Burns, Doane, Swecker & Mathis, L.L.P.
Blade configuration for a ventilation fan
 A structure of a ventilation fan provided with a plurality of blades has a performance curve characterized by a gentle slope throughout the wide operating range instead of an S-hysteresis curve, in order to overcome a fluctuation phenomena of the operating flow rate. The blade tip cross-section lies on a first imaginary cylindrical surface and an angle of attack and pitch angle of the blade tip are formed as respective trajections by intersecting the first cylindrical surface by a second cylindrical surface whose center axis has been rotated about two axes. 
Sansung Electronics Co., Ltd.
Y F
Y10S F04D
additional inventional
Jin-kyu Seungbae
Choi Lee