Patent ID: 7500825

Claim:
A centrifugal blower comprising: a fan having a plurality of blades; a casing housing said fan therein and having a discharge passage surrounding said fan, a suction port for drawing air therethrough into said discharge passage when said fan operates, and an outlet port for discharging air from said discharge passage therethrough out of said casing; an annular step disposed in said discharge passage in confronting relation to said suction port with said fan interposed therebetween; and a joint portion disposed in said discharge passage and inclined from said annular step radially outwardly and in a direction away from said suction port, said joint portion being joined at an acute angle to an outer wall of said discharge passage and becoming gradually horizontal toward said outlet port so as to be continuous to a bottom surface of said outlet port; said discharge passage having a cross-sectional area which is progressively greater radially outwardly toward said outlet port in the direction away from said suction port.