Spiral conveyor system with direct cage engagement

Abstract

To provide a spiral conveyor belt system that allows for improved engagement / disengagement interaction between a drum and the inner edge of the spiral conveyor belt while allowing for a longer shortened pitch and maintaining the required product support and belt support strength. The solution involves a grooved "ribless" cage bar cap, where the groove extends below the outer surface of the cage bar cap and is configured to engage with the inner ends of the belt support rods or belt link tabs. The bar cap grooves may be straight (approximately perpendicular to the outer surface) or angled to better engage and drive the belt and prevent it from slipping forward or outward against the drum outer boundary.

Description

[Technical Field]

[0001] Related Applications This application claims priority to U.S. Provisional Application No. 63 / 534,078, filed August 22, 2023, entitled "Spiral Conveyor System with Direct Cage Engagement," and U.S. Provisional Application No. 63 / 534,549, filed August 24, 2023, entitled "Spiral Conveyor System with Direct Cage Engagement," the disclosures of each of which are incorporated herein by reference in their entirety.

[0002] The present disclosure relates to direct drive spiral belt systems. Specifically, the disclosed invention relates to a spiral belt configured for direct belt drive cage engagement and a corresponding drive system. [Background technology]

[0003] Spiral conveyor belt systems are widely used in manufacturing and commercial food processing industries. Spiral systems are essentially conveyor belts that travel along a spiral-shaped path to transport items vertically on the belt along a long helical path. This is convenient for moving parts in one step across different vertical levels using a small footprint. Spiral belts used create long paths in small spaces, allowing food products to pass through coolers or ovens for longer time frames to freeze, cool, or cook food. The helical configuration used in spiral systems can accommodate hundreds of meters of belt in a relatively small floor area.

[0004] The conveyor belt surrounds a rotating drum. The drum may be an essentially continuous surface or may be formed from a series of spaced longitudinal bars within a cage assembly. The drum engages and advances the belt along the inner radius of the belt's helical path. In some systems, this is achieved by simple friction between the drum or cage and the inner radial edge of the belt, as described, for example, in U.S. Pat. No. 6,229,994. In other systems, features known as "cage bar caps," often made of plastic and connected to the longitudinal rods of the drum cage structure, engage with corresponding features on the inner belt radius, typically one of the protruding transverse belt rods, as described, for example, in U.S. Pat. No. 6,229,994. Additionally, the traction elements in spiral systems may include a central cage, sprockets on the outer links of the belt, or even a drive chain positioned underneath the self-stacking belt.

[0005] Powered rotation of the drum moves the belt along a helical path. The proper functioning of any spiral conveyor belt system requires a secure but releasable connection between the drum's outer surface, which may be a cage bar, and the belt's inner helical edge. Cage drums with vertical cage bars fitted with cage bar caps (typically U-shaped or flat bar links) are currently in widespread use. The "U" shape of the bar caps opens inward to connect with the cage bars and has opposing surfaces that engage the inwardly projecting rod ends of the belt, thereby driving the belt forward. This is shown in U.S. Pat. No. 5,629,499.

[0006] This and other designs have serious problems with belt engagement and tension control, which can cause the conveyor belt ("belt") to separate from the drum cage. Such separation can result in damage to the product the belt is carrying, damage to the belt, and damage to the drive cage. While not uncommon, complete separation can cause the belt to lose its upright position in the spiral structure, resulting in product loss and catastrophic damage to multiple components of the system. Specifically, cage bar distortion can occur due to a structurally weak design or a design that does not prevent the belt from moving forward relative to the drive member or outward from the drive cage.

[0007] Additionally, the inner radius of the belt spiral is determined by both the distance between the inner end of the belt support rod and the outer end of the belt support rod. This rod-to-rod distance is limited by the belt link design, the maximum belt shortening pitch along the inner edge belt path, and the belt expansion pitch along the outer edge belt path. The shortening pitch and expansion pitch refer to the distance between identical locations on adjacent belt links when the inner belt edge (shortening) or outer belt edge (expansion), respectively, is moving along a curved path. A longer "shortening pitch" affects the distance between belt structures that engage the drive drum along the helical radius of the inner belt edge, such as the inner end of the belt support rod or adjacent belt link tabs. This design is preferable over prior art because a longer pitch without sufficient belt rod support results in a loss of product support and belt strength. Small radius spiral conveyor belt systems require a smaller footprint due to the smaller inner radius of the helical path, thus offering an advantage over conventional systems that require larger floor space. The size of the inner radius is limited by the design of existing belt links. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 3,348,659 [Patent Document 2] U.S. Patent No. 4,932,925 [Patent Document 3] U.S. Patent No. 4,741,430 Summary of the Invention [Problem to be solved by the invention]

[0009] For at least the aforementioned reasons, there is a need for a spiral conveyor belt system that overcomes the drawbacks noted hereinabove. [Means for solving the problem]

[0010] Disclosed herein are embodiments of a spiral conveyor belt system. System embodiments allow for a longer, compressed pitch, enabling improved engagement / disengagement interaction between the drum and the inner edge of the spiral conveyor belt while maintaining the necessary product and belt support strength. In part, the disclosure relates to grooved "ribless" cage bar caps, in which the grooves extend below the outer surface of the cage bar cap and are configured to engage with the inner ends of the belt support rods or belt link tabs. The bar cap grooves may be straight (substantially perpendicular to the outer surface) or angled to better engage and drive the belt and prevent it from slipping forward or outward against the drum's outer boundary. In some embodiments, engagement is achieved through various link geometries, such as ρ ("rho")-shaped links for grid belts and Ψ ("psi")-shaped links for flex belts. Conventional belts employ links connected to two belt support rods. The link shapes disclosed herein connect at least three support rods, maintaining strength and product support while increasing the shortened pitch (as longer links are used to accommodate the additional support rods) and increasing the average distance between the ends of the support rods along the inner helical path radius in a fully retracted belt configuration. This gradual increase in shortened pitch results from the larger spacing between the rod ends in a specially designed drum-bar cap engagement. Various link shape embodiments allow for ribless or grooved engagement instead of the ribbed engagement between existing U-shaped links in the prior art. Additionally, the drum cage is designed to allow the belt to travel on a non-cylindrical, frusto-conical drum outer surface configured to transition between a larger first radius and a smaller, shortened second radius, measured from the drum outer surface to the central rotation axis. The decreasing radius between the belt infeed and belt outfeed on the drum outer surface reduces belt tension along the helical path and adds stability to the drum-belt interaction.

[0011] SUMMARY OF THE INVENTION A spiral conveyor system is disclosed, comprising: a belt formed from a plurality of segments and configured to move along a helical path, the belt having a belt width and inner and outer edges, the inner edge translating a helical path having an inner radius and the outer edge translating a helical path having an outer radius, each of the plurality of segments comprising at least one rod having an elongated shape with a central portion and terminating in inner and outer ends, and at least one link coupled to the at least one rod, each segment being movably coupled to two adjacent segments; and a drum generally shaped as a cylinder having a central longitudinal axis coaxial with the helical path and an outer boundary, the drum configured to rotate about the central longitudinal axis to releasably interact with each of the plurality of segments at their outer boundary, wherein the belt moves along the helical path due to continuous interaction of the drum outer boundary with the belt segments as the drum rotates.

[0012] In some embodiments, the inner radius of the helical path is less than about 1.6 times the width of the belt.

[0013] In some embodiments, the link comprises a first leg and a second leg, the first leg and the second leg being generally parallel. In some embodiments, the first leg comprises at least one circular opening and at least one semicircular opening, and the second leg comprises a slotted opening. In some embodiments, each of the rod inner ends is movably coupled to three links. In some embodiments, the first leg is rotatably coupled to two rods, the second leg is rotatably and slidably coupled to a third rod, and the third rod is rotatably coupled but not slidably coupled to an adjacent link.

[0014] In some embodiments, the drum interacts continuously with the belt segments through mechanical engagement with the inner rod ends or link tabs. In some embodiments, the central rod portion is not connected to the links. In some embodiments, the drum releasably engages the inner edge of the belt. In some embodiments, the drum comprises multiple bars arranged around the outer boundary, each bar configured to simultaneously releasably engage multiple inner belt rod ends.

[0015] In some embodiments, the bars are connected to a corresponding plurality of cage bar caps, and the cage bar caps reversibly interact with the inner edge of the belt. In some embodiments, the rod inner ends comprise angles. In some embodiments, the spiral drum system further comprises grooves disposed on at least some of the bars and tabs disposed on at least some of the links, where rotation of the drum causes the grooves to advance the belt along a helical path, thereby causing continuous engagement and disengagement of the tabs. In some embodiments, the drum is a ribless drum. In some embodiments, the drum engages the outer edge of the belt. In some embodiments, the system comprises a sprocket configured to engage the outer edge of the belt.

