Abstract:
A paper shredder that has a feed compartment, paper shredding implements and a shredded paper removal apparatus. A sprayer is disposed in the feed compartment and connected to a supply of fluid. The paper shredding implements are disposed to receive paper from the feed compartment and discharge shredded paper. The shredded paper removal apparatus is disposed to receive shredded paper discharged by the paper shredding implements. The shredded paper disposal container is arranged to receive shredded paper from the shredded paper removal apparatus. The supply of fluid may be a pressurized tank of water. A gate separates the feed compartment into a temporary holding area and feed area.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to a paper shredding assembly adapted for use on a truck or like vehicle.  
         [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, disclosed 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 has caused an explosion hazard and the feed mechanisms are awkward to use. The present invention is directed towards an improved paper shredder, particularly an improved mobile paper shredder using hammers.  
       SUMMARY OF THE INVENTION  
       [0006]     There is therefore provided in accordance with an aspect of the invention, a paper shredder that has a feed compartment, paper shredding implements and a shredded paper removal apparatus. A sprayer is disposed in the feed compartment and connected to a supply of fluid. The paper shredding implements are disposed to receive paper from the feed compartment and discharge shredded paper. The shredded paper removal apparatus is disposed to receive shredded paper discharged by the paper shredding implements. The shredded paper disposal container is arranged to receive shredded paper from the shredded paper removal apparatus. The supply of fluid may be a pressurized tank of water.  
         [0007]     In another aspect of the invention, a gate separates the feed compartment into a temporary storage space and a paper shredding space. The gate is preferably transversely between a feed opening into the feed compartment and the paper shredding implements. In a further aspect of the invention, the feed compartment contains a ramp sloping towards the paper shredding implements, and the gate terminates against the ramp.  
         [0008]     In other aspects of the invention, the paper shredder is mounted on a truck, the paper shredding implements comprise a rotary hammer mill, the shredded paper removal apparatus comprises an auger, and a sweep for sweeping paper in the feed compartment towards the paper shredding implements is provided.  
         [0009]     According to a further aspect of the invention, there is provided a method of shredding paper using a mobile truck mounted paper shredder, the method comprising the steps of temporarily storing paper in a feed compartment, supplying paper from the feed compartment to paper shredding implements to generate shredded paper, removing the shredded paper from the paper shredder; and spraying fire suppression fluid into the feed compartment to keep dust down caused by the paper shredding implements and reduce fire risk.  
         [0010]     According to a further aspect of the invention, there is provided a method of shredding paper using a mobile truck mounted paper shredder, the method comprising the steps of temporarily storing paper in a first portion of a feed compartment, removing the paper from the first portion of the feed compartment into a second portion of the feed compartment that feeds into paper shredding implements, shredding the paper with the paper shredding implements; and removing the shredded paper. Removing paper from the first portion of the feed compartment may comprise operating a sliding gate to allow paper to fall under operation of gravity from the first portion of the feed compartment into the second portion.  
         [0011]     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  
       [0012]     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:  
         [0013]      FIG. 1  is a side elevation showing the shredder mounted on a truck, the shredder being shown in section;  
         [0014]      FIG. 2  is a side elevation, partly in section, showing the first housing of the shredder on the truck and the storage container left standing on the ground awaiting pick up and removal;  
         [0015]      FIG. 3  is a front end elevation of the shredder, showing internals in broken lines;  
         [0016]      FIG. 4  is a side elevation, in section, showing the shredder and storage container linked in working relationship;  
         [0017]      FIG. 4A  is side view of the paper shredder of  FIG. 4 ;  
         [0018]      FIG. 5  is a perspective view, with part of the housing and some parts removed, showing the internals of the feed compartment of the shredder; and  
         [0019]      FIG. 5A  is a side view of a hopper divider according to the invention.  
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0020]     Having reference to  FIG. 1 , a paper-shredding assembly  1  is shown mounted on a truck  2 . The assembly  1  comprises a shredder  3  which remains with the truck. The assembly  1  further comprises a storage container  4  which can operatively connect with the shredder  3 , as shown in  FIG. 1 , or can be removed from the truck and be left standing on telescoping legs  5 .  
         [0021]     More particularly, the shredder  3  comprises a housing  6  forming an upper feed compartment  7  and a lower chamber  8 .  
         [0022]     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  having a hinged lid  14 . Lifting arms  15 , pivotally attached to the housing  6 , are provided to lift a receptacle  16  and tip it to empty contained paper into the paper feed opening  13 .  
         [0023]     A hydraulic cylinder  17 , pivotally attached to the housing  6  and arms  15 , is provided to actuate the arms. 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 .  
         [0024]     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.  
         [0025]     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 in ill is mounted to the side walls  11 . It is driven by a pulley and belt system  34  connected with the power takeoff (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 .  
         [0026]     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 is can apply increasing torque at constant rotational speed, to maintain its feed rate while compressing the shredded paper  44 .  
         [0027]     The storage container  4  is a discrete closed box having 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 . As previously stated the storage container  4  has telescoping legs  5  which can be extended to the ground.  
         [0028]     The truck used has an air ride suspension. Its deck can be lowered by letting air out of the suspension. In this way the truck can drive out from beneath the container  4  and leave it standing for recovery by a truck dedicated to moving containers to the paper recycling facility.  
         [0029]     In operation, a loaded receptacle  16  from the office is wheeled to the mobile shredder assembly  1 . The arms  15 , biased by the cylinder  52 , 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.  
         [0030]     Referring now to  FIGS. 4 and 4 A, a novel aspect of the present invention is shown. 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. 4A , 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 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/mil. 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 lox, cost and easy availability.  
         [0031]     Referring to  FIGS. 3 and 5 , a further novel aspect of the invention is shown. 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. 5 , but see  FIG. 5A  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 .  
         [0032]     An embodiment of the gate  52  is further illustrated in  FIG. 5A . 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 ribber 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.  
         [0033]     In both  FIGS. 5 and 5 A, 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 .  
         [0034]     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 removal apparatus” includes the auger and associated components, but any suitable paper removing apparatus may be used. The term “shredded paper disposal container” includes the container  4  but may include any suitable container, fixed or removable.  
         [0035]     Immaterial modifications may be made to the embodiments of the invention described here without departing from the invention.