BACKGROUND OF THE INVENTION

The present invention relates to an apparatus for mixing and aerating a composting material, and particularly to an apparatus which is suitable for use with a relatively light composting material such as straw.

Composting is a well-known method for converting solid wastes into a useful commodity. Composting of municipal waste and certain agricultural wastes is currently practiced on a relatively large scale. Composting is being considered for disposal of additional agricultural wastes as environmental regulations render traditional disposal methods unacceptable. In certain seed crop industries, grass seed for example, it has long been the practice to harvest the seed and then burn the relatively large volume of grass straw remaining. The grass seed industry is now under pressure however to abandon large scale burning of grass straw due to its effect on air quality. Similar pressures are being exerted on other segments of the agricultural industry as well. As a result, composting is receiving increasing attention as an alternative to some of the traditional agricultural waste disposal methods.

Agricultural composting in general involves the partial decomposition of a solid material by the action of aerobic bacteria. When practiced on a small scale, it is relatively easy to maintain the aerobic conditions required by the bacteria; it is much more difficult to do on a larger scale. Failure to maintain aerobic conditions throughout the composting material results in anaerobic decay of the material, which in this situation is less efficient than aerobic decomposition, and normally emits objectionable odors. This combination of undesirable characteristics provides strong incentive to maintain aerobic composting conditions at all times.

There are known machines for physically mixing compost to maintain aerobic conditions. An example is U.S. Patent No. 4,360,065 to Jenison et al. The Jenison cultivator comprises a horizontal rotating drum having a plurality of

cultivator blades in two helical rows. As the drum is rotated, the blades travel edgewise through a pile of composting material to move the material sideways and pile it in a generally triangular pile. The \'065 patent further describes other composting machines such as the Scarab, sold by Scarab Manufacturing and Leasing, Inc. of White Deer, Texas. U.S. Patent No. 3,369,797 to Cobey describes a compost turner and windrow forming machine having a transversely mounted rotating drum for the turning of compost piles and the redepositing of the turned up material in a windrow. Yet another composting apparatus is described in U.S. Patent No. 4,019,723 to Urbanczyk. The \'723 patent describes a mobile composter for manure which moves a rotating drum over masses of inoculated manure to flail it, mix it, cool it and aerate it, while moistening the particles as the same time. After being conditioned and moisturized, the material is formed into a pile by a rear outlet opening. As with the Cobey composter, the flails mounted on the drum of the Urbanczyk machine travel edgewise through the composting material for flailing and mixing. United States Patent No. 4,478,520 also to Cobey describes a compost turning machine which straddles a compost windrow while carrying a rotating drum for turning the composting material. The \'520 composter additionally has an adjuster auger system outboard of the rotating drum to collect additional material and deposit it in the path of the rotating drum. This is the Cobey machine referred to earlier.

These known composters are useful and effective for composting materials having a relatively high density, and which may require the addition of moisture for maintaining the proper composting conditions. However, known composting machines have proved unsuitable for use in composting relatively light, tough composting materials such as grass straw. Applicant has discovered that the unsuitability of known composting machines is due in part to their inability to throw light stringy composting materials such as straw clear of the drum to prevent the straw from fouling the drum paddles.

An additional limitation of known composting machines resides in the difficulty of transporting them from one location to another. When used in an

agricultural setting, this problem is particularly acute. It may useful for instance, to compost agricultural waste in the field where the crop is grown. Where adjacent fields are separated by a fence transporting known composting machines between fields often requires driving the machines short distances on public roads, or loading the machines onto transporters to deliver them to the adjacent fields. Commercial scale composters are so wide that they cannot be driven through standard gates and fences between adjoining fields. If the composting machine must be transported to a location other than an adjacent field the problem is further aggravated because of the width of the composting machine; it is simply too wide to be driven on a public highway. It therefore must be loaded on a low¬ boy type trailer, and to ed to the next location.

A need therefore exists for a composting machine which is suitable for use with relatively light agricultural waste products, or relatively light composting materials of any sort, and which is readily transportable between adjacent agricultural fields, or to a remote location.

SUMMARY OF THE INVENTION

It is a principal object of the present invention to provide a mixing and aerating machine for composting a wide variety of solid materials, including relatively light agricultural wastes such as grass straw.

It is another object of the invention to provide improved mixing and aeration of relatively light composting material by entraining the composting material in a stream of air for a sufficient time to thoroughly aerate the composting material.

It is another object of the invention to generate an air stream for entraining the composting material by rapidly rotating a drum assembly having a plurality of blades protruding therefrom.