[0016] In some embodiments, the drum further comprises an infeed section and an outfeed section, the infeed section and the outfeed section being disposed at different axial locations of the outer boundary, and interaction between the drum and the segments occurring along the length of the central longitudinal axis of the drum starting at the infeed section and ending at the outfeed section; a first radius between the infeed section and the outfeed section projecting from the longitudinal axis to the outer boundary; a second radius at one or both of the infeed section and the outfeed section projecting from the longitudinal axis to the outer boundary; and a sloped surface disposed at the outer boundary, the second radius being larger than the first radius and transitioning along the sloped surface to the first radius, the sloped surface configured to move the belt inward from the infeed section to the first radius and outward from the first radius to the second radius starting at the outfeed section.

[0017] Also disclosed is a spiral conveyor system comprising: a belt having a plurality of segments configured to move along a helical path, the belt having a belt width, an inner edge, and an outer edge, the inner edge translating the helical path along an inner radius and the outer edge translating the helical path along an outer radius, each of the plurality of segments comprising at least one rod having an elongated shape with a central portion and terminating in inner and outer ends, and at least one link connected to the at least one rod, each segment being movably connected to two or more adjacent segments; and a rotatable drum having a plurality of bars arranged about a central longitudinal axis to form a cage, and a plurality of bar caps attached to some or all of the plurality of bars, the bar caps defining an outer boundary of the drum, the drum rotating about a central longitudinal axis coaxial with the helical path and configured to releasably interact with each of the plurality of segments at their outer boundary, the belt moving along the helical path due to continuous interaction between the drum's outer boundary and the belt segments provided by the rotating drum.

[0018] In some embodiments, each of the plurality of bar caps comprises a groove. In some embodiments, the groove forms a non-orthogonal angle with the central longitudinal axis and is configured to releasably and simultaneously interact with two belt segment support rod ends bent at a corresponding non-orthogonal angle. In some embodiments, each of the plurality of bar caps comprises a tab.

[0019] The features and advantages of the present invention will become apparent to those skilled in the art from the following, more particular description of several exemplary embodiments of the disclosed systems and methods and the accompanying drawings. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a perspective view of an exemplary prior art spiral conveyor system. [Figure 2A] 1A and 1B are top views of a portion of a spiral conveyor belt made up of rod links and clevis links, respectively. [Figure 2B] 1A and 1B are top views of a portion of a spiral conveyor belt made up of rod links and clevis links, respectively. [Figure 3A] FIG. 1 is a top view of a prior art flex spiral conveyor belt with links in a retracted configuration. [Figure 3B] FIG. 2A is a top view of a prior art grid-type U-link spiral conveyor belt with the links in a retracted configuration; [Figure 3C] FIG. 1 is an enlarged perspective view of a prior art clevis; [Figure 4A] FIG. 1 is a perspective view of an embodiment of a three-rod belt link. [Figure 4B] FIG. 1 is a perspective view of an embodiment of a three-rod belt link. [Figure 5A] FIG. 1 is a perspective view of an embodiment of a low belt link. [Figure 5B] FIG. 1 is a perspective view of an embodiment of a low belt link. [Figure 5C] FIG. 1 is a perspective view of an embodiment of a low belt link. [Figure 6A]FIG. 1 is a diagram of a drum of a spiral conveyor system that moves a belt in a helical path. [Figure 6B] FIG. 1 is a perspective view of a length of belt. [Figure 7A] FIG. 1 is a perspective view of an exemplary embodiment of a Psilink component. [Figure 7B] FIG. 1 is a perspective view of an exemplary embodiment of a Psilink component. [Figure 7C] FIG. 1 is a perspective view of an exemplary embodiment of a Psilink component. [Figure 7D] FIG. 1 is a perspective view of an exemplary embodiment of a Psilink component. [Figure 8A] 10A-10C are perspective views of additional exemplary embodiments of psilink components. [Figure 8B] 10A-10C are perspective views of additional exemplary embodiments of psilink components. [Figure 9] FIG. 1 is a diagram of a portion of a spiral conveyor belt formed from Psi-links. [Figure 10] FIG. 10 is a perspective view of a group of tapered cage bar caps positioned around a drive drum. [Figure 11] FIG. 1 is a perspective view of a tapered cage bar cap. [Figure 12] FIG. 1 is a perspective view of a drum of a spiral conveyor system. [Figure 13] FIG. 1 is a top view of a portion of a low-link spiral conveyor grid belt being retracted at a curve. [Figure 14] FIG. 1 is a top perspective view of a three-rod rod link spiral conveyor belt being retracted at a curve. [Figure 15] FIG. 1 is a top view of a "three-rod" clevis spiral conveyor belt interacting with a series of ridgeless cage bar caps. [Figure 16A] FIG. 10 is a close-up view of the curved rod end belt interacting with the cage bar cap groove. [Figure 16B] FIG. 10 is a close-up view of the inner end of the bent support rod. [Figure 17A] FIG. 10 is a partial view of the cage bar cap. [Figure 17B] FIG. 10 is a partial view of the cage bar cap. [Figure 17C] FIG. 10 is a partial view of the cage bar cap. [Figure 17D] FIG. 10 is a partial view of the cage bar cap. [Figure 18] FIG. 10 is a perspective view of a ribless transition element. [Figure 19A] FIG. 10 is a cutaway top view of an arcuate portion of a drum having ribless transition elements alternating with cage bar caps. [Figure 19B] FIG. 10 is a perspective cross-sectional view of an arcuate portion of a drum having ribless transition elements alternating with cage bar caps. [Figure 20] FIG. 10 is a side view of an arcuate portion of a drum having ribless transition elements alternating with cage bar caps. [Figure 21] FIG. 10 is a perspective view of an arc portion of a drum having only a ribless transition element and no cage bar cap. [Figure 22A] FIG. 10 is a perspective view of an arc portion of a drum having only a ribless transition element and no cage bar cap. [Figure 22B] FIG. 10 is a close-up view of an arcuate portion of a drum having ribless transition elements alternating with cage bar caps. [Figure 23] FIG. 10 is a perspective view of an arc portion of a drum having alternating ribless transition elements and cage bars and an inlet ring. [Figure 24] FIG. 10 is a cutaway top view of an arcuate portion of a drum having ribless transition elements alternating with cage bar caps and inlet or outlet rings connected to the transition elements. [Figure 25] FIG. 1 is a top view of a portion of a belt with clevis links engaged on a ribless belt drum. [Figure 26] FIG. 1 is a top view of a portion of a belt with row links engaged on a ribless belt drum. [Figure 27A] FIG. 1 is an enlarged side view of a cage drum with an outlet ring. [Figure 27B] FIG. 1 is an enlarged side view of a cage drum with an outlet ring. [Figure 27C] FIG. 1 is an enlarged side view of a cage drum with an outlet ring. [Figure 28] FIG. 10 is a partial view of a link of a belt engaging and disengaging with a cage drum having an inlet ring and a transition element. [Figure 29] FIG. 10 is a top perspective view of a recessed outlet ring mounted on a cage drum. DETAILED DESCRIPTION OF THE INVENTION

[0021] Various exemplary embodiments of a spiral conveyor system are described herein. The system includes a belt driven by a drum along a helical path (spiral) utilizing a belt link design and drum engagement features, allowing for a tighter turning radius with reduced tension. System embodiments have advantages over existing spiral conveyor systems, such as using a smaller footprint and reducing the likelihood of belt separation, which can result in product loss or system damage.

[0022] The details of the spiral conveyor system with direct drum engagement will be described generally first and then with reference to the state of the several drawings. The concept of providing a spiral conveyor system with direct drum engagement that may enable a reduced pitch and the attendant benefits thereof are believed to be within the scope of this disclosure. Those skilled in the art will readily recognize the utility of such a system as disclosed herein across a range of belt link and cage bar cap designs, as well as the disclosed embodiments.

[0023] Definition: As used herein, a "cage" refers to a drum component that mechanically interacts with a belt to cause movement of the belt along a helical path. A "cage drive" is a type of drum. A cage drive is configured as an arrangement of generally vertical elements, such as cage bars, extending to generally circular end elements between them to form a generally cylindrical cage-like structure. The circular end elements may each have the same radius or different radii, and the drum itself may have a frusto-conical shape with either a decreasing or increasing radius from the lower drum end element to the upper drum end element. In that case, the end elements may have different radii, forming a generally tapered cylindrical cage.

[0024] As used herein, "belt" means an elongated, continuous, flexible structure formed from a plurality of links connected together with a plurality of rods oriented perpendicular to the links. In some embodiments, the belt comprises a mesh or wire grid that provides a surface on which products conveyed by the spiral conveyor system rest. "Belt" encompasses all structures and substructures that move along a helical path. "Belt" is used in certain disclosures herein loosely to refer to a limited length of the overall belt structure.

