Patent attributes
A purge air flow passage structure has an air flow passage for ventilating the purge air, a separation space that is provided in the air flow passage and separates dust in the purge air therefrom, and a filter that is provided in the air flow passage, is positioned upstream of the separation space, and collects dust in the purge air. The filter includes two or more shielding parts each of which has a plurality of passing holes r slits arranged in the width direction of the filter. The shielding parts are successively arranged in the air flow passage to be separated from each other by a predetermined distance in the air flow direction. Each of the shielding parts includes a wall portion facing upstream that is positioned such that the wall portion is struck by the purge air that passed through the passing hole of the neighboring upstream shielding part.
