US Patent 9903387 Ring fan and shroud assembly

A ring fan and shroud assembly having a fan, a shroud member, a recirculating flow member, and a plurality of curved guide vanes. The fan has a hub with a plurality of projecting fan blades and an outer ring member. The shroud member is positioned around the outer ring member. The recirculating flow member is on the shroud member and is positioned forward adjacent the outer ring member. The guide vanes are positioned within the recirculating flow member and define an inlet angle, which is nearly tangential with an outer entry diameter radial surface of the recirculating flow member, and an outlet angle that is nearly radial along an inner exit diameter of the recirculating flow member.