[0025] As used herein, "belt support rod," "belt rod," or "rod" all have the same meaning and refer to an elongated structure having a circular or oval cross-section extending perpendicular to the belt links. A belt rod extends the entire width of the belt. A belt rod may be substantially straight along its entire length, or in some embodiments, may have curved end sections to facilitate interaction with a belt drive drum, crank, or other drive structure.

[0026] As used herein, "cage bar" means a generally elongated structure that forms part of the structure or is disposed on the surface of the belt drive drum. The cage bar is part of the drive drum assembly and is not part of the belt. The cage bar, in some embodiments, interacts with the inner belt edge by "bar caps" that are attached to the bar.

[0027] As used herein, "link" refers to a structure located along one of the edges (inner and outer edges) of the belt. A link is part of the belt. In some embodiments, each single link is connected to two adjacent links (one front link and one rear link relative to the direction of belt travel) by two or three support rods.

[0028] As used herein, "cage bar cap" means a structure attached to a cage bar and configured to frictionally or mechanically interact with the belt edge. The cage bar cap is the connection point between the drive drum and the belt. Cage bar caps can be formed in a wide variety of configurations to interact with the belt edge in various ways, many examples of which are described herein.

[0029] As used herein, a "rib," "cage rib," or "bar cap rib" is a structure located on the outer surface of a cage bar or cage bar cap (the surface facing the inner belt edge). The rib protrudes from the outer surface of the cage bar or cage bar cap and interacts with the inner belt edge. A "ribless system" or "ribless cage bar" does not have ribs. That is, the drive drum does not engage the inner belt edge by a protruding structure, but rather by a non-protruding structure such as a groove, channel, or simply by friction with a generally flat surface.

[0030] As used herein, "system rotation ratio" means the ratio between the radius traversed by the inner belt edge along the helical path, i.e., the distance from the inner belt edge to the central axis of the helical path, and the belt width.

[0031] As used herein, "reduced pitch" means the linear distance from a point on a belt link to the same point on an adjacent belt link when the belt is in a fully (maximum) retracted configuration. As shown in the drawings and the following description, in a fully retracted configuration, the belt links slide relative to the belt rod along the belt's longitudinal axis, i.e., parallel to the direction of travel of the moving conveyor belt. The reduced pitch occurs along the inner edge of the belt adjacent to the cage drive drum when the belt is in a helical configuration, passing multiple times ("stages") around the cage drive drum. The inner edge of the belt travels a spiral path with an inner radius. The outer edge of the belt travels a similar helical path with an outer radius. Stated differently, the inner radius is the linear distance from the drive drum's central axis of rotation and the inner belt edge. The outer radius is the corresponding linear distance from the drive drum's central axis of rotation and the outer belt edge. The outer radius of the belt helical path (outer belt edge) is inherently larger than the inner radius of the belt helical path.

[0032] As used herein, "extended pitch" means the longest possible distance between two adjacent belt rods when the belt is in a fully extended configuration. As shown in the drawings and the following description, in a fully extended configuration, the belt links slide relative to the belt rods along the belt's longitudinal axis, i.e., parallel to the direction of travel of the moving spiral conveyor belt. The extended pitch occurs along the outer "free" edge of the belt opposite the cage drive drum when the belt is in a helical configuration making multiple passes around the cage drive drum. As the outer edge of the belt moves around the cage drive drum, it describes a helical path with an outer radius, traveling a path generally parallel to the inner helical path with an inner radius described by the inner edge of the belt.

[0033] As used herein, a "small radius system" refers to a spiral conveyor belt system configured to run along a helical path having an inside radius less than about 1.6 times the belt width. Correspondingly, a "reduced radius belt" refers to a spiral conveyor belt capable of running along a helical path having an inside radius less than about 1.6 times the belt width. Belts limited to helical paths having an inside radius equal to or greater than about 1.6 times the belt width are considered standard belts.

[0034] As used herein, "positive drive system" or "positive actuation system" means a belt system in which there is direct mechanical engagement between a cage bar cap feature and a corresponding feature on the belt, such as a support rod end, etc. This is in contrast to a friction drive system in which there is no such direct mechanical engagement between the cage drive and complementary features on the belt.

[0035] Spiral conveyor systems may be friction driven, as described in the Background section of this specification above, or may be driven by mechanical engagement between features provided by the cage drive and the conveyor belt. In some applications, friction drive, in which the drum engages the belt with motion induced solely by friction with the edges of the belt, is advantageous when some degree of backward slippage of the belt on the drum is desirable for proper operation. However, in other applications, slippage between the drum and belt is undesirable, and direct mechanical engagement between features on the belt and corresponding features on the drum drive cage is required. Therefore, a spiral conveyor system utilizing direct engagement between the drive cage and the conveyor belt is disclosed.

[0036] The belt links disclosed herein differ from prior art U-shaped grid belts and prior art rod-link parallel flex belts by the inclusion of grooved cage bar caps, row links ("ρ links"), and psi links ("Ψ links"). ρ links and Ψ links are capable of simultaneous engagement with three belt rod ends, whereas the prior art allows engagement with two belt rod ends. Each belt link (ρ link or Ψ link) is connected to two belt rods. In some embodiments, a third rod is connected to an adjacent link.

[0037] In a spiral belt system, the belt link design determines the shortened pitch of the belt links (the inner edge of the belt engaged by the drum between the infeed and outfeed sections) and the minimum radius of curvature of the inner edge of the belt path where the belt is engaged by the drive cage. When positioned at the inner belt radius of a spiral conveyor belt, the ρ and Ψ link configurations allow for longer shortened tips than prior art belt links, but paradoxically, have a smaller inner radius. The longer shortened pitch allowed by the link designs disclosed herein allows the ingress of the inner ends of the link tabs or belt support rods into grooves or channels on the cage bars or bar caps of a ribless spiral belt system. The link designs disclosed herein also simultaneously allow for a larger expansion pitch along the outer belt edge.

[0038] Increasing the shortened pitch provides several advantages for spiral conveyor systems driven by direct engagement between the belt and the drum. For example, belt-engagement features such as rod ends or link tabs could fit into grooves on the cage bars or cage bar caps. Alternatively, the drum could drive the belt directly by friction, without direct engagement between the belt features and the ribs or cage bar caps. For example, a smaller inner radius allows for the use of smaller-diameter drums, reducing the system's footprint. In some embodiments, belt links are configured to connect to three belt rods per link, as opposed to two rods per link. This substantially reduces the belt tension generated by the drum drive cage, reducing component wear and extending the system's uptime. Reducing tension along the inner radius of the belt path reduces the likelihood of unintended belt separation from the drum. Such unintended separation can lead to product loss or catastrophic damage to the entire spiral conveyor system.

[0039] For a prior art belt with an expanded pitch of approximately 1.0 inch, the shortened pitch is approximately 0.6 inch, measured approximately on a standard width belt. In a second prior art example, for a belt with an expanded pitch of approximately 1.5 inch, the shortened pitch is approximately 0.9 inch. For a cage bar cap to drive such a belt, the ribs on the cage bar cap must be at least narrower than the shortened pitch (plus manufacturing tolerances) to allow the cage bar cap to engage with the belt rod ends. For a drum equipped with cage bar caps to drive a belt in one of these prior art systems, the belt-engaging features, such as ribs on the cage bar cap, must be thinner than the shortened pitch to allow engagement between the belt rod and the cage bar ribs. In related systems with cage bar ribs positioned above the surface of the cage bar cap, the ribs must fit between the shortened pitch belt rod ends with some "play" to engage and drive the belt forward. Therefore, the thickness of the ribs must not exceed the shortened belt pitch. This is one reason why U-shaped belt links cannot interface with ribless cage bar caps and still be driven by the front faces of the ribless cage bar caps. For such prior art systems utilizing belts with U-shaped links, the minimum width of the cage bar caps must be at least about 1.0 inch.

[0040] The increase in inner spacing of belt shortening pitch provided by the Rho and Psi links disclosed herein is substantial, allowing the use of ribless cage bar caps or grooved caps in place of ribs extending above the surface of the caps. As such, the cage bar caps can be configured wider than ribs. The front face of a 1-inch-face ribless cage bar cap used in friction-driven spiral belt systems would also be able to drive a belt fitted with Rho or Psi links. This is not possible with prior art U-shaped links, which are too large to fit into the space between the cage bar caps to engage the belt.

