Comminuters comprising a series of rotatable upright comminuting roll positioned to define a comminuting chamber into which the material to be com minuted is ed, and containing a screening means to control the size of particulat matter exiting the comminuter, are well known. Such comminuters have typicall been large-scale machines requiring a relatively large power source to rotate th comminuter rolls, or to rotate a paddle impeller, to maintain orbital movement o the material being comminuted within the comminuting chamber to maximiz contacts between the comminuting rolls and the material being comminuted.

It is an object of the present invention to provide a comminuter that require a relatively smaller engine to provide rotational force and to eliminate the nee for an impeller, thereby reducing the overall power needs of the comminuter.

It is also an object of the present invention to provide a simpler and mor cost-effective comminuter.

Summary of the Invention The invention herein provides a method of comminuting that requires th introduction of the material to be comminuted into a tub or pan. The tub i rotated to impart a rotational motion to the material. The material is impacte by the teeth of a counterrotating disc. The resulting particles are screened an

those below a predetermined size are allowed to exit the tub. A comminuter for carrying out the method and reducing solid material to particulate orm includes a base and a tub rotatably mounted on the base. A first drive means is mounted on the base and associated with the tub for rotating the tub in a first direction. The tub includes a bottom wall and a disk is mounted on the base, but within the tub, for rotation in a plane parallel to the plane of the bottom wall of the tub. The diameter of the disk is smaller than the diameter of the tub and the axis of rota¬ tion of the disk is offset from the axis of rotation of the tub. A second drive means is mounted on the base and is drivingly associated with the disk for rotating the disk in a second direction, preferably opposite the tub rotation. A plurality of tooth members are mounted on the disk projecting from the disk into the tub to contact the material to be comminuted. A screening means is mounted in the bottom of the tub for allowing the exit of material of a predetermined size from the tub. In its preferred embodiment, the base of the comminuter is mounted on wheels to provide portability to the comminuter.

Prfef Description of the Drawings The objects and advantages of the present invention will be better under¬ stood by those of ordinary skill in the art and others, upon reading the ensuing specification, when taken in conjunction with the appended drawings, wherein: FIGURE 1 is an isometric view of one embodiment of the comminuter of the present invention mounted on a wheeled trailer;

FIGURE 2 is an isometric view of the comminuter of FIGURE 1 from a different viewing angle;

FIGURE 3 is an isometric view of a portion of the comminuter of FIGURE 1 showing the comminuting chamber and the toothed disk rotating therein;

FIGURE 4 is a somewhat schematic view of a portion of the comminuter of FIGURE 1 showing the drive system for the comminuting disk;

FIGURE 5 is an isometric view of a portion of the comminuting disk showing the arrangement of the teeth thereon; FIGURE 6 is an exploded isometric view of a preferred embodiment of a tooth for use in the comminuter of the present invention along with the tooth- mounting means shown in FIGURE 5;

FIGURE 7 is an isometric view of the assembled tooth and mounting means shown in FIGURE 6; FIGURE 8 is a side elevation view of the tooth assembly of FIGURES 6 and 7 showing its mounting on the disk;

FIGURE 9 is a front elevational view of the tooth assembly of FIGURE and

FIGURE 10 is an isometric view of a portion of the comminuter of FIGURE showing the interface between the input hopper and the comminuting chamber. Detailed Description of the Preferred Embodiment

FIGURES 1 and 2 show a preferred embodiment of a comminuter made i accordance with the principles of the present invention. The comminuter include a hopper 10 that is mounted atop a rectangular frame 12. Preferably, the fram 12 is constructed as a trailer suitable for hauling behind a tractor assembly (no shown) for movement of the comminuter from job site to job site. As such, th frame 12 has mounted on it an axle 14 that has suitable wheels 16 mounted there on. The frame 12 also has a pair of adjustable jack legs 18, of the type typicall associated with truck trailer assemblies, mounted at its front end to allow th trailer to stand when disconnected from a tractor assembly. A curtain assembly i mounted atop the hopper 10 and consists of the curtain frame 20, and a series o lengths of chain 21 hanging vertically from the curtain frame 20 to form a curtai that diminishes the amount of material that can be thrown up out of the hoppe and over the edge of the hopper onto the ground.

