Aoki, YohkoYohkoAokiRohlfing, JensJensRohlfing2023-12-042023-12-042023-08-23https://publica.fraunhofer.de/handle/publica/457495The invention relates to noise reduced blower means and their use in electric power tools and devices. The blower means comprise a housing (1), one or more air intake openings, a plurality of air exhaust openings (2), a fan disposed in the housing (1) and drivingly coupled to an electric motor for generating an air flow through said one or more air intake openings into the housing (1) and through said air exhaust openings out of the housing (1), and a plurality of spaced resonators (3) each having a wall which defines a resonator cavity and a resonator opening (4)which is in fluid communication with said resonator cavity and said air flow and points either in an upstream direction or a downstream direction of the air flow. As a result direct air borne sound transmission via the air exhaust openings (2) is reduced.enpatentEP4230873 A1EP20220158036