Fan and airflow guiding structure thereof

A fan includes an airflow guiding structure, an impeller and a guiding ring. The outer radius of the airflow guiding structure increases gradually from the top of the airflow guiding structure to the bottom of the airflow guiding structure. The airflow guiding structure includes a plurality of fins and a first space for accommodating a circuit device. The impeller is disposed on the airflow guiding structure and has a hub and several blades. The guiding ring connects to the airflow guiding structure via at least one connecting element. A predetermined distance is arranged between the inner surface of the guiding ring and the outer edges of the blades. An inlet is formed at the top of the guiding ring, and an outlet is formed between the bottom of the guiding ring and the outer surface of a sidewall of the airflow guiding structure. When the impeller rotates, the airflow enters the fan from the inlet and flows along the outer surface of the sidewall of the airflow guiding structure, then the airflow exits the fan through the outlet. The direction of the airflow passing through the outlet is different from the direction of the airflow passing through the inlet.

CROSS REFERENCE TO RELATED APPLICATIONS

This Non-provisional application claims priorities under 35 U.S.C. §119(a) on Patent Application No(s). 097115315, filed in Taiwan, Republic of China on Apr. 25, 2008, Patent Application No(s). 098107835, filed in Taiwan, Republic of China on Mar. 11, 2009, and Patent Application No(s). 098107836, filed in Taiwan, Republic of China on Mar. 11, 2009, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a fan and in particular to a fan and an airflow guiding structure thereof that can change the direction of the airflows of the fan.

2. Related Art

Since the performance of the electronic apparatuses has been improved, the heat dissipation device or system becomes one of the indispensable equipments of the electronic apparatuses. If the heats generated by the electronic apparatus can not be dissipated properly, the performance thereof may become worse and, even more, the electronic apparatus may be burnt out. As for the micro electronic devices such as the integrated circuits (ICs), the dissipation device is much more important. In view of the integrated density of the ICs being increasing and the progress of the packaging technology, the size of the ICs becomes smaller, and the heat accumulated in per unit area of the integrated circuits become higher. Therefore, the heat dissipation device with high heat dissipation efficiency has become one of the most important development areas in the electronic industry.

Fan is the most popular heat dissipation device in the present heat dissipation technology. According to the directions of the airflow entering and exiting from the fan, the fan can be classified to axial-flow fans and centrifugal fans.

In an axial-flow fan, the airflow enters the conventional axial-flow fan through the inlet and then exits through the outlet. The airflow direction entering into the inlet is roughly parallel to the airflow direction exiting from the outlet. On the other hand, in a centrifugal fan, the airflow enters the conventional centrifugal fan through the inlet and then exits through the outlet. The airflow direction entering into the inlet is roughly perpendicular to the airflow direction exiting from the outlet. Compared to the axial-flow fan, although the centrifugal fan can change the airflow direction, the centrifugal fan has the drawbacks of lower performance, lower airflow quantity and louder noise. Moreover, the centrifugal fan is hard to provide a multi-function fan in the current trend towards small size.

SUMMARY OF THE INVENTION

The present invention is to provide a fan and an airflow guiding structure thereof that can change the airflow direction of the conventional axial-flow fan as well as keeping the advantages of the conventional axial-flow fan such as high performance, large air quantity and low noise.

Furthermore, the present invention is to provide a fan and an airflow guiding structure thereof that can conduct heats away from a heat source by a plurality of fins of the airflow guiding structure, so as to enhance the heat dissipating efficiency of the fan.

Moreover, the present invention is to provide a fan and an airflow guiding structure thereof that has a first space for accommodating an exterior circuit device so as to economize the use of space, and the circuit device can be protected under the airflow guiding structure.

To achieve the above, the present invention discloses a fan including an airflow guiding structure, an impeller and a guiding ring. The outer radius of the airflow guiding structure increases gradually from the top of the airflow guiding structure to the bottom of the airflow guiding structure. The impeller is disposed on the airflow guiding structure and has a hub and a plurality of blades disposed around the hub. The guiding ring is connected to the airflow guiding structure via at least one connecting element. A predetermined distance is arranged between an inner surface of the guiding ring and outer edges of the blades. An inlet is formed at the top of the guiding ring, and an outlet is formed between the bottom of the guiding ring and an outer surface of a sidewall of the airflow guiding structure. When the impeller rotates, the airflow enters the fan from the inlet and flows along the outer surface of the sidewall of the airflow guiding structure, then the airflow exits the fan through the outlet. The direction of the airflow passing through the outlet is different from the direction of the airflow passing through the inlet. Furthermore, the airflow guiding structure is composed of a plurality of fins, and a first space is disposed in the airflow guiding structure for accommodating a circuit device.

