Abstract: The invention relates to a filter dedusting arrangement in a vacuum cleaner, wherein dedusting of the filter or filter-parts is effected by supplying a secondary airflow, in a known manner. The distinctive feature of the invention is that the secondary airflow through the filter for dedusting is controlled so that by utilizing differences in pressure a flap element arranged in a casing abruptly changes its position and opens and/or closes one or more openings in the casing so that the secondary airflow impinges impulsively on the surface of the filter to be dedusted. The impulsive supply of secondary air to the filter produces a much better cleaning action.