Patent ID: 8918999

Claim:
An aerodynamic trimmer head assembly for use in flexible line rotary trimmers that provides reduced drag on the line and cooling air flow for the head mechanism of a rotary trimmer during use, said assembly comprising: a trimmer head including a housing adapted to be operatively connected to a rotary trimmer to effect rotation of the head, said housing defining at least one opening therein for the passage of a length of line therethrough and having a generally curvilinear upper trimmer head surface; and a shroud defining an annular generally curvilinear portion and a plurality of laterally spaced ribs projecting from and extending downwardly and forwardly along an underside thereof, said shroud being operatively connected to said trimmer head for rotation with said trimmer head, said generally curvilinear portion of said shroud being disposed above and extending along said generally curvilinear upper trimmer head surface and said ribs extending between said generally curvilinear portions of said shroud and said upper trimmer head surface along curvilinear paths from an upper portion of said shroud to a lower portion thereof so as to define a plurality of air channels extending downwardly and forwardly between portions of said upper trimmer head surface and said shroud along said paths defined by said ribs, said channels defining a plurality of channel inlet openings disposed about an upper central portion of said shroud such that during rotation of said head and shroud, air is drawn downwardly through said channel inlet openings, into and through said channels and outwardly therefrom at a forward inclination about the length of line projecting from the housing thereby reducing aerodynamic drag on the line and cooling the drive mechanism of the rotary trimmer.