In addition, the present invention also discloses a fan including an airflow guiding structure, an impeller and a guiding ring. The outer radius of the airflow guiding structure increases gradually from the top of the airflow guiding structure to the bottom of the airflow guiding structure. The impeller is disposed on the airflow guiding structure and has a hub and a plurality of blades disposed around the hub. The guiding ring is connected to a module housing. A predetermined distance is arranged between an inner surface of the guiding ring and outer edges of the blades. An inlet is formed at the top of the guiding ring, and an outlet is formed between the bottom of the guiding ring and an outer surface of a sidewall of the airflow guiding structure. When the impeller rotates, the airflow enters the fan from the inlet and flows along the outer surface of the sidewall of the airflow guiding structure, then the airflow exits the fan through the outlet. The direction of the airflow passing through the outlet is different from the direction of the airflow passing through the inlet.

To achieve the above, the present invention further discloses an airflow guiding structure applied to an axial-flow fan. The axial-flow fan includes an impeller and a guiding ring. The impeller has a hub and a plurality of blades disposed around the hub. The airflow guiding structure is disposed underneath the impeller. The outer radius of the airflow guiding structure increases gradually from the top of the airflow guiding structure to the bottom of the airflow guiding structure. The guiding ring is connected to the airflow guiding structure via at least one connecting element. A predetermined distance is arranged between an inner surface of the guiding ring and outer edges of the blades. An inlet is formed at the top of the guiding ring, and an outlet is formed between the bottom of the guiding ring and an outer surface of a sidewall of the airflow guiding structure. When the impeller rotates, the airflow enters the fan from the inlet and flows along the outer surface of the sidewall of the airflow guiding structure, and then the airflow exits the fan through the outlet. The direction of the airflow passing through the outlet is different from the direction of the airflow passing through the inlet.

In addition, the present invention also discloses an airflow guiding structure applied to an axial-flow fan. The axial-flow fan includes an impeller and a guiding ring, the impeller having a hub and a plurality of blades disposed around the hub. The airflow guiding structure is disposed underneath the impeller. The outer radius of the airflow guiding structure increases gradually from the top of the airflow guiding structure to the bottom of the airflow guiding structure. The airflow guiding structure is connected to a module housing. A predetermined distance is arranged between an inner surface of the guiding ring and outer edges of the blades. An inlet is formed at the top of the guiding ring, and an outlet is formed between the bottom of the guiding ring and an outer surface of a sidewall of the airflow guiding structure. When the impeller rotates, the airflow enters the fan from the inlet and flows along the outer surface of the sidewall of the airflow guiding structure, then the airflow exits the fan through the outlet. The direction of the airflow passing through the outlet is different from the direction of the airflow passing through the inlet.

As mentioned above, in the fan of the present invention, the outer radius of the airflow guiding structure increases gradually from the top of the airflow guiding structure to the bottom of the airflow guiding structure. Thus, the direction of the airflow can be changed when the airflow flows along the outer surface of the sidewall of the airflow guiding structure and then exits the fan. Furthermore, the airflow guiding structure is composed of a plurality of fins, and a first space is disposed in the airflow guiding structure for accommodating a circuit device. Compared with the prior art, the present invention can not only change the direction of the airflow exiting from the fan, but also keeps the advantages of high performance, large quantity of exiting airflow and low noise. Moreover, the present invention enhances the heat dissipating efficiency of the fan and economizes the use of space by the structure of the airflow guiding structure.

DETAILED DESCRIPTION OF THE INVENTION

Please refer toFIG. 1AandFIG. 1B, a fan1according to a first embodiment of the present invention includes an airflow guiding structure10, an impeller12and a guiding ring14.

The outer radius of the airflow guiding structure10increases gradually from the top of the airflow guiding structure10to the bottom of the airflow guiding structure10, so that the outer surface of the airflow guiding structure10forms at least one curved surface. The impeller12is disposed over the airflow guiding structure10. The impeller12has a hub120and a plurality of blades122disposed around the hub120. A motor (not shown) is disposed within the hub120. The outer radius of the hub120increases gradually from the top of the hub120to the center of the hub120. Preferably, a ratio of the outer radius of the bottom of the airflow guiding structure10to the outer radius of the bottom of the hub120ranges from 1.3 to 3.