As can be seen, the material to be comminuted consists of various woo scraps or stumps 22 that are fed into the hopper using a loader (not shown). Th material 22 moves down through the hopper into a tub 24 mounted on the fram below the hopper 10. The tub is of cylindrical shape and is shown in dotted line i

FIGURE 1. The tub is surrounded by a cylindrical housing 26 that is supported b the frame members 28 and 30. Also shown in phantom line in FIGURE 1 is rotatable disk 32, which rotates within the tub. The disk has a series of teeth 3 mounted at various locations on the disk and projecting outwardly from the dis into the tub to contact the material 22 to be comminuted. The disk 32 is drive by a belt drive that is powered by a diesel engine 36 also mounted on the traile

12. The diesel engine also runs a hydraulic pump 37 that provides hydraulic pres sure to operate other portions of the comminuter, as will be described below. I addition, the diesel engine runs a blower 38 that is used to provide an airflo through the beam 30, which is hollow and which is better seen in FIGURE 3.

FIGURE 3 shows in greater detail the operation of the comminuter of th present invention. The outer cylindrical housing 26 is stationary relative to th trailer 10 while the tub 24 rotates within the cylindrical housing 26. The tub 2 includes a vertically arranged sidewall 40 that rotates within the housing 26. Th

tub 24 also includes a bottom wail comprised of a stationary circular portion 42 and an annular portion 44 that surrounds the stationary portion 42. The annular portion 44 is adjacent and perpendicular to the sidewall 40 and rotates with it. The annular portion 44 is comprised of a series of grate segments 46 that lie on an underlying framework. The grate segments 46 provide a screening function and have a plurality of holes 48 formed in them. The size of the holes 48 formed in the grate segments 46 determines the particle size that will exit the tub 24. If it is desired to change the size of the particles being produced, the grate segments 46 can be removed and replaced with other grate segments having holes of a different size formed therein. The grate segments 46 are spaced above the bottom of the cylindrical housing 26 to form a collection chamber 49 below the tub 24. An opening 50 is formed in the bottom of the cylindrical housing 26 and a corresponding opening 52 is formed in the top of the tube 30. The air passing from the blower 38 through the tube 30 causes an entrainment of the particles within the collection chamber into the airstream passing through the tube 30 so that they exit the end of the tube as shown by the arrow 54. Preferably, there is a constric¬ tion in the tube 30 to form a venturi to increase the velocity of the air passing through the tube at the position of the openings 50 and 52 to enhance the entrain¬ ment effect and thereby carry the particles away from the tub at a faster rate. In the illustrated embodiment, a plate 51 is mounted within the tube 30 just up¬ stream of the opening 52 to form the venturi restriction.

In the illustrated embodiment, the tub 24 is rotated in a clockwise direction, as shown by arrow 56, by the rotation of pneumatic tires 58 mounted on wheels that, in turn, are driven by hydraulic motors 60. As discussed earlier, the diesel engine 36 runs a hydraulic pump 37, which, in turn, provides high-pressure hydrau¬ lic fluid to the hydraulic motors 60. The hydraulic motors then drive the tires 58, which are in contact with the outer surface of the tub 24, to rotate the tub. Although only two such tires are shown in FIGURE 3, in fact, in the preferred embodiment, there are four tires spaced equidistant around the tub. The tub itself is mounted on a bearing that allows some lateral movement and the four tires 58 provide a centering force that keeps the tub rotating in an essentially noneccen- tric path but the tires have su ficient give so that, if a large piece of wood, such as a stump, or a piece of metal becomes lodged in the tub, there is some play for the tub to move with relation to the disk 32 so that the jam may free itself so that any serious damage to the comminuter caused by such a jam is prevented. Also, the tires can be inflated to a predetermined pressure so that they act as a clutch

in the event of a jam. If the tub is solidly jammed, the tires will slip on the sid wall 40, rather than trying to force the tub to the breaking point of some of th structural pieces. As can be seen in FIGURE 3, the disk 32 is rotatably mounte on an axis offset from the central axis of the tub 24. In the illustrated embod ment, the disk 32 is smaller in diameter than the tub 24 and, in fact, may b smaller in diameter than the inner diameter of the annular screening ring 44. I the illustrated embodiment, the disk 32 is rotated in a counterclockwise directio as shown by arrow 61. A quick-change hub 62 is provided to hold the disk on th shaft so that it can be easily removed in case it is necessary to replace or repa the disk.

The disk 32 contains a plurality of teeth 34 projecting therefrom and th comminuting action is carried out by the impact of the material in the tub again the teeth 34. The comminuting action is enhanced by the motion of the materi being tumbled as a result of the rotating motion of the tub. The teeth 34 on th rotating disk 32 rip and tear the material into smaller pieces. As the disk and tu rotate, the material continues to be impacted by the toothed disk and continues t be shredded and formed into particles of a size small enough to fit through th holes 48 in the grate segments 46, enter the collection chamber 49 below th bottom of the tub 24 for eventual entrainment in the airstream within tube 3 and exit from the comminuter. The teeth and the means for mounting them o the disk 32 will be discussed in greater detail below. However, it should be note that, in the preferred embodiment, the teeth that extend downwardly from th disk at its edges are set so that they just barely scrape the top surface of th bottom wall of the tub 24. This scraping action provides for further comminutio and the cleaning of the bottom of the comminuter and the holes in the grat segments 46 to keep the holes free of material.

