IMPELLER OF CENTRIFUGAL BLOWER

PURPOSE: To enhance the discharge pressure, rate of flow, and efficiency in low speed operation and construct impeller in a small size by furnishing aux. vanes adjacent to the pressure surface of the main vanes. CONSTITUTION: When a centrifugal blower is in operation and its rotary shaft 1 rotates, the air introduced from a suction port 6 flows in the illustrated direction by arrow, is pressurized by main vanes 5 and aux. vanes 7, and is forwarded to the place of service via a diffuser. The ax. vanes 7 are arranged adjacently to the respective pressure surfaces of the main vanes 5, and the length L1 of aux. vane 7 is made smaller than the vane length L of the main vane 5, so that there is no need of narrowing the flow path at the inlet end 5a of the main vane 5. Further the summarized vane area of the main vanes 5 and aux. vanes 7 is increased by approx. 20-50% of the conventional value, which causes increase of the discharge pressure. The outlet angle β2' of the aux. vane 7 is made greater than the outlet angle β2 of the main vane 5. Accordingly there is no risk of separation at the negative pressure surface 52 of the main vane 5, and the mean outlet angles of the main vane 5 and aux. vane 7 are enlarged, and the lift of the vane is increased. This causes increase in the work volume of the vane to lead to enhancement of the efficiency of blower.