It is yet another object of the present invention to generate an air stream flowing in a generally vortex like pattern within a housing on the underside of the

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composting machine for thoroughly mixing and aerating the composting material. These and other objects of the present invention will be described in the following specification and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a composting apparatus according to the present invention.

FIG. 2 is a rear view of a composting apparatus according to the present invention.

FIG. 3 is a left side view of an improved composting apparatus according to the present invention.

FIG. 4 is a right side view of an improved composting apparatus according to the present invention. FIG. 5 is a top view of a composting apparatus according to the present invention configured for treating composting material.

FIG. 6 is a top view of a composting apparatus according to the present invention configured for being driven sideways.

FIG. 7 is a front view of a composting apparatus according to the present invention configured for being towed sideways.

FIG. 8 is a right side cross-sectional view of the drum and paddle assembly according to the present invention.

FIG. 9 is an enlarged sectional view of the center portion of the drum and paddle assembly, showing the counter-rotating vortex-like airstreams generated when the assembly is rotated.

FIG. 10 is a top view of a right side paddle. FIG. 11 is a top view of a center paddle. FIG. 12 is a top view of a left side paddle.

FIG. 13 is a side view of a right side paddle showing the shear pin feature, and showing the released paddle in phantom.

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FIG. 14 is a front perspective view of a composter according to the present invention, having the drapes removed to expose the chamber and drum assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIGS. 1 and 2, a composter according to the present invention is shown generally at 10. Composter 10 includes frame 12 which is assembled from ladder-type left, right, and top subframes, 12a, 12b and 12c respectively. Frame 12 is supported at its front end by left and right drive wheels

14 and 16, and at the rear by left and right caster wheels 18 and 19. Each wheel mounted on an axle which is journaled into a supporting frame assembly 40. Each rear caster wheel is mounted into its respective frame assembly 40 by a vertical shaft journaled into frame assembly 40 as shown in FIG. 3. Each rear caster wheel may be locked into a transverse position by locking pin assembly 19 when desired as described below. Each frame assembly 40 includes an upright member 42 slidably received within a complementary vertical sleeve 44 of a mounting assembly 46. Frame assembly 40 may thereby be raised or lowered relative to the ground on upright member 42 by actuation of hydraulic cylinder 43, allowing the ground clearance of composter 10 to be raised or lowered during operation as more fully described below. Mounting bracket 46 is in turn pivotably mounted on frame 12 at brackets 48, allowing each frame assembly 40 and wheel to be pivoted by actuation of hydraulic cylinder 45 for different modes of operation as described below. As best seen by reference to FIG. 5, frame 12 includes upper deck 32 on which are mounted fuel tank 34, operator\'s cab 36, hydraulic oil tank 37, engine 38, and hydraulic pumps 40, 42 and 44. As readily appreciated by those skilled in the art, suitable auxiliary equipment for operation of the engine and drive components in dusty environments is also provided, such as rotating self-cleaning screen 41 of the cooling system of engine 38. Power for the operation of

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composter 10 is provided by hydraulic pumps 40, 42 and 44, which are driven by engine 38, preferably a 300 hp diesel engine such as Model NTH8559355 , manufactured by Cummins. Each hydraulic pump 40a and 40b, model 6421 as manufactured by Eaton, delivers pressurized hydraulic fluid to each of drum assembly drive motors 48a and 48b to reversibly drive rotating drum and paddle assembly 22 from each end. Hydraulic pumps 42a and 42b deliver pressurized hydraulic fluid to left and right drive motors 50 and 52 respectively. Pump 44a delivers pressurized fluid to hydraulic cylinders 43 for raising and lowering frame 12, while pump 44b provides pressurized fluid for operating hydraulic cylinders 45, and hydraulic cylinder 54 for raising and lowering tail section 31. Left and right drive motors 50 and 52 are separately controllable by the operator for steering and for driving left and right drive wheels 14 and 16 respectively through an appropriate drive assembly of a suitable design as could be readily determined by one skilled in the art. In the preferred embodiment, a planetary gear assembly, Model No.W-2 as manufactured by Fairfield is used on each the left side and right side drive wheel and motor assembly. The left side planetary drive assembly differs from that of the right side only in that it is rendered free wheeling for reasons described below by operation of an external T-handle. Composter 10 is steerable and drivable forwardly, rearwardly, and sideways as described below by virtue of the fact that each drive wheel is drivable forwardly and rearwardly independently of the other by appropriate hydraulic controls of standard design and well-known to those skilled in the art.