In FIGURE 4, in a somewhat schematic fashion, it can be seen that th disk 32 is driven by a belt drive system powered by the diesel engine 36. Th diesel engine 36 drives a shaft 64 that, in turn, drives a pulley 66 that has th drive belts 68 mounted thereon. From the pulley 66 the drive belts run to a pa of quarter-turn pulleys 70 and 72, which change the orientation of the belts an allow them to wrap in a horizontal orientation about a hub 74 that is driveabl connected to a shaft 76 upon which the disk 32 is mounted. The shaft 76 comes u through a hole formed in the bottom of the tub 24 and the quick-change hub 62 i mounted on top of the shaft 76 to hold the disk 32 in place on the shaft. It shoul be understood, by those of ordinary skill in the art and others, that other driv

means can be utilized to rotate the disk 32. However, this means has been found to be satisfactory, particularly since the drive shaft 64 can also provide power to a pulley 76 mounted on the shaft to drive a belt 78 mounted on the pulley 76. The belt 78 drives the blower 38, which provides air for the transport of particles from the comminuter. As mentioned earlier, the diesel 36 also runs the hydraulic pump 37 that provides hydraulic power to the hydraulic motor 60 for purposes of turning the tub 24. Therefore, it can be seen that the single diesel engine 36 provides power to the entire comminuter or turning the tub, the disk, and providing power for the particle removal system, without the need for further power plants. Referring now to FIGURE 5, the disk 32 is shown in greater detail. The disk 32 has a plurality of openings formed in it to accept comminuting teeth. In the preferred embodiment the teeth 80 are bow-tie shaped pieces, cut from steel plate, and mounted in a rectangular holder 82 that is welded into place on the disk 32 adjacent each of the holes. The holders 82 are mounted in various angles with relation to the surface of the disk to provide the teeth mounted in them with a variety of attack angles at which they will strike material within the commi¬ nuter. In the embodiment shown in FIGURE 5, for example, looking at the teeth mounted on the outer rim of the disk 32, the first tooth 80a has its first end raised above the horizontal plane and the tooth is at approximately a 60-degree angle, whereas the second tooth 80b is at an angle of approximately 60 degrees below the horizontal plane. The third tooth 80c lies approximately in the horizontal plane. The pattern is repeated for the following teeth 80d, 80e, 80f , and so on. Similarly, the teeth placed on the interior surfaces of the disk are also angled variously to provide a greater variety of contact angles with the comminuted materials. As discussed earlier, the lowermost edges of the teeth 80 are positioned to just barely come into contact with the upper surface of the bottom wall of the tub 24. In other words, the teeth 80 scrape the bottom wall of the tub 24 and the grate segments 46 to keep the holes in the grate segments 46 open.

The teeth 80 are held in place by an interference fit within the holder 82 and also are maintained by a bolt 84 that has a head 86 that contacts one edge of the tooth 80 and a shaft that fits into a collar 88, which is welded onto the disk oppo¬ site the tooth holder 82. A lock nut 90 threadably engages the bolt 84 and is threaded on the bolt shaft to tighten the head 86 against the tooth 80 to assist in holding the tooth in place. The construction of the tooth and its relationship to the holder 82 are shown in more detail in FIGURES 6, 7, 8, and 9. FIGURE 6 shows the tooth holder 82 as

