper side of the parts protecting case to suppress transmission of vibration of the fixed housing to the parts protecting case; a cup-shaped yoke including at least a conical portion, a cylindrical portion and a junction portion through which the conical and cylindrical portions are united, the yoke being connected to the drive shaft to rotate therewith; and a plurality of magnets held by the cylindrical portion of the yoke, wherein the junction portion of the yoke is shaped thin as compared with the conical and cylindrical portions.
REFERENCES:
patent: 4623812 (1986-11-01), Van De Griend
patent: 4883982 (1989-11-01), Forbes et al.
patent: 5402024 (1995-03-01), Watanabe et al.
patent: 5798589 (1998-08-01), Ohi et al.
patent: 4-109838 (1992-04-01), None
patent: 4-168942 (1992-06-01), None
patent: 6-205561 (1994-07-01), None
patent: 8-009616 (1996-01-01), None
patent: 10-191595 (1998-07-01), None
Kawarai Hiromi
Ohira Shigenori
Sunaga Hideki
Uchino Setsuya
Yagi Yoshihiro
Calsonic Kansei Corporation
Foley & Lardner
Mullins Burton
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