US20090175744A1

US20090175744A1 - Mini-fan with easy-starting structure

Info

Publication number: US20090175744A1
Application number: US12/265,484
Authority: US
Inventors: Horng Alex; Yin tso-kuo
Original assignee: Sunonwealth Electric Machine Industry Co Ltd
Current assignee: Sunonwealth Electric Machine Industry Co Ltd
Priority date: 2008-01-03
Filing date: 2008-11-05
Publication date: 2009-07-09
Also published as: TWM334625U

Abstract

A mini-fan with an easy-starting structure is proposed, which includes a fan housing a rotor, and a bottom. The fan housing has a plurality of coils, a control unit, and at least one globe-shaped attractor, with the at least one globe-shaped attractor being made of conductive magnetic material and arranged between adjacent two of the coils. The rotor has a permanent magnet ring facing the coils of the fan housing and having at least one pair of opposite magnetic poles, with each magnetic pole providing a high-intensity area. Consequently, one of the high-intensity areas is attracted by and faces the at least one globe-shaped attractor when the rotor is held at a stop position.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a mini-fan and, more particularly, to a mini-fan with an easy-starting structure.
2. Description of Related Art
FIG. 1 shows a conventional mini-fan including a fan housing 10, a rotor 20 and a bottom 30.
The fan housing 10 is formed as a hollow casing having a receiving cavity, with an outer annular wall forming a lateral outer surface of the fan housing, an inner annular wall 11 laterally defining the receiving cavity, and a coil-setting slot 12 formed between the two annular walls. The receiving cavity encircled by the inner annular wall 11 is for receiving the rotor 201 and the coil-setting slot 12 is for arrangement of a circuit board 40. The circuit board 40 is preferably selected from a flexible printed circuit board, which has an even number of coil sets 41 such as two coil sets 41 each having one coil as shown in FIG. 1, and a control unit 42 including a driver circuit and a Hall sensor. The control unit 42 electrically connects the coil sets 41, which is disposed between and adjacent to the coil sets 41 while only two coils are used. Furthermore, an easy-starting portion is formed between the two annular walls and is disposed between two adjacent coils of the coil sets 41. Said easy-starting portion includes a position hole 13 extending axially and an attracting member 14 received in the position hole 13. Said attracting member 14 is made of magnetic conductive material and in a shape of cylinder or quadrangular prism, and the shape of the position hole 13 is complementary to that of the attracting member 14.
The rotor 20 includes an axial shaft 21, a hub 22 arranged at one end of the axial shaft 21, a plurality of blades 23 formed on an annular surface of the hub 22 and extending outwards, and a permanent magnet ring 24 encircling the hub 22 and blades 23 and connecting with outer edges of the blades 23. The permanent magnet ring 24 has at least one pair of opposite magnetic poles, with the opposite magnetic poles being arranged in stagger and a boundary disposed between any two adjacent poles. Besides, between any two adjacent boundaries, a pole section wherein one of the poles is disposed provides a high-intensity area at the center thereof.
The bottom 30 provides an axial tube 31 at the center thereof, with a bearing 32 being received in the axial tube 31 for the axial shaft 21 of the rotor 20 to insert in. Thus, the rotor 20 is able to rotate respective to the bottom 30.
When the conventional mini-fan is assembled, the circuit board 40 is initially disposed in the coil-setting slot 12 of the fan housing 10, and then the fan housing 10 covers the outer of the rotor 20. And thereby, the permanent magnet ring 24 of the rotor 20 and the coil sets 41 of the circuit board 40 are able to face each other in radial. In operation, the control unit 42 detects the change of magnetic fields caused by the permanent magnet ring 24 and inputs changing currents into the coil sets 41 to generate alternative magnetic fields for actuating and driving the rotor 20. When the rotor 20 is going to be stopped, the attracting member 14 of the fan housing 10 attracts one of the high-intensity area to face the attracting member 14, so that the rotor 20 will be held at a position wherein the high-intensity area of pole sections and any coil of the coil sets 41 are arranged in stagger radially, and hence the rotor 20 is easy to be actuated for the next time.
However, when said easy-starting portion with the attracting member 14 is applied to a mini-fan, the attracting member 14 must be shaped in a small size, such as a quadrangular prism with a cross-sectional area of 0.6×0.6 mm²and a height of 1.5 mm. Wherefore, no matter the attracting member 14 is in the shape of cylinder or quadrangular prism, it will be very difficult to make up the conventional mini-fan.
For example, if the attracting member 14 is in the shape of a quadrangular prism, a process for making up the conventional mini-fan with the attracting member 14 is inserting a quadrangular prism having a length larger than a depth of the position hole 13 into the position hole 13, and then cutting off the quadrangular prism at an opening of the position hole 13. Either the above process is done manually or automatically, a raise in manufacture cost is unavoidable. Besides, rough edges of the cut quadrangular prism cause an unreliable combination between the fan housing 10 and the bottom 30, which results in a low quality in assembly.
Moreover, if the attracting member 14 is in the shape of a cylinder, it is preferred to initially make up the attracting member 14 by a turning process, and then the preformed attracting member 14 can be inserted into the position hole 13. However, because the attracting member 14 and chips produced during the turning process are similar in size, it is impossible to completely separate the attracting member 14 from the chips by a sorting machine, and thus an intervention of manual sorting is needed. Accordingly, there is a need for redesigning the conventional mini-fan.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a mini-fan with an easy-starting structure, with an attracting member being selected from a steel ball that has already been manufactured by mass production presently, so as to reduce the manufacture cost and rise the quality of assembly.
According to the preferred teachings of the present invention, a mini-fan with an easy-starting structure includes a fan housing, a rotor, and a bottom. The fan housing has a plurality of coils, a control unit, and at least one globe-shaped attractor, with the at least one globe-shaped attractor being made of conductive magnetic material and arranged between adjacent two of the coils. The rotor has an axial shaft and a permanent magnet ring facing the coils of the fan housing, with the permanent magnet ring having at least one pair of opposite magnetic poles, with each magnetic pole providing a high-intensity area. And the bottom has an axial tube with a bearing for the axial shaft of the rotor to insert in and revolve relative to the bottom. One of the high-intensity areas is attracted by and faces the at least one globe-shaped attractor when the rotor is held at a stop position.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter in connection with drawings. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinafter, and the accompanying drawings that are given by way of illustration only are not limitations of the present invention, wherein:

FIG. 1 shows an exploded perspective view of a conventional mini-fan with an easy-starting structure.

FIG. 2 shows an exploded perspective view of a mini-fan with an easy-starting structure in accordance with a preferred embodiment of the present invention.

FIG. 3 shows a top and cross-sectional view of the mini-fan with an easy-starting structure in accordance with the preferred embodiment.

FIG. 4 shows a side and cross-sectional view of the mini-fan with an easy-starting structure in accordance with the preferred embodiment according to section line A-A of FIG. 3.

In the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “end”, “bottom”, “axial”, “radial”, “lateral”, “outward” and similar terms are used hereinafter, it should be understood that these terms are reference only to the structure shown in the drawings as it would appear to a person viewing the drawings and are utilized only to facilitate describing the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIG. 2, which shows a preferred embodiment of the present invention of a mini-fan with an easy-starting structure including a fan housing 10, a rotor 20 and a bottom 30.
The fan housing 10 is formed as a hollow casing having a receiving cavity, with an outer annular wall forming a lateral outer surface of the fan housing, an inner annular wall 11 laterally defining the receiving cavity, and a coil-setting slot 12 formed between the outer annular wall and inner annular wall 11. The receiving cavity encircled by the inner annular wall 11 is for receiving the rotor 20, and the coil-setting slot 12 is for arrangement of a circuit board 40. The circuit board 40 is preferably selected from a flexible printed circuit board, which has an even number of coil sets 41 such as two coil sets 41 each having one coil as shown in FIG. 1, and a control unit 42 including a driver circuit and a Hall sensor. The control unit 42 electrically connects the coil sets 41 and is preferably disposed between and adjacent to the coil sets 41 while only two coils are used. Furthermore, an easy-starting portion is also formed between the outer annular wall and inner annular wall 11 with the easy-starting portion being disposed between two adjacent coils of the coil sets 41. Said easy-starting portion includes a position hole 13 extending axially and at least one globe-shaped attractor 15 received in the position hole 13. The globe-shaped attractor 15 is made of magnetic conductive material, and is preferably selected from a steel ball of stainless steel “SUS304”. Furthermore, it is preferable to apply steel balls that have already been manufactured by mass production presently to the proposed mini-fan as the globe-shaped attractor 15.
The rotor 20 includes an axial shaft 21, a hub 22 arranged at one end of the axial shaft 21, a plurality of blades 23 formed on an annular surface of the hub 22 and extending outwards, and a permanent magnet ring 24 encircling the hub 22 and blades 23 and connecting with outer edges of the blades 23. The permanent magnet ring 24 has at least one pair of opposite magnetic poles, with the opposite magnetic poles being arranged in stagger and a boundary disposed between any two adjacent poles. Besides, between any two adjacent boundaries, a pole section wherein one of the poles is disposed provides a high-intensity area at the center thereof.
The bottom 30 provides an axial tube 31 at the center thereof, with a bearing 32 being received in the axial tube 31 for the axial shaft 21 of the rotor 20 to insert in and revolve relative to the bottom. Thus, the rotor 20 is able to rotate respective to the bottom 30.