flame cut from a piece of rectangular stock. The tooth holder 82 has a recta gular aperture 92 formed through the long dimension of the holder 82. A slot cut in one face of the holder 82, slightly narrower than the rectangular ape ture 92, providing ledges 94 and 96 along the slot. Wedge pieces 98, of identic shape, are welded into the holder 82 within the aperture 92 on opposite sides the aperture. FIGURE 7 shows the wedges 98 in their mounted position. Aft the wedges 98 are welded in place, the tooth member 80 is driven into the slot a the rectangular aperture 92 until one edge of the tooth 80, shown as the right ed in FIGURES 6 and 7, rests against the bottom of aperture 92. As can be seen FIGURE 8, which is a side view of the tooth assembly, the bottom edge of t tooth 80 is resting on the block 82 and the bolthead 86 makes a third contact wi the tooth providing a three-point mounting system that provides great stability the tooth when it is in place on the disk. In addition, the placement of t wedges 98 imparts a slight twist, which is shown in somewhat exaggerated fashi in FIGURE 9, as indicated by arrows 102 and 104, to pin the tooth against t opposing edges of the ledges 94 and 96. In this manner, the tooth 80 is tight wedged into the tooth holder 82, and resists loosening due to the impact of t tooth with the material being comminuted. Preferably, as shown in FIGURES and 7, the side edges of the tooth 80 have a flat spot formed therein to accept t head 86 of the mounting bolt, and provide good contact between the bolthead a the edge of the tooth. Also, preferably, the tooth 80 is symmetrical so that, wh the tooth becomes worn on one edge from contact with material being comm nuted, it can be turned over and the second edge exposed to the material bei comminuted, thereby giving a much longer life to each individual tooth member. As is apparent from FIGURES 1 and 2, the hopper 10 has planar sidewal that slope downwardly and inwardly to form the hopper 10. The tub 24, on t other hand, is a cylindrical shape and it is therefore necessary to mate th square-sided hopper with a round-sided tub. A sealing means has been formed the interface between the hopper and the tub to prevent excess spillage of mat rial out of the tub, through the space between the bottom of the hopper and t top of the tub, while maintaining the ability to rotate the tub relative to t hopper. This sealing means is illustrated in FIGURE 10, which is a view of t comminuter looking down into the hopper 10. The hopper 10 includes sidewal 106, 108, and 110, which are shown in FIGURE 10, and a fourth sidewall that is n visible in FIGURE 10. The bottom of the hopper 10 is comprised of angled wal 112, 114, and 116 to represent one side of the hopper; a similar configuration

- o -

present on the other side of the hopper, which is not visible in FIGURE 10. A series of bars 118 is welded to the bottom of the hopper and each bar is essentially an extension of the edge of its respective wall 112, 114, and 116, as shown in FIGURE 10. The bars 118 are relatively small compared to the hopper but do extend below the bottom edge of the hopper. Coincidentally, the top of the tub 24 includes a lip 120 that extends inwardly from the vertical wall 40 of the tub below the interface with the hopper 10. The top of the lip 120 has a series of ridges 122 formed thereon, which extend above the lip 120 and are in close proximity to but do not touch the bottommost portions of the bars 118. The ridges 122 radiate approximately tangentially from the inner top edge of the lip 120 to the outer edge of the lip 120. The ridges 122 and bars 118 are arranged so that, in the preferred mode of operation wherein the tub 24 rotates in a clockwise direction, the ridges 122 and bars 118 are sweeping against one another to form a continuous seal of the space between the hopper and the tub. It should be understood that the term "seal" in the context of the present invention does not mean an airtight or watertight fit but only that large particles are pre¬ vented from passing through the space. Certainly, some dust and small particles will escape through this coarse sealing arrangement.

In a preferred embodiment, the drive means that drive the tub and the disk have a transmission attached that allows the direction of rotation of the tub or the disk or both to be reversed. In the event of a jam it is desirable to be able to reverse the direction of rotation of the disk or tub to clear the jam. The hydraulic motors 60 used to drive the tires 58 that turn the tub 24 can be operated in either direction and a valving change to alter the direction of low of hydraulic luid to the motors is all that is needed to reverse motor direction. The rotation of the disk is mechanically driven and it is necessary to include a mechanical transmis¬ sion to reverse the belt drive to cause a reversal of the direction of rotation of the disk. Referring again to the drive means for the tub, the hydraulic system that delivers fluid to the motors 60 includes a valve system that applies a prede- termined fluid pressure to the motors but will vent pressure if the tub jams. The venting of pressure prevents breakage of mechanical parts, since it will not attempt to force the tub to turn if the resistance is too great. Conditions leading to a tub jam include an overfull tub or a piece of scrap metal that becomes jammed in the tub. The comminuter disclosed herein uses a rotating tub to move the material to be comminuted in an orbital manner. A disk having several teeth projecting from

it in various locations and orientations is rotated parallel to the bottom of the t so that the teeth on the disk impact the material being comminuted. Preferabl the disk is rotated in the opposite direction to the tub rotation. A screeni means keeps the particles of material in the tub until they reach a small enou size to drop into a collection chamber below the tub and are removed to a remo location. While a preferred embodiment of such a comminuter has been describ herein, it should be understood that the illustrated and described embodiment exemplary only and that changes can be made to that embodiment, while remai ing within the scope of the present invention. For example, a screening means constructed of a series of crossed reinfor ing rods could replace the apertured segments pictured herein. Also, other dri systems could replace those described above. While an air entrainment system used to move the particles from the collection chamber, it would be possible use a conventional conveyor to accomplish that task. The precise configuration the teeth and the tooth-mounting means described herein could also be change Because of the changes that could occur without exceeding the scope of th invention, the invention should be defined solely with reference to the claims th follow.