Abstract:
A mulch plate positioned over the chute outlet of conventional mowers so that the clippings are drawn back under the mower by the circulation of air induced by covering the mower chute with the adjustable mulch plate. The clippings are recirculated until they are sufficiently small in size, at which point they are released as mulch. An adjustable mulch plate is also contemplated so that the mulch plate can be raised or lowered to increase or decrease the entrained volume between the mulch plate and the chute outlet. Because the mulch plate is adjustable, mulching can be performed on any length or height of grass (even wet grass) and for hedge trimmings and leaves. An air baffle is also provided for preventing debris from escaping between the mulch plate and the chute outlet.

Description:
This application is a continuation-in-part of U.S. application Ser. No. 08/047,802 filed Apr. 15, 1993 now U.S. Pat. No. 5,337,545. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to a mulching arrangement, and, in particular, to an adjustable mulch plate attachment for lawn mowers which can be used with any length or height of grass (even wet grass) and for hedge trimmings and leaves. The mulch plate recirculates grass clippings under the lawn mower until fine particles of mulch are deposited onto the lawn. 
     2. Description of the Prior Art 
     Mulching allows for maintaining an even soil temperature, controlling weeds and enriching soil, whereby a mixture of organic material (such as straw, peat moss or leaves) is spread over a landscape. When grass clippings from a lawn mower are sufficiently reduced in size to small particles, they may serve as a mulching agent. Conventional mowers, however, are incapable of refining grass clippings to a sufficiently small size. The typical lawn mower propels a rotary blade to cut grass into clippings and either deposits those clippings onto the lawn or directs them into a catcher. Clippings discarded on a lawn take weeks to decompose and can turn to a thatch and smother the soil rather than fertilizing it, unless the clippings are raked and removed. Catchers are undesirable since mowing must be interrupted frequently to empty the contents of the catcher. In either event, the wasted time could be better spent cutting additional grass. 
     Alternatively, mulching lawn mowers reduce expenses, increase crew efficiency and decrease waste. Mulching lawn mowers are designed to cut grass clippings into tiny particles that decompose quickly once returned to the lawn, providing nourishment and moisture to the underlying soil. In theory, mowing time can be cut, fertilizer, trash bag and water expenses reduced, and productivity enhanced. Unfortunately, mulching lawn mowers used today are only useful under special conditions and require frequent maintenance. For example, mulching mowers normally require short, dry grass, flat landscapes and frequently honed blades. These mowers also leave uncut strips that necessitate recutting, especially on lawns having a high moisture content, tall grass or hills. In addition, moist grass that is cut has a tendency to stick to the underside of the conventional mulching mower, reducing the mulching capability and eventually dropping clumps of grass on the lawn. 
     Conventional mulching mowers suffer from the foregoing shortcomings or they are too complex to operate reliably. For example, U.S. Pat. No. 5,117,616 to McLane discloses a mulching lawn mower that deposits clippings in front of the mower for recirculation. McLane&#39;s mower comprises a deck which covers a rotating blade and a curved deflector which lies adjacent an opening provided in the deck between the front wheels. The deflector redirects air and grass exiting the opening downward in front of the mower. The positioning of the opening and deflector at the front of the deck allows the mower to run over grass clippings a second time, but if the grass is too wet, the opening clogs and suction under the deck becomes insufficient to lift the wet clippings off the lawn and into the cutting area. 
     An air-floated mulch recycle system, issued to Fassauer in U.S. Pat. No. 5,123,235, employs an air-floated housing having a rotatable cutting blade, an open bottom, an air intake opening conduit and a rear discharge port. A mulch recycling system comprised of a conduit attaches to the discharge port to receive grass clippings produced by the mower for delivery to the front of the mower for recutting. An air impeller means pressurizes air to float the mower, but inhibits the mower&#39;s ability to draw grass clippings into the mulch recycling system. Moreover, dry grass is preferred for cutting since wet clippings are difficult to lift into the blade, stick to the underside of the housing and clog the tubular chute used in the mulching system. 
     Another mulching device is disclosed in U.S. Pat. No. 5,048,279 issued to Badawey, and is utilized as a leaf mulcher for use with a rotary blade lawn mower. The leaf mulcher comprises a rotary blade lawn mower, a grass outlet and a screen mounted on the mower over the outlet. The screen provides a cutting edge for leaves dispersed from the outlet of the mower but does not facilitate the mulching of grass clippings, is easily clogged and is ineffective on damp lawns. 
