Abstract:
A pallet having a coupling mechanism for use with an accumulating conveyor of the type using an endless chain having upper and lower runs driven by sprockets defining transitional portions or curvilinear chain paths. The pallet includes an upper guide bar and a lower guide bar. The lower guide bar including at least one side engagement surface having notches formed therein. Wherein, the rollers of the chain engage and are retained in the notches whereby the pallet is coupled to the chain and the chain transfers the pallet through the transitional portion or curvilinear chain path of the conveyor.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     The instant application claims priority to U.S. Provisional Patent Application Ser. No. 60/504,246 filed Sep. 19, 2003, the entire specification of which is expressly incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a pallet conveyor and, more particularly, to an over and under conveyor having a mechanism for moving the pallet around the curved sections located at each end of the conveyor.  
       BACKGROUND OF THE INVENTION  
       [0003]     Pallet conveyors, sometimes referred to as accumulating conveyors or over and under conveyors, utilize an endless chain that is driven between two sprockets. Typically, loaded pallets are transported on the upper portion of the conveyor, often referred to as the upper run, and are carried back to the beginning of the conveyor on the lower portion thereof, often referred to as the lower run. The pallets travel by friction, that is, the weight of the pallet and any load thereon frictionally engages the pallet with the chain and causes the pallet to move with the chain on the upper run. The weight of the pallet creates a sufficient frictional force to transport the pallet on the lower run.  
         [0004]     The pallets, however, must be transferred between the upper and lower runs about the curved ends of the conveyor. Accordingly, during travel about or around the curved ends of the conveyor, the pallets are typically secured or otherwise coupled to the endless chain. Various arrangements are known for operatively coupling or attaching the pallets to the chain. In some prior designs, clutches have been used. In others, an independent third gear on a shaft has been used. In still other of these prior art designs, the pallet is pinned to the chain. Securing the pallet to the chain enables the chain to drive or transport the pallet around the curved section. These arrangements provide a mechanism to lift the pallet from the lower run to the upper run, and prevent the pallets from sliding, or in effect freefalling, from the upper run to the lower run.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention is a pallet having a coupling mechanism for use with an accumulating conveyor. The pallet includes upper and lower guide bars that support the pallet during travel on the upper and lower runs of the endless chain of the conveyor. According to the present invention, the coupling mechanism includes the lower guide bar having a pair of side engagement surfaces. The side engagement surfaces having notches formed therein, whereby the lower guide bar engages the endless chain during travel about the curved sections of the conveyor to secure the pallet to the endless chain and transport the pallet about the curved ends of the conveyor.  
         [0006]     One advantage of the present invention is that once the pallet completes its travel through the curved section of the conveyor, the side engagement surfaces of the lower guide bar lose contact or disengage from the endless chain allowing for frictional travel along either the upper or lower runs.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a fragmentary side view illustrating a plurality of pallets according to the present invention transported on an endless chain type conveyor;  
         [0008]      FIG. 2  is a fragmentary view illustrating a pallet according to the present invention transported on an endless chain type conveyor;  
         [0009]      FIG. 3  is a side view of a pallet according to the present invention shown transported on an upper run of an endless chain type conveyor;  
         [0010]      FIG. 4  is a side view of a pallet according to the present invention shown transported on a lower run of an endless chain type conveyor;  
         [0011]      FIG. 5  is a side view of a pallet according to the present invention shown transported on a curved section of an endless chain type conveyor;  
         [0012]      FIG. 6  is a schematic view of the lower guide bar of a pallet according to the present invention shown engaging the endless chain;  
         [0013]      FIG. 7  is a fragmentary, sectional side view of a pallet according to the present invention supported on the endless chain;  
         [0014]      FIG. 8  is a fragmentary side view illustrating a plurality of pallets according to an alternate embodiment of the present invention transported on an endless chain type conveyor;  
         [0015]      FIG. 9  is a side view of a pallet according to an alternate embodiment of the present invention shown transported on an upper run of an endless chain type conveyor;  
         [0016]      FIG. 10  is a side view of a pallet according to an alternate embodiment the present invention shown transported on a lower run of an endless chain type conveyor;  
         [0017]      FIG. 11  is a side view of a pallet according to an alternate embodiment of the present invention shown transported on a curved section of an endless chain type conveyor; and  
         [0018]      FIG. 12  is a schematic view of the lower guide bar of a pallet according to an alternate embodiment of the present invention shown engaging the endless chain. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]     Referring now to  FIGS. 1-2  and  7 , an accumulating or pallet conveyor, seen generally at  10 , is shown. The conveyor  10  is supported on a frame  12  including a plurality of upright members interconnected by brace members (not shown). As is known, with most accumulating or pallet conveyors the frame  12  supports sprockets  14  positioned at each end of the frame assembly  12 . An endless chain  16  is positioned about the respective sprockets  14 . The chain  16  progresses through a chain path having an upper portion or chain path  20 , a lower portion or chain path  22  and a transitional portion or curvilinear chain path  24 . The radius of curvature or specific shape of the curvilinear path  24  is defined by the sprockets  14  connecting the upper and lower chain paths  20 ,  22 .  
