STRUCTURE OF AIR BLOWING FAN

PROBLEM TO BE SOLVED: To attain a large quantity of air and reduced noise by positioning the trailing end face of an impeller on a cylindrical surface with a radius, corresponding to the trailing end face of the impeller, around a rotation axis, and forming an attack of angle and a pitch angle of the impeller trailing end face in the structure of a ventilation fan formed of a locus of the radius of a main cylinder and a locus obtained by making the other cylinder intersect the main cylinder. SOLUTION: The rotating direction of a fan is counterclockwise from the axis +y view, and the inflow direction is -y. A radius R1 corresponds to the trailing end face of an impeller on a main cylindrical surface around a rotation axis, and a radius R2 corresponds to a blade hub. A radius R0 is the radius of a cylinder intersecting a cylinder with a radius R1 . The intersecting cylinder is inclinedly passed to have optional α, β angles so as to meet on the reference plane (θ=0) of the main cylinder, that is, the axis of the main cylinder with the radius R0 is turned downward from the reference plane (y=0) and rotated by an angle α around a y-axis after moving a coordinate axis horizontally, and an x" axis is rotated by an angle β to coincide with a z" axis.