[0041] An additional benefit of ribless cap engagement, besides allowing for a larger shortened pitch, is a more secure engagement between the cage bar cap and the belt. This is because the rib engagement with the belt limits the belt's forward (in the direction of belt travel) or outward slippage, as opposed to cage bar caps with grooved engagement features. Thinner ribs can deflect on larger rib drive systems under higher belt tensions or loads, promoting belt disengagement from the cage bar drive.

[0042] In contrast, for some embodiments having retractable rho or psi links connected to adjacent rods 1.08 inches apart, the pitch is 1.48 inches. In some embodiments, the reduced-radius rho or psi link belt has a reduced pitch of 1.38 inches, thus more than doubling the pitch when compared to prior art clevis links for the same adjacent rod distance in a fully expanded belt. Although the belt in a positive drive spiral system is not intended to slide backward (opposite the belt's direction of travel), during operation around a curve, the belt is prone to outward bias as it is turned around each turn of the spiral path, especially at higher belt speeds and heavier belt loads as a result of angular momentum. Ribbed drive systems, as previously discussed, facilitate breakaway in such systems. However, because the use of grooved cage bar caps described herein allows for movement in an additional degree of freedom ("DOF") and achieves positive engagement between the cage bar caps and the belt links, a belt having edge features capable of positively engaging the grooved cage bar caps is necessary for optimal operation of the system.

[0043] A belt 102 with three support rods 111 per link is inherently stronger than prior art two-rod belts, providing greater support for products conveyed on the belt 102. Conversely, converting a prior art two-rod-per-link configuration to a three-rod link as disclosed herein by adding an additional rod to each link also increases the belt's shortened pitch, eliminating the need for the drive drum to incorporate features, such as cage ribs, that protrude above or below the belt's running surface. Increasing the shortened pitch to allow for a ribless drive drum without adding a third belt support rod would undesirably reduce the belt's product support. The use of grooved cage bar caps as disclosed herein positively engages the belt while limiting its movement on the cage drive in the forward, rearward, and radial (outward) directions, thereby reducing the possibility of unwanted belt disengagement and catastrophic system failure.

[0044] In some embodiments described herein, the grooves in the cage bar caps may be angled (not radially aligned with the central axis rotation of the drive cage).

[0045] Spiral belts with two radially aligned rods (extending across the belt generally perpendicular to the direction of travel) connected to each belt link have been described in the prior art. However, for spiral belt systems using positive engagement drives, belt stability is essential to protect the conveyed product. Spiral belts with three rods connected to each belt link are more stable than belts with two rods per link. Two of the three rods connected to each belt link described herein move with the belt, either up or down the belt travel path, as the belt travels over "bumps" or imperfections in the helical path. Having the two rods move more evenly together reduces "bob" motion of the product.

[0046] The belt in a positive drive system must be precisely controlled at the infeed and outfeed locations of the helix by a torque motor to maintain the proper belt tension to resist belt breakaway. If the outfeed torque motor does not provide enough torque, the belt upstream from the outfeed can sag, potentially resulting in breakaway if the cage-belt engagement features do not provide forward or outward resistance to the belt's movement relative to the cage. In some cases, insufficient torque combined with a lack of forward and outward resistance can cause belt "waves" that propagate along the helix. Similarly, if the infeed torque is too high, the belt will not easily retract along the helical path to properly engage the cage end cap features. Friction-drive spiral systems do not require a torque motor and instead use a standard speed motor.

[0047] In some spiral belting systems, the engagement between the cage bar end caps and belt features is configured to allow the belt to run around a cage drive with a varying helix diameter, such as a tapered cage drive. This is known in the industry as a "bevel" or "taper." When a belt starts at a progressively smaller larger radius and runs along a helical path until the belt exits the helix, belt tension decreases along the helical path. This requires that belt links that enter the helix but are not yet engaged with the cage drive be able to move rearward relative to the cage as the helical radius decreases until engagement occurs. As a result, in some embodiments, the outer cage bar design exhibits bevels or fillets on the front, rear, or both front and rear sides of the cage bar or cage bar cap, depending on the embodiment. The partitioned sides allow the belt to slide to the outer boundary of the drum (up to the cage bar or bar cap) until the link tabs or inner ends of the belt rods contact and engage the cap grooves, positively driven by the drive belt interaction and appropriately restrained to minimize forward or outward belt movement.

[0048] In some embodiments, the belt engages the cage drive end cap groove with the inner belt rod edge, which may be perpendicular or inclined relative to the tangent line of the helical path. The belt rod edge embodiments disclosed herein limit forward and outward movement of the belt as it travels along the helical path by providing uniform positive drive engagement at each engagement point on the outer boundary of the drum. This allows for higher drum rotational speeds (revolutions per minute, or "rpm"), smoother operation, and the need for less precise control of inflow torque, outflow torque, and overall belt tension. In some embodiments disclosed herein, belt movement up or down relative to the travel path is reduced when the inner belt rod edge becomes an engagement feature that interacts with a groove (configured as a groove or slot feature) in the cage bar or bar cap. Compared to the long, flat engagement surface of a protruding cage bar cap flap or tab feature located on the bar of the bar cap, such as in prior art drum belt spiral drive systems, the contact surface area is reduced to a single line or a few locations along the curved cage bar or bar cap.

[0049] In friction drive spiral systems, rearward slippage between the neutralized inner edge and the cage bar, known as "overdrive," is desirable and necessary for proper operation of the system. Belt tension in friction drive systems is much higher than in positive drive systems where the belt is configured to engage the cage bar features.

[0050] In embodiments of the systems disclosed herein, the use of rho- or psi-shaped links may yield up to a 25% reduction in material costs for forming the links, as rho- and psi-links are formed with only one leg, as opposed to the two legs of the clevis links currently used in the industry. The use of single-leg links also reduces belt weight, further reducing the energy costs of operating the system. In some embodiments, belt links with two legs may be used at the outer belt edges under tension (larger outer radii of the spiral), while links with only one leg may be used at the inner belt radii of the spiral, where belt tension is essentially zero.

[0051] Belt slippage on a friction drive system moves the belt's inside links relative to adjacent links. When the belt path has a larger radius of curvature, the inside links move more because they are designed to go through a shorter bend radius so that the links are fully retracted and do not nest within each other. Links moving to a smaller cage diameter tend to slide backward relative to the direction of belt travel to accommodate the shorter cage circumference. For this reason, embodiments utilizing cage bar caps with beveled surfaces located on the leading edge of the cage bar 212 or bar cap are important to ensure that the belt edge engagement feature (i.e., link tabs or inside rod ends, for example) does not catch on the leading edge of the cage bar cap before full engagement with the cap groove 214 occurs in a positive drive system.

[0052] In friction drive systems, friction between the drum's outer boundary (cage bars or bar caps) and the belt can change due to dirt, oil, product, or other debris. Whether the friction resulting from such debris increases or decreases, increased belt tension typically results, potentially leading to failure. For example, even if the cage drum driving the belt loses friction with the belt due to oil on the cage (drum's outer boundary), the delivery motor, which ensures the belt engages the sprocket, continues to pull the belt at the same initial speed as before the oily condition. This increases belt tension and can cause the belt to break away or reverse in a friction drive system. Therefore, some prior art friction systems provide a smooth contact point between the drive cage drum and the belt to ensure proper rearward sliding. Some designs achieve this by creating a smooth, protruding foot on the surface of the belt link facing the cage drum. Other designs create a smoother surface by placing a large curvature in the belt rod, which may also aid in short-term engagement due to features on the cage drum that match the curved inner rod end, for example. Such systems provide a brief, light mechanical engagement that assists the friction drive to aid in belt running. More recent developments have employed positive drive operation to increase the engagement period and eliminate rearward slippage between the belt and cage drive, but the current belt-cage interaction, while working well to prevent rearward slippage, does not provide true engagement as it does not restrict forward or outward belt movement.

[0053] Prior art belt designs for positive drive systems engage drum ribs (cage bar end caps) that protrude from the cage surface to eliminate only rearward slippage. The belt can engage the caps with rods, tabs, or protruding legs that extend radially toward the cage drum's central axis of rotation, but as previously mentioned, these belt designs still allow forward and outward radial movement of the belt. This is especially true in larger systems or when cage bars can bend if a force imbalance occurs during operation of the equipment.

[0054] Belts can deviate from their helical path in positive drive systems for several reasons. These include increased cage rotational speed, belt pitch variations, changes in ambient temperature, or increased friction from worn support rails. To prevent belt deviance, the belt must be properly tensioned by a torque feed-off motor. Current designs have engagement features but no provision for limiting radial belt movement, so insufficient tension or rib distortion can cause the belt to deviate. Current direct drive systems require precise output-path torque control to prevent radial belt slippage backward or outward along the helical path. A better-constrained belt / cage drive system would not require complex and precise infeed and outfeed tension control. Reduced wear on the engagement surfaces between the belt and cage drive elements due to reduced outfeed and infeed tension would extend the useful life of the belt and cage bar end caps.

