MULTI-BLADE CENTRIFUGAL FAN

摘要

The problem of a low efficiency of a free end portion of a multi-blade centrifugal fan is solved, and a general air supply volume is thereby increased. A plurality of first blades (3) are arranged annularly on a rotary base (1). A row of first blades (3) have free end surfaces which are inclined with respect the axis (C) of rotation as if the outer circumferential end portions of the blades are cut off, and an annular baffle plate (9) is joined to the inclined free end surfaces. A plurality of second blades (11) are arranged annularly on the baffle plate (9). The width of each second blade (11) is apparently smaller than that of the first blade (3), so that clearances (13) exist between the inner circumferential portions of the second blades (11) and the free end surfaces of the first blades (11). A row of second blades (11) function as a centrifugal fan sucking the air from free end openings (15) into the inner circumferential clearances (13) and blowing out the air to the outer circumferential side thereof. The baffle plate (9) may not be provided. A plurality of annular current distributing plates (19) may be fixed to the outer circumferential portions of the blades (3, 11).