         [0020]     A series of pallets or article carriers  30  are shown supported on the endless chain  16  in various positions on the conveyor  10 . The pallets  30  include a load supporting member  50  upon which a load to be carried by the pallet  30  is placed. As best seen in  FIGS. 2, 7 , the endless chain  16  comprises a triple strand chain, including three strands  16   a,    16   b,    16   c,  wherein two of the strands  16   a,    16   b  are disposed about the sprockets  14 . The third strand  16   c  extends inwardly from the first two strands  16   a,    16   b  and operates in a known fashion to support the pallets or article carriers  30 .  
         [0021]     The pallets or article carriers  30  are supported on the third strand  16   c,  depending on the position of the pallet  30  on the chain path  18 , by an upper guide bar  32  or a lower guide bar or dog  34 . The upper guide bar  32  and lower guide bar  34  are connected and secured to the pallet  30  in a spaced relationship by a mounting member or support flange  36 . As shown in  FIGS. 1, 2  and  7 , when the pallet  30  is on the upper chain path  20 , it is supported on the chain  16  by a support surface  52  of the upper guide bar  32  contacting or resting on the third strand  16   c  of the chain  16 . Thus the frictional force between the chain  16  and the upper guide bar  32 , resulting from the weight of the pallet  30  and any article supported thereon, causes the pallet  30  to travel with the chain  16 .  
         [0022]     As shown in  FIGS. 2, 4  when the pallet  30  is on the lower chain path  22 , it is supported on the chain  16  by a support surface  54  of the lower guide bar  34  contacting or resting on the third strand  16   c  of the chain  16 . Again, the frictional force between the chain  16  and the lower guide bar  34  causes the pallet  30  to travel with the chain  16  through the lower chain path  22 .  
         [0023]     It will be appreciated that while the pallet  30  is on the upper chain path  20  or lower chain path  22 , the pallet  30  can slip relative to the chain  16 . However, when the pallet  30  is in the curvilinear path  24 , the pallet  30  cannot slip relative to the chain  16 .  
         [0024]     As set forth above, the transitional portion or curvilinear chain path  24  of the chain  16  extends or travels upward between the upper chain path  20  and the lower chain path  22 . Initially, it is necessary to lift or drive the pallet  30  around the transitional or curvilinear path  24  from the lower chain path  22  to the upper chain path  20 . This may be accomplished by coupling or connecting the pallet  30  to the drive chain  16 . Also, it is advisable to connect or couple the pallet  30  to the chain  16  during movement of the chain  16  about the transitional portion or curvilinear chain path  24  that extends or travels downward between the upper chain path  20  and the lower chain path  22 . Coupling the pallet  30  to the chain  16  helps to control the movement of the pallet  30  and prevent it from simply dropping downward due to the force of gravity over the downward transitional portion or curvilinear chain path  24  of the chain  16 .  
