WO2012162352A1 - Lame aérodynamique de tondeuse à gazon - Google Patents

Lame aérodynamique de tondeuse à gazon Download PDF

Info

Publication number
WO2012162352A1
WO2012162352A1 PCT/US2012/039068 US2012039068W WO2012162352A1 WO 2012162352 A1 WO2012162352 A1 WO 2012162352A1 US 2012039068 W US2012039068 W US 2012039068W WO 2012162352 A1 WO2012162352 A1 WO 2012162352A1
Authority
WO
WIPO (PCT)
Prior art keywords
blade
lawn mower
cutting blade
flow agitators
mower blade
Prior art date
Application number
PCT/US2012/039068
Other languages
English (en)
Inventor
Lennie D. Rhoades
Steven C. BRINKMAN
Christopher Roth
Original Assignee
Husqvarna Consumer Outdoor Products N.A., Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Husqvarna Consumer Outdoor Products N.A., Inc. filed Critical Husqvarna Consumer Outdoor Products N.A., Inc.
Publication of WO2012162352A1 publication Critical patent/WO2012162352A1/fr

Links

Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01D—HARVESTING; MOWING
    • A01D34/00—Mowers; Mowing apparatus of harvesters
    • A01D34/01—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus
    • A01D34/412—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having rotating cutters
    • A01D34/63—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having rotating cutters having cutters rotating about a vertical axis
    • A01D34/73—Cutting apparatus

