US20080085189A1

US20080085189A1 - Micro fan

Info

Publication number: US20080085189A1
Application number: US11/602,202
Authority: US
Inventors: Alex Horng; Tso-Kuo Yin
Original assignee: Sunonwealth Electric Machine Industry Co Ltd
Current assignee: Sunonwealth Electric Machine Industry Co Ltd
Priority date: 2006-10-04
Filing date: 2006-11-21
Publication date: 2008-04-10
Also published as: TW200817590A; KR100800573B1; JP2008088971A; GB2442475B; FR2906943A1; JP4457101B2; GB2442475A; DE102006055380A1; GB0701545D0

Abstract

The present invention relates to a micro fan, including an impeller, a fan seat and a bottom cover plate, wherein the impeller has a shaft seat stationarily disposed at one end of a spindle and a plurality of blades extended from a periphery of the shaft seat, a top ring and a bottom ring are disposed on a top and a bottom ends of an outer rim of each blade, and a permanent magnet is disposed on a periphery of each blade and is positioned between the top and bottom rings. The impeller of the present invention requires only a single bearing to rotate the impeller therein, and thus there will be no concentricity alignment issue. Furthermore, an air inlet on the fan seat has no impediment at all and is subjected to no blockage, thereby not only increasing the air supply rate and smoothening the air flow field.

Description

FIELD OF THE INVENTION

The present invention relates to a micro fan, and more particularly to one having a structure that presents no concentricity alignment issue, increases supply air rate and smoothens air flow field.

BACKGROUND OF THE INVENTION

As depicted by Appendix 1, patent number, 593897 (Taiwan patent), Brushless DC micro fan, together with the illustration of FIG. 1, the invented micro fan includes an angular hub 30, two bearings 31, a permanent magnet set 32, an impeller set 33 and a coil set 34.
The angular hub 30 has an air outlet 301, a cover plate 302 and an air outlet 303. The bearings 31 ate fixed by the angular hub 30 and the cover plate 302 along with their respective support rods, and the two bearings 31 shall be coincided axially to support rotation of the spindle 321 therein.
The impeller set 33 has several blades 331 extended in a radial direction, and the permanent magnet set 32 is enveloped in the impeller set 33 and is disposed at the center thereof and on the spindle 321.
The coil set 34 is formed by a plurality of coils provided on a flexible circuit board 341, and the coils are electrically connected therebetween to generate an oscillating magnetic field, thereby driving the permanent magnet set 32 to rotate the impeller set 33 for heat dissipation.
However, the impeller set 33 of the aforementioned brushless DC micro fan is disposed and fixed on the spindle 321, and the spindle is rotated between the two bearings that are pivotally disposed on both ends of the spindle 321. As a consequence, such structure gives rise to several disadvantages as follows:
(1) concentricity alignment difficulty of the two bearings 31—As the impeller set 33 is rotated between the two bearings 31 that are pivotally disposed on both ends of the spindle 321, the concentricity alignment accuracy between the two bearings 31 matters a lot directly to the rotation deviation of the entire impeller set 33. The higher a concentricity error value between the two bearings 31 is, the more rotation deviation of entire impeller set 33 is. Whereas, the two bearings 31 are positioned on the angular hub 30 and the cover plate respectively, making the alignment of the two bearings 31 even harder.
(2) limited air supply area of the air inlet 303—The cover plate 302 located beside the air inlet 303 is incorporated with a support rod to fix the bearing 31. In other words, the support rod and the bearing 31 stride across the air inlet 303 to result in blockage to the air supply area and affect the air supply rate accordingly.
(3) liability of turbulence and vibration—As the support rod and the bearing 31 stride across the air inlet 303, the air supply area is blocked, the air flow of the air inlet 303 is impeded, and turbulence and vibration are thus easily triggered.
As such, to completely tackle the issue intrinsic to the above-mentioned brushless DC micro fan, a micro fan with a brand new idea must be aggressively conceived and developed to resolve the alignment difficulty issue of the spindle.