     While the aforementioned background art discloses various designs for mulching debris from a rotary lawn mower, there is no disclosure of a low profile design that is adaptable to most mowers and capable of reducing clippings of various types (e.g., high grass or wet grass), and under diverse conditions, to a mulch for discarding as a nutrient into lawns. There is, therefore, a need for a mulching lawn mower that is able to reduce clippings from tall and wet lawns into fine particles for depositing the particles back into the lawns as a fertilizing nutrient. This invention is intended to solve these problems which are not adequately resolved by the background art. 
     SUMMARY OF THE INVENTION 
     The present invention includes a mulching arrangement comprising an adjustable mulch cover or plate which adaptably attaches to the chute of conventional lawn mowers to facilitate the refinement of grass clippings into tiny particles for dispersal into lawns as a fertilizing agent. The typical lawn mower with which this invention is best suited comprises a housing having a deck with an integrally formed peripheral skirt, a chute or outlet located on the front, rear or side of the mower adjacent, and usually defined by, the skirt, a motor supported by the housing, and rotatable blades that depend from the underside of the deck. The rotating blades are preferably high-lift blades with aerodynamic features that enhance the creation of a low pressure above the cutting blades which lifts grass into the blades for cutting. 
     In one embodiment, the outlet of the mower is shielded by a mulch cover or plate. The mulch cover is comprised of a front plate connected to an upper support flange, a lower lip, and partial end walls, all of which depend inwardly toward the mower deck. The upper support flange is provided with support brackets that pivotally connect to the lawn mower, allowing the mulch cover to be lifted for inspection of the blade area or for cutting in confined spaces. In addition, one or both of the support brackets is pivotally connected to a mulch plate angle adjustment support on the lawn mower which allows the mulch plate to be secured in a variety of positions with respect to the lawn mower chute. Each angle corresponds to a different mulching or entrained volume for accommodating different grass conditions, e.g., long grass, wet grass, etc. By &#34;entrained volume&#34; is meant the space under and adjacent to the mower deck through which the clippings pass during cutting, mulching, and expulsion from the mower. If the mulch plate begins to clog, the operator simply raises the mulch plate to the next higher setting, until the grass is mulched satisfactorily. The lower lip prevents matter from being thrown past the mulch plate when the plate is rotated beyond a lowermost position. In addition, an air flow baffle may be used with the adjustable mulch plate if the plate is adjusted to be used at large angles and entrained volumes, so as to protect the operator from being struck by debris exiting between the mower chute and the mulch plate and to reduce the accumulation of debris on the top surface of the mower. 
     The upper flange of the mulch cover may be connected to the front plate in such a way that it is positioned at an angle relative to horizontal to facilitate adjustment of the mulch plate relative to the deck through a variety of positions, each of which alters the dimensions of the entrained volume to correspond to lawn conditions and to foster the recirculation of clippings and other mulchable material. The lower lip of the mulch plate prevents clippings ejected through the chute and received by the cover from prematurely dropping into the grass due to gravity before they are sucked back below the blades for recurring. The lower lip also completes the partial enclosure over the chute or outlet to create a channel for the circulation of air to control the flow of grass clippings within the entrained volume. The front end wall of the mulch plate depends from the upper flange along the front of the mulch plate, leaving a space (&#34;front opening&#34;) between the bottom edge of the end walls and the lower lip on each side. A space is also defined by the rear end wall and lip (&#34;rear opening&#34;). These spaces provide a front opening and a rear opening for permitting air and debris to escape from the entrained volume to achieve the right pressure balances inside the entrained volume. It is believed that clippings that are mulched to a sufficiently reduced size are expelled out of the front opening in the cover, while larger clippings are pulled back into the entrained volume by the air flow created by the rotating blades, and in particular by the reduced pressure above the rotating blades. A hinged safety flap may be employed to cover all or a portion of the rear opening to maintain proper air circulation and to prevent clippings not yet satisfactorily mulched within the entrained volume from escaping while releasing heavier debris that would otherwise clog the mulching chamber. hinged safety flap is biased in a closed position by gravity or any other biasing element. 
     Unlike the background art, the present invention forms a variable volume pressurized chamber and a unique air ventilation system by partially shielding the outlet of the chute with the mulch cover. When the mower blades are rotated, a flow of air is created due to low pressure above the blades such that grass is drawn upward with the air flow into the rotating blades, ejected out the chute, and redirected by the mulch cover back into the housing for recirculation. The mulching arrangement utilizes pressure gradients created under the deck to accelerate air so that grass clippings expelled by the centrifugal and air pressure forces of the rotating blades are blocked from exiting the chute beyond the mulch plate and consequently are pulled back into the cutting volume below the mower deck. During operation, a lower pressure is produced above the rotating blades than below the blades, creating a suction that lifts grass and clippings into the blades. The centrifugal force created by the rotating blades forces the clippings outwardly through the chute where they engage the mulch cover. The adjustable mulch cover constrains the clippings until the air flow created by the blade rotation lifts and carries the clippings into the blades. 