[0055] The exemplary embodiments disclosed herein limit or eliminate rearward or outward radial movement not through engagement with belt clips or other engagement means with other elements of the system, but through grooved cage bar caps that interact with matching belt rod end shapes. In some prior art systems, belt clips are added to the bottom of the belt, for example, causing the clips to press against the support rails. However, the embodiments disclosed herein are simpler and more efficient. Belt clip solutions are problematic because placing the clips on either the inside (drive cage side) or outside of the belt prevents occasional belt flipping by an operator, which is necessary to even out wear and "stretch" across the belt components, resulting from the large tension differential between the inside (driven) and outside edges. Occasional belt flipping to even out wear is normal industry practice. The embodiments disclosed herein maintain belt symmetry and pose no problems for periodic flipping as part of the regular, established practices employed industry-wide for maintaining spiral conveyor belt systems.

[0056] The prior art disclosed special link designs that bent the ends of the rods to create a smoother surface for cage contact and engagement with the cage drum of a positive drive system, providing a weld-free link. The link and cage bar cap embodiments disclosed herein are designed to create a truly positive engagement surface with the cage drum of a positive drive system.

[0057] The belt link and cage bar cap embodiments disclosed herein allow for a more reduced pitch between belt links running along the inner edge of the helical path. As previously mentioned, the system rotation ratio of positive drive systems is typically 0.9 to 1.6 or greater. Spiral conveyor systems with helical path rotation ratios less than 1.6 require a center link row to maintain belt rod alignment and prevent twisting and belt separation, in addition to the inner and outer belt link rows found in all belt systems, whether straight or spiral, regardless of rotation ratio. Compared to the embodiments disclosed herein, grid and flex belt link designs known in the industry would have a much smaller reduced pitch, making the belt stiffer and preventing "play" along the inner edge of the spiral belt path. Some of the spiral conveyor belt system embodiments disclosed herein allow for a larger reduced pitch, adapted to engage cage bar cap groove features provided by the belt's inner edge, allowing the belt to move up and down but not forward or radially outward. Spiral belt system designs that allow the belt to move radially outward, forward (in the direction of belt travel), or backward are undesirable in positive drive systems for at least the reasons already mentioned. The embodiments disclosed herein properly confine the belt to the cage, stabilizing engagement and reducing product movement, resulting in a smoother running system and extending the useful life of system components.

[0058] FIG. 1 is a perspective view of an exemplary prior art spiral conveyor system. It shows the prior art system 1100 with a belt 1102 engaging a drum 1200 along a helical path indicated by the arrow labeled 1101. The engagement between the belt 1102 and the drum 1200 begins at an infeed section 1220 and ends at an outfeed section 1221, as shown. The prior art system illustrated in FIG. 1 depicts an aspect common to all spiral conveyor systems. The belt translates vertically along a helical path, driven by a rotating drum that engages the belt at multiple locations where the inner belt edge 1105 contacts cage bars 1212. The belt 1102 may move in either direction, as indicated by the arrow in FIG. 1, depending on the direction of rotation of the drum 1200. The example cage drum 1200 illustrated in FIG. 1 has an elliptical cross-section. In practice, existing drums may be circular, elliptical, or tapered in cross-section, depending on the application for which the spiral belt system is used. Therefore, the embodiments disclosed herein are not intended to be limited to any particular drum shape, but are presented as examples only.

[0059] 2A-2B are top views of a portion of a prior art spiral conveyor belt comprised of U-links. In the two illustrated examples, FIGS. 2A-2B show several connected segments of a prior art belt 1100 and are provided to generally illustrate the operation of a spiral conveyor belt. Those skilled in the art will be familiar with the prior art belt structure illustrated in FIGS. 2A-2B and the functionality described below. The section of the prior art belt 1100 in the illustrated example is curved due to the way the spiral conveyor belt bends as it travels along the helical belt path. The belt 1100 has an inner edge 1105 and an outer edge 1106 relative to the curve of the helical belt path. The connected segments forming the belt 1100 include a plurality of links 1105 connected to rods 1121 such that each generally U-shaped link 1121 is free to rotate around each rod 1111. Additionally, each link 1121 may slide along a slotted opening in the arm of the link 1121, which is not visible in these top views but is shown in the perspective link view of FIG. 3A below. In the embodiment shown in FIG. 2B, each link is connected to two rods 1111. Each rod 1111 has an inner end 1113 and an outer end 1114 defined by whether the rod ends run along the inner or outer radius of curvature of the helical path. As can be seen in FIG. 2B, the inner ends 1113 are much closer together than the outer ends 1114. The movement of the inner rod ends 1113 closer together along the inner edge of the helical path is necessary to shorten the belt to accommodate the circumferential length of the belt with a shorter inner radius. The rod 1111 is slidably coupled to a slot (not shown) formed in the link 1121, allowing the inner edge 1105 to shorten after the belt enters the drum infeed section 1220 and lengthen as the belt exits the drum at the outfeed section 1221. The shortened inner edge 1105, with the rod ends closer together than when the helical conveyor belt is traveling along a straight path, is also known as a "reduced pitch."The belt embodiments described herein allow for longer compressed pitches over prior art belts due to the design of the belt links.

[0060] FIG. 3A is a top view of a prior art small radius grid spiral conveyor belt with the links in a retracted configuration. FIG. 3B is a top view of a prior art small radius flex spiral conveyor belt. FIG. 3C is an enlarged perspective view of a prior art clevis link. FIGS. 3A-3C show several examples of prior art belts to illustrate the structure and certain functional elements of existing belt links. The belt link 1102 shown in FIG. 3A is a plate link. The belt link 1102 shown in FIG. 3B is a prior art clevis link, the details of which are shown in FIG. 3C. The belt 1102 has a front portion and a rear portion relative to the direction of travel indicated by arrow T. Upon inspection, the belt rod inner ends 1113 appear to be minimally separated from each other where they are connected to the links 1113. The separation distance of the inner ends 1113 may vary depending on the structure of the links 1121.

[0061] As shown in FIG. 3C , a prior art U-shaped link 1121 typically includes at least one circular opening 1124 and at least one slotted opening 1125. Each link 1121 is connected to exactly two rods 1111. Each rod 1111 is connected to exactly two links 1121. The first rod 1111 passes through the circular opening 1141 in the front link 1121 and the slotted opening 1125 in the rear link. In this manner, the rod 1111 can move forward or backward relative to the direction of travel T, where it is fixed to the front link by the circular opening 1124, while it is free to slide along the slotted opening 1125 in the rear link. This allows the rear link to move forward relative to the front link as the link moves around a curved path. The rod ends 1113 move closer together as the length of belt 1102 enters the helical path, and the rod inner ends 1113 slide along the slot openings 1125 in the rear links, allowing the belt 1102 to be configured further apart as it exits the helical path. In some embodiments of the system 100, the belt 102 is a "mixed link" belt formed from links 121 having two or more overall shapes or configurations.

[0062] Increasing the shortened pitch (i.e., the distance between the rod inner ends 1113 along the belt inner radius of the helical path) allows for a smaller inner radius (inner radius 107 shown in FIG. 6A). Belt link embodiments disclosed herein are configured to minimize the shortened pitch of a spiral conveyor belt.

[0063] 3-rod belt link; low link A reduced pitch spiral belt may be configured to minimize the distance between belt rod ends along the inside edge of the helical path by connecting one link to three rods instead of the prior art two-rod belt link described hereinabove. Belt links connected to three belt rods per link are shown and described in the following drawings.

[0064] 4A-4B are perspective views of an example of a three-rod belt link. FIGS. 4A-4B illustrate an embodiment of a belt link 121. The link 121 is a three-rod belt link configured to connect to three belt support rods 111. In some embodiments, the link 121 is formed as a unitary body having an open shape (e.g., FIGS. 4A-4B). In other embodiments, the link 121 forms a closed shape 127 (i.e., as illustrated in FIGS. 5A-5C). The link 121 may (but need not) include multiple sections joined at angles and has a first leg 122 and a second leg 123 that are generally parallel to each other along the entire length of the link. The first leg 122 may have a shorter overall length than the second leg 123, and the link 121 is a U-shaped three-rod link. Additionally, the second leg 123 includes a slotted opening 125, while the first leg 122 does not. The first leg 122 includes two circular openings 124. The second leg 123 includes one circular opening 124 and one slotted opening 125, as shown in FIGS. 4A-4B. In some embodiments, the link 121 includes two first legs 122, each positioned relative to the second leg 123. In some embodiments, the link 121 includes a shoulder 128 along each of the first and second legs 122, 123, as shown. The shoulder 128 increases the distance between the legs 122 and 123, creating more space for adjacent links 121 to nest within one another. While FIGS. 4A-4B illustrate an embodiment of a U-shaped link 121, other configurations of the link 121 shaped like an open "U" are possible. In particular, the circular openings 124 and the slotted openings 125 may be spaced at different intervals or at various locations along the first and second legs 122, 123, respectively. The spacing of the circular openings 124 determines whether the multiple support rods 111 of the assembled belt 102 are evenly or unevenly spaced along the direction of travel. The shoulders 128 may be orthogonal (FIG. 4B) or non-orthogonal (FIG. 4A) to the major axis "X" of the first leg 122 or second leg 123.

