Arrangement for radial fans

Claim 1

A radial flow fan having a fan wheel (9) which rotates in one direction on an axis (2) and which comprises a ring of circumferentially spaced blades (11), each extending between a disc-like axially inner end plate (10) and a concentric axially outer end ring (14) through which air flows to the inside of the ring of blades (11) to be propelled radially outward by them, and a housing (1) within which the fan wheel (9) rotates and which has an inner end wall (4) that is substantially coplanar with said inner end plate (10), an outer end wall (5) which is spaced axially outwardly from said end ring (14) and wherein there is an air inlet (16), and a spiral side wall (3) which extends around the fan wheel (9) in divergent relation to the fan wheel periphery from a tongue (20) location to an outlet (21) and which cooperates with said end walls (4, 5) and the ring of blades (11) to define a duct (18) around the fan wheel (9), said duct (18) merging at said outlet (21) into an outlet pipe (19) which is joined to the side wall (3) at said tongue (20) location and serving to conduct to said outlet pipe (19) air propelled through the ring of blades (11), said fan being characterized by: A. said fan wheel (9) having an axial length (L) which is between 80% and 120% of its radius (R); B. said duct (18) (1) being of continuously increasing cross-section area in said direction of fan wheel (9) rotation from said tongue (20) location to said outlet (21) and (2) having at said outlet (21) a cross-section area at least equal to the radius (R) of the fan wheel times its axial length (L); C. a vane (23) connected to said outer end wall (5) and projecting obliquely axially inwardly therefrom and away from said outlet (21) into the ring of blades (11) for guiding incoming air into the ring of blades at the portion thereof that is remote from said outlet (21), said vane (23) (1) having a substantially straight side edge (27) that lies closely adjacent along its length to the ring of blades (11) at the inside thereof, and (2) having an inner end edge (25) which extends from the axially inner end of said side edge (27) substantially radially inwardly away from the ring of blades; D. said air inlet (16) being defined by (1) said vane (23), and (2) an arcuate radially inwardly facing edge (32) of said outer end wall (5) which extends around not substantially more than half of the circumference of the ring of blades (11) and is substantially entirely at the side of said axis (2) that is remote from said outlet (21); and E. a baffle (26) projecting edgewise substantially radially from said vane (23) and extending across said ring of blades (11) towards said spiral side wall (3), said baffle having (1) an axially inner edge (28) adjacent to said end ring (14) and extending radially outwardly from the axially outer end of said side edge (27), and (2) an opposite outer edge adjacent and substantially parallel to said outer end wall (5).