Patent Publication Number: US-2022219906-A1

Title: Self-stacking spiral belt conveyor with smooth diameter reduction

Description:
BACKGROUND 
     The invention relates generally to power-driven conveyors and, more particularly, to spiral belt conveyors. 
     Conveyor belts are typically used for conveying bulk material, such as foodstuffs or other materials, that must be transported through a cooled or refrigerated environment. Typical conveyor belts have the advantage that relatively little energy is required for transporting the bulk material across horizontal surfaces. The conveyance of bulk material, however, is limited by such systems to horizontal routes or to routes with only relatively small inclines. To overcome greater heights or inclines, it is necessary to transfer the bulk material to another conveyor system, for example, a bucket chain conveyor. In the transport of material to be refrigerated, it is often desirable to maximize the time of transport within the cooled environment. It is desirable to provide a conveyor belt system that transports goods along an extended path. 
     Spiral belt conveyors, in which a conveyor belt follows a helical path, are used in certain applications because they allow for an extended path with minimal floor space. For example, spiral belt conveyors are often used in freezers and ovens to provide a long conveying path with a small footprint. 
     Self-stacking spiral belts are used to form a helical path with minimal framing. A self-stacking conveyor belt uses side plates or side guards coupled to the side edges of the conveyor belt to form a self-supporting stack. The belt travels in a straight path until it enters a spiral or helical configuration at a tangent infeed point. When aligned in the helical configuration, the lowest tier of the belt is supported by a frame or drive system, while the upper tiers are supported by the lower tiers. The interface between adjacent tiers is designed to keep the belt supported and laterally aligned. The tiers are laterally aligned by resting the upper edge of a lower side guard against the bottom side edge of the belt in a tier above. 
     Some self-stacking spiral belts are positively driven without slip by vertical drive bars on the periphery of a drive drum whose diameter is greatest at the tangent infeed point to reduce tension in the belt. The bottom ends of the drive bars are recessed slightly above the level of the tangent infeed point. But until the belt reaches the level of the drive bars, it is pulled along only by belt pull and frictional contact between its inside edge and the drive drum. To keep the tension in the belt as low as possible, the distance between the tangent infeed point and the level of the bottom ends of the drive bars has to be small. 
     SUMMARY 
     One version of a spiral conveyor embodying features of the invention comprises an arrangement of drive members that extend in length from tops to bottoms and define a cylinder having a vertical axis about which the arrangement of drive members is rotatable and a conveyor belt arranged to follow a helical path in multiple tiers up or down the drive members. The conveyor belt extends in thickness from a top side to a bottom side and in width from an inner side at the drive members to an outer side and includes inner side supports standing up from the top side at the inner side and outer side supports standing up from the top side at the outer side to support the bottom side of the conveyor belt at the inner and outer sides on the tier above on the helical path. The outer side supports have first locking structure, and the conveyor belt has second locking structure at the outer side at the bottom side that engages the first locking structure on the tier below to lock the tiers together. The drive members have an outer face along which the conveyor belt rides on the helical path and whose distance from the vertical axis is greater at the bottom of the drive member than at the top for an upgoing conveyor belt on the helical path or is greater at the top of the drive member than at the bottom for a downgoing conveyor belt on the helical path. The drive members include ridges that extend radially outward of the outer faces along a portion of the length of the drive members to positively drive the conveyor belt without slip along the helical path. 
     Another version of a spiral conveyor comprises a conveyor belt that extends in width from a first side to a second side and includes first side supports standing up from the first side and second side supports standing up from the second side and including locking structure. Drive members each include a first segment and a second segment and extend in length in a generally vertical direction and rotatable about a vertical axis. At least some of the plurality of drive members are arranged to positively engage the conveyor belt only in the first segment and drive the conveyor belt without slip on a helical path in tiers locked together by the locking structure. The drive members are arranged to space the conveyor belt from the vertical axis so that the distance of the conveyor belt from the vertical axis varies along the length of the drive members. 