[0065] Link 121, link 131 and / or link 150 (links 131 and 150 are described herein below) are slidably and rotatably coupled to rod 111 at slotted opening 125. Link 121, link 131 and / or link 150 are only rotatably coupled to rod 111 at circular opening 124 and semicircular opening 126.

[0066] The link 121 may also include a tab 129 configured to engage with a cage bar cap 213 on the belt drive drum 200. Engagement of the tab 129 with the cage bar cap 213 positioned on the rotating drum 200 moves the belt 102 along a helical path. While FIG. 4A illustrates the tab 129 positioned near the end of the leg 122, this is exemplary and not intended to be limiting. In some embodiments, the tab 120 is positioned at the end of the leg 123. In some embodiments, the tab 129 is positioned some length of the leg 122 or 123 beyond the leg end. In some embodiments, including the one illustrated in FIG. 4A, the tab 129 extends from the leg 122 at a non-orthogonal angle. This is exemplary and not intended to be limiting. In some embodiments, the tab extends perpendicular to the leg 122 or 123. In some embodiments, the tab 129 forms an angle with the leg 122 or 123 that is less than about 90 degrees. 4A, tab 129 forms an angle of greater than about 90 degrees with leg 122 or leg 123. In some embodiments, tab 129 angled greater than or less than 90 degrees with first leg 122 or second leg 123 provides a more secure engagement and smoother coupling and uncoupling with infeed portion 220 and outfeed portion 221, respectively. In some embodiments, such as that shown in FIG. 4B and others, link 121 does not include tab 129.

[0067] While the belt links 121 illustrated in Figures 4A-4B may appear similar to the prior art links 1121 described above, each link 121 connects to three support rods, as opposed to the two-rod connection of the prior art 1121 links. For example, moving from left to right across each link 121 illustrated in Figures 4A-4B, for every single link 121, a rod 111 (not shown) connects to the link 121 at a first pair of circular openings 124, a second rod 111 connects at a second pair of circular openings 124, and a third rod 111 connects at a single slotted opening 125. This is discussed further below with respect to Figure 6.

[0068] 5A-5C are perspective views of an example low belt link. FIGS. 5A-5C illustrate a link 121 having a closed shape 127 from which extend legs 123. A first leg 122 forms one side of the illustrated four-sided closed shape 127, and a second leg 123 forms the other side of the closed shape 127 opposite the first leg 122. The first leg 122 includes a circular opening 124 and a semicircular opening 126. The second leg 123 includes a semicircular opening 126 and a slotted opening 125. In the exemplary embodiment illustrated in FIG. 5C, the second leg 123 is formed from two parallel segments, each with a slotted opening 125. In the exemplary embodiment illustrated in FIGS. 5A-5C, the second leg 123 is single-walled. The exemplary embodiment illustrated in Figure 5C also shows a tab 129 extending from the first leg 122 at an angle less than 90 degrees. Each link 121 illustrated in Figures 5A-5B is configured to connect to three rods 111. Moving from left to right, the first rod 111 passes through two circular openings 124, the second rod 111 passes through a semicircular opening 126, and the third rod 111 passes through a slotted opening 125. The advantages associated with the three-rod connection of each link 121 over prior art two-rod links are described in more detail herein below.

[0069] FIG. 6A is a diagram of a drum of a spiral conveyor system that moves a belt in a helical path. FIG. 6A shows a drum 200 surrounded by a helical path 101, which is depicted as a curved, spiral arc with an arrow at its top. The helical path 101 represents any helical path that a belt 101 described herein may follow. The helical path 101 is measured from the central axis of rotation "A" and has an inner radius 107 along which the inner edge 105 of the belt 102 follows. The helical path 1015 is measured from the central axis of rotation A and has an outer radius 108 along which the outer edge 106 of the belt 102 follows. For all belts 102 moving along the helical paths 101 / 1015, the outer radius 108 is greater than the inner radius 107. The drum 200, in some embodiments, rotates in the direction "R" illustrated in FIG. 6A. In some embodiments, R is a left-handed rotation. In some embodiments, R is a right-handed rotation. 6A, the helical path 101 moves from bottom to top, with the belt 102 contacting the drum 200 at an infeed section 220 at the bottom of the path 101 and terminating contact with the drum 200 at an outfeed section 221 at the top of the path 101. In some embodiments, the helical path 101 moves from top to bottom, with the belt 102 contacting the drum 200 at the top of the path 101 and terminating contact with the drum 200 at the bottom of the path 101. In system 100, the rotation of the drum 200 causes the belt 102 to move along the helical path 101, beginning at the infeed section 220 and ending at the outfeed section 221.

[0070] FIG. 6B is a perspective view of a length of belt. FIG. 6B shows the connection of two open links 121 similar to the open links 121 illustrated in FIGS. 4A-4B. For a belt 102 moving in a running direction "T," the links 121 are referred to relative to each other as a front link 142 and a rear link 143 relative to the running direction T of the belt 102. Multiple links 121 are connected together by rods 111 to form a complete belt 102. For a "three-rod link" belt, a belt segment 110 includes one complete link 121 connected to three rods 111 at their inner and outer ends 113 and 114 (not shown). That is, a total of two links 121 are connected to the inner and outer ends 113 and 114 of three rods 111 per segment 110. A prior art "two-rod link" belt segment has one complete link connected to the inner and outer ends of two rods. That is, it has only two links and two rods per segment.

[0071] FIG. 6B also shows two links 121 and four rods 111 forming one complete segment 110. Each link 121 is connected to three rods 111 at the inner edge 113 of the rod 111. However, each inner end 113 is connected to either two links 121 or one link 121. For example, a rod 111 passing through a central set of semicircular openings 126 in a link 121 passes through only that single link. However, a rod 111 passing through one of a set of circular openings 125 in a slotted opening 125 is connected to two links 121—a rear link and a front link relative to the direction of travel of the belt 102, marked by arrow "T" in FIG. 6B. The links 121 may rotate about the central axis of the rod 111 to which it is connected at either the circular opening 124, the semicircular opening 126, or the slotted opening 125. Additionally, rods 111 connected by slotted openings 126 allow links 121 to translate (slide) along the direction of travel, whether forward or backward relative to links 121 of adjacent segments 110. As will become apparent from an examination of FIGURE 6, the slidable connection of links 121 to rods 111 at slotted openings 125 allows two adjacent inner rod ends 113 to move closer together along the inner radius 107 of belt 102 moving along helical path 101, while outer ends 114 of rods 111 may remain separated to allow outer edges 106 to travel a greater distance relative to inner edges 105 as belt 102 moves around helical path 101. This movement of inner rod ends 113 closer together around the rotational path represents a shortened pitch.

[0072] Plate Link and Psi Belt 7A-7D are exemplary embodiments of psi-link components. FIGS. 7A-7D show an individual embodiment of an inner portion 152 of a psi-link 150. The inner portion 152 includes at least one circular opening 125 and one slotted opening 124. The slotted opening 124 allows the inner ends 113 of the rods 111 connected to the inner portion 152 to slide forward or backward within the opening 124 as the inner edge 105 of the belt 102 moves along the helical path 101. The sliding movement of the inner ends 113 creates a shortened pitch. In some embodiments, two rods 111 are connected to each inner portion 152. In some embodiments, three rods 111 are connected to each inner portion 152. FIG. 7A is an example of a "three-rod" psi-link 150 in which three rods 111 are connected to each inner portion 152. 7B-7D show an embodiment of a “two-rod” psi-link 150 in which two rods 111 are connected to each inner portion 152. FIG.

[0073] 8A-8B are additional exemplary embodiments of a psi-link component. FIGS. 8A-8B show individual embodiments of an outer portion 151 of a psi-link 150. In some embodiments, such as that illustrated in FIG. 8A, the outer portion 151 includes one circular opening 124 and one slotted opening 125. In some embodiments, such as that illustrated in FIG. 8B, the outer portion 151 includes only two circular openings 124 and no slotted openings 125. In some embodiments, the outer portion 151 additionally includes a tab 129 for engaging with a cage bar cap 213 of a cage 210 of a drum 200.

