WO1997044998A1 - Apparatus for converting string trimmer to mulcher and vacuum - Google Patents

Abstract

A kit for converting a conventional string trimmer to perform mulching and vacuuming as well as trimming functions is disclosed, wherein the trimmer to be converted has a power shaft (12) with opposing proximal and distal ends, a power-providing unit (16) disposed upon the proximal end thereof, and a string head coupling disposed on the distal end thereof. The converting apparatus includes a collar bracket (34) adjacent the distal end of the trimmer, and struts (36) projecting from the collar bracket and supporting a surrounding fan shroud (38). A mulching fan (22) having blades (26) pitched to move air distally through the shroud, and teeth for finely dividing debris, is coupled with the trimmer's standard trimmer head coupling. A curved air duct (40) is engaged with the shroud and projects distally therefrom. A debris bag (44) suspended from the trimmer's shaft has a collector portion (50) which is engaged with the proximal rim of the fan shroud. Alternative fan embodiments include a fan having multiple debris-dividing projections on the upstream faces of its air-moving blades, and a fan having elongate, narrow cutting blades disposed above and below the plane of the conventional fan blades.

Description

APPARATUS FOR CONVERTING STRING TRIMMER

TO MULCHER AND VACUUM

BACKGROUND OF THE INVENTION

1. Field Of The Invention The present invention relates generally to hand-held, powered machinery for cutting vegetation, and more specifically to apparatus for converting string trimmers to perform other yard care functions.

2. Description Of The Related Art It has long been recognized that great economy and efficiency are possible when a device can be put to multiple uses. This concept has been applied liberally to powered yard care machines of the type such as small tractors, and the like, which have a power take-off able to be coupled with various apparatus for performing different tasks. In other cases, machines initially intended to be used for a single purpose may be retrofitted with apparatus for performing auxiliary functions. In relation to the vegetation cutting arts, specifically, lawn mowers have a long history of being modified for different uses. For example, a mower's standard grass-cutting blade may be replaced with a mulching blade for chopping up yard waste such as dead leaves, and the like And, United States Patent No. 3,995,348 issued to Chernosky m 1976 shows a vacuum cleaner attachment for a lawn mower. However, the mobility, and therefore the usefulness, of a conventional lawn mower is limited by its size, despite the versatility it might offer with access to a full range of auxiliary attachments .

The need for more nimble grass and weed cutting and trimming apparatus gave rise to the popularity of powered string trimmers, and the like. And, the availability of a convenient power take-off on such hand-held devices, expectedly, spurred development of add-on apparatus for other yard care purposes. Currently, kits for modifying a string trimmer to function as an edger, a cultivator, a brush cutter, a blower and a vacuum are known. But, none of these devices performs a mulching function.

Light-duty mulchers, such as the down-feed type able to be positioned on a stand over a trash can are known. But, before use, these require that the yard waste be gathered up near the mulcher. And, then the waste must be fed through by hand.

Rote, in United States Patent No. 5,245,726 issued in 1993, shows a portable device able to mulch and vacuum light yard waste such as fallen leaves, pine needles, twigs and the like. But, Rote's device has no versatility. It is unable to be easily converted to other purposes; and, it appears very awkward to use .

Thus, it would be very advantageous if easily portable and hand-manipulable apparatus were available for mulching yard waste. And, it would also be beneficial if such apparatus had the additional capability to perform a vacuuming function. Yet further, such mulching and vacuuming apparatus would be much more useful if it were versatile enough to be easily convertible to other purposes. SUMMARY OF THE INVENTION The apparatus of the present invention is assembled from a kit for converting a conventional string trimmer to perform mulching and vacuuming functions, and it is adapted to overcome the above-noted shortcomings and to fulfill the stated needs. The string trimmer this kit is adapted to convert should have a power shaft with opposing proximal and distal ends; a power-providing unit disposed upon its proximal end; and, a string head coupling disposed on its distal end. Included m the kit is a fan with blades pitched away from a plane perpendicular to its rotational axis and at an acute angle to the blade's surface. Each blade includes a projection from its upstream surface for finely dividing debris, each projection including a leading cutting edge nonparallel to the fan's rotational axis. The kit also includes elements for engaging the fan with a conventional string trimmer's string head coupling; a fan shroud; and, a receptacle engageable with the fan shroud for collecting and retaining finely divided debris. Alternative fan embodiments include a fan wherein each blade has a plurality of upstream debris-dividmg projections, a fan having elongate, narrow cutting blades disposed above and below the plane of the conventional fan blades . It is an object of the present invention to provide a kit for quick and easy conversion of a conventional string trimmer to apparatus able to vacuum up, mulch and carry light yard waste.

