A centrifugal fan arrangement

Abstract

A centrifugal fan arrangement (7) comprises an inlet duct (6) for an incoming flow of air, and a fan (1; 1a; 1b) formed by a front shroud (2) which is arranged concentrically around an end portion (4) of the inlet duct (6). A back plate (3) is provided and a plurality of fan blades (4) are arranged between the front shroud (2) and the back plate (3). Each one of the fan blades (4) has a leading edge (4a) and trailing edge (4b), and the diameter (d1) of the inlet duct (6) is smaller than the inlet diameter (d2) of the front shroud (2), so that a gap (9) is formed between the inside of the front shroud (2) and the outside of the inlet duct (6), the gap (9) extending around the circumference of the inlet duct (6). The centrifugal fan arrangement (7) is configured so that the diameter (d3) of the gap (9), at an exit portion (6a) of the inlet duct (6), is greater than the inlet diameter (d2) of the front shroud (2); and the diameter (d3) of the gap (9), at the exit portion (6a) of the inlet duct (6), is also greater than or equal to a diameter (d4) which is defined by the position of each leading edge (4a) of the fan blades (4).

Dependencies are inferred from the claim text.