Abstract:
A mobile paper shredder has a first feed compartment, a first receptacle lift associated with the first feed compartment for conveying paper to the first feed compartment, paper shredding implements disposed to receive paper from the first feed compartment and discharge shredded paper, a conveyor disposed to receive shredded paper discharged by the paper shredding implements and to convey shredded materials to a storage container disposed to receive shredded paper from the conveyor, a second feed compartment on the storage container, and a second receptacle lift associated with the second feed compartment for conveying paper into the second feed compartment, the storage container disposed to receive paper from the second feed compartment to store the paper for hauling away. The mobile paper shredder permits the operator to load both paper for shredding and paper that does not require shredding simultaneously, thus saving time and energy previously required to shred all materials, including materials that did not require shredding.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to an improved mobile paper shredder having a dual capacity as a shredder and a transfer truck.  
         [0002]     Truck-mounted paper shredding assemblies (“shredders”) are commonly in use today. These units move about from one office to another to shred often confidential paper documents.  
         [0003]     For a long time, mobile paper shredders used knives or cam type cutting devices to shred the paper into strips. In general, these shredders rely on manual feeding of paper to ensure that the paper enters the machine at an even thickness and rate. As a consequence, they are relatively slow in processing paper.  
         [0004]     U.S. Pat. No. 5,542,617, issued to D. E. Rajewski, discloses the use of a rotary hammer mill to shred the paper. Canadian patent No. 2,225,900 issued, Sep. 26, 2000, discloses a further truck-mounted paper shredder. The shredder uses a reciprocating plunger to feed a rotary hammer mill, which shreds the paper. An auger is used to transfer the shredded paper into a discrete storage container. The container includes a suction device to pull dust through the assembly into a filter in the container. The container is separate so that it can be removed when loaded and left standing for later pick up, allowing the truck and shredder to take on an empty container and move on to the next job.  
         [0005]     While these hammer-type paper shredders appear to have performed their intended functions, paper dust caused by the hammer action caused an explosion hazard and the feed mechanisms were awkward to use. Canadian patent application 2,432,199, filed Jun. 13, 2003 by the inventor of the present application, sought to remedy some of these problems. It discloses an improved feed mechanism, as well as a sprayer to keep down dust caused by the paper shredding implements.  
         [0006]     While the sprayer works well to reduce the risk of an explosion hazard, further improvements to a paper shredder, particularly an improved mobile paper shredder using hammers are disclosed in U.S. patent application Ser. No. 10/771,122 filed Feb. 4, 2004 by the present inventor. It discloses an auger with wear plates on the flights that may be made of spark resistant material and may be replaced.  
         [0007]     The same application also describes an improved transfer truck for times when either the location of the materials for shredding or the quantity of materials for shredding make it inconvenient to shred the materials on site. For example, if the location is far from a recycling facility or otherwise particularly remote, the added time and expense involved in shredding the materials on-site and then hauling them to another location for recycling, or alternatively, in leaving the container on-site for later retrieval, might make it uneconomical or not feasible to shred materials on-site if there is a lack of extra containers to be left behind. Also, some sites may have such a great quantity of materials for shredding that multiple containers would be required, and in consequence, multiple trips to retrieve those containers would also be required.  
         [0008]     While the transfer truck described allows for sorting materials at the time of collection rather than requiring sorting at a shredding and/or recycling facility, it has the drawback of not having the capability of the mobile shredder. At the same time, the mobile shredders known in the art assume that all materials picked up at a location require shredding, and therefore, everything goes through the shredder, even if this is not necessary.  
       SUMMARY OF THE INVENTION  
       [0009]     There is therefore provided in accordance with an aspect of the invention, a mobile paper shredder, comprising:  
         [0010]     a first feed compartment;  
         [0011]     a first receptacle lift associated with the first feed compartment for conveying paper to the first feed compartment;  
         [0012]     paper shredding implements disposed to receive paper from the first feed compartment and discharge shredded paper;  
         [0013]     a conveyor disposed to receive shredded paper discharged by the paper shredding implements and to convey shredded materials to a storage container disposed to receive paper from the conveyor;  
         [0014]     a second feed compartment on the storage container;  
         [0015]     and a second receptacle lift associated with the second feed compartment for conveying paper into the second feed compartment, the storage container disposed to receive paper from the second feed compartment to store the paper for hauling away.  