The guiding ring14is connected to the airflow guiding structure10via a plurality of connecting elements16. A predetermined distance is arranged between the inner surface of the guiding ring14and the outer edges of the blades122. An inlet141is formed at the top of the guiding ring14, and an outlet142is formed between the bottom of the guiding ring14and the outer surface of the sidewall of the airflow guiding structure10. The diameter of the guiding ring14decreases gradually from the top of the guiding ring14to a portion of the guiding ring14adjacent to the top of the blade122, so as to guide more airflows into the fan3through the inlet141. A first predetermined distance “Dx” is defined between the top of the guiding ring14and the top of the blades122. The conjunction of the blades122and the hub120has a length “Dy”. The ratio of “Dx” to “Dy” ranges from 0.3 to 1. With regard to the external appearance, the fan3of the present invention can be classified as an axial-flow fan.

When the motor drives the impeller12to rotate (the guiding ring14is not rotated), the airflow enters the fan3from the inlet141and flows along the outer surface of the sidewall of the airflow guiding structure10, then the airflow exits the fan3through the outlet142. Thus, the direction of the airflow passing through the outlet142is different from the direction of the airflow passing through the inlet141. In the embodiment, the direction of the airflow passing through the outlet142is roughly perpendicular to the direction of the airflow passing through the inlet141, this is similar to the conventional centrifugal fan. Furthermore, the shape of the airflow guiding structure10can minimize the air pressure loss while changing the airflow direction.

Please refer toFIG. 2AandFIG. 2B, which show another two embodiments of the hub ofFIG. 1Aof the present invention. The outer radius of the hub120aofFIG. 2Aincreases gradually from the top of the hub120ato the bottom of the hub120a, so that the outer surface of the hub120aforms at least one curved surface for guiding the airflow smoothly. The outer radius of the hub120bofFIG. 2Bincreases gradually from the top of the hub120bto the bottom of the hub120b, so that the outer surface of the hub120bforms at least one inclined surface.

Please refer toFIG. 3AandFIG. 3B, which show two embodiments of the airflow guiding structures of the present invention. The outer radius of the airflow guiding structure10aincreases gradually from the top of the airflow guiding structure10ato the bottom of the airflow guiding structure10a, so that the outer surface of the airflow guiding structure10aforms at least one inclined surface. The outer radius of the airflow guiding structure10bincreases gradually from the top of the airflow guiding structure10bto the bottom of the airflow guiding structure10b, so that the outer surface of the airflow guiding structure10bforms at least one inclined surface and at least one curved surface.

Please refer toFIG. 3CandFIG. 3D, which show a fan2according to a second embodiment of the present invention. The difference between the fan2of the second embodiment of the present invention and the fan1of the first embodiment of the present invention is that the fan2further includes a first circuit device26, a second circuit device28and a covering plate29. A first space203is disposed in the airflow guiding structure20and close to the bottom204of the airflow guiding structure20, so that the first circuit device26(aninverter, a controller, a rectification circuit, a controlling circuit or a motor driving circuit for example) which is supposed to be disposed outside the fan2can be fixed on an inner wall203aof the first space203by at least a fixing element201(ascrew, a rivet or other elements having the capability of fixing), so as to economize the use of space, and the first circuit device26can be protected under the airflow guiding structure20.

Besides, the top surface202of the airflow guiding structure20has at least a through hole205, so that the first circuit device26can be electrically connected with the second circuit device28or other element through the through hole205. The covering plate29is connected with the bottom of the inner wall203aof the first space203of the airflow guiding structure20, thus the first circuit device26disposed in the first space203is hidden. In other embodiments, the first circuit device26can be fixed on the covering plate29by at least a fixing element.

The second circuit device28can be a circuit board in this embodiment, and a driving circuit is disposed on the circuit board for driving the motor21of the fan2. A predetermined distance is formed between the bottom of the motor21and the top surface202of the airflow guiding structure20, so that a second space206is formed between the motor21and the airflow guiding structure20, and the second circuit device28is disposed in the second space206. The circuit board (second circuit device28) has at least a through hole281for connecting with a connecting part212of the stator of the motor21. In other embodiments, the second circuit device28can be fixed on the motor21by at least a fixing element.

Please refer toFIG. 4A, which shows a sectional view of a fan3according to a third embodiment of the present invention. The difference between the fan3of the third embodiment of the present invention and the fan1of the first embodiment of the present invention is that the bottom of the hub320has a recess portion321for facilitating the molding process. In addition, the top of the airflow guiding structure30has a protruding portion301disposed corresponding to the recess portion321of the hub320.

