US20070009353A1

US20070009353A1 - Airflow generating structure and the apparatus thereof

Info

Publication number: US20070009353A1
Application number: US11/175,438
Authority: US
Inventors: Chiang-Cheng Huang; Chien-chung Sun
Original assignee: Risun Expanse Corp
Current assignee: Risun Expanse Corp
Priority date: 2005-07-07
Filing date: 2005-07-07
Publication date: 2007-01-11

Abstract

An airflow generating structure and the apparatus thereof includes a hub, a holding section extended outwards from one end of the hub, and a plurality of spoilers located on the periphery of the holding section in the axial direction that are spaced from one another. Each of the spoilers has two curved surfaces and an outer edge inclined outwards so that the area that all the tips of the spoilers enclose is larger than that of the holding section. Air is sucked in through one end of the hub remote from the holding section and flows towards the other end, and is discharged through the periphery of the holding section.

Description

FIELD OF THE INVENTION

The present invention relates to a fan and particularly to an airflow generating structure and the apparatus thereof with less operational noise and a higher flow rate.

BACKGROUND OF THE INVENTION

A fan mainly aims to discharge airflow and result in forced convection. In general a fan draws air in a direction parallel with the spindle axis of the impeller and drives the air through the blades. The airflow direction depends on the geometric structure of the impeller. Refer to FIGS. 1A through 1C for the geometric structure of an impeller. According to the relative directions of intake and discharge airflow, a fan can be classified in one of the three types: axial-flow fan 1, radial-flow fan 2 and diagonal-flow fan 3.
Referring to FIGS. 1A and 2, the directions of intake and discharge airflow of the axial-flow fan 1 are the same. The axial-flow fan 1 has the advantages of a simple structure and lower fabrication cost. Hence it is widely used in air-conditioning systems or radiators. The axial-flow fan 1 generally has a hub 1 a and a plurality of blades 1 b extended outwards from the periphery of the hub 1 a. When the hub 1 a is driven and rotates, the blades 1 b drive the air to flow along the spindle direction of the hub 1 a. The flow rate of the axial-flow fan 1 depends on the tangential velocity of the blades 1 b. The tangential velocity at the areas of the blades 1 b near the center of the hub is lower than those distant from the center of the hub (V=ω×r, where V is the tangential velocity, ω is the rotational velocity of the hub 1 a, and r is the distance from the center of the spindle). Hence the closer the areas of the blades 1 b are to the hub 1 a, the lower the generated dynamic pressure, and the less prominent the effect of airflow intake and discharge will be. For the radiators that have a more complicated structure and higher flow resistance, the dynamic pressure generated by the axial-flow fan is not high enough to effectively drive the airflow to pass through the radiators.
Moreover, while the axial-flow fan 1 is rotating, the distal ends of the blades 1 b impact the air to make noise. The noise becomes greater as the rotational velocity increases. The frequency of the noise also increases accordingly. The high frequency noise makes people's hearing very uncomfortable. In addition, while the blades 1 b cut through the air, there are often vortexes generated in the flow field near the distal ends of the blades 1 b, which in turn disturbs the distal ends of the blades 1 b. As the blades 1 b are extended outwards radially from the hub 1 a, such a mechanical structure works like cantilever beams. When subject to the vortex, the blades 1 b will wobble and vibrate. When operated for a longer period of time, the vibrations could cause system resonate and the junctures of the blades 1 b and the hub 1 a could be damaged. After suffering from torsion and bending constantly and repeatedly, if the rigidity of the blades 1 b is not large enough, the blades 1 b could be ruptured and broken. Moreover, besides the vibrations generated during the rotation of the blades 1 b, back and forth movements may also occur to the hub 1 a due to the assembly clearance in the axial direction. This engenders another source of vibration and noise. Hence not only the noise is greater, the risk of system resonance also increases.
To increase the flow rate of the axial-flow fan 1, the general approach is to increase the rotational velocity of the fan. But a higher rotational velocity makes the distal ends of the blades impact the air more severely, and the noise gets louder. To increase the flow rate without increasing the noise, another approach is to modify the profile of the blades 1 b to make the distal ends of the blades 1 b cut through the air more smoothly. This makes the profile of the blades 1 b more complicated, and a precise injection molding process has to be adopted to fabricate the blades 1 b, adding more difficulties to mold tooling and injection molding process, and more cost and time to manufacturing.
Referring to FIGS. 1B and 3, the radial-flow fan 2 draws air in the axial direction and discharges airflow in the radial one. The direction of intake is vertical to that of discharge. The radial-flow fan 2 has a plate 2 a, a plurality of blades 2 b axially mounted on one side of the back plate 2 a and a covering plate 2 c located on the front side of the back plate 2 a and the blades 2 b. The covering plate 2 c has an air inlet 2 d in the center.
The air outlets 2 e are formed round the periphery of the radial-flow fan 2, and the area in this part of the radial-flow fan 2 can experience a maximum tangential velocity during rotation. Hence all the air leaving the radial-flow fan 2 is discharged at the maximum tangential velocity. The dynamic pressure of the airflow generated by radial-flow fan is higher than that generated by the axial-flow fan 1. However, in the radial-flow fan 2, the air intake takes place in the axial direction. While the air discharge takes place in the radial direction, the airflow is forced to alter its direction by 90 degrees in the radial-flow fan 2. Such an abrupt change in the streamline and flow path can cause vortex and stagnant flow to occur within the radial-flow fan 2, and the actual flow rate will decrease and the flow resistance increase.
Referring to FIGS. 1C and 4, the diagonal-flow fan 3 includes a hub 3 a and a plurality of blades 3 b surrounding the hub 3 a. The hub 3 a is conical to enable the fan to draw air in the axial direction. When the airflow reaches the surrounding of the hub 3 a, it is pushed by the blades 3 b and channeled by the hub 3 a to be discharged at an angle directing outwards, and there is an angle between the directions of the intake airflow and the discharge one. The diagonal-flow fan 3 is a modification of the axial-flow fan 1 previously discussed. Its airflow discharge surface has a radius greater than that of the air intake surface. Hence the discharge airflow has a higher tangential velocity than that of the intake one, and thereby both the generated dynamic pressure and the flow rate are increased. However, not all of the airflow of the diagonal-flow fan 3 is discharged on the edge of the blades at the maximum tangential velocity. Compared with the radial-flow fan 2, its generated dynamic pressure is still lower, and hence the flow rate is smaller.

