a ventilating exhaust fan including a housing unit , a motor module , a panel module , and an exhaust assembly is provided . the exhaust assembly fixed on a side surface of the housing unit is improved by replacing single piece stopping flake with two - piece stopping flakes in order to reduce air flow friction , thereby overcoming the shortcoming of existing technique of stopping flake which , relying on gravity for reposition , gives rise to larger air flow friction . furthermore , the noise of the existing pipeline exhaust fan is also reduced by adopting the methods of injection molding of motor module with volute as one entity , and by adhering to volute bottom sponge layer , which in turn is adhered to the base plate of exhaust fan housing .