While the present invention is not intended to be defined or limited by reference to any specific dimensions, in both prior art composters and the present invention there is an efficiency of operation resulting from incorporation of a relatively long drum assembly, 17 feet or more for example. Accordingly, the overall width of the composter will be even greater than the drum length, while the overall length of the frame of the composter is preferably no greater than 8\' 6". While providing more efficient operation by requiring fewer passes to process

a given amount of composting material, the overall width of prior art composters prevents them from being driven through standard fence gates between adjacent fields, and requires that they be transported over public roads by truck and trailers designed for transporting heavy equipment. The present invention overcomes these limitations and cost disadvantages of prior art composters by providing for the first time a composter which may be driven sideways under its own power through standard fence gates or over public roads for short distances, and which may be towed for longer distances over public roads when necessary. The means of configuring the present invention for so doing will now be described. As described above and best seen by reference to FIG. 5, each wheel is mounted on a frame assembly 40 which is pivotable between a first position for accommodating forward and rearward travel of composter 10, and a second transverse position for accommodating sideways travel of the composter. Each frame assembly 40 is moved between the first and second positions by a dedicated hydraulic cylinder 45, which is controlled by means of appropriate controls (not shown) from operator\'s cab 36.

Referring now to FIGS. 1 and 14, drum assembly 22 is mounted transversely within chamber 24. Chamber 24 is an open-ended housing consisting of a top wall 26, left and right side walls 28 and 30, and tail section 31 (FIG. 5). Front opening 25 is partially shrouded as shown in FIG. 1 by front drapes 33a-c.

Tail section 31 , essentially a rearwardly extending projection of chamber 24, extends rearwardly from rear opening 27. Tail section 31 may be described as a generally planar frame having rearwardly and inwardly extending side members pivotally attached to frame 12 at one end, and to lateral member at their outer ends. Drapes 39 are hung from each side member and the lateral member as best seen in FIG. 2. The drapes may be made from any suitable material. In the present embodiment, they are fabricated from grade 2 SBR in the form of 1/2" thick conveyor belt material. Tail section 31 is pivotable by hydraulic cylinder 54 between a lowered operational position and a raised stowed position for use during transport of the composter . Rear drapes 35 are hung from each side and

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the rear of tail section 31 and from angled frame members defining rear opening 27 as shown. Chamber 24 serves to contain direct the air streams and composting material during operation of composter 10, and to reform the composting material into a windrow after mixing and aerating as more fully described below.

Drum assembly 22 is journaled at opposite ends in left and right subframes 12a and 12b. Hydraulic motors 48a and 48b are mounted on left and right subframes 12a and 12b, and reversibly drive drum assembly 22 by means of shafts 49a and 49b when supplied with pressurized hydraulic fluid from hydraulic pumps 40a and 40b as described above. Drum assembly 22 includes drum 56, a hollow cylinder having closed ends, onto which are welded shafts 57a and 57b (not shown). Shafts 57a and 57b are journaled into frame 12, and drivably connected with drum assembly drive motors 48 as described above.

Turning now to FIGS. 8-12, a plurality of left and right paddles 58 and 60 respectively, and center paddles 62 are mounted on the outer cylindrical surface of drum 56 as shown. The paddles are preferably arranged in four evenly spaced helical rows along the length of the drum, each row traversing 90° about the drum from one end to the other. It is to be understood that more or less rows of paddles may be used. Left and right paddles 58 and 60 are mounted generally to the left and right of the center point of the drum respectively, while center paddles 62 are mounted along a central portion of the drum. Center paddles 62 are preferably interspersed with the left and right paddles along portions of the drum as shown in FIG. 9. Minor variations in the number and arrangement of center paddles interspersed with left and right paddles arc possible in accordance to the present invention.

Each paddle has a base section 64 by which it is pivotably attached to bracket 66, which in turn is welded to drum 56 as shown in detail in FIG. 13. Each paddle is additionally secured in position by a shear pin 68 inserted into hole 70. Shear pin 68 serves to release the paddle to pivot rearwardly if impacted by a solid object during rotation of drum assembly 22. A deflector plate 71 is attached

at a rearward angle to a forward edge of bracket 66. Each paddle includes a cutting edge 72 formed on the leading edge of paddle body 74. Extending transversely from the trailing edge of left and right paddles 58 and 60 is a single paddle portion 76 extending inwardly toward the longitudinal center of drum 56. Center paddles 62 each have a pair of opposed paddle portions 78 extending outwardly toward opposite ends of drum 56. The paddle portions are preferably disposed at an angle slightly less than perpendicular relative to the paddle body. Each paddle portion serves to generate an air stream directed upwardly of the drum and in the direction of the free end of the paddle when the drum is rotated in a direction such that the paddle travels upwardly and then rearwardly in its circular path around the drum. Stated slightly differently, the normal direction of rotation of the drum assembly is in the opposite direction of wheel rotation when the composter is being driven forward.