Definitions

  • Example embodiments generally relate to lawn mowing equipment and, more particularly, relate to an aerodynamically improved blade for use with lawn mowing equipment.
  • Lawn care and other outdoor tasks associated with grooming and maintaining property are commonly performed using various tools and/or machines that are configured for the performance of corresponding specific tasks. Certain tasks, like grass cutting, are typically performed by lawn mowers.
  • the lawn mowers may, in some cases, be walk- behind models that lawn mowers are typically compact, have comparatively small engines (e.g., less than 200 cubic centimeters (cc)) and are relatively inexpensive.
  • riding lawn mowers such as lawn tractors, can be quite large and sometimes have engines exceeding 400 cc.
  • Riding lawn mowers can sometimes also be configured with various functional accessories (e.g., trailers, tillers and/or the like) in addition to grass cutting components.
  • Riding lawn mowers provide the convenience of a riding vehicle as well as a typically larger cutting deck as compared to a walk-behind model. Robotic mowers have also been introduced to attempt to make lawn care a mostly automated process.
  • most lawn mowing today is performed using horizontal rotation of a cutting blade about an axis.
  • the cutting blade is typically suspended at a fixed or selectable distance above the ground, inside a shielded enclosure that may be referred to as a cutting deck.
  • a shielded enclosure that may be referred to as a cutting deck.
  • grass that stands tall enough to encounter the blade is cut and often also expelled either to the side or rear of the lawn mower.
  • the clippings may be collected in a bag, or merely discarded onto the ground.
  • the cutting blade may become dulled or fouled through use, which may reduce cutting efficiency.
  • a dull or fouled cutting blade may tend to rip through blades of grass and tear them. This increases drag on the cutting blade and causes fuel inefficiency and more damage to grass. Even when a sharp cutting blade is operated in an environment where grass is relatively tall or thick, the cutting blade may tend to have increased drag to thereby slow the cutting blade and reduce cutting efficiency.
  • some example embodiments may provide an aerodynamically improved cutting blade.
  • some embodiments may provide for the inclusion of flow agitators or turbulators (e.g., dimples, bumps, peaks and valleys, protrusions and/or the like) to be disposed on the surface of the cutting blade.
  • the flow agitators may generate vortexes or eddy currents that may reduce drag on the cutting blade as the cutting blade rotates, and may therefore increase cutting efficiency.
  • the flow agitators may, in some cases, also prevent blade fouling and/or improve the hardness of exposed surfaces.
  • the flow agitators may be provided via any of a number of ways and in various different patterns, shapes and/or sizes in order to enable relatively low cost manufacture of an aerodynamically improved cutting blade.
  • Some example embodiments may therefore improve lawn mower cutting performance.
  • some example embodiments may increase cutting blade performance and resistance to fouling.
  • FIG. 1 illustrates a perspective view of a cutting blade with flow agitators in the form of dimples disposed over an entirety of the surface of the cutting blade according to an example embodiment
  • FIG. 2 illustrates a perspective view of a cutting blade with flow agitators disposed only over a portion of the surface of the cutting blade that is proximate to the blade edge according to an example embodiment
  • FIG. 3 illustrates a perspective view of a cutting blade with flow agitators disposed over the surface of the cutting blade at portions of the cutting blade that are distant from the axis of rotation of the cutting blade according to an example embodiment
  • FIG. 4 illustrates a perspective view of a cutting blade where the flow agitators are depressions having a shape other than the dimple shape of FIGS. 1-3 according to an example embodiment
  • FIG. 5 illustrates a cross section of the example embodiment of FIG. 1 taken through line A-A' to show how the flow agitators may affect flow characteristics of air passing over the cutting blade according to an example embodiment.
  • Some example embodiments may improve the performance of a vegetation cutting device (of which a lawn mower is one example) by reducing the drag on the rotating cutting blade via adding flow agitators to the surface of the cutting blade.
  • the addition of flow agitators to the surface of the cutting blade may also increase boundary layer energy in general to discourage grass clippings, dirt and/or other debris from adhering to the surface of the cutting blade to thereby inhibit blade fouling.
  • the flow agitators may be provided on the surface of the cutting blade in a number of different ways during the production process. Some of these ways may actually improve the hardness of the cutting blade as well.
  • the shape and size of the flow agitators, the portion of the cutting blade over which they are disposed, and/or the pattern in which they are dispersed over the surface of the cutting blade may be modified to produce a number of different alternative example embodiments.
  • FIGS. 1-4 illustrate some examples of different configurations for a cutting blade of various example embodiments.
  • FIG. 1 illustrates a perspective view of a cutting blade with flow agitators in the form of dimples disposed over an entirety of the surface of the cutting blade according to an example embodiment.
  • FIG. 2 illustrates a perspective view of a cutting blade with flow agitators disposed only over a portion of the surface of the cutting blade that is proximate to the blade edge according to an example embodiment.
  • FIG. 3 illustrates a perspective view of a cutting blade with flow agitators disposed over the surface of the cutting blade at portions of the cutting blade that are distant from the axis of rotation of the cutting blade according to an example embodiment.
  • FIG. 1 illustrates a perspective view of a cutting blade with flow agitators in the form of dimples disposed over an entirety of the surface of the cutting blade according to an example embodiment.
  • FIG. 2 illustrates a perspective view of a cutting blade with flow agitators disposed only over a portion of the surface of
  • FIG. 4 illustrates a perspective view of a cutting blade where the flow agitators have a shape other than the dimple shape of FIGS. 1-3 according to an example embodiment.
  • FIG. 5 illustrates a cross section of the example embodiment of FIG. 1 taken through line A-A' to show how the flow agitators may affect flow characteristics of air passing over the cutting blade according to an example embodiment.
  • the cutting blade 10 may include one or more fixing mechanisms such as a cutout hole 12 positioned within the cutting blade 10 to enable the blade to be rotatably attached to the lawn mower (or other vegetation cutting device) within a cutting deck.
  • the cutout hole 12 may be centrally located on the cutting blade 10 such that the cutting blade 10 may be mounted onto a shaft that is operably connected to an engine of a lawn mower to rotate the cutting blade 10 around an axis of rotation 14.
  • connection of the cutting blade 10 to the shaft may also be accomplished by other means instead of passing a portion of the shaft (or an extension of the shaft) through a cutout hole.
  • the fixing mechanism could alternatively include combinations of grooves, protrusions, straps, bolts, clamps, or other structural features to fix the cutting blade 10 to a rotating apparatus. Rotation of the cutting blade 10 may then rapidly swing the cutting blade 10 through a plane that is horizontal and substantially parallel to the surface of the ground during lawn mower operation.
  • the cutting blade 10 may include a blade body 20 that may extend in opposite directions away from the cutout hole 12 and may include both a top surface (shown in FIGS. 1-4) and a bottom surface (not shown in FIGS. 1-4).
  • the blade body 20 may have a substantially rectangular cross section over portions of the cutting blade 10.
  • the blade body 20 may include various bent portions along the length of the cutting blade 10 to, for example, allow a blade edge 30 positioned at each respective end of the blade body 20 to be at a different height than the portion of the blade body 20 that actually facilitates attachment to the lawn mower.