SUMMARY OF THE INVENTION

As previously discussed, the conventional axial-flow fan has the drawbacks of a lower flow rate, causing more noise and greater vibrations at higher rotational velocities, and a shorter service life due to vibration of the blades. As for the radial-flow fan, the structure thereof forces the airflow to change the path of flow abruptly, posing more resistance to the airflow and thereby reducing the flow rate. Though the diagonal-flow fan combines the structures of the radial-flow fan and the axial-flow fan with the advantages of a higher discharging tangential velocity and a greater generated dynamic pressure than those of the axial-flow fan, the generated dynamic pressure and flow rate still have the room for improvement.
In view of aforementioned problems, the primary object of the present invention is to provide an airflow generating structure and the apparatus thereof that has a high flow rate in a less noisy operating condition, and can also generate a higher dynamic pressure of discharge airflow, and is more desirable for use in radiators with a higher flow resistance.
In order to achieve the foregoing object, the airflow generating structure according to the invention includes:
a hub which has a top end and a bottom end, a holding section extended radially from the perimeter of the bottom end that has a holding surface on one side, and a plurality of spoilers located on the periphery of the holding surface that has an inner edge close to the hub and a outer edge remote from the hub. The outer edge inclines outwards from the root of the spoilers so that the area enclosed by the tips of the spoilers is greater than that of the holding section.
By means of the structure set forth above, the spoilers are formed axially on the holding section, and the number of the spoilers installed can be greater (than that of the axial-flow fan with radially installed spoilers) to discharge more airflow and the rotational velocity could be reduced compared with the axial-flow fan for the same amount of flow rate. A lower rotational velocity can reduce impact of the air at the tips of the spoilers and reduce the noise. The holding surface is pressed by the airflow to confine the position of the airflow generating structure, so that the back and forth movements and vibrations caused by the assembly clearance can be minimized.
Moreover, the inclination angle between the spoilers and the axial direction can lead the airflow to change the path of flow less abruptly. Thereby, the vortex and stagnant flow around the hub are reduced, and the flow resistance decreases. As a result, the flow rate increases accordingly. As the airflow is discharged on the outmost area of the airflow generating structure, a maximum tangential velocity could be got to generate a higher dynamic pressure.
The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A through 1C are schematic diagrams for the three types of conventional fans showing the corresponding airflow intake and discharge directions thereof;
FIG. 2 is a perspective view illustrating a conventional axial-flow fan;
FIG. 3 is a perspective view illustrating a conventional radial-flow fan;
FIG. 4 is a perspective view illustrating a conventional diagonal-flow fan;
FIG. 5 is a perspective view illustrating a first embodiment of the invention;
FIG. 6 is a cross-sectional view of FIG. 5;
FIG. 7 is a schematic view of the flow field of the first embodiment of the invention;
FIGS. 8, 9 and 10 are schematic views of the first embodiment in use conditions;
FIG. 11 is a perspective view of a second embodiment of the invention;
FIG. 12 is a perspective view of a third embodiment of the invention;
FIG. 13 is a perspective view of a fourth embodiment of the invention;
FIG. 14 is a perspective view of a fifth embodiment of the invention;
FIG. 15 is a cross-sectional view of FIG. 14; and
FIG. 16 is a schematic view of the flow field of the fifth embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 5 and 6 for a first embodiment of the invention, the airflow generating structure 10 includes a hub 11, a holding section 12, a plurality of spoilers 13 and a stabilization ring 14.
The hub 11 has a top end 111 and a bottom end 112. The top end 111 is substantially formed in a convex shape. The bottom end 112 has a concave portion 113 to hold a spindle 15 protruding outwards.
The holding section 12 is substantially an annular plate integrally formed on the periphery of the bottom end 112, and is extended outwards from the hub 11, and has a holding surface 121 on one side, facing upwards.
Each of the spoilers 13 has a convex surface and a concave surface to form a curved profile. Each spoiler 13 has a root 131 and a tip 132, and has a height approximated to that of the hub 11. The root 131 is fastened to the holding section 12. The spoilers 13 are located round the periphery of the holding section 12 in an equally-spaced manner. The tip 132 is remote from the holding section 12. Hence the spoilers 13 are extended upwards from the holding surface 121. Each spoiler 13 further has an inner edge 133 close to the hub 11 and an outer edge 134 remote from the hub 11. The outer edge 134 inclines outwards to form an inclined angle with the center axis of the hub 11. Therefore, the area enclosed by the tips 231 of the spoilers 13 is larger than that of the holding section 12. When air passes axially through the spoilers 13, it goes through the outer periphery of the holding section 12 and has a component velocity, parallel with the center axis of the hub 11, to leave the airflow generating structure 10.