         [0016]     These and other aspects of the invention may be found in the detailed description that follows and in the claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     There will now be described a preferred embodiment of the invention, with reference to the drawings by way of illustration only, in which like reference characters denote like elements and in which:  
         [0018]      FIG. 1  is a side elevation showing a shredder mounted on a truck, the shredder being shown in section;  
         [0019]      FIG. 2  is a front end elevation of the shredder, showing internals in broken lines;  
         [0020]      FIG. 3 a  perspective view, with part of the housing and some parts removed, showing the internals of the feed compartment of the shredder;  
         [0021]      FIG. 4  is a side view of a hopper divider according to the invention;  
         [0022]      FIG. 5  is a side elevation, in section, showing the shredder and storage container linked in working relationship;  
         [0023]      FIG. 6  is side view of the paper shredder of  FIG. 6 ;  
         [0024]      FIG. 7  is a perspective view of the auger assembly; and  
         [0025]      FIG. 8  is a perspective view of the dual receptacle lifts on the paper shredding assembly. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0026]     Having reference to  FIG. 1 , a paper-shredding assembly  1  is shown mounted on a truck  2 . The assembly  1  comprises a shredder  3 , a storage container  4 , and receptacle lifts  5 A and  5 B.  
         [0027]     More particularly, the shredder  3  comprises a housing  6  forming an upper feed compartment  7  and a lower chamber  8 .  
         [0028]     The feed compartment  7  is generally rectangular and has top, bottom and side walls  9 ,  10 ,  11  and first and second ends. At its first end, the top wall  9  forms a paper feed opening  13 A having a hinged lid  14 A. In one embodiment, the receptacle lift  5 A may comprise lifting arms  15 , pivotally attached to the housing  6 , provided to lift a receptacle  16 A and tip it to empty contained paper into the paper feed opening  13 A. A hydraulic cylinder  17 , pivotally attached to the housing  6  and arms  15 , is provided to actuate the arms.  
         [0029]     In a preferred embodiment, the receptacle lifts  5 A and  5 B, as shown in  FIG. 8 , comprise guides  86 A and  86 B which permit movement up and down for receptacle holders  87 A and  87 B to which attach receptacles (not shown) containing materials to be shredded or simply hauled away, as the case may be. The guides  86 A and  86 B are pivotally attached to hydraulic cylinders  88 A and  88 B, provided to force the guides  86 A and  86 B outward and cause the receptacles (not shown) to tilt and be emptied into the feed openings  13 A and  13 B.  
         [0030]     Rubber belting  18  hangs partway down from the compartment top wall  9  and divides the compartment  7  into first and second sections  19 ,  20 . The feed compartment bottom wall  10  forms a hammer mill opening  21  adjacent its second end. A sloped baffle  100  extends down from the first end side wall  11  and combines with the belting  18  to form a downwardly tapering feed passage  101 .  
         [0031]     A plunger  22  is located beneath the baffle  100  and on the bottom wall  10  at its first end. The plunger  22  extends transversely across the width of the feed compartment  7 . A hydraulic cylinder  24  is connected at one end with the plunger  22  by a lug  25  extending through a slot (not shown) in the bottom wall  10 . At its other end, the cylinder  24  is connected with a stationary lug  26  connected to the underside of the bottom wall  10 . The cylinder  24  contracts to advance the plunger  22  along the bottom wall  10  toward the hammer mill opening  21  and expands to retract the plunger to the first end of the compartment  7 . The cylinder  24  is actuated by the truck&#39;s hydraulic system (not shown). It is contemplated that an auger could be substituted for the plunger  22 . However, the plunger  22  is preferred.  
         [0032]     A hammer mill  30  is positioned in the lower chamber  8  immediately below the opening  21 . The mill  30  comprises a shaft  31  carrying flails or hammers  32 . It is contained within a semi-circular screen  33 . The hammer mill is mounted to the side walls  11 . It is driven by a pulley and belt system  34  connected with the power take-off (not shown) of the truck  2 . The hammer mill  30  is positioned so that its hammers  32  will protrude through the opening  21  up into the feed compartment  7  when rotating. A wall  35  combines with the housing  6  to form a narrowing hopper  36  for guiding shredded paper produced by the mill down to the auger assembly  40 .  
         [0033]     The auger assembly  40  comprises a screw auger  41  working within a transfer tube  42 . It is mounted to the compartment side walls  11  and is below and aligned with the hammer mill  30 . The transfer tube  42  is semi-circular along its length within the lower chamber  8  and then changes to a fully tubular form as it extends through the side wall  11 . As shown, the auger assembly  40  protrudes out of the housing  6 . The auger at this end is longer than the tube  42  so that the flights  43  will release the paper being transferred and act like a screw to compress paper in the storage chamber  47 . The auger  41  is driven by the pulley and belt assembly  34 . The auger  41  is coupled to the assembly  34  by a planetary gear (not shown) so that it can apply increasing torque at constant rotational speed, to maintain its feed rate while compressing the shredded paper  44 .  