Having described the construction of the preferred embodiment, its operation will now be explained. The primary function of composter 10 is to shred, mix and aerate solid composting material. While a wide range of materials can be accommodated, the preferred embodiment is particularly suited to the composting of relatively light agricultural wastes such as straw and grass. Referring now to FIGS. 4 and 6, to configure the composter for being driven sideways, each hydraulic cylinder 43 is activated to lower frame 12 onto the ground and to raise each wheel several inches above the ground. Tail section 31 is retracted to its raised stowed position by hydraulic cylinder 54. Each frame assembly 40 is pivoted to its transverse position as shown in FIG. 6; left and right drive wheels 14 and 16 are thereby aligned transversely, as are left and right rear caster wheels. Left drive wheel 14 is then drivably disengaged from left drive motor 50 by pushing T-handle 78 inward to disengage the planetary gear drive as discussed above. Each hydraulic cylinder 43 is then activated to lower each wheel and raise frame 12 above the ground. Composter 10 is now configured for being driven sideways. It is propelled in this configuration by right drive wheel 16, now facing in the direction of "forward travel", which by virtue of being fitted

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with flexible hydraulic supply and return lines is operable in the transverse position. Steering is accomplished by operation of hydraulic cylinder 45 to "swing" right drive wheel 16 slightly as required to adjust the direction of travel. After arriving at the desired location, the composter is reconfigured to its composting mode by reversing the foregoing procedure.

If it is necessary to transport the composter a greater distance, a second transporting configuration is provided which allows the composter to be flat- towed by a truck. As before, each wheel is raised above the ground, pivoted to its transverse position, and the wheels lowered, raising frame 12 above the ground. Left drive wheel 14 is drivably disengaged as before, and left rear castor is locked against castoring action by pin assembly 19. As best seen in FIG.7, a pair of auxiliary towing wheel assemblies 80a and 80b are then mounted on the right side of frame 12 by being inserted into channels 82a and 82b, and yokes 84a and 84b respectively, and secured therein by locking pins 86. Auxiliary towing wheel assemblies 80a and 80b are additionally secured by lateral link 86 which is pinned into bracket 88 and frame 12 as shown. Right side drive wheel 16 and right rear castor 20 are then raised to lower the right side of frame 12 onto towing wheel assemblies 80a and 80b. As shown in FIG. 2, fifth-wheel assembly 90 is an articulated, hinged frame assembly which is normally stored in a retracted position, and which is extended and locked into position as shown in FIG. 7 for being hooked to a truck (not shown) for towing composter 10. Fifth-wheel assembly 90 may be raised and lowered by any suitable winch assembly 92 (FIG. 6). Composter 10 thus configured may be conveniently towed over public roads with considerably less expenditure of time, effort and expense when compared to prior art composters. Upon arriving at its destination, towing wheel assemblies

80a and 80b are removed and composter is reconfigured for operation by reversing the above procedure.

While suitable for use with various composting materials, the preferred embodiment of the present invention is of particular value in the treatment of relatively light composting materials such as straw or grass wastes. Prior art

11 composters have proven generally unsatisfactory for processing such wastes due to their inability to effect adequate aeration of the materials to ensure aerobic conditions throughout the material, and due to their inability to effect adequate removal of excess moisture from the material when required. Applicants have discovered a solution to these problems in the form of the present invention wherein a novel drum and paddle assembly 22 is rotated at high speed in a direction opposite to that of prior art composters. In addition to directly impacting the composting material for shredding it, the rotating drum assembly 22 also draws air from ahead of the composter into chamber 24 and generates a high-speed stream of air in chamber 24. The high speed air stream entrains the relatively light materials and circulates them in overlapping, counter-rotating circular patterns within chamber 24 for thoroughly aerating and mixing them. The entrained materials are suspended and circulated in the air streams, and then redeposited in a windrow to the rear of the rotating drum. As a further advantage, after mixing and aerating the composting materials as described, the present invention redeposits the materials in a relatively tall, more squared-off windrow having a higher volume of materials per unit of surface area than known composters.

To begin a composting operation, engine 38 is started, and drum drive motors 48a and 48b are engaged to counter-rotate drum assembly 22, preferably at approximately 550 RPMs. Composter 10 is now raised or lowered to a desired ground clearance by activation of hydraulic cylinders 43. By so doing, composter 10 can be adjusted to process more or less material. This unique ability of the present invention allows for a more efficient composting operation by permitting greater volumes of material to be formed into a single windrow and processed in a single pass, resulting in more efficient use of the available ground area, and less processing time for a given amount of material. The height adjusting ability is additionally useful in that as the composting process partially decomposes the windrow of material, the volume of material decreases. The present invention allows the operator to readily adjust for the volume decrease without any decrease

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in the effectiveness of mixing and aeration.