     Yet another version of a spiral conveyor comprises a spiral stacker belt having a plurality of first and second supports at first and second sides of the stacker belt capable of traveling up or down a helical path of multiple tiers spaced apart and supported by the first and second supports on the tier below. Drive members extending in length in a generally vertical direction are rotatable about a vertical axis. At least some of the drive members each include a positive-drive segment having drive ridges and an entrance segment devoid of drive ridges. The entrance segment is below the positive-drive segment for an upgoing spiral stacker belt and is above the positive-drive segment for a downgoing spiral stacker belt. The spiral stacker belt enters a helical path about the plurality of drive members along the entrance segment and is positively driven without slip up or down the helical path by the drive ridges in the positive-drive segment. Multiple tiers of the spiral stacker belt wrap around the entrance segment before engaging the positive-drive segment. 
     In another aspect, a conveyor belt module embodying features of the invention comprises a central portion that extends longitudinally from a first end to a second end, laterally from a first side to a second side, and in thickness from a top side to a bottom side. A side support stands up from the top side at the second side. A distal end of the side support has locking structure laterally facing either inward or outward. Laterally facing locking structure at the bottom side of the second side engages the locking structure of the side support of another such conveyor module below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a self-stacking spiral conveyor embodying features of the invention. 
         FIG. 2  is an isometric view of a belt module used to construct a self-stacking belt for a spiral conveyor as in  FIG. 1 . 
         FIG. 3  is an enlarged axonometric view of an outer side support with locking structure for the belt module of  FIG. 2 . 
         FIG. 4  is an enlarged isometric view of the outer side of the belt module of  FIG. 2  with the side support removed. 
         FIG. 5  is an enlarged bottom isometric view of the outer side of the belt module of  FIG. 2  with the side support of  FIG. 3  installed. 
         FIG. 6  is an axonometric view of two outer side supports as in  FIG. 3  locked together. 
         FIG. 7  is an isometric view of a portion of two tiers of a self-stacking belt made of belt modules as in  FIG. 2  locked together at the outer side of the belt. 
         FIG. 8  is an axonometric view of a portion of a spiral drive drum usable in a self-stacking spiral conveyor as in  FIG. 1 . 
         FIG. 9  is an enlarged vertical elevation view of the entry portion of the drive drum of  FIG. 8 . 
         FIG. 10  is a vertical elevation view of the entry portion of the drive drum of  FIG. 8  showing the engagement of the lower tiers of the conveyor belt with the drive drum. 
         FIG. 11  is an axonometric view of another version of a locking outer side support for a belt module as in  FIG. 2 . 
         FIG. 12  is an axonometric view of outer side supports as in  FIG. 11  shown interlocked from tier to tier. 
         FIGS. 13A and 13B  are enlarged views of the outer side supports of  FIG. 12  just before and after interlocking engagement. 
     
    
    
     DETAILED DESCRIPTION 
     A self-stacking spiral conveyor system is shown schematically in  FIG. 1 . The spiral belt conveyor  10  conveys articles vertically along a substantially helical path. The spiral belt conveyor includes a conveyor belt  12 —a spiral self-stacking, or stacker, belt—arranged in a helical stack  11 , comprising tiers  13  of the belt stacked serially and directly on one another. The belt travels around various take-up, idle, and feed sprockets  22  as it makes it way from the exit at the top of the stack back to the entrance at the bottom. Alternatively, the belt may enter at the top and exit at the bottom of the stack. The spiral belt conveyor  10  may be used within a refrigerator or a cooler, for example, providing the articles being conveyed with an extended route for cooling, or within a heating system for baking, proofing, or heating products. 
     The conveyor belt  12  is constructed of a series of rows, each comprising one or more belt modules  14 , like the belt module of  FIG. 2 . A row may comprise a single module spanning the width of the belt or a number of side-by-side modules. The exemplary belt module  14  includes a central portion  16  that extends longitudinally in a direction of belt travel  15  from a first end  18  to a second end  19 , laterally from an inner side  20  to an outer side  21  and in thickness from a top side  22  to a bottom side  23 . A first set  24  of hinge elements is formed along the first end  18  of the module; a second set  26 , along the second end  19 . Rod openings  28 ,  29  in the hinge elements align to form lateral passageways through the first and second sets  24 ,  26  of hinge elements. The passageways admit a hinge rod (not shown) that connects a row of similar side-by-side modules to an adjacent row of modules into a conveyor belt. The first set of hinge elements  24  along a row of modules interleaves with the second set of hinge elements  26  of a longitudinally adjacent row to form a hinge with the hinge rod. The rod openings  28 ,  29  through one or both of the leading and trailing hinge elements may be elongated in the direction of belt travel to allow the belt to collapse at the inside of a turn, while the outside edge expands. 
