Abstract:
An asymmetrical vibrator is provided, which is actuated by compressed air. The vibrator operates in a case, which has two bores disposed parallel on opposite sides of the casing. One of the bores is smaller than the second bore and the piston operating in the small bore is called the slow piston, since it is actuated with air to a relatively slow motion and the piston operating in the second larger bore is called the fast piston, since it is moves at a larger speed when driven directly by the compressed air. The asymmetric vibration motion can be employed to transport materials upwardly in factories and assembly stations. The air operated asymmetric vibrators need low maintenance and do not entail the spark dangers caused by the presence of electrical wiring for electrical drive motors.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention generally relates to vibratory feeding mechanisms and, more particularly to an improved asymmetrically accelerated vibrator which uses pistons activated by compressed air.  
       BACKGROUND OF THE INVENTION  
       [0002]     A vibratory conveyor includes a generally elongate horizontal or slightly inclined tray or pan having a planar surface. The tray is moved slowly forward to shift the goods, relative to the planar surface of the tray, and is then pulled rearwardly at a high return acceleration so that the goods slide along the planar surface of the tray. In this way, the goods are effectively transported along the conveyor tray. Vibratory conveyors, which are sometimes referred to as differential impulse conveyors, linear motion conveyors, or shaker conveyors provide a significant advantage in that goods may be transported along the tray in a manner that does not require engagement with the parts by secondary fixtures or the like (no moving tray parts) which could damage the goods.  
         [0003]     Various prior art mechanisms for driving vibratory conveyors are known in the art including reciprocating pistons, driven three and four bar linkages, and mechanisms employing a plurality of flywheels suspended from the tray. For example, U.S. Pat. Nos. 6,079,548; 5,850,906; 5,794,757; 5,699,897; 5,579,890; 5,404,996; 5,351,807; 4,593,603; 4,436,199; 4,339,029; and 4,019,626 disclose drive mechanisms suitable for use with vibratory conveyors.  
         [0004]     In U.S. Pat. No. 4,593,603, issued to Johnson, an asymmetrical vibrator is provided which is actuated by compressed air. The vibrator operates in a case which has two parallel bores disposed on opposite sides of the case. One of the bores is smaller than the other. A piston operates in the smaller bore, and is called the slow piston. The slow piston is actuated with air to a relatively slow motion. A piston also operates in the larger bore, and is called the fast piston. The fast piston moves at a higher speed when driven by compressed air. This structure results in asymmetric vibratory motion, which can be employed to transport materials. Johnson utilizes a poppet valve to regulate the exchange of compressed air between the bores. this standard has been quite prone to severe wear, which shortens its useful working life and degrades the performance of the overall device. An improved means of regulating compressed air exchange in asymmetrically accelerated vibrators is desirable to overcome these problems.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention provides an asymmetrically accelerated vibrator having a case defining a first bore and a second bore that are arranged in coaxial relation to one another. The first and second bores are also arranged in regulated fluid communication with a source of compressed fluid. A first piston having a first diameter is disposed in the first bore, and a second piston having a second diameter is disposed in the second bore. A mechanical connection between the first and second pistons is provided such that those pistons are caused to oscillate in unison by regulated application of compressed fluid from the compressed fluid source. A ball-valve is disposed in fluid regulatory relation between the first bore, the second bore, and the source of compressed fluid. In this way, a flow of the compressed fluid may be switched between the first bore and the second bore upon interaction with a portion of the second piston.  