         [0034]     Alternatively, as shown in  FIG. 7 , the transfer tube  42  may have a relief slot  84  in the top to allow paper to be removed from the auger  41  in the event of a jam in the transfer tube  42 . The relief slot  84  has the added advantage of allowing shredded material to spill out of the transfer tube  42  over a broader area during normal operation.  34 . If the transfer tube has a relief slot  84 , the flights  43  may be confined entirely within the transfer tube  42 .  
         [0035]     The auger assembly  40  may also be driven by a direct drive from the vehicle transmission. In this embodiment, the vehicle engine is connected to the transmission, from which a shaft  34  extends to a gear on the rear axle. The gear will have a high speed, low speed and neutral position. A pulley hub on the shaft is connected by a pulley to the auger through an auger gear that also has a neutral position. To drive the auger, the rear gear on the vehicle is place in neutral and the auger gear engaged. In this manner, the auger may be driven by the vehicle transmission.  
         [0036]     As shown in  FIG. 5 , the storage container  4  has an inlet  45  through which the auger assembly  40  extends. A filter  46  is mounted to the container  4  within the upper reaches of the storage chamber  47  and is connected with an external blower  48 . The blower  48  exerts suction to pull air through the shredder  3  and storage chamber  47  to remove dust. The dust accumulates in the filter  46  and can be dislodged at the end of the shredding run by an air hammer  49 , so that it drops into the loaded storage chamber  47 .  
         [0037]     In operation, a loaded receptacle  16  from the office is wheeled to the mobile shredder assembly  1 . In the embodiment shown in  FIG. 2 . the arms  15 , biased by the cylinder  51 , are actuated to lift and tip the receptacle so that its contents are dumped into the feed compartment front section  19 . The paper slides down the baffle  100  to the front of the plunger  22 . The plunger biases it to the hammer mill opening  21 . The hammers  32  engage and drive the paper into the impact fingers (not shown) to shred the paper. The belting  18  isolates paper thrown up by the hammers and keeps it in the compartment back section  20 . Shredded paper exits the hammer mill screen  33  and drops through the hopper  36  into the open auger  41 . The flights  43  of the auger advance the shredded paper into the storage chamber  47 . The last few flights  43 , located beyond the end of the transfer tube  42 , function to compress the shredded paper as it fills the chamber  47 . The blower  48  functions to draw produced dust through the shredder  3  and storage container  4  into the filter  46 , wherein the dust collects. The air hammer  49  can be actuated at the completion of shredding, to dislodge the dust so that it drops into the loaded storage removal for removal.  
         [0038]     In a preferred embodiment, as shown in  FIG. 8 , the receptacle ( 16  in  FIG. 2 , but not shown in  FIG. 8 ) will be attached to receptacle holder  87 A for shredding or  87 B if shredding is not required. The receptacle holder  87 A or  87 B moves in an upwardly fashion on the guides  86 A or  86 B to the top of the guides  86 A or  86 B where the guides  86 A or  86 B abut the opening  13 A or  13 B. The cylinder  88 A or  88 B moves the guides  86 A or  86 B outward to cause the receptacle (not shown) to tip and empty its contents into the opening  13 A or  13 B. Shredding of materials is as previously described. Receptacle lift  5 A, comprising the guides  86 A, receptacle holder  87 A, and cylinder  88 A, which is associated with the shredder  3  operates independently of receptacle lift  5 B, comprising the guides  86 B, receptacle holder  87 B, and cylinder  88 B, which is associated with the storage container  4 . Receptacle lifts  5 A and  5 B may also be operated at the same time.  
         [0039]     Referring now to  FIGS. 2 and 3 , a sliding gate  52  divides the feed compartment  7  into a temporary storage space A and a paper shredding space B. The gate  52  is preferably mounted transversely between the feed opening  13  and the hammers  32 . The gate  52  may slide on guides (not shown) on either side of the feed compartment  7  or may be supported by a rack (not shown in  FIG. 4 , but see  FIG. 5  discussed below) or other suitable mechanism in the feed compartment  7 . The gate  52  may terminate in its travel against the ramp or sloping baffle  100 .  