Please refer toFIG. 4B, which shows a sectional view of a fan4according to a fourth embodiment of the present invention. The difference between the fan4of the fourth embodiment of the present invention and the fan1of the first embodiment of the present invention is that the guiding ring44is connected to a module housing38, so that the guiding ring44can be disposed around and adjacent to the impeller12. The bottom of the guiding ring44is arranged adjacent to the bottom of the outer edges of the blades122. In this case, the bottom of the guiding ring44is protruded and exceeding the bottom of the outer edges of the blades122, and a second predetermined distance “Dz” is defined between the bottom of the guiding ring44and the bottom of the outer edges of the blades122. The ratio of “Dz” to “Dy” ranges from 0 to 0.5.

Please refer toFIG. 4C, which shows a fan5according to a fifth embodiment of the present invention. The difference between the fan5of the fifth embodiment of the present invention and the fan1of the first embodiment of the present invention is that the connecting elements56of the fan5are connected to the predetermined positions of the outer surface of the bottom of the airflow guiding structure50, respectively. But in the first embodiment ofFIG. 1B, the connecting elements16of the fan1are connected to the predetermined positions of the outer surface of the top of the airflow guiding structure10, respectively.

Please refer toFIG. 5AandFIG. 5B, which show a fan6according to a sixth embodiment of the present invention. The difference between the fan6of the sixth embodiment of the present invention and the fan1of the first embodiment of the present invention is that the airflow guiding structure60of the fan6is composed of a plurality of fins600which is made by metal (copper or aluminum for example). The fins600are arranged radially, i.e., the gap between two adjacent fins600increases gradually from the interior of the airflow guiding structure60to the outer edge of the airflow guiding structure60, and the shape of each fin600can be curved or flat, as shown inFIG. 6AandFIG. 6B. Or, a claw portion can be disposed at the outer edge of each fin600, as shown inFIG. 6C.

Besides, the top surface of the hub620of the impeller62has a plurality of balance holes623, so that when the rotation of the impeller62is imbalanced, a suitable number of balance materials can be placed in the balance holes623according to the rotation status of the impeller62, so as to avoid the swing of the impeller62and make the impeller62to rotate stably.

Furthermore, the hub620of the fan6has an intake624located at the center of the top surface of the hub620. A base625and a plurality of ribs626are disposed in the intake624, one end of each rib626are disposed around the edge of the intake624orderly, and another end of each rib626are connected with the base625, so that the intake624is divided into a plurality of openings627(each opening627is formed between two adjacent ribs626). Therefore, airflows can pass through the openings627, and heats generated by the motor disposed under the hub620can be dissipated.

Please refer toFIG. 7AandFIG. 7B,FIG. 7Ais a sectional view of the fan along line C-C′ ofFIG. 5Aapplied to a heat source, andFIG. 7Bshows the fan inFIG. 5Abeing applied to two heat source. InFIG. 7A, the fan6is disposed on a heat source80a(a CPU of a host of a computer or other electronic elements such as IC for example), and the bottom surface of the airflow guiding structure60is tightly connected with the heat source80. Because the airflow guiding structure60is made of metal and the airflow guiding structure60of the fan6is composed of a plurality of fins600, the heats generated by the heat source80can be conducted away from the heat source80through the airflow guiding structure60and its fins600, then, the heats conducted to the fins600will be dissipated when the airflow generated by the rotation of the impeller62passes through the fins600. Therefore, the airflow guiding structure60can not only change the direction of the airflow, but also has the capability of heat dissipation. Further, the fan6can be designed to meet practical requirements, such as for using onto more than one heat sources. As shown inFIG. 7B, the fan6can be disposed on two heat sources80band80cfor dissipating heats generated by these two heat sources80band80c.

Furthermore, please refer toFIG. 7C, the difference between the fan7and the fan6of theFIG. 7AorFIG. 7Bis that the center of the bottom of the airflow guiding structure70of the fan7is hollow, thus a metal mass71, which is made of copper or aluminum, can be disposed in the airflow guiding structure70by hot plugging. The first step of hot plugging is to heat the airflow guiding structure70until the airflow guiding structure70at 300 degrees centigrade. Then, place the mass71into the expanded airflow guiding structure70and cool the airflow guiding structure70rapidly, so as to combine the mass71and the airflow guiding structure70tightly. After the mass71is combined in the airflow guiding structure70, the bottom surface of the mass71is flush with the bottom surface of the airflow guiding structure70, so that the bottom surface of the mass71can be tightly connected with the heat source80.

In summary, the present invention can change the airflow direction of an axial-flow fan by the airflow guiding structure whose outer radius increases gradually from the top of the airflow guiding structure to the bottom of the airflow guiding structure. Furthermore, the present invention also keeps the advantages of the conventional axial-flow fan, such as low noise, large quantity of exiting airflow and high heat-dissipation efficiency.