| 摘要 |
<p>PCT No. PCT/FI90/00182 Sec. 371 Date Jan. 3, 1992 Sec. 102(e) Date Jan. 3, 1992 PCT Filed Jul. 12, 1990 PCT Pub. No. WO91/01586 PCT Pub. Date Feb. 7, 1991.The invention relates to a fan for an electrically operated machine, comprising a propeller (1) arranged axially about the machine and including a hub (8) and several blades attached to it and projecting substantially radially from it; and a cover (2) surrounding the propeller (1) in the front and on the sides and comprising a suction opening (3) on the suction side of the propeller (1) and an opening (7) on the pressure side for passing ventilation air into the machine parts to be cooled. To achieve a fan of simple construction, good efficiency and low noise level the blades (9) have a radius of curvature (R) and they are attached to the hub (8) at a blade angle ( alpha ) between 25 DEG and 70 DEG ; a gap (S) defined between the suction opening (3) or its cylindrical extension (5) and the blades (9) of the propeller (1) in the axial direction is no more than 20% of the outer diameter of the propeller (1); the inner diameter (DA ) of the suction opening (3) before the propeller (1) is 0.8 to 1.6 times the outer diameter (DS) of the propeller; and the inner diameter of the cover (2) is at least 1.2 times the outer diameter (DS ) of the propeller or the inner diameter (DA) of the suction opening, depending on which one of them is larger.</p> |