         [0006]     In an alternative embodiment of the invention, an asymmetrically accelerated vibrator is provided that includes a case having a first open-ended chamber and a second open-ended chamber that are arranged in coaxial relation to one another. The first and second open-ended chambers are also arranged in regulated fluid communication with a source of compressed fluid. A first piston having a first diameter is disposed in the first open-ended chamber, and a second piston having a second diameter is disposed in the second open-ended chamber. A compressed fluid conduit is defined within the case, and arranged in fluid communication between a compressed fluid intake port and a threaded recess that is defined in the case between the first open-ended chamber and the second open-ended chamber. The threaded recess is terminated by a radiused seat-wall having a through-bore that opens into the second open-ended chamber. A mechanical connection between the first and second pistons is provided such that those pistons are caused to oscillate in unison by regulated application of compressed fluid from the compressed fluid source. A ball-valve is disposed within the threaded recess such that when the ball-valve is engages the seat-wall, a segment of the ball-valve projects into the second open-ended chamber. This segment is engagable by a portion of the second piston. In this way, fluid flow regulation is provided between the first open-ended chamber, the second open-ended chamber, and the source of compressed fluid so as to switch a flow of the compressed fluid between the first open-ended chamber and the second open-ended chamber upon interaction of the segment of the ball-valve with the portion of the second piston.  
         [0007]     In another embodiment, an asymmetrically accelerated vibrator is provided that includes a case having a first bore and a second bore arranged in coaxial relation to one another and in regulated fluid communication with a source of compressed fluid. A first piston is provided having a first diameter and disposed in the first bore. A second piston is also provided having a second diameter and disposed in the second bore. The second piston also includes a compound valve that is positioned within the second bore, and comprises a valve-actuator projecting therefrom. The valve-actuator includes a chamfered end that is suitable for engaging an alternating portion of a ball-valve. A mechanical connection is formed between the first and second pistons such that the pistons are caused to oscillate in unison by regulated application of compressed fluid from the compressed fluid source. The ball-valve is disposed in fluid regulatory relation between the first bore, the second bore, and the source of compressed fluid so as to switch a flow of the compressed fluid between the first bore and the second bore upon interaction with the chamfered end. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     These and other features and advantages of the present invention will be more fully disclosed in, or rendered obvious by, the following detailed description of the preferred embodiment of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts and further wherein:  
         [0009]      FIG. 1  is a cross-sectional elevational view of an asymmetrically accelerated vibrator formed in accordance with the present invention;  
         [0010]      FIG. 2  is a broken-way portion of the asymmetrically accelerated vibrator shown in  FIG. 1 ;  
         [0011]      FIG. 3  is a perspective view of a threaded stem and ball valve formed in accordance with the present invention;  
         [0012]      FIG. 4  is a cross-sectional view of the threaded stem and ball-valve shown in  FIG. 3 ;  
         [0013]      FIG. 5  is an enlarged broken-way view of a side portion of the asymmetrically accelerated vibrator shown in  FIGS. 1 and 2 , showing an initial charging of gas for operation of the device;  
         [0014]      FIG. 6  is an enlarged broken-way cross-sectional view similar to  FIG. 5 , but showing a subsequent stage of operation of the device in accordance with the present invention;  
         [0015]      FIG. 7  is a broken-way cross-sectional view illustrating operation of a ball-valve in accordance with the present invention;  
         [0016]      FIG. 8  is an enlarged broken-way cross-sectional view of another side portion of the asymmetrically accelerated vibrator shown in  FIG. 1 , showing a further stage of operation of the device in accordance with the present invention; and  
         [0017]      FIG. 9  is an enlarged broken-way cross-sectional view of an alternative embodiment of the invention shown in  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]     This description of preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. The drawing figures are not necessarily to scale and certain features of the invention may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness. In the description, relative terms such as “horizontal,” “vertical,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms including “inwardly” versus “outwardly,” “longitudinal” versus “lateral” and the like are to be interpreted relative to one another or relative to an axis of elongation, or an axis or center of rotation, as appropriate. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. The term “operatively connected” is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship. In the claims, means-plus-function clauses are intended to cover the structures described, suggested, or rendered obvious by the written description or drawings for performing the recited function, including not only structural equivalents but also equivalent structures.  