     The belt modules  14  are preferably injection molded out of a thermoplastic material, such as polyethylene, polypropylene, acetal, nylon, or a composite resin. The belt modules may have any suitable configuration and are not limited to the exemplary embodiment. 
     Side supports  30 ,  32  are coupled to each side edge of the conveyor belt row. In the embodiment of  FIG. 2 , a single module  14  spans an entire row, with side supports  30 ,  32  standing up from each side of the module. Alternatively, a row of the conveyor belt may comprise a plurality of modules arranged side-by-side, with an inner side support  32  coupled to the inner side  20  of an inner module and an outer side support  30  coupled to the outer side  21  of an outer module. The side supports may be integrally formed with the module, or may be coupled to the module using screws, bolts, ultrasonic welding, a snap-fit connection, or other suitable fastening means. The side supports facilitate stacking of the belt in the helical configuration, as each module rests on a side support on a lower tier. 
     As shown in  FIG. 3 , the outer side support  30  has locking structure  34  at the top edge and complementary locking structure  36  at the bottom. The outer support  30  has a base  35  from which two legs  38 ,  39  extend upward to a bridge  40  at the top. The complementary locking structure  36 , along with a guide  42 , is formed in the bottom of the base  35 . As shown in  FIGS. 4 and 5 , the outer side support  30  snaps in place in an opening  44  in the outer side  21  of the belt module  14 . The complementary locking structure  36  of the outer support  30  extends downward from the module to engage the top locking structure of the tier below. The locking structure shown in this example is in the form of rounded teeth, but could be realized with different interlocking geometries, such as sawtooth, triangular, or any other suitable interlocking geometry. 
     The outer side support  30  shown in  FIG. 3  has a large opening  46  bounded by the base  35 , the two legs  38 ,  39 , and the bridge  40 . But for strength, the outer side support  30  may include a diagonal strut  48  as in  FIG. 2 , or the outer side support may be a plate devoid of an opening. If the outer side support  30  is integral with the module  14 , the lower locking structure  36  and the guide  42  would instead be formed on the bottom side  23  of the module. 
       FIG. 6  shows the engagement of the top locking structure  34  of the outer support  30  of a lower tier with the complementary locking structure  36  of a higher tier. When the two tiers are interlocked, they do not slip relative to each other in the direction of belt travel  15 , as shown in  FIG. 7 . Furthermore, the upper locking structure  34  is also restrained against lateral wander by laterally spaced depending guides  50 ,  52  extending longitudinally at the bottom side of the belt. As shown in  FIG. 5 , the guide  52  and the guide  42  on the bottom of the outer side support  30  together form a bilateral guide. 
     A drive drum  54  for a self-stacking spiral conveyor is shown in  FIGS. 8-10 . The drum  54  has an arrangement of parallel drive members  56  that extend in length generally vertically from tops  58  to bottoms  59  and define a cylinder. The drum  54  is rotated conventionally by a drum drive including a motor and a gear train (not shown). The drum  54  and the drive members  56  on its periphery rotate about a vertical axis  60  (as also shown in  FIG. 1 ). The vertical axis of rotation  60  is also the axis of symmetry of the cylinder, whose diameter varies. The drive members  56  have outer faces  62  that contact the inner side  20  of the belt at the end of driven protrusions, such as drive lugs  64  ( FIG. 2 ), protruding radially inward toward the vertical axis from the inner side to set the distance between the vertical axis and the stacker belt  12 . 
