Patent Publication Number: US-3874641-A

Title: Agitator assembly for a discharge hopper

Description:
United States Patent [191 Tolan [451 Apr. 1, 1975 AGITATOR ASSEMBLY FOR A DISCHARGE 3,232,486 2/1966 Ofner 222/196 X Primary Examiner-Stanley H. Tollberg Assistant Examiner-Norman L. Stack, Jr. Attorney, Agent, or F irm-Robert E. Ross [5 7] ABSTRACT An agitator assembly for use with a discharge hopper, in which a pair of agitator members are suspended from a movable support member so as to be positioned adjacent opposite hopper wall portions, said movable support member being attached to a fixed support member by a pair of pneumatic bellows disposed at opposite ends thereof, and control means is provided for actuating said bellows alternately, whereby said agitator members are raised and lowered alternately.  
 6 Claims, 5 Drawing Figures PIU&#39;ENTIEB 1 I975 O O O O O O O M W WWW WW o o o o o o o V 00 s O O O AGITATOR ASSEMBLY FOR A DISCHARGE HOPPER BACKGROUND OF THE INVENTION In the feeding of powdered, granular, flake, or the like material from a supply hopper onto a conveyor or into containers, at common problem is bridging&#34; of the material in the hopper, whereby a self-supporting arch of the material forms between the opposite walls of the hopper. Many devices have been utilized for preventing or correcting such bridging, such as means for vibrating the hopper walls, pulsating devices, internal mechanical agitators, all of which have disadvantages. Most of the devices used heretofore for this purpose must be built as an integral part of the hopper when the hopper is originally constructed. Devices of the vibrating type, which may be attached to the outside wall of an existing hopper, are not effective with large hoppers because of the large mass involved, and are not effective at all with certain types of material such as wood chips. Mechanical agitating devices have had the disadvantage of high original cost and of requiring considerable maintenance expense due to the fact that the moving parts of the device, such as bearings, are covered or intermittently exposed to the material being fed. When agitating devices must be repaired, the hopper and any upstream or downstream equipment is out of operation.  
 SUMMARY OF THE INVENTION This invention relates to an agitator assembly for use with a feed hopper of the type described, which may be readily assembled with an existing hopper and which may be readily assembled for repair or removal and replacement of the agitator members. The assembly comprises a fixed support for attachment to an existing hopper, which support may span the hopper at an upper portion. and a movable support member attached to the fixed support by a pair of pneumatic bellows, one bellows being disposed at each end of the movable support. Depending from each end of the movable support is an agitator member which may be of any shape best suited for the type of material being fed by the hopper. The agitator members may be positioned to lie parallel to opposite wall portions in spaced relation thereto. Means is provided for actuating said bellows, that is, to cause them to extend and contract, alternately, so that the agitator members are alternately moved by the resulting rocking motion of the movable support member, to destroy any bridging of material in the hopper. In a preferred form of the invention, the movable support is supported only by the bellows, so that there are no bearings, pivots, or the like to wear or become jammed by the material in the hopper.  
 BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view, partly broken away, of a discharge hopper having agitator means embodying the features of the invention;  
  FIG. 2 is a view in section of the hopper assembly of FIG. I, with the actuating bellows in the unpressurized condition;  
  FIG. 3 is a view in section taken on line 33 of FIG. 2;  
  FIG. 4 is a view similar to FIG. 2 showing the movement of the agitator member during operation of the device, the full line showing the position thereof when one bellows is energized, the dashed line showing the position of the agitator when the other bellows is energized;  
  FIG. 5 is a schematic view of an electricial and pneumatic control circuit for controlling the operation of the agitator mechanism of FIGS. l-4.  
 DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Referring to the drawing, there is illustrated a feed hopper which comprises inclined side walls 12 leading to a discharge opening 14 for transferring material from a storage hopper 16 to a conveyor 18 for further processing or packaging.  
  Disposed within the hopper is an agitator assembly 20 which comprises a fixed member 22 spanning the hopper and a movable member 24 attached to the fixed member by a pair of expansible bellows 26 and 28. The movable member 22 comprises an upper portion 30 which carries pneumatic fittings 32 to supply air to the bellows and a lower portion 34 suspended from the upper portion and disposed below the fixed member. Suspended from opposite ends of the lower portion 34 is a pair of agitator members 36 which, in the illustrated embodiment, are in the form of grids disposed in spaced relation to and parallel to the adjacent side walls of the hopper when the agitator is in the at rest position. In the illustrated embodiment the side walls of the hopper taper in size from the width of the supply hopper at the top to the width of the discharge opening at the bottom. The agitator members have a corresponding taper, however they are narrower than the corresponding dimension of the side wall.  
