Patent ID: 7037077

Claim:
A radiator fan, in which a plurality of propeller blades are attached to a boss and which forces air flow, wherein an attachment angle θ 1 at a propeller blade base portion projected onto a plane parallel to an attachment surface of the propeller blades with respect to the boss is set in a range of 35 to 45 deg, wherein an inclination angle θ 2 at a propeller blade tip portion is set in a range of 15 to 22 deg, wherein a number of the propeller blades N, a chord length Ct at the propeller blade tip portion, and an outer circumference length π×Df of the propeller blade are set such as to satisfy a relationship: 0.65< N×Ct /(π× Df )<0.85, wherein a tip broadening ratio of the propeller blades is set to within a range of Ct/Cb= 1.5 to 2.1, based on the chord length Ct at the propeller blade tip portion and a chord length Cb at the propeller blade base portion, and a sweep angle θ 3 with respect to a rotation direction of the fan, defined by a line that passes through a rotation axis of the fan and bisects the chord Cb at the propeller blade base portion and a line that passes through a rotation axis of the fan and bisects the chord Ct at the propeller blade tip portion, is set within a range of 15 to 25 deg.