[0074] As with the clevis links 121 and row links 131 described herein, variations in the placement and configuration of the circular openings 124 and slotted openings 125 in the plate links are within the scope of this disclosure.

[0075] FIG. 9 is a diagram of a portion of a spiral conveyor belt formed from psi-links. FIG. 9 shows that a complete link 102 formed as a psi-link includes two outer portions 151 and one inner portion 152. Each end of the inner portion 153 is sandwiched between the two outer portions 151 and configured to slide forward or backward between the outer portions 151 along the belt travel direction T. As shown in FIG. 9, each successive link 102 is connected to the previous link 102 so that the end of the inner portion 152 is sandwiched between the two outer portions 151. The example shown in FIG. 9 is the "two-rod" link mentioned above. As the inner edge 105 of the belt 102 moves along the helical path 101, the concerted movement of the rods 111 connected within the single slot opening 125 creates a shortened pitch. In the example shown, the two central rods 111 depicted in FIG. 9 may move closer together until the tabs 129 contact the nearest edges of the adjacent outer links 151. The degree to which the rods 111 move closer together in this example, i.e., the shortened pitch, is determined by the length of the slotted openings 126 in either the inner portion 152 or the outer portion 151, depending on where the slotted openings 124 are located in any particular embodiment.

[0076] The presence of tabs 129 at the leading end of each link 102 causes a drum 200 (not shown) to engage the belt 102, moving the belt 102 along a travel direction T shown in Figure 9. Various embodiments of the system 100 employing different interactions between the drum 200 and the belt links 121 are described in greater detail below.

[0077] Figure 10 is a perspective view of a group of tapered cage bar caps arranged around the periphery of a drive drum. Figure 10 shows a circular array of cage bar caps 213, each of which, in some embodiments, would be attached to a cage bar 212 of the drum 200. The outer boundary 206 of the drum 200 is shown and is defined by the outermost surfaces of the bar caps 213. The bar caps 213 can be considered the substructure of the drum 200.

[0078] FIG. 11 is a perspective view of a tapered cage bar cap. FIG. 11 shows that the bar cap 213 includes a cap groove 214 disposed opposite the bar couple 215. In some embodiments, including the one illustrated in FIG. 11, the bar cap 2113 includes a sloped surface 227. The sloped surface 227 expands from a first radius 225 to a longer second radius 116. The first radius 225 is defined as the linear distance from the surface of the sloped surface where the cap groove 214 is located at its narrowest point to the central longitudinal axis of rotation "A" of the drum. The second radius 226 is defined as the linear distance from the surface of the sloped surface where the cap groove 214 is located at its widest point to the central longitudinal axis of rotation "A" of the drum. In some embodiments, the cap groove 214 includes an edge that is perpendicular to the cage bar 212. In some embodiments, the cap groove 214 includes a beveled edge to facilitate smooth engagement and disengagement of features located along the inner edge 105 of the belt 102. The beveled edge, in some embodiments, is angled outward relative to the inner belt edge 105. In some embodiments, the beveled edge is angled inward relative to the inner belt edge 105. Each bar couple 215 is configured to attach to a cage bar 212 (see FIG. 12 below). FIG. 11 additionally shows a cage ring 222 contacting the tapered cage bar cap 213 at the vertical offload point of the drum 200, above which the belt 102 does not engage the bar cap 213. In some embodiments, the cage ring 222 is coupled to a recessed area of ​​the bar cap 213. The cap groove 214 (not shown) terminates at the ring 222. When a drum coupling feature (such as tab 129, rod inner end 113, or similar feature) located on belt 201 contacts ring 222, belt 201 separates from drum 200. In some embodiments, ring 222 is located on the discharge portion 221 of drum 200 to facilitate smooth separation of belt 102 from drum 200. Ring 222 is configured and positioned on drum 200 to prevent rattling disengagement of belt 102 from drum 200.

[0079] In some embodiments, cap groove 214 is lined with a material different from the primary material forming the structure of bar cap 213. In some embodiments, cap groove 214 is lined with polytetrafluoroethylene ("PTFE" or "Teflon").

[0080] 10-11 illustrate an embodiment of system 100 configured to engage drum 200 at infeed section 220 and disengage at outfeed section 221 as inner edge 104 of belt 102 travels up or down the ramp found in bar cap 213 illustrated in these two figures and in some other embodiments. As inner edge 104 travels along the ramp, belt 102 engages drum 200 gradually rather than abruptly, allowing for a gradual transfer of belt thrust from drum 200 to belt 102. As a result, the embodiment of system 100 utilizing ramped bar cap 213 as illustrated in FIGS. 10-11 is more stable, and belt 102 is better confined and less likely to uncontrollably disengage from drum 200, resulting in product loss or catastrophic failure of system 100.

[0081] FIG. 12 is a perspective view of a drum of a spiral conveyor system. FIG. 12 illustrates a drum 200 having an arrangement of bars 121 that, in some embodiments, form a structure with the appearance of a cylindrical cage. Accordingly, such an embodiment of the drum 200 is also referred to as a "cage drum," and the bars 212 are also referred to as "cage bars." In some embodiments, an elongated bar cap 213 (omitted for clarity and not shown in FIG. 12 ) is coupled to each cage bar 212 and provides features, such as cap grooves 214, that interact with the inner edge 105 of the belt 102. A cage ring 222 is also shown, surrounding the bar caps 213 and positioned around the drum 200 at the level of the belt discharge 221 to facilitate smooth separation of the belt 102 from the drum 200.

[0082] In the embodiment illustrated in FIGS. 10-12, the belt 201 moves up or down the drum 200 while contacting the tapered bar caps 213 along the belt inner edge 105. For example, as seen in FIG. 1, the belt 102 wraps around the drum 200 in multiple levels or stages stacked on top of each other, thereby describing a helical path 101. An embodiment of the system 100 incorporating the tapered bar caps 213 (e.g., as illustrated in FIG. 10) includes a gradually varying inner radius 107 for each stage of the drum 200, created by the tapered outer surface of the bar caps 213. The radius 107 may decrease from the bottom to the top of the drum 200 across the stages of the belt 102 in some embodiments. In other embodiments, the radius 107 may increase from the bottom to the top of the drum 200 across the stages of the belt 102.

[0083] FIG. 13 is a top view of a portion of a roll-link spiral conveyor grid belt being retracted at a curve. FIG. 13 shows the belt 102 moving along a helical path with a direction of travel "T" indicated by the dark arrow. A series of roll links 131 is shown along the inner edge 105 of the belt 102, and a corresponding series of roll links 131 is shown along the outer edge 106 of the belt 102. Examination of FIG. 13 reveals that in this and some other embodiments, each roll link 131 is connected to three rods 111, i.e., each roll link 131 is a "three-rod link." It can also be seen that the closed shapes 127 of the roll links 131 along the inner edge 105 of the belt 102 are positioned closely together, while the closed shapes 127 of the corresponding roll links 131 along the outer edge 106 of the belt 102 are spaced farther apart. The reduced pitch CP is shown in FIG. 13 and is defined as the shortest linear distance between the centers of two adjacent rod inner ends 113 along the inner edge 105 of the belt 102. A "reduced pitch belt" comprises a belt 102 having a width (see FIG. 14 below) divided by the reduced pitch CP equal to less than 1.6. The differential spacing of the rod inner ends 113 of adjacent rods spaced between the inner edge 105 (reduced pitch "CP") and the rod outer edge 106 is necessary for the belt 102 to move along the helical path 101, with the path length of the inner edge 105 being shorter than the path length of the outer edge 106. Furthermore, when the belt 102 separates from the drum 200 at the let-off section 221, the belt 102 typically travels a linear path with essentially equal link separation distances at the inner edge 105 and outer edge 106. Movement of adjacent links 121, including low link 131 and psi link 150, relative to one another is permitted by semicircular openings 126, as can be seen in several figures and in consideration of Figure 13. The shorter the distance of the reduced pitch CP, the smaller the radius of the helical path 101 permitted, allowing the system 100 to occupy a smaller footprint on a floor or other supporting surface, increasing the efficiency of the system 100.By allowing increased movement between adjacent rods 111 and links 121, a belt system 100 with a small shortened pitch reduces compressive forces along the inner edge 103 of the belt 102, which can cause the belt 102 to sag or separate from the drum 200, possibly causing catastrophic failure of the spiral conveyor system.