     The drive members  56  are divided into entrance segments  74  and positive-drive segments  66  that have ridges  68  extending radially outward of the outer faces  62 . The ridges  68  have drive faces  70  that engage the driven protrusions at the inner side of the stacker belt  12  and drive it on the helical path without slip. In the example of  FIGS. 8-10 , the ridges  68  are formed on the positive-drive segments  72  of the drive members  56  for which the outer faces  62  are at a constant distance from the vertical axis  60 . The belt entrance segments  74  are devoid of ridges and provide flat outer faces  62  that contact the inner side  20  of the stacker belt  12 . The belt  12  comes into initial contact with the drive drum  54  at a tangent infeed point  76  in the entrance segment  74 . As the belt  12  enters the entrance portion tangentially into its helical path, the lowest tier  78  engages the bottom of the second tier  80 . The inner and outer supports  30 ,  32  of the lowest tier move into supporting contact with the bottom side of the tier above. And the upper locking structure of the outer support  32  of the lowest tier interlocks with the lower locking structure of the tier above. Because of the interlock, the upper tiers help drive the lower tiers in the entrance segment  74  even though the lower tiers are not positively driven by the ridges  68  in the positive-drive segment  72 . This allows multiple belt tiers to be in contact with the entrance portion before they gradually advance along the helical path into positive engagement with the ridges  68 . 
     To reduce belt tension, the entrance segment  74  has a transition portion, or segment  82 , in which the distance of the outer face  62  from the vertical axis  60  varies from a maximum distance at a lower distal end  86  to a lesser minimum distance at a proximal end  87  to the positive-drive segment  72 . The entrance segment  74  may also include a lower entry portion  88  whose outer face  62  is a constant distance, i.e., the maximum distance of the transition portion  82 , from the vertical axis  60 . The gradual reduction in the cylindrical drum&#39;s effective diameter, i.e., the distance from the vertical axis  60  to the inner side  20  of the stacker belt  12  in the entrance segment  74 , helps lower the belt tension as it enters the positive-drive segment  72  and first engages the drive ridges  68 . Even though the entrance segment  74  contacts multiple tiers, it is still shorter than the positive-drive segment  72 , which engages more tiers around the drum. 
     Another version of a locking outer side support usable in a belt module as in  FIG. 2  is shown in  FIG. 11 . The support  90  differs from the support  30  of  FIG. 3  in that its locking structure is not upward-facing. Rather its locking structure  92  as shown in  FIG. 12 , is laterally facing on an upper bridge  94  at the ends of two legs  96 ,  97  extending up from a base  98 . The locking structure  92  faces inward on the supports  90  on even (or odd) belt rows and outward on the supports  90 ′, on odd (or even) belt rows. Extending down from the base  98  are two depending guides  100 ,  101 . The guides  100 ,  101  have laterally facing locking structures  102 ,  103  shown in this example as rows of triangular teeth that match triangular teeth on the upper locking structure  92  on the bridge. Like the outer side support  30  of  FIG. 3 , the side support can be a replaceable piece or can be integrally formed with the module body. Or the base can be integrally formed with the module body, and the legs and bridge made to fasten to the module body. Also formed in the base  98  is a plow  104  that protrudes downward into a gap  106  between the facing locking structures  102 ,  103 . The plow  104  is shown as an elongated triangular wedge with angled faces that extend the length of the base  98 . 
       FIG. 13A  shows two adjacent outer supports  90 ,  90 ′ just before locking engagement with the laterally facing locking structure  102 ,  103  of the belt tier above. Beveled faces  108 ,  109  on the guides  100 ,  101  direct the bridges  94  of the side supports  90 ,  90 ′ into the gap  106 . When the bridges  94  reach the vertex of the plow  104 , the bridge of the side support  90 ′ with the outward-facing locking structure is pushed by the outer angled face of the plow  104  outward into engagement with the complementary locking structure  103  on the inward-facing face of the tier above as shown in  FIG. 13B . And the bridge of the side support  90  with the inward-facing locking structure is pushed by the inner angled face of the plow  104  inward into engagement with the complementary locking structure  102  on the outward-facing face of the tier above. In that way, the plow  104  wedges the two consecutive side supports  90 ,  90 ′ apart and into interlocking engagement with the tier above. The lateral interlocking engagement of the tiers allows the outer side supports  90 ,  90 ′ to move with less vertical displacement than with the side supports of  FIG. 6 . 
     Although the features of the invention described in detail are for an upgoing spiral stacker belt, the same features can be used in a downgoing spiral. For a downgoing spiral the entrance segment would be inverted and reside on the drive drum above an inverted positive-drive segment from which the stacker belt would exit at its lower end. It would also be possible for the ridges to extend onto the entrance portion for either an upgoing or a downgoing spiral conveyor.