PURPOSE: To obtain the fan with a high ventilating efficiency by a method wherein an axial flow impeller is provided coaxially at the suction port of a fan case covering a centrifugal impeller and the outer diameter of the axial flow impeller as well as the diameter of the suction port of fan case are specified.
CONSTITUTION: The centrifugal impeller 10 is attached to the shaft 9 of a motor 8 and an air guide 11 is arranged around the impeller 10 while the fan case 12 is provided so as to cover those equipments. The axial flow impeller 14 is fixed to said shaft 9 at the suction port 13 of the fan case 12. Further, the outer diameter Da of the axial flow impeller 14 is designed so as to be in the relation of Dc> Da>0.85Dc, here, Dc shows the diameter of the suction port 13 of the fan case 12. According to this method, air stream flows into the centrifugal impeller smoothly.
MORI KUNIHITO
YAMAOKA MIKIO
YAMAURA IZUMI
