Motor

Details Motor Motor

1999-10-08

2001-06-05

Ramirez, Nestor (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C029S598000, C384S114000

Reexamination Certificate

active

06242830

ABSTRACT:

BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to a motor well adaptable for a CD-ROM driver, a DVD-ROM drive or others.
2. Related art
A brushless motor, disclosed in JP-A-8-331820, has been known for a motor used for the CD-ROM drive, for example. The brushless motor follows. A rotary shaft is supported with aid of a radial bearing as a sintered oil-impregnated bearing and a thrust plate within a cylindrical bearing housing. The radial bearing is located in the upper portion of the bearing housing. The inside diameter of the lower part of the bearing housing is larger than that of the upper part thereof. A dish-like thrust cap is mounted on the lower part of the bearing housing. A thrust plate is disposed between the lower end of the rotary shaft and the thrust cap.
The motor is capable of preventing bearing lubricating oil from flowing out of a thrust receiving portion since the dish-like thrust cap is mounted on the lower part of the bearing housing, and a thrust plate is disposed between the lower end of the rotary shaft and the thrust cap. In the radial bearing fixed to the bearing housing, the lubricating oil receives a pumping action with rotation of the shaft, and flows downwardly of the inner wall of the bearing housing. The oil thus flowing out reaches a portion where the thrust cap is attached to the bearing housing. Even if the thrust cap is attached in press fitting manner, a minute gap will possibly be formed between the cap and the housing since those members are separate members. If such a gap is present, oil will leak through the gap outside the thrust cap.
When a disc is attached to the disc hub integral with the rotary shaft, a force is applied to the fixing portion for the thrust cap and the bearing housing in a direction in which the thrust cap is pulled out. As a result, the oil is likely to flow outside from the fixing portion.
SUMMARY OF INVENTION
Accordingly, an object of the present invention is to provide a motor which is free from the flowing of bearing lubricant oil outside the bearing housing, and has a long lifetime and a high reliability.
An aspect of the present invention, there is provided a motor comprising:
a cup-like bearing housing integrally including a cylindrical portion, a bottom portion and a hollow portion defined by said cylindrical portion and said bottom;
a radial bearing held in said hollow portion while being in contact with the inner surface of said cylindrical portion;
a thrust receiving plate disposed at said bottom portion of said cup-like bearing housing; and
a rotary shaft rotatably supported by said radial bearing in a state that an extreme end thereof is in contact with said thrust receiving plate.
In the present invention, the bearing housing, which is shaped like a cup, includes a cylindrical portion and a bottom portion closing one end of the cylindrical portion. Therefore, in the resultant motor, no bearing oil flows outside from the bottom portion of the bearing housing.
Shaping a metal sheet by drawing process forms the bearing housing. Therefore, the number of parts required is reduced. The unit form of the bearing housing eliminates the leakage of bearing oil out of the housing.
A gap, which may be utilized for an oil reservoir, is formed between the inner surface of the cylindrical portion of the bearing housing and the outer surface of the radial bearing. Provision of the gap prevents the bearing oil from leaking out of the bearing housing, elongates a lifetime of the motor, and allows bearing oil replenishment at the time of assembling the rotor into the structure.


REFERENCES:
patent: 5399025 (1995-03-01), Higuchi et al.
patent: 5466070 (1995-11-01), Nakasugi
patent: 5623382 (1997-04-01), Moritan et al.
patent: 5628569 (1997-05-01), Hayakawa et al.
patent: 5736799 (1998-04-01), Harano et al.
patent: 5762423 (1998-06-01), Mori et al.
patent: 5793561 (1998-08-01), Ibaraki et al.
patent: 5822846 (1998-10-01), Moritan et al.
patent: 5885005 (1999-03-01), Nakano et al.
patent: 6023114 (2000-02-01), Mori et al.
patent: 8-331820 (1996-12-01), None

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