SUMMARY OF THE INVENTION

In view of the foregoing concern, the present invention thus provides a micro fan including an impeller, a fan seat, and a bottom cover plate.
The impeller has a spindle, a shaft seat is stationarily disposed at one end of the spindle, a plurality of blades extended from the periphery of the shaft seat, a top ring and a bottom ring are provided at a top end and a bottom end of an outer rim of each blade, and a permanent magnet is disposed on an outer rim of each blade and is fixed between the top and the bottom rings.
An angular wall is provided in the fan seat, in which the center of the angular wall is inserted by the impeller, and the angular wall is surrounded by stator containing slots. An air inlet is disposed at a position, in which the fan seat corresponds to the impeller. An air guiding flange inclined inwardly is provided inside the air inlet, and the diameter of an inner hole of the air inlet shall be slightly smaller than the maximum outer diameter of the impeller.
An air outlet is provided at the center of the bottom cover plate, a plurality of support rods are linked with a shaft tube inside the air outlet, and the shaft tube is provided a bearing therein, such that the spindle of the impeller can be inserted in the bearing in a rotational manner.
Since the spindle of the impeller of the present invention just relies on single bearing for support and rotation, it is free of the concentricity alignment issue in the first place and is subjected to no blockage as a result of no impediment to the air inlet of the fan seat. Meanwhile, each of the blades of the impeller can be extended upwards to the most exterior end of the air inlet to thereby increase the air supply rate and smoothen air flow field.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view showing the assembly of the prior art (patent number (Taiwan patent), 593897);

FIG. 2 is a 3D exploded view showing a preferred embodiment of the present invention;

FIG. 3 is a 3D exterior view showing the impeller of the micro fan in the present invention;

FIG. 4 is a cross sectional view showing the impeller of the micro fan in the present invention; and

FIG. 5 is a cross sectional view showing the assembly of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention relates to a micro fan, as shown in FIG. 2, mainly including an impeller 10, a fan seat 20 and a bottom cover plate 21.
Illustrated by reference to FIG. 3 and FIG. 4, the impeller 10 has a spindle 11, a shaft seat 12 is disposed at one end of the spindle 11, a plurality of blades 13 are extended outwardly from an outer periphery of the shaft seat 12, and a top ring 14 and a bottom ring 15 are disposed on the rim of each blade 13, wherein the top ring is concavely disposed on the top edge of the outer rim of each blade 13, and the bottom ring 15 is concavely disposed on the bottom edge of the outer rim of each blade 13. A permanent magnet 16 is disposed on the outer rim of each blade and is fixed between the top ring 14 and the bottom ring 15. A snap protrusion 151 is optionally disposed on one side of either the top ring 14 or the bottom ring 15 (the bottom ring is selected in FIG. 4) in the vicinity of the permanent magnet 16, such that the permanent magnet 16 is firmly coupled with the top and bottom rings 14, 15 to prevent from being disengaged during rotation.
The fan seat 20 has an angular wall 201 therein to allow formation of a space for accommodating the impeller 10 in the central portion of the angular wall 201, and a stator containing slot 202 is formed between an outer periphery of the angular wall 201 and a wall of the fan seat 20. An air inlet 203 is formed over the top side of the fan seat 20, an air guiding flange 204 inclined inwards is disposed around the air inlet 203, and the diameter of an inner hole of the air inlet 203 shall be slightly smaller than the maximum outer diameter of the impeller 10 to prevent the impeller 10 from falling off.
An air outlet 211 is formed at the center of the bottom cover plate 21 and has a shaft tube 213 having an abrasive plate 22, a bearing and a positioning plate 24 therein, wherein the shaft tube 213 is integrally coupled with the inner wall of the air outlet by means of a plurality of support rods 212, and a fitting edge 214 is disposed on the outer periphery of the air outlet 211.
As shown in FIG. 2 and FIG. 5, a magnetic absorption positioning plate 25 is provided on the inner side of the fitting edge 214 of the bottom cover plate 21. The spindle 11 of the impeller 10 is inserted in the bore of the bearing such that the impeller 10 can be pivotally disposed on a top side the bottom cover plate 21 in a rotational manner.
A stator set 26 is disposed in the stator containing slot 202 of the fan seat 20, and then the impeller 10 is encased in the fan seat. The stator set 26 and the permanent magnet 16 of the impeller 10 are partitioned by the angular wall 201 and are mutually coincided, such that an oscillating magnetic field of the stator set 26 can drive the impeller 10 to rotate. Moreover, while the angular wall 201 of the fan seat 20 is inserted in the fitting edge 214, the magnetic absorption positioning plate 25 is snapped and positioned, thereby exerting a downward magnetic attraction force on the permanent magnet of the impeller 10 to secure a stable rotation of the impeller 10 by means of attraction of the track of the magnetic absorption positioning plate 25.
In contrast to the conventional brushless DC micro fan, the present invention is at least characterized by:
(1) no spindle alignment issue—The shaft seat 12, blades 13 and so forth of the impeller 10 are stationarily fixed at one end of the spindle 11, and the other end of the spindle 11 is inserted in the bearing 23. As the support and rotation reply on only a single bearing 23, there will be no concentricity alignment issue.
(2) large air supply rate—As the impeller 10 is supported by the bearing 23 and rotated therein, the air inlet 203 on the top side of the fan seat 20 is fully cleaned out and is free of any blockage. Therefore, the blades on the impeller 10 can be extended upwards to an extreme outer end of the air inlet, thereby increasing the area of the blades directly in contact with air flow and augmenting the air supply rate.
(3) smooth air flow field and no turbulence—Since the air inlet 203 is cleaned out and has no blockage, the air flow field is smooth and result in no issue of turbulence, vibration and noise accordingly.
In sum, from the above-mentioned characteristics those features not only has a novelty among similar products and a progressiveness, but also has an industry utility
While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.

