US Patent 7543561 Swirl generator

A swirl generator is arranged in a duct through which air is sent from the exterior to an air cleaner. The swirl generator has a plurality of guide vanes, which change the flow direction of an air flow. Each of the guide vanes has a guide fin that adjusts the air flow and a deflecting fin that applies swirl force to the air flow. The deflecting fin is configured by an upstream portion and a downstream portion, which are connected together at a predetermined angle. The upstream portion and the downstream portion each have a cross section extending linearly along a cylindrical plane coaxial with a nose cone.