Abstract: The present invention is directed to a centrifugal fan assembly (19) for the debris collection arrangement (100) of a road cleaning machine (10). The assembly (19) comprises a casing (101), a rotatable impeller (103) and a wall (107). The casing (101) comprises a volute portion (30) connected to an outlet passageway (31), a corner (106) being formed therebetween. The impeller (103) comprises a plurality of blades (25) and is located in the volute portion (30) proximate the corner (106). The wall (107) separates the outlet passageway (31) into a first and second passageway (36, 37) and extends to an inner end (102) proximate the impeller (103). The inner end (102) is positioned, and the impeller (103) is arranged, such that when a blade (25) passes the inner end (102) a second pressure wave is formed that destructively interferes with a first pressure wave formed by a blade (25) passing the corner (106).

Abstract: The present invention is directed to a centrifugal fan assembly (19) for the debris collection arrangement (100) of a road cleaning machine (10). The assembly (19) comprises a casing (101), a rotatable impeller (103) and a wall (107). The casing (101) comprises a volute potion (30) connected to an outlet passageway (31), a corner (106) being formed therebetween. The impeller (103) comprises a plurality of blades (25) and is located in the volute portion (30) proximate the corner (106). The wall (107) separates the outlet passageway (31) into a first and second passageway (36, 37) and extends to an inner end (102) proximate the impeller (103). The inner end (102) is positioned, and the impeller (103) is arranged, such that when a blade (25) passes the inner end (102) a second pressure wave is formed that destructively interferes with a first pressure wave formed by a blade (25) passing the corner (106).