  • the blade edge 30 may be defined as a tapered edge of the blade body 20 to form a relatively sharp cutting surface for cutting vegetation (e.g., grass).
  • the blade edge 30 may extend along a leading edge 32 of each respective end of the blade body 20.
  • the leading edge 32 may be defined as the edge of the blade body that encounters vegetation first when the cutting blade 10 is rotated around the axis of rotation 14.
  • the cutting blade 10 may rotate in a clockwise direction when performing cutting operations so that the blade edge 30 is at the leading edge 32 and effective cutting of vegetation may be performed.
  • a trailing edge 34 of each respective end of the blade body 20 may be defined as the edge of the end of the blade body that is opposite of the leading edge 32.
  • some example embodiments may provide for the inclusion of flow agitators or turbulators in the form of dimples 40 on a surface of the blade body 20.
  • FIG. 4 illustrates an example in which the flow agitators or turbulators are provided in the form of triangular- shaped depressions 50.
  • other embodiments may employ some form of protrusion as the flow agitators.
  • the flow agitators or turbulators may be provided via grooves, depressions such as dimples (e.g., semi-spherical depressions), protrusions, alternate peaks and valleys, bumps, depression lines or channels, texture strips, hammered finish markings, and/or the like having any consistent shape, combinations of different shapes or even random shapes.
  • the flow agitators or turbulators may reduce drag on the cutting blade 10 as the cutting blade 10 rotates about the axis of rotation 14.
  • flow agitators e.g., dimples 40 or triangular-shaped depressions 50
  • the flow agitators may be disposed over an entirety of the top surface (and/or the bottom surface) of the cutting blade 10 (as shown in FIG. 1 for an example embodiment employing dimples 40).
  • the flow agitators may be formed to each have the same size (as shown in FIGS. 1-4).
  • some embodiments may include flow agitators having a variety of different sizes.
  • the flow agitators may be distributed over the surface of the cutting blade 10 with a consistent density or with varying densities in different alternative embodiments. For example, some embodiments may provide higher dimple densities near distal ends of the cutting blade 10 than the dimple density provided closer to the axis of rotation 14. Still other example embodiments may increase dimple density near the blade edge 30 and reduce dimple densities as proximity to the leading edge 32 increases (and therefore also as proximity to the trailing edge 34 decreases).
  • Dimple size may also vary based on proximity to the leading edge 32 in some embodiments.
  • the dimples 40 may be about 0.01 inches deep and about 0.15 inches in diameter. However, the depth and/or diameter of the dimples 40 may be adjusted higher and lower than these sizes in some embodiments.
  • Dimples 40 may also be disposed in any of a number of different patterns. In FIGS. 1-3, dimples 40 are disposed substantially linearly across portions of the surface of the cutting blade 10 along lines that are substantially parallel to the longitudinal length of the cutting blade 10.
  • shapes other than dimple shapes are used for providing the flow agitators (e.g., the triangular-shaped depressions 50 or other shapes), those shapes may be provided in any of a plurality of different orientations, patterns, shapes and/or sizes as well.
  • flow agitators may instead only be placed at specific regions of the cutting blade 10.
  • the flow agitators e.g., dimples 40
  • the flow agitators may only be disposed on the leading edge 32 side of the blade body 20 proximate to the blade edge 30 (as shown in FIG. 2).
  • These location-specific flow agitators may be disposed on the top and/or bottom surface of the cutting blade 10.
  • flow agitators may be placed only in portions of the blade body 20 that are not proximate to the axis of orientation 14 (as shown in FIG. 3).
  • the flow agitators may be disposed over the surface of the cutting blade 10 at locations that are selected based on their aerodynamic impacts with respect to increasing turbulent flow at the surface of the cutting blade 10 and decreasing drag on the cutting blade 10.
  • FIG. 5 illustrates a cross section of a portion of the cutting blade 10.
  • a high pressure area is formed at the leading edge 32 of the cutting blade 10 as the cutting blade 10 rotates at cutting speeds.
  • a laminar flow will be established over the leading edge 32 of the cutting blade 10.
  • the laminar flow would tend to pass over the surface of the cutting blade 10 and spread apart as the trailing edge is approached to form a turbulent wake region.
  • the turbulent wake region is formed behind the cutting blade 10 and is characterized by airflow that is fluctuating and agitated, resulting in a low pressure region behind the trailing edge 34.
  • a larger wake, or low pressure area, behind the trailing edge 34 will generally increase the amount of drag on the cutting blade 10.
  • a dashed line 100 is shown in FIG. 5 to illustrate the expected laminar flow profile that would be
  • the dashed line 100 tends to leave a relatively large wake, and therefore a relatively large amount of drag is induced.
  • Flow agitators 110 which could be dimples, protrusions, depressions and/or the like of any shape or size as described above, may be provided along the surface of the cutting blade 10 to reduce the drag forces.
  • the flow agitators 110 create a thin turbulent layer (indicated by the plurality of eddy currents 120 shown in FIG. 5) that clings to the surface of the cutting blade 10.
  • a boundary layer 130 may be energized by the turbulence introduced by the flow agitators 110.
  • laminar flow may stay attached to the surface longer to reduce the size of the wake behind the cutting blade 10.
  • the drag on the cutting blade 10 may be substantially reduced.
  • the inclusion of flow agitators 110 may increase turbulent flow at the surface of the cutting blade 10 to correspondingly increase the Reynolds number for the rotating cutting blade 10 such that drag on the cutting blade 10 is reduced.
  • Reduced drag may enable the lawn mower to rotate the blade more freely.
  • the lawn mower may, for example, rotate the cutting blade 10 in a more fuel efficient manner that may also lead to more efficient cutting by the cutting blade 10, even in higher load situations (e.g., where vegetation is thick or high).
  • the increased turbulence in the boundary layer may discourage grass clippings, dirt and/or other debris from clinging or adhering to the blade edge 30 to foul the blade edge 30.
  • This discouragement of blade fouling may keep the blade edge 30 in better condition for efficient cutting for a longer period of time than blades without flow agitators 110. This may also increase fuel efficiency over time.
  • the point at which the dashed line 100 extends away from the boundary layer 130 may define a point of flow divergence that may form an advantageous location for the inclusion of the flow agitators 1 10.
  • a relatively small amount of flow agitators 110 e.g., one or two rows as shown in FIGS. 2 and 4 may be positioned proximate to the point of flow divergence.
  • the flow agitators that are disposed on the surface of a cutting blade may be created via any of a plurality of different ways.
  • dimples or flow agitators having some other shape may be stamped or rolled into the surface of a metal lawn mower blade.
  • flow agitators may be formed by casting the cutting blade to include the flow agitators.
  • plastic deformation may be employed by using heat or pressure to make the workpiece more conductive to mechanical forces. The flow agitators may then be formed on the workpiece using mechanical forces.
  • the flow agitators may be cut or machined into the surface of the cutting blade via drilling, grinding, milling, employing laser cutting or other burning methods, utilizing erosion techniques, and/or the like.
  • processes used to create the flow agitators may add hardness to the cutting blade and further improve durability of the cutting blade.
  • the inclusion of depressions such as dimples or protrusions such as bumps or ridges may provide for harder exposed surfaces of the lawn mower cutting blade. Blade life and performance may therefore be improved.