The stabilization ring 14 is formed on the outside of the tips 132 to couple all the spoilers 13 together to provide a rigid bracing, so that the adjacent tips 132 of the spoilers 13 can be maintained at a constant interval apart without wobbling when subject to the turbulence of airflow.
Refer to FIG. 7 for the combinational and operational relationships of the hub 11, holding section 12 and spoilers 13.
When the airflow generating structure 10 rotates, a flow field is created to suck the air in above the hub 11. The airflow disperses before reaching the top end 111, and flows to the surrounding of the hub 11, then passes through the spaces between the spoilers 13, and blows out downwards through the surrounding of the holding section 12, to turn into an axial discharge airflow.
Refer to FIGS. 8, 9 and 10 for an airflow generating apparatus 100, which adopts the airflow generating structure 10 of the invention. It includes the airflow generating structure 10 in a frame 20, driven by a motor 30, to generate airflow in the axial direction.
The frame 20 includes four sidewalls 21 that form an annular area 22 in a circular manner to hold the airflow generating structure 10. The annular area 22 has an inlet 23, an outlet 24, a seat 25 and a plurality of bracing rods 26 located in the outlet 24.
The motor 30 includes a rotor 31, a stator 32 and a circuit board 33. The circuit board 33 is flatly mounted onto the seat 25. The stator 32 is located on the circuit board 33. The rotor 31 is annular-shaped and mounted into the concave portion 113 of the hub 11.
The airflow generating structure 10 is located in the annular area 22 of the frame 20, with the hub 11 pivotally coupled to the stator 32 via a spindle 15 protruding from the hub 11. The rotor 31 surrounds the periphery of the stator 32. The electric current runs through the circuit board 33 to the windings on the stator 32 to generate a magnetic field, driving the rotor 31, which in turn makes the airflow generating structure 10 rotate.
The air is sucked in from the top end 111 of the hub 11 by the rotation of the spoilers 13, passes through the spoilers 13 to be accelerated, then flows axially through the periphery of the holding section 12 and is discharged through the outlet 24 as the flow field shown in FIG. 7.
By means of the construction and operation set forth above, the invention can achieve many functions. As the spoilers 13 are extended axially, they can be arranged more densely at a greater number to draw more air in. Hence the invention can generate a higher flow rate for the same rotational velocity as opposed to a conventional axial fan with spoilers installed radially. The tangential velocity on the tips 132 of the spoilers 13 is also reduced, and thereby the spoilers 13 bear less impact from air and the degree of wobbling can be lowered and damage prevented. Moreover, the lower tangential velocity can reduce air impact on the spoilers 13 and thereby oppress the generation of high frequency noises.
Meanwhile, the stabilization ring 14 can stabilize the spoilers 13. By coupling together all the tips 132 of the spoilers 13 to form a steady and unified structure, the wobbling and vibration of the spoilers 13 can be decreased substantially and the possibility of damage be minimized. The coupling of all the tips 132 of the spoilers 13 by the stabilization ring 14 also makes spoilers 13 move in the air more smoothly, hence the performance of the airflow generating structure 10 can be improved.
During the intake process, the holding section 12 works as a surface under pressure. The airflow exerts a pressure against the stator 32 and seat 25 of the airflow generating structure 10. Hence the airflow generating structure 10 is held against by such a pressure and cannot move back and forth axially during operation, which also reduces noise generation that might occur otherwise due to the back and forth movements of the airflow generating structure 10 and system vibrations.
In addition, after the air is sucked in along the center axis of the airflow generating structure 10, the airflow can be channeled smoothly from the upper side of the hub 11 towards the perimeter of the holding section 12 due to the guidance of the inclined angle between the outer edge 134 of the spoilers 13 and the center axis of the hub 11. Compared with the conventional radial-flow fan, the current invention can reduce vortex and stagnation flow around the hub 11 and minimize the flow resistance, hence the generated dynamic pressure is higher.
