Abstract: An air cleaner includes a housing, a filter element, a fan wheel and a motor. The fan wheel includes a rear end plate, a front end plate, and a plurality of fan blades that are mounted between the rear end plate and the front end plate. A central opening of the front end plate is defined as an airflow inlet of the fan wheel. An airflow outlet of the fan wheel is defined between an outer edge of the front end plate and an outer edge of the rear end plate. The rear end plate has an outer diameter defined as D1. The front end plate has an outer diameter defined as D2. D2 is less than D1, and 0.88 < D ? ? 2 D ? ? 1 < 0.92 . The air cleaner can eliminate a self-loss area of jet streams of the fan wheel and attain the object of reducing noise, without reducing air volume.

Abstract: A method of producing a centrifugal fan wheel without a volute casing includes a design of an outer diameter of a fan wheel and a shape design of a fan blade. The centrifugal fan wheel of the invention reduces the absolute velocity of the fan blade by decreasing an outer diameter of the fan blade to thereby eliminate a self-loss area of jet streams and attain the object of reducing noise. The invention calculates the best air outlet angle and the best air intake angle of the aerodynamic performance through mathematical derivation of aerodynamic equation and theory to thereby achieve the largest output of air volume within the smallest range of full pressure loss.