It is a further object of the present invention to provide apparatus for mulching and vacuuming yard waste which is easy to carry, and easy to control m use.

Yet another object of this invention is to provide mulching and vacuuming apparatus which is safe to operate.

Yet a further object of the present invention is to provide mulching and vacuuming apparatus which is inexpensive to manufacture.

Still a further object of the present invention is to provide the consumer with an inexpensive way add the value of mulching and vacuuming functions to a conventional string trimmer.

And another object of this invention is to provide a mulching blade which is better able to conserve its rotational speed under heavier mulching loads.

Still further objects of the inventive kit and apparatus disclosed herein will be apparent from the drawings and following detailed description thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of the mulcher/vacuum apparatus of the invention, after conversion of a powered string trimmer with the kit of the invention FIG. 2 is an enlarged side elevational view of the distal portion of the mulcher/vacuum apparatus, with its debris bag removed to reveal the struts which support the fan housing.

FIG. 3 is a perspective view of the downstream side of the mulching fan of the invention.

FIG. 4 is a bottom plan view showing the upstream side of the fan of FIG. 3.

FIG. 5 is a top plan view of a first alternative mulching fan. FIG. 6 is a side elevation view of the first alternative mulching fan of FIG. 5.

FIG. 7 is a top plan view of a second alternative mulching fan.

FIG. 8 is a perspective view of the second alternative fan of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now specifically to the drawings, FIGS. 1 and 2 show the mulching and vacuuming apparatus of the invention, which is generally identified herein with reference numeral 10, and is comprised of a conventional string trimmer converted with the kit disclosed herein. Thus, as shown m FIG. 1, mulcher/vacuum 10 continues to include the converted string trimmer's frame and drive system. Specifically, conventional string trimmer elements m mulcher/vacuum 10 include flexible drive shaft 12, shaft housing 14, engine 16, proximal handle 18 and distal handle 20. Shaft housing 14 is generally linear from its proximal end where engine 16 is mounted, through adjacent proximal handle 18 and distal handle 20, and through shaft housing 14's mid-length. The distal end of shaft housing 14 is curved m the embodiment of mulcher/vacuum 10 shown, although straight-shafted string trimmer shafts may be accommodated by one having ordinary skill in the art applying slight alterations to the preferred structure disclosed herein. Throughout the following disclosure, the convention of referring to the relative disposition of elements as proximal or distal shall be with reference to engine 16 situated at the butt-end of shaft housing 14. Thus, elements closer to engine 16 are proximal, while elements farther from engine 16 are distal.

In mulcher/vacuum 10, mulching fan 22 is coupled to the distal end of drive shaft 12, replacing the conventional trimmer's cutting head. As shown in FIGS. 3 and 4, fan 22 is an axial-type fan and includes a central, standard trimmer head coupling 24. Fan 22's four blades 26 are pitched to draw air in a distal to proximal direction when installed on a clockwise-drive string trimmer. That is, the proximal side of fan 22, shown in FIG. 3, is its downstream face; and, the distal side of fan 22, shown m FIG. 4, is its upstream face. An alternative fan with oppositely pitched blades is necessary for converting a trimmer with a counter-clockwise drive.

The outermost half, or so, of the leading edge of each blade 26 is preferably sharpened to facilitate cutting. Sharpened fan blade edge 27 may be fashioned by molding, grinding or other means known in the art.