  Referring to FIG. 4, there is illustrated an electricial and pneumatic control circuit for the agitator, which comprises a four-way valve V operated by solenoid S. Power to the solenoid is supplied from any suitable power source P through a timer T, which may be adjusted to control the rate at which the solenoid S is energized and deenergized. When the solenoid is energized, the four-way valve is moved to admit air from a suitable air supply A to one of the bellows, and when the solenoid is dc-energized, the four-way valve returns to its other position to admit air to the other bellows and to release the pressure from the first bellows. Quick exhaust valves Q may be provided at the bellows, so that the air in the bellows need not return to the four-way valve to exhaust, but may exhaust directly from the bellows to obtain faster release of air.  
  The motion imparted to the movable member 24 by the alternate bellows action is a rocking motion. As one bellows is pressurized and extended, the other bellows is being exhausted and retracted, and serves as a pivot about which the member 24 moves. The agitators therefore move between the full line position and the dashed line position of FIG. 3, whereby one agitator moves downwardly and away from the adjacent wall and the other moves upwardly and toward its adjacent wall, with the bottom end of the grids moving back and forth over the discharge opening 14.  
  This oscillatory motion of the agitators prevents any bridging of the material in the hopper, and insures a continuous flow of material out of the discharge opening. The use of pneumatic bellows allows considerable force to be applied to the material in the hopper, such as may be required to agitate wet, heavy, or lumpy material. With an air supply of psi and a bellows diameter of 6 inches, a force of about 2,000 pounds can be applied to the agitator member, however such high force does not result unless it is required by the resistance to movement met by the agitator.  
  The rate of cycling of the agitator depends on the material being fed, but is generally relatively slow. For example, in feeding of wood chips, a cycle rate of 1-15 cycles per second may be used.  
  Although in the illustrated embodiment, a pair of bellows is provided, in some installations it may be possible to provide a single bellows at one end of a movable member with a pivot at the other end. For certain types of material, it may also be desirable to support the movable member centrally from the fixed member by a pivot.  
  Although the use of pneumatic bellows in the manner illustrated is advantageous, due to the lack of pivots, bearings, or other mechanical devices, the motion imparted by the alternately energized pair of bellows can be substantially achieved by mechanical means or by pneumatic or hydraulic pistons.  
  One of the advantages of the agitator means disclosed herein is the fact that it may be added to an existing feed hopper without major structural modification. The agitator assembly must, of course, be dimensioned to fit the particular hopper into which it is to be assembled. Another advantage of the disclosed agitator assembly is the fact that the agitators may be readily removed from the hopper for repair, or for transfer to another hopper of similar size.  
  Another advantage of the illustrated structure is the fact that the fixed member and movable member, in extending across the hopper above the opening helps to support the column of material in the hopper, so that the weight thereof does not rest on the conveyor belt,  
 which would tend to interfere with the operation of auxiliary vibratory equipment at the conveyor, by damping out the vibrations and rendering the equipment ineffective.  
  Since certain other changes may be made in the illustrated embodiment without departing from the scope of the invention, it is intended that all matter contained herein be interpreted in an illustrative and not a limiting sense.  
 I claim:  
  1 An agitating device for use with a discharge hopper of the type having side walls and a discharge opening, said device comprising a support and an agitator member secured to the support by a pair of spaced fluid extensible means, and means for actuating said fluid extensible means alternately.  
  2. An agitating device for use with a discharge hopper of the type having side walls and a discharge opening, said device comprising a support and at least one agitator member depending from the support, said support comprising a fixed portion and a movable portion connected by a pair of spaced pneumatic extensible means, and means for actuating said pneumatically extensible means alternately so that a rocking motion is imparted to the movable portion of the support.  
  3. An agitator device for use with a discharge hopper of the type having inclined walls leading to a discharge opening, said device comprising a fixed support member dimensioned to span the hopper and be supported thereby, a movable support disposed above the fixed support and connected thereto by a pair of fluid extensible bellows, a pair of agitator members depending from the movable support, and means for alternately actuating said bellows to cause them to extend and retract alternately.  
  4. A discharge hopper, comprising a hopper body having side walls leading to a discharge opening and at least one agitator plate disposed in said hopper, and means for oscillating said plate in said hopper, said means comprising fluid actuated extensible means connected between the agitator plate and a fixed member.  
  5. A discharge hopper as set out in claim 4 in which a pair of agitator plates are provided in the hopper in spaced relation to each other above the discharge opening, and a pneumatic bellows is associated with each plate, and means is provided for actuating said bellows alternately.  
  6. A discharge hopper as set out in claim 5 in which said plates are suspended from opposite ends of a movable support bar, and said pneumatic bellows are connected between the fixed member and opposite ends of