Please turn to FIGS. 3 and 4 now. When the preferred embodiment of the mini-fan of the present invention is assembled, the circuit board 40 is initially disposed in the coil-setting slot 12 of the fan housing 10, and then the fan housing 10 covers the outer of the rotor 20. And thereby, the permanent magnet ring 24 of the rotor 20 and the coil sets 41 of the circuit board 40 are able to face each other in radial. In operation, the control unit 42 detects the change of magnetic fields caused by the permanent magnet ring 24 and inputs changing currents into the coil sets 41 to generate alternative magnetic fields for actuating and driving the rotor 20. When the rotor 20 is going to be stopped, the globe-shaped attractor 15 of the fan housing 10 attracts one of the high-intensity area to face the globe-shaped attractor 15, so that the rotor 20 will be held at a stop position wherein the high-intensity areas of pole sections and any coil of the coil sets 41 are arranged in stagger radially while one of the high-intensity areas faces the globe-shaped attractor 15, and thus the rotor 20 is easy to be actuated for the next time.
Thus, the mini-fan with easy-starting structure of the present invention has several benefits shown as the following. First, the cost of the globe-shaped attractor 15 is low while it is selected from steel balls that have already been manufactured by mass production presently. And second, the globe-shaped attractor 15 can be easily inserted into the position hole 13 without cutting that causes rough edges. Therefore, the globe-shaped attractor 15 never affects a combination between the fan housing 10 and the bottom 30, and a high quality in assembly is thereby provided.
While the principles of this invention have been disclosed in connection with specific embodiments, it should be understood by those skilled in the art that these descriptions are not intended to limit the scope of the invention, and that any modification and variation without departing the spirit of the invention is intended to be covered by the scope of this invention defined only by the appended claims.

Claims

1. A mini-fan with an easy-starting structure, comprising:

a fan housing having a plurality of coils, a control unit, and at least one globe-shaped attractor, with the at least one globe-shaped attractor being made of conductive magnetic material and arranged between adjacent two of the coils;

a rotor having an axial shaft and a permanent magnet ring facing the coils of the fan housing, with the permanent magnet ring having at least one pair of opposite magnetic poles, with each magnetic pole providing a high-intensity area; and

a bottom having an axial tube with a bearing for the axial shaft of the rotor to insert in and revolve relative to the bottom;

wherein one of the high-intensity areas is attracted by and faces the at least one globe-shaped attractor when the rotor is held at a stop position.

2. The mini-fan with an easy-starting structure as defined in claim 1, wherein the globe-shaped attractor is a steel ball.

3. The mini-fan with an easy-starting structure as defined in claim 1, wherein the globe-shaped attractor is made of stainless steel “SUS304”.

4. The mini-fan with an easy-starting structure as defined in claim 1, wherein the at least one globe-shaped attractor is received in a position hole.

5. The mini-fan with an easy-starting structure as defined in claim 1, wherein the fan housing has a receiving cavity for receiving the rotor, with an outer annular wall forming a lateral outer surface of the fan housing, an inner annular wall laterally defining the receiving cavity, and a coil-setting slot formed between the outer annular wall and inner annular wall for arrangement of a circuit board, with the coils and control unit being arranged on the circuit board.

6. The mini-fan with an easy-starting structure as defined in claim 5, wherein the circuit board is a flexible printed circuit board.

7. The mini-fan with an easy-starting structure as defined in claim 1, wherein the rotor further has a hub arranged at one side of the axial shaft and a plurality of blades formed on an annular surface of the hub and extending outwards, with the permanent magnet ring encircling the blades and connecting with outer edges of the blades.