     It is an object of the invention to provide a device for attachment to lawn mowers which causes mower clippings to recirculate under the lawn mower until fine particles of mulch are produced for dispersal into lawns as a fertilizing agent. 
     An additional object of the instant invention is to provide a mulching arrangement comprised of a cover that shields a lawn mower chute while providing a unique air venting system to create an air circulation pattern that continuously recycles mower clippings under the housing. 
     A further object of the instant invention is to provide a mulching arrangement for use with conventional lawn mowers that reduces grass clippings into tiny particles so that raking and bagging are no longer necessary, thereby saving time and money. 
     Another object of the instant invention is to provide a mulching arrangement that pivotally connects to a lawn mower so that complete removal of the mulch plate is unnecessary when mulching is not to be performed. 
     Another object is to provide an adjustable mulch plate that can be secured to a mower at different angular orientations to create different entrained volumes for mulching any length or height of grass (even wet grass) and for hedge trimmings and leaves. 
     A further object of the instant invention is to provide a mulching arrangement that is simple in design and construction. 
     Still another object is to provide a mulching arrangement for use with various lawn mowers that is capable of reducing leaves and other lawn debris into fine particles of mulch. 
     Yet another object of the invention is to provide a mulching arrangement that is useful and effective in wet and tall grass, and on uneven terrain. 
     Another object of the invention is to provide an adjustable mulching arrangement that protects the operator from debris exhausted from the mulch plate when the mulch plate is raised to create a large entrained volume for cutting tall grass or wet grass. 
     Still another object of the invention is to provide an adjustable mulching arrangement that prevents an accumulation of debris on the deck of the mower when the mulch plate is raised. 
    
    
     In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the mulch plate of the instant invention attached to a convention lawn mower; 
     FIG. 2 is an exploded view of the mulch plate and the lawn mower housing; 
     FIG. 3 is a bottom view of the mulch plate and lawn mower housing; 
     FIG. 4 is a partial perspective view of the mulch plate attached to a mower deck showing a hinged flap in its normally closed position; 
     FIG. 5 is a partial perspective view of the mulch plate attached to the mower deck showing the hinged flap in an open position; 
     FIG. 6 is a front end view of the mulch plate attached to the mower deck; 
     FIG. 7 is a front end view of the mulch plate rotated relative to the mower deck; 
     FIG. 8 is a front cross sectional view of the mulch plate and lawn mower housing; 
     FIG. 9 is a front cross sectional view of the mulch plate in operation; 
     FIG. 10 is an exploded view of another embodiment of the invention and a conventional mower deck; 
     FIG. 11 is a cross sectional view of the adjustable mulch plate with an air restrictor according to another embodiment of the invention; 
     FIG. 12 is a cross sectional view of the adjustable mulch plate and air restrictor with the mulch plate in an intermediate position; and 
     FIG. 13 is an exploded view of the adjustable mulch plate and air restrictor. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the drawings, FIGS. 1-9 depict a mulching arrangement generally characterized by the reference numeral 10, comprising a mulch plate or cover 11 connected to a conventional lawn mower 12. The lawn mower 12 is comprised of a housing 13 having a deck 14 integrally combined with a depending skirt 16 around its peripheral edge, a motor 18 attached to the upper side of deck 14, a plurality of rotatable blades 20 suspended from the underside of the deck 14 and a discharge chute or outlet 22 defined by a portion of the skirt 16 in the side of the housing 13. The lawn mower is supported by front wheels 15 and rear wheels 17 which allow the lawn mower to be transported easily over the ground. The rotatable blades 20 which depend from the deck 14 are typically aerodynamic or high-lift in design, such that when driven by the motor 18, grass is lifted for cutting and simultaneously propelled outward towards the chute 22. Grass clippings, along with other shredded debris, are prevented from immediately leaving the chute 22 by the mulch cover 11, which is attached to the deck 14 adjacent the chute 22. 
