| 摘要 |
There is provided a centrifugal air blower capable of effectively suppressing noise caused by the shapes of a tongue part and a bell mouth formed in a scroll casing. The centrifugal air blower includes: a fan 3 composed of a bottom plate 6 fixed to a rotating shaft, multiple blades 8 whose bases are fixed to the outer circumference of the bottom plate, and an annular rim 9 provided concentrically with the bottom plate to couple distal ends of the blades; a scroll casing 4 for housing the fan and having a suction port 11 on one end side in an axial direction of the rotating shaft; a spiral flow passage 19 formed around the fan in the scroll casing; and a tongue part 16 for suppressing an inflow of air from the end of winding to the beginning of winding of the spiral flow passage. A portion of the tongue part on the other end side in the axial direction of the rotating shaft is inclined to increase a dimension of overhanging in a counter-rotating direction of the fan toward the other end side in the axial direction of the rotating shaft. |