         [0040]     An embodiment of the gate  52  is further illustrated in  FIG. 4 . In this embodiment, the upper part of the walls  11  of the shredder form a hopper  60  having a hinged lid  62 . The hinged lid  62  has flanges  64  which surround the opening  13  through which paper may be fed into the shredder. The lower part of the walls  11  surround a paper shredding compartment  65  that contains a hammer mill  30 . A ribbed arcuate feed floor  66  guides paper from the hopper  60  towards the hammer mill  30 . A further ribbed feed floor  68  extends at the rear of the shredding compartment  65 . The hammers  32  pass through between ribs of the ribbed floors  66 ,  68  in conventional fashion. Shredded paper falls through to an auger  40  below the hammer mill  30 . Gate  52  slides on a rack  70  that is secured to the compartment  65 . A hydraulic cylinder  72  may be used to open and close the gate  52 . A further hydraulic cylinder  74  for opening the lid  62  is mounted on an arm  76  extending from the rack  70  and attached to the lid  62  through a pivoting link  78 . Both hydraulic cylinders  72 ,  74  may be powered by the truck hydraulics.  
         [0041]     In both  FIGS. 3 and 4 , gate  52  divides the shredder into paper storage compartment A and shredding compartment B. The gate  52  may be closed to allow paper to be placed in A while paper in B is being shredded. Once paper in B is shredded, the gate  52  may be opened while the feed compartment opening remains closed to release paper from A into B. This arrangement provides an air lock effect that reduces discharge of paper fragments and dust into the air and regulates the supply of paper into the paper shredding compartment  65 .  
         [0042]     Referring now to  FIGS. 5 and 6 , a water sprayer  53  is disposed in the feed compartment  7 , and is connected through a line  54  to a supply tank  56 . The supply tank  56  is preferably a pressurized supply of water, that may be pressurized using compressed air from the truck  2 . The sprayer  53  may be any suitable arrangement of nozzles that discharges water as shown in  58  into the feed compartment  7  at any convenient location that allows the water spray to envelope the hammers  32  and cause dust to settle. As shown in  FIG.7 , the sprayer  53  may be formed by a pair of nozzles  53 A,  53 B fed respectively by lines  54  and  54 A, and which are mounted on opposed side walls  11  and  11 A of the paper shredder. A continuous supply of water should be chosen that is sufficient to remove dust particles from the air, but not saturate the paper. An exemplary water feed rate is 1 gal/minute for a paper feed rate of 6000 lbs/hr. A typical water feed rate range is 0-5 gal/min. The nozzles  53 A,  53 B may be mounted about 12 inches above the hammer mill  30 . Nozzles such as are used for spraying crops may be used. The moist environment generated by the water sprayer  53  keeps dust down and reduces the risk of an explosion. Other fire suppression fluids may be substituted for the water, but it is preferred to use water due to its low cost and easy availability.  
         [0043]     To further reduce the risk of an explosion hazard, the auger  41  may be equipped with wear plates  83  on the flights  43 , as shown in  FIG. 7 . The wear plates  83  also help to stabilize the auger  41  in operation and to reduce wear. In a preferred embodiment, the flights  43  have a tolerance ranging from ⅜″ to ¾″ between the auger  41  and the transfer tube  42 . Attached to the flights  43  are wear plates  83  that stick out approximately ⅜″. The wear plates  83  may be made of any suitable spark resistant material, but in a preferred embodiment, the wear plates  83  are made out of aluminum. When the wear plates  83  have been worn down, they can be easily replaced. This is more economical than replacing the auger  41 , and also increases the safety of the system by reducing the likelihood of causing sparks that may ignite the shredded material and dust produced by the hammer mill  30 .  
         [0044]     The mobile paper shredder  1  with dual receptacle lifts has the advantage of reducing the time required to pick up materials from a location. Previously, materials would have to be shredded, even when this was not required by the customer. With dual receptacle lifts, it is possible to process materials more quickly because the shredder can be bypassed by loading such materials directly into the storage container  4  via receptacle lift  5 B.  
         [0045]     The mobile shredder  1  can also be provided with storage for receptacles in compartments  90  in front of the shredder  3 . The rear  92  of the storage container  4  may be provided with doors that swing outwardly, or with a clamshell that opens in an upward fashion, or with any other suitable means of accessing the storage container  4 . The storage container  4  may also be provided with an ejector wall  94  to push the paper out of the storage container. The ejector wall may have a ramp  94  at its base. The floor of the storage container  4  may be flat, but could also have ribs  96 . If desired, the storage container  4  may also be separated into separate compartments, one for shredded paper and one for unshredded paper, with separate removal doors for each compartment and corresponding mechanisms for forcing paper towards and through the removal doors.  
         [0046]     In the claims, the term “paper shredding implements” includes the described preferred hammers  32  and associated components, but any suitable paper shredding implements may be used. The term “shredded paper disposal container” includes the container  4  but may include any suitable container, fixed or removable.  
         [0047]     Immaterial modifications may be made to the embodiments of the invention described here without departing from the invention.