         [0019]     Referring to  FIG. 1 , an asymmetrically accelerated vibrator  5  formed in accordance with the present invention comprises a case  10 , a piston  14 , a piston assembly  16 , and a vibratory carriage assembly  20 . More particularly, case  10  is generally rectilinear in outer profile, and is preferably made from a stable material suitable for structural support, such as, cast iron, aluminum and plastic. An air conduit  22  is defined within an upper portion of case  10 . Air conduit  22  is arranged in fluid communication between an air intake port  23  and a threaded recess  24 , that is often defined in a central portion of case  10 . Threaded recess  24  is sized and shaped to receive a substantially spherical ball-valve  25  and a correspondingly threaded stem  27 . Ball-valve  25  is often formed from a light weight, wear and corrosion resistant material, such as, aluminum alloys or glass-filled polymers ( FIGS. 3 and 4 ). Threaded stem  27  includes a radiused bottom end  28  and a central passageway  26 . Central passageway  26  communicates with an opening  35  ( FIG. 4 ) located within the threads on the outer surface of threaded stem  27 . A semi-circumferential slot  36  is often formed in threaded stem  27  so as to intersect with opening  35  ( FIGS. 3 and 4 ).  
         [0020]     Threaded recess  24  in case  10  comprises a radiused, i.e., curved, seat-wall  30  having a centrally defined through-bore  31  that provides for fluid communication with the interior of threaded recess  24  ( FIGS. 5-7  and  9 ). Radiused seat-wall  30  and radiused bottom end  29  of threaded stem  27  both preferably comprise a curvature that is complementary to spherical ball-valve  25 .  
         [0021]     Case  10  has defined within it a first blind bore or open-ended chamber  32  and a second blind bore or open-ended chamber  33  that are arranged in spaced apart coaxial relation to one another, and in substantially parallel relation to air conduit  22 . First open-ended chamber  32  often has a smaller diameter than second open-ended chamber  33 . A feed-bore  34  fluidly communicates between conduit  22  and first open-ended chamber  32 , and is arranged in spaced relation to threaded recess  24 . Through-bore  31  of threaded recess  24  intermittently communicates with the interior of second open-ended chamber  33  via the movement of ball-valve  25  ( FIG. 7 ). An open-ended passageway  45  is defined in a lower portion of case  10 , and is disposed in substantially parallel, spaced relation to both air conduit  22  and first and second chambers  32 , 33 . An exhaust-bore  47  fluidly communicates between second open-ended chamber  33  and open-ended passageway  45 .  
         [0022]     Piston  14  often comprises a solid cylinder of metal including an annular groove  50  defined adjacent to a first end  52 . An o-ring  51  is often positioned within annular groove  50  so as to provide for a substantially airtight seal between piston  14  and the interior surface of case  10  that defines first open-ended chamber  32 . A second end  53  of piston  14  is operatively interconnected with a portion of vibratory carriage  20 . Referring to  FIGS. 1 and 8 , piston assembly  16  includes a valve  58 , an adjustment pin  60 , and a second piston  62 . More particularly, valve  58  comprises a substantially cylindrical, open-ended profile defined by an annular outer wall  66  and a bottom wall  67 . Annular outer wall  66  often includes a lead-in portion  70 , a trailing portion  71 , and a valve-actuator  72 . Trailing portion  71  has a somewhat larger diameter than lead-in portion  70 . Bottom wall  67  includes a centrally defined through-bore, with feed bores  73  arranged adjacent thereto.  
         [0023]     Valve-actuator  72  projects radially outwardly from the outer surface of lead-in portion  70  so as to comprise a length that extends from the outer surface of lead-in portion  70  to the interior surface of care  10  that defines second open-ended chamber  33 . In an alternative embodiment, a compound valve  85  comprises a substantially cylindrical base portion  86  that is similar in general shape and size to valve  58 . A valve-actuator  87  projects outwardly from a central portion of a leading end of compound valve  85 , and includes a lead-in chamfer  88  ( FIG. 9 ).  
         [0024]     Adjustment pin  60  comprises an elongate shaft  75  having a head  77  that projects radially outwardly from a first end and a spaced-away threaded portion  80  at a second end. Shaft  75  is sized to be slidingly passed through the bore in bottom wall  67  of valve  58 , with head  77  engaging bottom  67  so that adjustment pin  60  is firmly engaged with valve  58 . Second piston  62  often comprises a solid cylinder of metal including an annular groove  81  defined adjacent to a first end  82 . An o-ring  84  is positioned within annular groove  81  so as to provide for a substantially air-tight seal between piston  62  and the interior surface of case  10  that defines second open-ended chamber  33 . A second end  83  of piston  62  is operatively interconnected with a portion of vibratory carriage  20 . Second piston  62  often has a larger diameter than first piston  14 . For example, the ratio of diameters of first piston  14  to second piston  62  is often in the range of about 1 to 1.25 to about 1 to 2.  