     The essence of the present invention is found in the mulch cover 11, which provides a means for blocking the expelled mower clippings such that the clippings are recycled back into the cutting chamber 21 defined by the mower deck 14. The mulch cover 11 is comprised of a side wall or plate 24 formed with an upper support flange 26, a lower lip 28, a rear end wall 30, and a front end wall 32, all of which generally enclose the chute 22. The mulch cover 11 attaches to the deck 14 between front wheel 15 and rear wheel 17, wherein the side wall 24 is disposed in a generally vertical plane normal to the path of exiting clippings to block and contain same when the mulch cover 11 is in the position shown in FIGS. 1, 4, 5, and 6. The upper support flange 26 acts as an upper wall or ceiling and preferably forms an obtuse angle with side wall 24 along its upper edge. The rear end wall 30 and the front end wall 32 depend downwardly from opposite sides of the upper support flange 26 and, preferably, but not by limitation, normal to the end wall 24 to provide partial side enclosure walls. Moreover, the heights of the rear end wall and the front end wall are preferably less than that of the side wall 24 so as to create front and rear vents or air escape openings. A lower lip 28 is connected to and protrudes inwardly from side wall 24. The lower lip 28 in the preferred embodiment forms a right angle with the end wall 24, but may be otherwise and still fall within the scope of the instant invention. A front opening 36 is defined by the area between the bottom edge of front end wall 32 and lower lip 28, while a rear opening is defined by the area between rear end wall 30 and lower lip 28. A hinged flap 38 may be attached to the lower edge of rear end wall 30 to cover the rear opening. 
     The attachment of mulch cover 11 to the housing 13 is facilitated by support brackets 40 which protrude from the upper surface of upper support flange 26. The support brackets 40 pivotally mate with corresponding support members 42 that protrude from the housing in proximity of the chute 22. Alternatively, the mulch cover 11 may be fixedly secured to the housing 13. When aligned, apertures 41 and 43, found in support brackets 42 and corresponding apertures 41&#39;, 43&#39; defined by support member 42, respectively, facilitate the connection of same. A crossbar 44 protrudes vertically from the upper side of the deck 14 along the upper edge of chute 22, adjacent members 42. Upon attachment, the free edge of upper flange 26 rests on the upper edge of the crossbar 44, and air vents 46, 48 are formed at the end walls 30, 32 and between the top edge of the crossbar 44 and the mulch cover 11. The air vents 46, 48 allow air to escape from the pressurized chamber 50 formed by the cover 11 and chute 22. 
     The structure and arrangement of the instant invention is unique in that an entrained volume or chamber 50 employing a novel pressure gradient maintenance arrangement is formed on a side of the mower by placing mulch plate 10 adjacent the chute 22. A pressure gradient and, it is believed, a vortex of air are produced under the housing and in the volume 50 when the blades are rotated, such that grass is pulled upward into the rotating blades 20 where it is cut and ejected toward and out of the chute 22, into the volume 50, constrained momentarily there and then sucked into the cutting volume below the blades for recutting until the desired reduction in size, in mulching, has been accomplished. 
     Referring to FIGS. 8 and 9, the rotation of the high-lift blades 20 creates a higher pressure above the blades than below the blades, such that grass is lifted upward into the cutting edge and clippings are ejected outward by the centrifugal force of the blades through the chute 22 into the volume 50. When viewed from the front of the lawn mower, the air vortex V circulates in a clockwise direction, such that air is drawn upwardly over the blades out into the entrained volume 50 and back under the blades into the low pressure volume 21a. By placing a mulch cover 11 over the chute 22, pressure differentials are created and utilized to create an air vortex that circulates from under the housing into the volume 50 and back into the cutting volume. The mulching arrangement utilizes the pressure differentials created under the deck to accelerate air so that grass clippings C expelled by the centrifugal force of the rotating blades get pulled back into the cutting volume. Through experimentation, it has been observed that the clippings expelled from the post-cut volume 2lb collect generally toward the front of the mulch cover 11 near the front end wall 32, while clippings C already sufficiently reduced are expelled out of volume 50. Larger clippings are pulled back into the cutting volume 21 by the air flow, as shown by the larger arrow in FIG. 9. Mulch cover 11 constrains the material at its rear 36 long enough for the air vortex created by the blade rotation to lift and carry the clippings from the volume 50 back the cutting volume 20. Clippings recirculated into the high pressure volume 21a are drawn to the cutting edge of the blades 20 via the suction created from the low pressure volume 2lb above the blades. The lower lip 28, while providing the lower portion of mulch cover 11, prevents heavier clippings ejected from the cutting area 21 from prematurely dropping to the ground before being recirculated into the blades by the air vortex. The front opening 36 allows clippings that have been sufficiently refined to escape through that opening. Large debris, such as rocks or twigs, exit the housing 13 with enough force such that they displace hinged flap 38 and escape. Flap 38 may be positioned over the rear opening in a normally closed position such as that shown in the drawings. The air vents 46 and 48 act as pressure release orifi to maintain the proper pressure gradient in the volume 50 and cutting volume 20. Of course, the vent openings must be designed so that they are not too large. Otherwise, a vortical circulation of air would not occur and an acceptable pressure gradient would not be established. The rotation of the blades 20 is clockwise when viewed from the bottom so that the centrifugal force is directed toward the chute 22. 