Mulching fan 22 has a short tooth 28 projecting from the outermost edge of the upstream face of each of its blades 26. Each tooth 28 is generally triangular m shape, and has a steeply-sloped leading cutting edge 30, and trailing reinforcing portion 32 with a shallowly-sloped edge. Cutting edge 30 is shorter than the edge of trailing reinforcing portion 32, and the former is preferably sharpened while the latter need not be. Cutting edge 30 should be sloped away from being perpendicular to the plane of fan 22 's rotation. That is, cutting edge 30 is nonparallel to fan 22's rotational axis, and at an acute angle to blade 26' s surface. This angled disposition of cutting edge 30 avoids the problem which arises when a cutting edge is perpendicular to the plane of rotation, that being a pronounced and unacceptable slowing of the fan's rotational speed when under a heavy mulching load. In contrast, when angled, as is cutting edge 30, the edge contacts the incoming debris with less direct force, thereby resulting in less reduction m fan 22 's speed of rotation. But, owing to the greater length of the cutting edge than a blade projecting the same distance perpendicular to the plane of rotation would have, a slicing action is effected, thus conserving fan 22 's speed under heavier mulching loads. Here, it should be understood that the heavier mulching loads a fan with teeth 28 shaped as described is able to handle are higher volumes of light yard waste such as leaves, pine needles, small twigs, paper and the like. It should not be understood that any greater ability to cut larger sticks or other thicker, denser materials is effected. Trailing reinforcing portion 32 increases the overall durability of each tooth 28, making each tooth 28 less likely to be bent by impacts to its leading cutting edge 30.

As illustrated in FIG. 4, the outermost edge of each of fan 22's blades 26 has an arcuate shape corresponding to a portion of a circular arc. As further illustrated therein, each tooth 28 is similarly curved, such that its outer face follows the arc of the outer edge of its respective blade 26.

Fan 22 may be manufactured in any manner and from any materials conventional m the art. It is preferred that each blade 26 and its respective tooth 28 be fashioned from a single piece of sheet metal, as by stamping or bending. However, blades 26 and teeth 28, and even head coupling 24, may be cast, molded or otherwise fashioned from any suitably rigid, durable material, such as certain plastics and the like, without departing from the spirit of the invention. And, any pitched axial fan blade shape which is known in the art to conduct air in an upstream to downstream direction will suffice, as long as it includes a tooth 28 projecting from its upstream face. Yet further, the fan of the invention may have any number of blades. And, an alternative embodiment of fan 22 may be fashioned to accomplish similar functions when driven in a counter¬ clockwise direction. Yet further alternative fan embodiments are disclosed herein below. As shown in FIG. 2, collar bracket 34, disposed a short distance from the distal end of shaft housing 14 and from fan 22, supports struts 36 which, in turn, suspend generally-cylindrical fan shroud 38 around fan 22. Fan shroud 38's diameter should only be slightly larger than the diameter of fan 22. Air duct 40 is generally cylindrical in cross section, and of the same diameter as fan shroud 38. Fan shroud 38's distal rim is engaged with air duct 40's proximal rim in a conventional manner which permits air duct 40 to be disengaged from fan shroud 38, as desired. Air duct 40 is preferably slightly curved, and it also preferably includes a somewhat wave-shaped, diagonally-cut distal rim 42, as shown in the drawing figures .

Debris bag 44 is preferably constructed of woven textile fabric, as is known in the vacuum cleaner art. As is clear from comparison of FIGS. 1 and 2, distal collector portion 46 of bag 44 wraps around and covers struts 36, and binds securely around the proximal rim of fan shroud 38. A longitudinal seam 48, made releasably sealable with mating strips of hook and loop fabric assures secure engagement and, at once, makes bag 44 very easy to open wide while dumping the contents of its receptacle portion 50. A small aperture 52 at the proximal end of seam 48, wraps and seals around shaft housing 14. A suspension strap 54 permits receptacle portion 50 to hang from hook 56 at shaft housing 14 ' s mid-length. In use, when engine 16 is running, fan 22 draws air in and drives it m a distal to proximal direction, through duct 40 and shroud 38, and into debris bag 44. Air duct 40' s somewhat wave-shaped, diagonally-cut distal rim 42 can be lowered all the way down to an underlying surface, while still permitting air to enter duct 40, thereby avoiding overloading engine 16. When debris such as light yard waste is drawn up into shroud 38 with incoming air, a vortex is created therewithin by fan 22. This vortex slings the debris centrifugally outward toward shroud 38's inner wall and into the path of sharpened leading fan blade edges 27 and teeth. As sharpened edges 27 and teeth 28 engage the debris, it is sliced up into finely divided mulch and drawn beyond fan 22 into debris bag 44. Once full, debris bag 44 may be disengaged from .shroud 38 by splitting releasable seam 48 and removing suspension strap 54 from hook 56. Then, bag 44 is easily emptied through the wide opening created by seam 48 m receptacle portion 50.