         [0025]     Vibratory carriage assembly  20  includes a interface plate  90 , a first stop  92 , a second stop  94 , and a toggle-shaft  96 . Interface plate  90  is positioned atop the upper portion of case  10  so as to cover the top of threaded stem  27  within threaded recess  24 . First stop  92  and second stop  94  are fastened to spaced-apart ends of interface plate  90  so as to project downwardly in substantially parallel relation to case  10 . In this position, first stop  92  is arranged in confronting relation to second end  53  of first piston  14  and second stop  94  is arranged in confronting relation to second end  83  of second piston  62 . Toggle-shaft  96  projects outwardly from a free end  97  of first stop  94  in parallel relation to first open-ended chamber  32  and second open-ended chamber  33  so as to be received within open-ended passageway  45  in the lower portion of case  10 . Toggle-shaft  96  is long enough to extend through open-ended passageway  45  and just close-off exhaust-bore  47 .  
         [0026]     An asymmetrically accelerated vibrator  5  is assembled in accordance with one embodiment of the present invention in the following manner. First piston  14  is arranged so that its first end  52  is positioned in coaxial confronting relation with first open-ended chamber  32  of case  10 . O-ring  51  is positioned within annular groove  50 , and then first piston  14  is moved toward case  10  until first end  52  is positioned adjacent to feed-bore  34 .  
         [0027]     Piston assembly  16  is first assembled by positioning adjustment pin  60  within bottom wall  67  of valve  58 . In this position, head  77  is located flush against the interior surface of bottom  67 . Threaded end  80  is threadingly engaged with a correspondingly threaded blind bore defined in first end  82  of piston  62 . An o-ring  84  is positioned within groove  81  in first end  82  of piston  62 . Once assembled, piston assembly  16  is arranged such that valve  58  is arranged in co-axial confronting relation with second open-ended chamber  33  of case  10 . Once in this position, piston assembly  16  is moved toward case  10  so that valve  58  enters second open-ended chamber  33  while o-ring  84  engages the interior surface defining second open-ended chamber  33 .  
         [0028]     Threaded stem  27  and ball-valve  25  are also assembled to case  10 . More particularly, ball-valve  25  is first dropped within recess  24  so that a portion of ball-value  25  engages seat-wall  30  such that a spherical segment  89  of ball-valve  25  extends into second open-ended chamber  33  from through-bore  31 . Once in this position, threaded stem  27  is threadingly engaged with threaded recess  24  so as to retain ball-value  25  within threaded recess  24 . It will be understood that as threaded stem  27  is engaged with threaded recess  24 , central passageway  26 , via slot  36 , is arranged in open flow communication with the interior of air conduit  22 .  
         [0029]     With first piston  14  and piston assembly  16  assembled to case  10 , and ball-valve  25  loosely positioned within threaded recess  24 , vibratory assembly  20  may be assembled to case  10 . More particularly, interface plate  90  with first stop  92  and second stop  94  projecting outwardly from spaced-apart ends is positioned in overlying relation to a top surface of case  10 . Once in this position, interface plate  90  is moved toward case  10  until first stop  92  and second stop  94  are positioned adjacent to second end  53  of first piston  14  and second end  62  of piston  62 , respectively. Once in this position, stops  92 ,  94  are releasably fastened to pistons  14 ,  62  by fastening means well known in the art, e.g., threaded bolts or screws. A tray  100  is then positioned atop interface plate  90  so that loose piece items, e.g., bolts  99 , may be manipulated by use of asymmetrically accelerated vibrator  5 .  
