Vortex reducing mower blade

• US 6,301,868 B1
• Filed: 08/26/1999
• Issued: 10/16/2001
• Est. Priority Date: 08/26/1999
• Status: Expired due to Fees

• Current Assignee: James D. "Dave" Siplinger
• Original Assignee: James D. Siplinger
• Inventors: Siplinger, James D.
• Primary Examiner(s): Will, Thomas B.
• Assistant Examiner(s): MAMMEN, NATHAN SCOTT
• Application Number:
  US09/383,710
• Time in Patent Office: 782 Days
• Field of Search: 56/175, 562/55, 562/95, 56D/IG.19, 56D/IG.20, 302/76, 303/57
• US Class Current: 56/295
• CPC Class Codes: A01D 34/73 Cutting apparatus

Abstract

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.

Claims

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.

2. The vortex reducing mower blade of claim 1 wherein each boundary-layer fence is angled downwardly and has the shape of a wedge defined between an upper border common with the respective upwardly-angled lift pane1 and a lower border defined by an imaginary trailing continuation of the outboard edge of the respective leading flat panel.

3. The vortex reducing mower blade of claim 2 wherein each boundary-layer fence is angled downwardly at generally a right angle.

4. The vortex reducing mower blade of claim 2 wherein each boundary-layer fence is angled downwardly in a curving sweep.

5. The vortex reducing mower blade of claim 4 wherein each boundary-layer fence is angled downwardly in the curving sweep such that the termination of which is generally oriented straight down.

6. The vortex reducing mower blade of claim 1 wherein the trailing edges extend generally straight and generally parallel to a span-wise-extending plane containing the upright axis.

7. The vortex reducing mower blade of claim 6 wherein the outboard edges are generally contained in a chord-wise-extending plane that is parallel to the upright axis, whereby the trailing tip regions are generally right-angled corners.

8. The vortex reducing mower blade of claim 1 further comprising one or more span-wise spaced, chord-wise elongated vortilons distributed across either the upper or lower surfaces of the end panels inboard from the outboard edges.

9. A vortex reducing mower blade comprising:

an elongated mower blade extending span-wise between spaced outboard ends and having a central mounting portion for mounting to a depending spindle;

the mower blade further having leading cutting panels proximate the outboard ends thereof and formed with respective leading cutting edges for rotating through a common cutting plane, as well as having trailing lift panels respectively located behind the leading cutting panels and inclined upwardly from the cutting plane to terminate in trailing edges, wherein said trailing lift panels have a span-wise extension at least generally co-extensive with the leading cutting panel'"'"'s span-wise extension in order to provide operatively cooperative suction across a span of grass blades that come under the cutting 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;

wherein proximate each outboard end the blade further includes a chord-wise extending boundary-layer fence which is 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.

10. The vortex reducing mower blade of claim 9 wherein each boundary-layer fence is angled either upwardly or downwardly at generally a right angle.

11. The vortex reducing mower blade of claim 10 wherein said blade is 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.

12. The vortex reducing mower blade of claim 9 wherein each boundary-layer fence is angled either upwardly or downwardly in generally a curving sweep.

13. The vortex reducing mower blade of claim 12 wherein said blade is produced 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.

14. The vortex reducing mower blade of claim 9 wherein the trailing edges extend generally straight and generally parallel to a span-wise-extending plane containing the spindle axis.

15. The vortex reducing mower blade of claim 14 wherein the outboard ends are generally contained in a chord-wise-extending plane that is parallel to the spindle axis, whereby the trailing tip regions are generally right-angled corners.

16. A vortex reducing mower blade for use with a rotary lawn mower having a motor and a depending drive shaft, comprising:

a level cutting edge on each leading edge thereof and extending between span-wise extremes,

an airlift on each trailing edge thereof, wherein said airlift has a span-wise extension is at least generally co-extensive with the span-wise extent of the level cutting edge between said span-wise extremes thereof said airlift accordingly providing an operatively cooperative suction across a span of grass blades that come under the level cutting edge and thereby promote upward straightening of the grass blades and hence a more even trim height, and

outboard ends extending between the terminations of the leading and trailing edges, which outboard ends meet with the trailing edges generally meet at a respective vortex-shedding trailing tip region, wherein 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, whereby said boundary-layer fences reduce the production and/or strength of vortices in the wake of the trailing tip regions of the blade and thereby 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.

17. The vortex reducing mower blade of claim 16 wherein each boundary-layer fence is angled either upwardly or downwardly at generally a right angle.

18. The vortex reducing mower blade of claim 17 wherein said blade is 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.

19. The vortex reducing mower blade of claim 16 wherein each boundary-layer fence is angled either upwardly or downwardly in generally a curving sweep.

20. The vortex reducing mower blade of claim 19 wherein said blade is produced 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.