Centrifugal fan

Claim 1

A centrifugal fan, comprising a housing having a generally flat front wall with an inlet opening at substantially the center thereof, a back wall spaced from said front wall and defining therebetween the interior of said housing, and a side wall having eight sections providing said housing with an octagonal outer and inner cross-section, said housing having an outlet opening arranged in one of the eight sections of said octagonal side wall; impeller means for sucking air through the inlet opening and for centrifugally driving such air along the interior of said housing and through the outlet, said impeller means including a rotatable impeller shaft extending through the back wall of said housing and an impeller supported and driven by said shaft and located in said housing, said impeller having fan blades for imparting radial flow to the air within said impeller and housing in a first rotational direction as said impeller rotates, said fan blades being curved rearwardly relative to said first rotational direction; said outlet opening having an upstream edge and a downstream edge relative to said first rotational direction of radial flow of air; said impeller having an outer diameter which is smaller than the diametral distance between two opposite sections of said octagon side wall of the housing; and a deflector arranged within said housing downstream of said outlet opening between the interior of said housing and said impeller with a first wall extending generally radially inwards from said downstream edge of said outlet opening to the neighborhood of the circumference of said impeller and facing the air radially flowing in said first rotational direction, and a second wall extending from said first wall in said first rotational flow direction of the air to the inner side wall of said housing substantially in a spiral-like curve outwards to the housing side wall, said deflector extending from the front wall to the back wall.