         [0030]     Referring to  FIGS. 5, 6 ,  8 , and  9 , asymmetrically accelerated vibrator  5  operates in the following manner. An elastic fluid, such as compressed air, is introduced through air intake port  23  into air conduit  22 , such that air conduit  22 , feed-bore  34 , a portion of first open-ended chamber  32 , and central passageway  26  are all pressurized. As a consequence, first piston  14  is forced outwardly by the pressurized gas located within the open portion of first open-ended chamber  32 . As this occurs, first piston  14  moves first stop  92 , and thereby, interface plate  90  and toggle-shift  96  away from case  10 .  
         [0031]     As interface plate  90  moves, under the influence of first piston  14 , second stop  94  presses second end  83  of second piston  62  thereby driving piston assembly  16  inwardly into second open-ended chamber  33  of case  10 . As valve  58  moves inwardly under the influence of second piston  62 , valve-actuator  72  engages segment  89  of ball-valve  25  that is extending from through-bore  31  into the interior of second open ended chamber  33 . As this occurs, valve-actuator  72  engages ball-valve  25  thereby dislodging it from seat-wall  30  and through-bore  31 , and providing an escape pathway for the compressed air trapped in first open-ended chamber  32 , air conduit  22 , and feed-bore  34 . Advantageously, valve-actuator  72  does not cause appreciable wear or other damage to any particular portion of ball-valve  25 , since during each cycle of asymmetrically accelerated vibrator  5 , a different portion of ball-valve  25  forms segment  89 . This structure provides for a significant increase in the operating life of the device.  
         [0032]     Alternatively, when using compound valve  85 , as cylindrical base portion  86  moves inwardly under the influence of second piston  62 , valve-actuator  87  engages segment  89  of ball-valve  25  that is extending from through-bore  31  into the interior of second open ended chamber  33 . As this occurs, valve-actuator  87  engages ball-valve  25  thereby dislodging it from seat-wall  30  and through-bore  31 , and providing an escape pathway for the compressed air trapped in first open-ended chamber  32 , air conduit  22 , and feed-bore  34 . Advantageously, valve-actuator  87  does not cause appreciable wear or other damage to any particular portion of ball-valve  25 , since during each cycle of asymmetrically accelerated vibrator  5 , a different portion of ball-valve  25  forms segment  89  which is engaged by chamfered lead-in  88 . ( FIG. 9 ).  
         [0033]     As a result, compressed air flows through central passageway  26  and into second open-ended chamber  33 . At the same time, toggle-shaft  96  uncovers exhaust port  47  so that the compressed air can escape second open-ended chamber  33  into the ambient environment. As compressed air fills second open-ended chamber  33 , piston assembly  16  is caused to move outwardly under the influence of the pressurized air. As this happens, second end  83  of piston  62  engages second stop  94  of vibratory assembly  20 , thereby reversing the movement of interface plate  90  and first stop  92 . As a consequence, first stop  92  presses first end  53  of first piston  14  driving first piston  14  back into first open-ended chamber  32 . As a consequence of this reversing movement, piston assembly  16  is moved outwardly again disengaging valve-actuator  72  from segment  89  of ball-valve  25 , thereby allowing ball-valve  25  to be positioned in seat-wall  30  thereby reblocking through-bore  31 . Once this occurs, the pressurized air from air intake  23  once again pressurizes air conduit  22 , feed-bore  34 , and first open-ended chamber  32  thereby causing a new cycle of operation of asymmetrically accelerated vibrator  5 .  
         [0034]     Asymmetric accelerated vibrator  5  allows removal of parts and material from areas which are inaccessible or inconvenient to reach by other means such as under a machine or a punch press. In addition asymmetric accelerated vibrator  5  does not require any electrical connections since it is operated by compressed air. This allows application of this device in areas where electrical currents and voltages are to be avoided. If an inclined tray is attached to one asymmetric accelerated vibrator  5 , this can be followed by more inclined trays so as to provide an upward motion of material placed on the trays during operation of each Asymmetric accelerated vibrator  5 . Preferably asymmetrically accelerated vibrator  5  runs at about 300 to 550 strokes per minute.  
         [0035]     It is to be understood that the present invention is by no means limited only to the particular constructions herein disclosed and shown in the drawings, but also comprises any modifications or equivalents within the scope of the claims.