Claims

1. A micro fan, comprising:

an impeller having a spindle, a shaft seat stationarily disposed at one end of said spindle, a plurality of blades extended from an outer periphery of said shaft seat, and a permanent magnet disposed on an outer rim of each said blade;

a fan seat having an angular wall for said impeller to be centrally inserted therein, a stator containing slot located beside an outer periphery of said angular wall for accommodating a stator set, and an air inlet disposed on a top side of said fan seat; and

a bottom cover plate having an air outlet disposed centrally, a plurality of support rods located inside said air outlet and linked with a shaft tube, a bearing located inside said shaft tube for said spindle of said impeller to be centrally inserted in said bearing in a rotational manner.

2. The micro fan of claim 1, wherein an air guiding flange is disposed at said air inlet and has an inner edge formed by inclined inwardly, and an inner hole of said air inlet is slightly smaller than a maximum outer diameter of said impeller.

3. The micro fan of claim 1, wherein a top ring and a bottom ring are disposed on a top end and a bottom end on an outer edge of each said blade, and said permanent magnet is fixed between said top ring and said bottom ring.

4. The micro fan of claim 3, wherein a snap protrusion is disposed on one side of said top ring and located in the proximity of said permanent magnet.

5. The micro fan of claim 3, wherein a snap protrusion is disposed on one side of said bottom ring and located in the proximity of said permanent magnet.

6. The micro fan of claim 1, wherein a fitting edge is disposed on an outer periphery of said air outlet for said angular wall to be inserted in, a magnetic absorption positioning plate is disposed on an inner side of said fitting edge and is snapped and positioned while said angular wall is fitted with said fitting edge.

7. A micro fan, comprising:

an impeller having a spindle, a shaft seat stationarily disposed at one end of said spindle, a plurality of blades extended from an outer periphery of said shaft seat, and a permanent magnet disposed on an outer rim of each said blade and is fixed between a top ring and a bottom ring;

a fan seat having an angular wall for said impeller to be centrally inserted therein, a stator containing slot located beside an outer periphery of said angular wall for accommodating a stator set, an air inlet disposed on a top side of said fan seat, and an air guiding flange disposed at said air inlet and having a diameter of an inner hole of said air guiding flange is less than a maximum outer diameter of said impeller; and

8. The micro fan of claim 7, wherein said air guiding flange has an inwardly-inclined inner edge.

9. The micro fan of claim 7, wherein said top ring and said bottom ring are positioned at a top end and a bottom end of each said blade of said impeller.

10. The micro fan of claim 7, wherein a snap protrusion is disposed on one side of said permanent magnet in the proximity of said top ring.

11. The micro fan of claim 7, wherein a snap protrusion is disposed on one side of said permanent magnet in the proximity of said bottom ring.

12. The micro fan of claim 7, wherein a fitting edge is disposed on a periphery of said air outlet for said angular wall to be inserted therein, a magnetic absorption positioning plate is provided on an inner side of said fitting edge to be snapped and positioned while said angular wall is inserted in said fitting edge.