Refer to FIG. 11 for a second embodiment of the invention that provides an airflow generating structure 40 with an improved air channeling effect. It includes a hub 41, a holding section 42, a plurality of spoilers 43 and a stabilization ring 44 that are largely like those previously discussed. The main distinction of the two is that there is a round angle 45 formed between the juncture of the holding section 42 and the hub 41. Hence when the airflow passes rapidly from the upper side of the hub 41 towards the holding section 42, the round angle 45 can channel the airflow smoothly to the periphery of the holding section 42 and discharge the airflow through the lower side of the hub 41, to avoid directly hitting the holding section 42. Hence kinetic energy loss of air can be reduced, and the flow rate and dynamic pressure can be maintained without dropping too much.
Refer to FIG. 12 for a third embodiment of the invention that provides an airflow generating structure 50 with an improved air channeling effect. It includes a hub 51, a holding section 52, a plurality of spoilers 53 and a stabilization ring 54 that are largely like those depicted in the first embodiment. The main distinction of the two is that there is a plurality of air vents 521 located on the periphery of the holding section 52 and arranged in an alternate manner relative to the spoilers 53. The setup of the air vents 521 can increase the area of ventilation and reduce flow resistance, to increase flow rate of the airflow generating structure 50.
Refer to FIG. 13 for a fourth embodiment of the invention that provides an airflow generating structure 60. It includes a hub 61, a holding section 62, a plurality of spoilers 63 and a stabilization ring 64. The holding section 62 is extended from one end of the hub 61. The spoilers 63 have one end located on the periphery of the holding section 62 in an equally-spaced manner. The stabilization ring 64 surrounds the outside of the tips of the spoilers 63 resulting in a stabilization effect, so that the spoilers 63 do not wobble when airflow is generated. The difference between the fourth embodiment and the first is that the holding section 62 has a plurality of openings 621 on the area surrounding the hub 61, and there is a plurality of blades 622 round the hub 61. The openings 621 can increase the volume of intake airflow around the hub 61 to boost the flow rate. The blades 622 can disturb the flow field around the hub 61, agitate the stagnation flow around the hub 61 to facilitate the movement of the airflow in that area, and hence increase the flow rate.
Refer to FIGS. 14 through 16 for a fifth embodiment of the invention that provides an airflow generating structure 70. It is largely constructed like the first embodiment. The airflow generating structure 70 includes a hub 71, a holding section 72, a plurality of spoilers 73 and a stabilization ring 74.
The holding section 72 is extended from one end of the hub 71. The spoilers 73 have one end located on the periphery of the holding section 72 in an equally-spaced manner.
Each of the spoilers 73 has a root 731 and a tip 732, an inner edge 733 close to the hub 71 and an outer edge 734 remote from the hub 71. The root 731 is fastened to the holding section 72. The stabilization ring 74 couples all the tips 732 of the spoilers 73 together
The outer edge 734 inclines outwards to form an angle with the center axis of the hub 71. The inner edge 733 also inclines outwards to form another angle with the center axis of the hub 71. Compared with the first embodiment, in this embodiment the inner edge 733 also tilts outwards as the outer edge 734, thus the hollow space between the spoilers 73 and the hub 71 shrinks. The resulting geometric profile is more streamlined and the airflow can move through the fan structure more smoothly. With the hollow space between the spoilers 73 and the hub 71 shrunk, the space to trap the airflow is reduced. The intake airflow will be discharged sooner through the inner rim 733 of the spoilers 73. Hence vortex and stagnation flow can be minimized because the airflow is trapped and stays within the fan structure for a shorter time, which reduces the resistance posed on the airflow when passing through the airflow generating structure 70.
Although the invention looks somewhat like the diagonal-flow fan in terms of air intake and discharge directions, the spoilers are located on the outer periphery of the holding section, thus the airflow passes through the spoilers and leave the airflow generating structure around the area with a maximum radius from the center of the airflow generating structure and has a higher tangential velocity to generate a greater dynamic pressure. Given the aforementioned reasons, the current invention is advantageous over the radial-flow fan.
In addition, the spoilers of the invention are formed in a curved profile, and have an outer edge forming an angle with the axis of rotation, hence airflow can be directed and channeled smoothly from the upper side of the hub towards the peripheral edge of the holding section. Therefore the vortex and stagnation flow around the hub will be minimized and flow resistance reduced. To sum up, the current invention not only produces a dynamic pressure and flow rate approximated to those of the radial-flow fan but also overcomes the disadvantage of a high flow resistance thereof.