Having selected the appropriate height, the operator now drives composter 10 forward to engage the composting material. As the composter engages and proceeds along the windrow, the composting material is mixed and aerated by the action of the counter-rotating drum assembly. We define counter-rotation to mean rotation in a counterclockwise direction when viewed from the right end of the drum assembly, or stated slightly differently, in the opposite direction of rotation of forward rolling drive wheels 14 and 16. Counter-rotating drum assembly draws air into chamber 24 from ahead of the composter in the form of an upwardly and rearwardly directed air stream ahead of the drum assembly, providing significant advantages as will be further explained. As composter 10 approaches, the upwardly flowing air stream first engages the windrow ahead of the drum assembly and entrains a portion of the material which travels in the air stream and which does not directly engage the counter-rotating drum assembly. Counter-rotating drum assembly 22 then engages the remaining material which is deflected by deflector plate 71 toward cutting edge 72, where the material is shredded, and then entrained in the air stream. While the precise amounts of material shredded in each pass of the composter are not known with certainty, in the processing of grass straw, for example, 3-4 passes through the composting material will normally produce a thoroughly shredded composting material.

The entrained composting material is propelled upwardly and rearwardly in a pair of generally rotating vortex-like airstreams. Each airstream rotates generally upwardly and outwardly from the center of the drum, and spirals toward the rear of chamber 24. The airstreams overlap at their inner portions, providing repeated exchange of entrained material therebetween. As the air streams begin to lose their velocity, the composting material begins to drop out of the air stream and is redeposited into a windrow. Applicants have discovered for the first time that this method of composting relatively light composting materials such as straw and grass wastes solves the aforementioned shortcomings of prior art composters; namely, that is that the relatively light wastes of this nature can be sufficiently

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13 aerated, mixed and dried as necessary by being entrained in and contacted with a relatively large volume air drawn into a mixing chamber by a drum and paddle design according to the present invention.

The airstreams are generated according to the preferred embodiment by the left, right and center paddles previously described. As best seen in FIG.9 and 14, each row of paddles according to the present invention includes a group of paddles having paddle portions 76 facing toward opposite ends of the drum. As the drum is rotated , each paddle portion 76 draws air into chamber 24 and generates a series of airstreams flowing in the direction of the drum rotation and laterally outwardly toward the end of the drum. The series of airstreams generated by the two group of similarly oriented paddle portions 76 combine to form a pair of oppositely rotating airstreams, each of which is rotating outwardly and spiralling rearwardly within chamber 24. The interspersing of paddles having opposite facing paddle portions 76 near the center of the drum creates a region in which the oppositely rotating airstreams overlap. In the overlapping region, composting material is continuously exchanged between the airstreams, providing more thorough mixing of the composting materials than has heretofore been possible. The relatively light materials remain entrained in the airstreams for a relatively long time, until the air stream slows sufficiently to cause the material to fall from the airstream. In this way, the composting material is afforded an extended contact time for aeration and drying. As the airstreams spiral rearward, they exit chamber 24 through rear opening 27 and rear tail portion 31. Rear drapes 35 serve to limit the rearward travel of the airstreams and any entrained or thrown composting materials. Applicants have discovered that the mixing and aerating effectiveness of the present invention is significantly enhanced by the use of tail section 31 , which apparently serves to promote the formation and rearward extension of the rotating airstreams, extending the contact time between the air and composting materials. The ability of the present invention to provide extended, intersticial aeration of relatively light composting materials has not been possible with prior art composters, and represents a significant advance in

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the art.

A further benefit of the present invention over prior art composters is related to the large volume of fresh air which is continually drawn into chamber 24 and into intimate contact with the composting material. This feature is also of significant benefit when composting heavier materials which may not be readily entrained in the airstream, and which are mixed primarily by being thrown upwardly and rearwardly due to contact with paddle portions 76. Even so, with the large amount of air drawn into chamber 24 in the form of high-speed air streams, these heavier materials are contacted with significantly more air under more effective aerating conditions than is possible with known composters.

Having illustrated and described the principles of my invention in a preferred embodiment thereof, it should be readily apparent to those skilled in the art that the invention can be modified in arrangement and detail without departing from such principles. I claim all modifications coming within the spirit and scope of the accompanying claims.