Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
2000-05-04
2001-11-13
Freay, Charles G. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
Reexamination Certificate
active
06315529
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a computer component and more particularly to a cooling fan with anti deflection arrangement.
BACKGROUND OF THE INVENTION
Conventionally, blades of rotor of cooling fan are thermoplastic substances formed by injection molding. It is often found that not all blades mounted on fan have the same weight due to the uncontrollable amount of variation in the manufacturing process. As such, shaft of fan may deflect to one side in high speed rotation which in turn cause a rough rotation of shaft and a uneven contact between shaft and bearing. This situation and others such as noise and overworn are even worse in cooling fan with a single ball bearing provided. This significantly shortens the useful life of cooling fan.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide an improved cooling fan with a means for preventing shaft of rotor from deflecting so as to prolong the useful life thereof.
To achieve the above and other objects, the present invention provide a cooling fan comprising a rotor, a stator, a circuit board, a base, and a magnetic plate wherein rotor includes a plurality of blades, a magnetic recess, and a shaft; stator has a plurality of posts; circuit board has a plurality of apertures corresponding to the posts; and base includes a bearing and a sleeve. In assembly, posts of stator are inserted into apertures of circuit board, shaft of rotor is inserted through stator and circuit board to secure in the bearing of base, and magnetic plate is located between stator and circuit board wherein the annular edge of magnetic plate is corresponding to and lower than magnetic recess of rotor by a predetermined gap, and is spaced apart from the poles of stator.
The principles of the invention in operation is that magnetic recess of rotor is magnetically attracted by magnetic plate so as to generate an axial attractive force for restraining the radial deflection of rotor within an acceptable minimum such that the original radial deflection of shaft in rotation caused by uneven weights of blades are much eliminated and corrected, thereby reducing friction between shaft and bearing during rotation for achieving a smooth operation.
In a first aspect of the invention, magnetic plate is adhered to one side of circuit board.
In a second aspect of the invention, magnetic plate has a plurality of dents corresponding to apertures of circuit board for securing stator, magnetic plate, and circuit board together by inserting posts of the stator through dents of the magnetic plate into the apertures of the circuit board.
In a third aspect of the invention, the side of circuit board with magnetic plate adhered thereon is a smooth surface without any circuit devices provided thereon.
In a fourth aspect of the invention, magnetic plate is of annular shaped.
In a fifth aspect of the invention, magnetic plate is of strip shaped.
In a sixth aspect of the invention, magnetic plate is of block shaped.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.
REFERENCES:
patent: 4861237 (1989-08-01), Shriraki et al.
patent: 4987331 (1991-01-01), Horng
patent: 5099181 (1992-03-01), Canon
patent: 5288216 (1994-02-01), Bolte
patent: 5492458 (1996-02-01), Horng
patent: 5947704 (1999-09-01), Hsieh
patent: 5997267 (1999-12-01), Lee
patent: 6109892 (2000-08-01), Horng
patent: 6132170 (2000-10-01), Horng
Freay Charles G.
Pro-Techtor Inter-national Services
Rodriguez William
Tranyoung Technology Corp.
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