         [0025]     As best seen in  FIGS. 5 and 6 , the lower guide bar  34  has two beveled or arcuate side engagement surfaces  38 . While the side engagement surfaces  38  are shown herein as part of the lower guide bar  38 , they may also be separate from the lower guide bar  38  and still perform their intended function, which is to engage the endless chain  16  when the pallet  30  is positioned in the transitional portion or curvilinear chain path  24  and couple the pallet  30  on the endless chain  16  whereby it is carried or transferred by the endless chain  16  through the transition portion or curvilinear chain path  24 .  
         [0026]     A plurality of arcuate notches  40  are formed in the side engagment surfaces  38 . The arcuate notches  40  typically have a radius of curvature equal to that of the rollers  42  of the chain  16 . As shown in  FIGS. 5 and 6 , when the pallet  30  travels through the transitional portion or curvilinear chain path  24 , the rollers  42  of the third strand  16   c  of the chain  16  engage the arcuate notches  42  on the side engagement surfaces  38 . Additionally, rollers  42  of the third strand  16   c  of the chain engage the support surface  52  of the upper guide bar  32 . Engagement of the chain  16  in this manner couples the pallet  30  to the chain  16  enabling the chain  16  to drive or carry the pallet upward from the lower run or chain path  22  to the upper portion or chain run  20  or, to control the descent of the pallet  30  from the upper run  20  to the lower run  22 .  
         [0027]     It should be understood that the upper guide bar  32  cooperates with the lower guide bar  34 , specifically the side engagement surfaces  38 , to maintain the rollers  42  of the chain  16  within the arcuate notches  40  located on the side engagement surfaces  38 . As shown in  FIG. 6 , the radius  44  of the chain path  16  about the sprocket  14  is determined by the radius of the sprocket  14  and remains constant. Thus, as the pallet  30  travels about the transitional portion or curvilinear chain path  24 , the chain  16  is constrained between the respective guide bars  32 ,  34  whereby the rollers  42  of the chain  16  engage both the lower guide bar  34  and the upper guide bar  32 . Additionally, as the radius of curvature, as defined by the sprockets  14 , of the chain  16 , decreases, the respective length of the lower guide bar  34  will also decrease. This decrease may also include an increase in the bevel angle or a decrease in the radius of curvature of the side engagement surfaces  38 . Further, the spacing between the upper guide bar  32  and lower guide bar  34  may also be varied to maintain a sufficient contact force between the chain  16  and the guide bars  32 ,  34  to move the pallet  30  through the transitional portion or curvilinear chain path  24 .  
         [0028]     When the pallet  30  reaches the end of the transitional portion or curvilinear path  24 , the chain  16  flattens out or, resumes its linear path, whereby the pallet  30  then rests on the respective support surface of either the upper or lower guide bars  32 ,  34  depending on the direction of travel of the pallet  30 . As set forth above, the spacing or distance between the respective support surfaces of the upper and lower guide bars  32 ,  34  is dependent upon the radius of curvature  44  of the chain  16 . In addition, the depth, and shape of the arcuate notches  40  located in the side engagement surfaces  38 , along with the angle or degree that the side engagement surfaces  38  are beveled with respect to the support surface of the lower guide bar  34  can also be varied depending upon the radius of curvature  44  along with the type and style of chain  16 .  
         [0029]     It should be understood that the above mechanism provides an efficient manner of coupling or connecting a pallet  30  to a chain  16  of a conveyor  10  to control and effect movement of the pallet  30  through the transitional portion or curvilinear chain path  24  of the conveyor  10 .  
         [0030]      FIGS. 8-12  show an alternate embodiment having a alternate arrangement of the support flange  36  and the load supporting member  50 . These Figures also show a different size lower guide bar  32  for use with a sprocket of different radius.  FIG. 9  also shows that there may be a gap, preferably of about {fraction (1/32)} inch between the upper guide bar  32  and the roller  42 . This gap helps to alleviate binding of the upper guide bar  32 . The gap, however, should not be so large as to allow the side engagement surfaces  38  of the lower guide bar  32  to disengage from the chain  16 .  
         [0031]     It will thus be seen that the objects of the invention have been fully and effectively accomplished. It will be realized, however, that the foregoing specific embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the scope of the following claims.