Alternative fan configurations may be employed to alter or improve the performance of the mulcher/vacuum apparatus. A first alternative fan 58 shown in FIGS. 5 and 6 includes at least one additional tooth 60 projecting from the upstream face of alternative fan blade 62. Tooth 60 is spaced a short distance inward from, and generally parallel to the plane of, a tooth on the outermost edge of fan blade 62. That outermost tooth may be configured substantially as tooth 28 described herein above. Just as tooth 28, tooth 60 preferably includes a steeply-sloped, sharpened leading cutting edge 30, and a trailing reinforcing portion 32 with a shallowly-sloped edge.

Additional teeth 60 aid in the efficiency of the mulching operation because, although the fan's vortex slings most debris outward such that it contacts, primarily, the outermost ends of the blades, some debris passes the fan closer to its axis of rotation. In mulching greater volumes of debris all at once, more debris may follow this route, and additional teeth 60 are therefore required for efficient mulching. And, depending on the application, each blade may even include several additional teeth.

Yet a second alternative embodiment of a fan is shown m FIGS. 7 and 8. Second alternative fan 64 has a central head coupling 24 similar to that in the other fan embodiments. Generally conventional fan blades 66 project therefrom, although each preferably includes a sharpened portion 27 along about half the length of its leading edge. Teeth 28 and 60, such as are shown m the other embodiments, may be added as well, although they are not shown m FIGS . 7 and 8.

Second alternative fan 64 also includes four radially- disposed, narrow supplemental cutting blades. Two opposed lower supplemental cutting blades 68 project from head 24 below fan blades 66, and two opposed upper supplemental cutting blades 70 project from head 24 thereabove . That is, cutting blades 68 and 70 are below and above the plane of fan blades 66, respectively. Lower and upper supplemental cutting blades 68 and 70 are disposed at right angles to one another, and cutting blades 68 and 70 are also preferably offset from fan blades 66. Each supplemental cutting blade 68 and 70 is narrow and elongate, having a cross-section which is thicker in its middle and thinner toward its edges. At least the outer half, or so, of the leading edge of each blade 68 and 70 is preferably sharpened 72 to facilitate cutting. Debris drawn, with air, by wide fan blades 66 from an upstream to a downstream direction, toward second alternative fan 64, first contacts lower (upstream) cutting blades 68, then contacts sharpened fan blades 66 and finally contacts upper (downstream) cutting blades 70. Cutting blades 68 and 70 create little resistance against fan 64' s rotation, but yield greater mulching ability to the mulcher/vacuum apparatus, overall.

The foregoing detailed disclosure of the inventive apparatus and kit is considered as only illustrative of the preferred embodiment of, and not a limitation upon the scope of, the invention. Those skilled m the art will envision many other possible variations of the structure disclosed herein that nevertheless fall within the scope of the following claims.

And, alternative uses for this inventive apparatus and kit may later be realized. Accordingly, the scope of the invention should be determined with reference to the appended claims, and not by the examples which have herein been given.

Claims

CLAIMSI claim:

1. A kit for converting a string trimmer to a mulching vacuum, wherein said trimmer has a power shaft with opposing proximal and distal ends, a power-providing unit disposed upon said proximal end thereof, and a string head coupling disposed on said distal end thereof, said kit comprising: a. an axial fan having at least one blade pitched away from a plane perpendicular to said fan's rotational axis; b. means for finely dividing debris, said means projecting from a pitched surface of said pitched blade, said means further including a leading cutting edge nonparallel to said fan's rotational axis and at an acute angle to said blade's surface; c. means for engaging said fan with said string head coupling; d. means for shrouding said fan; and, e. means engageable with said shrouding means for collecting and retaining said finely divided debris.

