초록 ▼

A vortex reducing mower blade for use with a rotary lawn mower having a motor and a depending drive shaft has a cutting edge on each leading edge thereof, an airlift on each trailing edge thereof, and outboard ends extending between the terminations of the leading and trailing edges. The outboard en

A vortex reducing mower blade for use with a rotary lawn mower having a motor and a depending drive shaft has a cutting edge on each leading edge thereof, an airlift on each trailing edge thereof, and outboard ends extending between the terminations of the leading and trailing edges. The outboard ends generally meet with the trailing edges at respective trailing corner- or tip-regions. Each outboard end has margins formed as a boundary-layer fence that is angled either upwardly or downwardly relative to a given relative up direction which is parallel to the central axis of the depending drive shaft. These boundary-layer fences reduce the production and/or strength of vortices in the wake of the trailing corner- or tip-regions of the blade. Each boundary-layer fence may be angled either upwardly or downwardly at generally a right angle. To produce a blade this way, generally the blade might be produced from flat steel stock including that each boundary-layer fence is formed as separate weldment from comparable flat steel stock for attaching in position by means of welding. Alternatively, each boundary-layer fence may be angled either upwardly or downwardly in generally a curving sweep. Producing a blade this way can be accomplished by producing the blade as a unit from a single stock piece of flat steel including that the boundary-layer fences are configured therein by means of a brake, stamping or press-forming operation.

대표청구항 ▼

[ I claim:] [1.]1. A vortex reducing mower blade comprising:a rotary mower blade adapted for rotation about an upright axis and extending span-wise between spaced end portions that terminate in outboard edges, each end portion comprising a leading flat panel originating from a leading edge sharpened

[ I claim:] [1.]1. A vortex reducing mower blade comprising:a rotary mower blade adapted for rotation about an upright axis and extending span-wise between spaced end portions that terminate in outboard edges, each end portion comprising a leading flat panel originating from a leading edge sharpened to define a cutting edge and a chord-wise trailing lift and joined to and angled upwardly in trailing relationship to the leading flat panel and terminating in a trailing edge, wherein said trailing lift panel has a span-wise extension that generally at least matches the leading flat panel's span-wise extension in order to provide an applied suction across a span of grass blades that come under the flat panel's cutting edge and thereby promote upward straightening of the grass blades and hence a more even trim height, and wherein each pair of trailing edges and outboard edges generally meet at a respective vortex-shedding trailing tip region; and,a boundary-layer fence forming a margin of the outboard edge of each lift panel, each boundary-layer fence angled either upwardly or downwardly for reducing the production and/or strength of vortices in the wake of the trailing tip regions of the blade whereby the boundary-layer fences weaken such detrimental effects of vortices as swirling and downward blowing on the grass blades that come under the trailing tips which if not weakened would overcome much of the upward straightness promoted by the applied suction and then wreck the evenness of the trim.