PURPOSE: To suppress noise to a low level even if an axial flow fan 15 arranged in eccentricity for a radiator, by forming an opening on a shroud on the upstream side from an axial flow fan and introducing atmosphere into an air passage.
CONSTITUTION: When a fan 2 is arranged in eccentricity for a radiator 1, the revolution noise increases in comparison with that in the case where center adjustment is performed, because a fan blade 5 passes through two regions A and B having the strong imbalance of pressure, and the order component of the revolution noise increases. Accordingly, a slit shaped opening 6 is formed on a shroud 3 having a small opening area in the A region on the downstream side from the radiator 1, on the upstream side from the fan blade 5 of the fan 2, and the inside of the shroud is allowed to communicate to the atmosphere. At this time, at the position of the opening 6, the pressure in the A region reduces than that in the B region, and a slight quantity of atmosphere flows. Accordingly, the imbalance of the pressure in the upstream part of the fan 2 can be reduced, and the revolution noise can be suppressed.
AKAIKE SHIGERU
KITADA MOTOHIRO