2. The kit of Claim 1, wherein said debris dividing means is disposed adjacent an outermost edge of said pitched blade.

3. The kit of Claim 1, wherein said debris dividing means projects from an upstream face of said pitched blade.

4. The kit of Claim 1, wherein said debris dividing means comprises a generally triangular cutting blade.

5. The kit of Claim 1, wherein said debris dividing means further includes means for reinforcement behind said leading cutting edge.

6. The kit of Claim 1, wherein said leading cutting edge of said debris dividing means is steeply-sloped, and wherein a rearward reinforcement portion of said debris dividing means comprises a shallowly-sloped, trailing edge.

7. The kit of Claim 1, wherein said pitched blade has an arcuate outer edge, and wherein said debris dividing means, projecting from said pitched surface, has a face curved to follow the arc of said pitched blade's arcuate outer edge.

8. The kit of Claim 1, further including a curved air duct distal to said shrouding means.

9. The kit of Claim 1, wherein said fan shrouding means is supportable by struts engageable with said power shaft .

10. The kit of Claim 1, wherein said debris collecting and retaining means comprises a bag having a collector portion securable around said shrouding means and a receptacle portion suspendable from said power shaft.

11. A mulching vacuum, comprising: a. a power shaft with opposing proximal and distal ends; b. a power-providing unit disposed upon said power shaft's proximal end; c. a fan at said power shaft's distal end, said fan including means for drawing air m a distal to proximal direction; d. means projecting from a distal face of a blade of said fan for finely dividing debris; e. a shroud around said fan; f. means for supporting said shroud on said power shaft; g. means engageable with said shroud for collecting and retaining said finely divided debris.

12. The kit of Claim 11, further including an air duct distal to, and coaxial with, said shroud.

13. The kit of Claim 11, wherein said shroud supporting means comprises struts.

14. The kit of Claim 11, wherein said debris collecting and retaining means comprises a bag having a collector portion secured around said shroud and a receptacle portion suspended from said power shaft.

15. An axial mulching fan for a yard waste vacuum, comprising: a. at least one fan blade pitched away from a plane perpendicular to said fan's rotational axis; and, b. means for finely dividing debris, said means projecting from an upstream face of said pitched blade, said means further including a leading cutting edge nonparallel to said fan's rotational axis and at an acute angle to said blade's surface.

16. The kit of Claim 15, wherein said debris dividing means is disposed adjacent an outermost edge of said pitched blade.

17. The kit of Claim 15, wherein said debris dividing means comprises a generally triangular cutting blade.

18. The kit of Claim 15, wherein said debris dividing means further includes means for reinforcement behind said leading cutting edge.

19. The kit of Claim 15, wherein said leading cutting edge of said debris dividing means is steeply-sloped, and wherein a rearward reinforcement portion of said debris dividing means comprises a shallowly-sloped, trailing edge.

20. The kit of Claim 15, wherein said pitched blade has an arcuate outer edge, and wherein said debris dividing means, projecting from said pitched surface, has a face curved to follow the arc of said pitched blade's arcuate outer edge.

21. An axial mulching fan for a yard waste vacuum, comprising: a. at least one fan blade pitched away from a plane perpendicular to said fan's rotational axis; and, b. a plurality of teeth projecting from an upstream face of said pitched blade, each of said teeth including a leading cutting edge nonparallel to said fan's rotational axis and at an acute angle to said blade's surface.

22. An axial mulching fan for a yard waste vacuum, comprising: a. a central coupling; a. a plurality of wide fan blades projecting radially from said central coupling, each said fan blade being pitched in a like direction away from a plane perpendicular to said fan's rotational axis, whereby when said fan is rotated, said fan moves air in an upstream to a downstream direction; b. a plurality of narrow cutting blades projecting radially from said central coupling, said cutting blades being disposed out of a plane in which said fan blades reside.

23. The fan of Claim 22, wherein said cutting blades are disposed on an upstream side of said plane of said fan blades.

24. The fan of Claim 22, wherein said cutting blades are disposed on a downstream side of said plane of said fan blades .

25. The fan of Claim 22, wherein said cutting blades are disposed on both an upstream side and a downstream side of said plane of said fan blades.