Patent Application
20090169389
1. Technical Field
The present invention relates to impellers and cooling fans using the same, and more particularly to an impeller which can generate more airflow with a low level of noise.
2. Description of Related Art
With continuing development of the electronic technology, electronic components such as CPUs generate more and more heat which is required to be dissipated immediately.
Conventionally, a cooling fan is used to produce an airflow which can remove heat from the electronic component. The cooling fan comprises a stator and an impeller being rotatable with respective to the stator. The impeller further comprises a hub and a plurality of blades radially and outwardly extending from the hub. In use, the blades of the impeller rotate around the stator to drive the airflow to flow towards the electronic component, thus cooling the electronic component continuously.
Increasing a revolving speed of the impeller relatively increases the amount of airflow, therefore a heat dissipation efficiency is relatively improved. However, increasing the revolving speed may correspondingly cause a rise of a noise level generated by the cooling fan, thus making a user near the fan feel uncomfortable.
What is needed, therefore, is an impeller which can overcome the above-mentioned disadvantage.
The present invention, in one aspect, provides an impeller which generates more airflow without generating more noise. The impeller includes a hub, and a plurality of blades radially extending from the hub. Each of the blades includes a windward surface and a leeward surface which has a different configuration with the windward surface. The windward surface has a tip portion selected from a group consisting of forward curved surface and planar surface. The leeward surface has a tip portion selected from a group consisting of planar surface and backward curved surface.
The present invention, in another aspect, provides a cooling fan using the impeller. The cooling fan includes a bottom housing, a top cover covering the bottom housing, and impeller and stator accommodated in a space formed between the bottom housing and the top cover. The impeller includes a hub, and a plurality of blades radially extending from the hub. Each of the blades includes a windward surface and a leeward surface which has a different configuration with the windward surface. The windward surface has a tip portion selected from a group consisting of forward curved surface and planar surface. The leeward surface has a tip portion selected from a group consisting of planar surface and backward curved surface.
Other advantages and novel features of the present impeller and cooling fan will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which:
Reference will now be made to the drawing figures to describe the preferred embodiment in detail.
Referring to
The impeller 16 includes a hub 162 and a plurality of blades 164 radially and outwardly extending from the hub 162. An air channel 122 is formed between free ends of the blades 164 and an inner surface of a sidewall of the bottom housing 12 of the cooling fan 10. In operation of the cooling fan 10, the impeller 16 rotates in the bottom housing 12 along a counterclockwise direction and drives an airflow to flow towards an air outlet 124 of the cooling fan 10.
Referring to
In the present impeller 16, the tip portions 1641, 1642 of the windward and leeward surfaces 164a, 164b of the blades 164 of the impeller 16 are respectively to be forward curved surfaces and planar surfaces. The present impeller 16 generates more airflow than an impeller whose windward and leeward surfaces have planar tip portions, and generates less noise than an impeller whose windward and leeward surfaces have forward curved tip portions. Therefore, the windward surfaces 164a impel more air to flow towards the air outlet 124 of the impeller 16, and the leeward surfaces 164b decrease noises generated during operation of the impeller 16. Thus, the present impeller 16 is optimized to generate more airflow without generating more noise.
Referring to
Referring to
In the hereinabove embodiments of the present impeller 16, 26, 36, the tip portions 1641, 2641, 3641 of the windward surfaces 164a, 264a, 364a and the tip portions 1642, 2642, 3642 of the leeward surfaces 164b, 264b, 364b of the blades 164, 264, 364 of the impeller 16, 26, 36 are different types of surfaces which have different capabilities in driving airflow and decreasing noise. Therefore, the present impeller 16, 26, 36 can be optimized to generate more airflow without generating more noise.
It is to be understood, how ever, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