Claims

1. An airflow generating structure comprising:

a hub having a holding section extended from one end thereof; and

a plurality of spoilers in a curved shape having one ends located on the periphery of the holding section and spaced from one another, and the other ends enclosing an area greater than that of the holding section.

2. The airflow generating structure of claim 1, wherein each of the spoilers includes a convex surface and a concave surface.

3. The airflow generating structure of claim 1, wherein each of the spoilers includes:

a root fastened to the holding section;

a tip remote from the holding section;

an inner edge close to the hub; and

an outer edge remote from the hub.

4. The airflow generating structure of claim 3, wherein the outer edge of the spoiler directs outwards such that there is an inclined angle between the outer edge and the center axis of the hub.

5. The airflow generating structure of claim 3, wherein the inner edge of the spoiler directs outwards such that there is an inclined angle between the inner edge and the center axis of the hub.

6. The airflow generating structure of claim 3, wherein all the tips of the spoilers are coupled together by a stabilization ring.

7. The airflow generating structure of claim 1, wherein there is a round angle at the juncture of the holding section and the hub.

8. The airflow generating structure of claim 1, wherein the holding section includes a plurality of air vents located on the periphery thereof and arranged in an alternate manner relative to the spoilers.

9. The airflow generating structure of claim 1, wherein there is a plurality of blades round the hub.

10. The airflow generating structure of claim 1, wherein the holding section includes a plurality of openings on the area close to and round the hub.

11. An airflow generating apparatus comprising:

a hub having a holding section extended from one end thereof;

a plurality of spoilers in a curved shape having one ends located on the periphery of the holding section and spaced from one another, and the other ends enclosing an area greater than that of the holding section; and

a motor for driving and rotating the hub.

12. The airflow generating apparatus of claim 11, wherein each of the spoilers includes a convex surface and a concave surface.

13. The airflow generating apparatus of claim 11, wherein each of the spoilers includes:

a root fastened to the holding section;

a tip remote from the holding section;

an inner edge close to the hub; and

an outer edge remote from the hub.

14. The airflow generating apparatus of claim 13, wherein the outer edge of the spoiler directs outwards such that there is an inclined angle between the outer edge and the center axis of the hub.

15. The airflow generating apparatus of claim 13, wherein the inner edge of the spoiler directs outwards such that there is an inclined angle between the outer edge and the center axis of the hub.

16. The airflow generating apparatus of claim 11, wherein there is a round angle at the juncture of the holding section and the hub.

17. The airflow generating apparatus of claim 11, wherein all the tips of spoilers are coupled together by a stabilization ring.

18. The airflow generating apparatus of claim 11, wherein the holding section includes a plurality of air vents located on the periphery thereof and arranged in an alternate manner relative to the spoilers.

19. The airflow generating apparatus of claim 11, wherein there is a plurality of blades round the hub.

20. The airflow generating apparatus of claim 11, wherein the holding section includes a plurality of openings on the area close to and round the hub.