     It should be noted that the present invention is useful for dry lawns as well as wet ones, where the unique air circulation system causes wet clippings to be rapidly shaken dry, reducing the tendency of clippings to stick to the underside of the housing 13. It should be further noted that this system is also capable of mulching leaves and small twigs that are commonly picked up by a lawn mower. The mulch cover also blocks larger matter discharged from the mower such that injuries are prevented. The venting system facilitated by vents 46, 48 meters the amount of air that circulates under the housing and in the volume 50. Too large an opening in the form of vents 46, 48 prevents the clippings C from being recirculated. Meanwhile, too small an opening in the form of vents 46, 48 dampens the air circulation pattern V. 
     FIG. 10 shows another embodiment of the invention comprising an adjustable mulch plate 100 generally similar to the mulch plate 11 in FIGS. 1-9, but which may include an extended lower lip 130 and a longer support bracket 110 defining a first aperture and a second aperture, A and B, respectively, instead of one aperture 41&#39; as in the previous embodiment. The support bracket 110 is pivotally connected to an angle adjustment support 120, which is secured to the deck 14 of the lawn mower, with any conventional connection such as a bolt and nut arrangement 107 inserted through aperture A and a corresponding aperture 109 provided in the angle adjustment support 120. The angle adjustment support 120 is also provided with a series of angle adjustment apertures C, each of which may be aligned with aperture B on support bracket 110 when the support bracket 110 is connected to the angle adjustment support 120. A pin 140 is placed through aperture B and one of the angle adjustment apertures C on the support 120. In this manner, the position of the mulch plate 100 and, accordingly, the size of the entrained volume chamber 50, can be adjusted depending on the type of mulching to be performed. For example, larger entrained volumes are necessary to maintain proper mulching for wet or tall grass. The mulch plate 100 can be secured in various different positions, and the operator has control over the size of the entrained volume and can easily modify the position of the mulch cover for a desired job by removing pin 140, adjusting the orientation of plate 100, and reinserting pin 140 through aperture B and a corresponding one of aperture C. A channel 150 is provided in the crossbar 44 so that the mulch plate 100 can be rotated into and beyond the position shown in FIG. 7. This is necessary since the end of the support bracket 110 adjacent the pin 140 rotates outwardly beyond the crossbar 44 when the mulch plate 100 is rotated over the mower such as when the mower is being transported or stored. Also, the mulch plate includes an extended (safety) lip 130 so that, when mulch plate 100 is raised, the plate 100 still tends to prevent debris from being projected from the chute and the mulch plate which could result in an injury to the operator or others in close proximity to the mower. 
     FIGS. 11-13 show yet another embodiment of the invention wherein the mulch plate 100 includes an air constrictor 200 for preventing debris from being expelled from between the upper flange 26 of the mulch plate 100 and the top edge of the crossbar 44. The air constrictor 200 may, for example, comprise a long hinge (e.g., a piano hinge), a first member 201 which is secured to the underside of the upper flange 26, and a second member 202 which defines slots 220 (see FIG. 13) which are slidably engaged with pins 210 secured to the outboard side of the crossbar 44 or the outboard edge of the deck 14 of the mower. When the mulch plate 100 is lifted, as shown in FIG. 12, the constrictor 200 is opened, and the lower half 202 is slidingly raised against the edge of the deck 14 and/or the crossbar 44 by virtue of the arrangement of pins 210 and slots 220. The constrictor 200 prevents debris from being projected out from between the chute and the mulch plate toward the operator (which can pose a particular danger where, for example, the mower is a riding type mower), as well as preventing debris from being deposited on the deck 14 of the mower. The mulch plate 100 and constrictor 200 may be made from metal, wood, plastic, rubber or almost any other material so long as it serves its intended purpose. 
     The instant invention has been shown and described herein in what are considered to be the most practical and preferred embodiments. It is recognized, however, that departures may be made therefrom within the scope of the invention and that obvious modifications will occur to those persons skilled in the art.