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  • Life Sciences & Earth Sciences (AREA)
  • Environmental Sciences (AREA)
  • Harvester Elements (AREA)

Abstract

L'invention concerne une lame de tondeuse à gazon pouvant comprendre un mécanisme de fixation, un corps de lame et une arête de lame. Le mécanisme de fixation peut faciliter la fixation de la lame de tondeuse à gazon à un arbre rotatif à proximité de l'axe de rotation de la lame de tondeuse à gazon. Le corps de lame peut s'étendre dans des directions opposées à l'écart du mécanisme de fixation. Le corps de lame peut comprendre une surface supérieure et une surface inférieure. L'arête de lame peut être disposée pour être positionnée au niveau d'un bord d'attaque d'au moins une extrémité du corps de lame lorsque la lame de tondeuse à gazon est mise en rotation autour de l'axe de rotation en réponse à la rotation de l'arbre rotatif. Le corps de lame peut comprendre une pluralité d'agitateurs de flux disposés au moins à proximité de l'arête de lame.
PCT/US2012/039068 2011-05-24 2012-05-23 Lame aérodynamique de tondeuse à gazon WO2012162352A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201161489430P 2011-05-24 2011-05-24
US61/489,430 2011-05-24

Publications (1)

Publication Number Publication Date
WO2012162352A1 true WO2012162352A1 (fr) 2012-11-29

Family

ID=47217690

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2012/039068 WO2012162352A1 (fr) 2011-05-24 2012-05-23 Lame aérodynamique de tondeuse à gazon

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Country Link
WO (1) WO2012162352A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3420804A1 (fr) * 2017-06-28 2019-01-02 Deere & Company Lame de coupe pour un broyeur de paille

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5918450A (en) * 1994-12-30 1999-07-06 Kraemer-Maschinen U. Druckluftsysteme Gmbh Blade shape
US20070227113A1 (en) * 2006-03-30 2007-10-04 John Schuyler Rotary mower blade
US20100139231A1 (en) * 2008-12-10 2010-06-10 Washburn Iv Edward Nollie Rotary mower blade integrating aerodynamic elements.

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5918450A (en) * 1994-12-30 1999-07-06 Kraemer-Maschinen U. Druckluftsysteme Gmbh Blade shape
US20070227113A1 (en) * 2006-03-30 2007-10-04 John Schuyler Rotary mower blade
US20100139231A1 (en) * 2008-12-10 2010-06-10 Washburn Iv Edward Nollie Rotary mower blade integrating aerodynamic elements.

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3420804A1 (fr) * 2017-06-28 2019-01-02 Deere & Company Lame de coupe pour un broyeur de paille
US20190000018A1 (en) * 2017-06-28 2019-01-03 Deere & Company Chopping Blade for a Straw Chopper
US10874050B2 (en) 2017-06-28 2020-12-29 Deere & Company Chopping blade for a straw chopper

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