Field of the Invention
The present invention relates to an improved structure of fan blades and in particular to an improved structure of fan blades, which improves the combination of the fan blades and the hub.
Description of Prior Art
The current fan blades are combined with the hub mainly by wrapping by injection or welding in which the plastic fan blades combined with the metal hub is the most popular case. In such a structure, the metal hub is placed in a mold and then the melted plastic material is filled around the perimeter of the metal hub by the injection molding. When the plastic material is cooled, plural fan blades are formed at the perimeter of the metal hub. However, when the disposition of a structure of ultra-thin fan blades is required, the ultra-thin fan blades lacks structural strength and the fan blades cannot increase pressure to guide the air flow. What's worse is when the fan rotates with overspeed, the fan blades will not operate properly due to eccentric deflection.
Moreover, the skilled person in the art replaces the plastic fan blades with metal fan blades with higher structural strength. The metal fan blades are fabricated independently and then are combined with the metal hub by welding, which can overcome the disadvantage of insufficient structural strength in the plastic fan blades. However, it is difficult to control the balance of the combination of the metal fan blades and the metal hub by welding. Also, the solder used in welding between the metal fan blades and the metal hub is prone to cause unbalanced situations during the rotation.
Therefore, how to maintain proper combination strength between the metal fan blades and the metal hub and an operating stability without eccentric deflection is the focus which the inventor and the related manufacturers in this industry have been devoting themselves to.