[0084] The embodiment of belt 102 presented herein is a retractable, positive drive belt for helical conveyor systems, including system 100 and some existing systems. The belt is made of a metal or metal alloy and is oriented generally perpendicular to the outer surface of a drum, cage drum, or the outer surface of a plurality of cage bar caps 213 that are connected to bars 212 of cage drum 200. Links 121, 131, and / or 150 of belt 201, having at least one slot opening 125, allow movement of links 121, 131, and / or 150 relative to adjacent links, allowing belt 102 to "retract" along inner edge 105 as belt 102 travels along helical path 101 having inner radius 107. This retractability allows belt 201 to wrap around the curved outer surface of drum 200, driving belt 201 forward without creating distorting forces across belt 201 that would tend to flex belt 102 and separate it from drive drum 200, as described more fully herein. Stated another way, as the belt 102 enters a curve, the linear distance between links along the outer edge 106 increases, while the linear distance between links along the inner edge 105 decreases. In some embodiments, the rods 111 are overlaid with a wire mesh (not shown), the individual sections of which are also configured to expand or contract depending on the section of overlap along the curved belt path. Additionally, the design of the row links 131 disclosed herein provides

[0085] The concept of reduced pitch is described with reference to Figure 13, which is by way of example and not by way of limitation. Long rod links, psi links, and three rod U-links may also be configured to facilitate a smaller reduced pitch of belt 102 within system 100.

[0086] FIG. 14 is a top perspective view of a rod-link spiral conveyor belt being retracted at a curve. FIG. 14 shows the belt 102 moving along a helical path with a direction of travel "T" indicated by the dark arrow. A series of links 121 is shown along the inner edge 105 of the belt 102, and a corresponding series of links 121 is shown along the outer edge 106 of the belt 102. Each link 121 has two circular openings 124 and one slotted opening 125 and is connected to three rods 111. While the shortened pitch is not marked in FIG. 14, an examination reveals that the rod links 121 along the inner edge 105 overlap each other substantially more than the corresponding rod links 121 along the outer edge 106. As suggested by examination of the figure, this allows adjacent rod inner ends 113 to be positioned much closer together along the inner edge 105. The belt width "W" is the shortest total linear distance from the innermost portion of the inner edge 105 to the outermost portion of the outer edge 106. Also shown in Figure 14 are cage bar caps 213 along the drum 200. Each bar cap 213 interacts with a link 121 along the inner edge 105 at a tab 129 of the link 121, thereby moving the belt 102 along the travel direction T. In the embodiment illustrated in Figure 14, and in some other embodiments, every other tab 129 interacts with a bar cap 213. Note that the cage bars 212 of the drum 200 are not shown and have been omitted for ease of understanding.

[0087] FIG. 15 is a top view of a "three-rod" U-link spiral conveyor belt interacting with a series of cage bar caps. FIG. 15 illustrates an additional embodiment of a "reduced pitch" belt having "three-rod" links, where each link 121 is a U-link. Each U-link 213 in this exemplary embodiment is connected to three rods 111. In some embodiments, the links 121 include tabs 129 configured to engage with the bar caps 213, as shown. Additionally, note that the multiple links 121 illustrated in FIG. 15 are maximally shortened, with every other rod 111 positioned adjacent to an adjacent rod 111 at a reduced pitch. The cage bars 212 of the drum 200 are omitted from FIG. 15 for ease of understanding.

[0088] FIG. 16A is a close-up view of a curved rod belt interacting with cage bar caps. FIG. 16A shows a row link 131 connected to two rods 111 at their inner rod ends 113. As shown in the figure, each rod 111 has a curved inner rod end 113. In this and some other embodiments, the bar caps 213 include cap grooves 214 with diagonal sides angled to match the curved inner rod ends 113. In some embodiments, a non-orthogonal connection between the bar caps 213 and the inner rod ends 113 has been found to promote smoother connection and disconnection between the belt 102 and the drum 200 at the infeed section 220 and the outfeed section 221, respectively. FIG. 16A also shows the location of a slotted opening 125 in the second leg 123 of the row link 131. The first leg 122 includes a circular opening 124 and a semicircular opening 126 (not shown in FIG. 16A ).

[0089] 16B is a close-up view of the bent rod inner end. FIG. 16B shows the inner end 113 of the rod 111, where the inner end 113 has a button-like shape. In some embodiments, the inner end 113 has a button, mushroom cap, or similar bulge shape that facilitates smooth and secure connection and disconnection of the belt 102 from the bar cap 213 of the drum 200.

[0090] Cage bar cap FIGS. 17A-17D are views of portions of cage bar caps. FIGS. 17A-17D illustrate various shapes and configurations of cap grooves 214. As illustrated in FIG. 16 above, the bar caps 213 may be configured to interact with the inner edges 105 of the belt 102 in various ways. The spiral conveyor system 100 is driven by friction or positive mechanical engagement between the drum 200 and the belt 102. FIG. 17A illustrates a bar cap 213 with cap grooves 214 configured to receive the straight red inner edges 113, which are generally perpendicular to the bar couples 215. The bar couples 215 are recesses defined by the bar cap 213 to receive the cage bars 212 (e.g., as illustrated in FIG. 12). FIG. 17D illustrates a similar configuration in which the cap grooves 214 are generally perpendicular but shallower. The shallower perpendicular cap grooves 214 are suitable for interacting with the links 121 at the tabs 129 in some embodiments of the system 100. FIG. 17C shows a bar cap 213 with a non-orthogonal cap groove 214, similar to that illustrated in FIG. 16. The non-orthogonal cap groove 214 may, in some embodiments, be adapted to interact with an angled rod inner end 113 or an angled tab 219. Finally, FIG. 17B shows no cap groove 214, only a smooth surface facing the inner edge 105 of the belt 102 opposite the bar couple 215. An embodiment of the system 100 with a bar cap 213 without a cap groove 214, similar to that illustrated in FIG. 17B, frictionally interacts with the rod inner end 113 of the belt 102 to translate the belt 102 along the helical path 101.

[0091] Drum 200 may rotate using any method known in the mechanical arts. Examples include a motor drive coupled to drum 200 directly or through a transmission. The motor drive, in some embodiments, is an electric motor. In some embodiments, the motor drive is an internal combustion engine. Drum 200 includes an internal structure (not shown) known in the art, such as a central shaft with multiple struts extending radially outwardly and extending along a central longitudinal axis of rotation, supporting a skin or other structure to which multiple cage bars 212 are connected. The skin, in some embodiments, may be a continuous surface or a discontinuous cage-like surface.

[0092] In some embodiments, belt 102 is driven by a drive member (not shown) that transmits a force to belt 102 at a location off drum 200, which passively directs belt 102 along helical path 101 without transmitting any motive force to belt 102. This may include "pulling" the belt along the belt path at a location off drum 200. Some non-limiting examples of drive members include sprockets of various shapes configured to interact with links 121, 131, and / or 150, or to interact with rod 111 or overlapping mesh connected to rod 111, in some embodiments. The drive member may interact with belt 102 at inner edge 105 or outer edge 106, but the interaction may occur at a location on the belt path where the belt travels a generally straight path rather than helical path 101 or other non-linear, curved path. The drive member may be driven by a motor, such as an electric motor, an internal combustion engine, or other power source appropriate for the application. In some embodiments, the motor may be a constant torque motor so that the tension in the belt 102 can be controlled within a desired range. In some embodiments, weighted take-up rollers (not shown) may be provided to help maintain belt tension and reduce belt slack within the system 100. Controlling and maintaining optimal belt tension helps maintain stable engagement between the belt 102 and the drum 200, prevents belt "jump" and other forms of belt disengagement, and minimizes destabilizing vibrations in the infeed section 220 and outfeed section 221.

[0093] Ribless cage drum Before proceeding to a detailed description of the drawings, the ribless cage drum is described herein above. Figures 18-22B illustrate certain key elements of the ribless cage drum previously described herein. In some embodiments, the ribless cage drum includes transition elements that facilitate onboarding, i.e., engagement of the belt 102 with the drum 200, at the infeed section 220 and offboarding, i.e., disengagement of the belt 102 from the drum, at the outfeed section 221. As illustrated in the various figures herein, in some embodiments, onboarding occurs below the drum 200. By "below" is meant the closest lower side of the outer boundary 206 of the drum 200 relative to the floor or other drum support surface. By "above" is meant the closest upper side of the outer boundary 206 of the drum 200 relative to the floor or other drum support surface. With this relationship in mind, in some embodiments of the system 100, the infeed section 220 is located further below the drum outer boundary 206 than the outfeed section 211. In these embodiments, the product on belt 102 moves upward along helical path 101. An example of such an embodiment is shown in Figure 6A. In some embodiments, infeed section 220 is higher than outfeed section 211 at drum outer boundary 206, i.e., outfeed section 221 is lower than infeed section 220, and the product on belt 102 moves downward along helical path 101 (not shown).

[0094] In some embodiments, the ribless drive system relies on elements attached to the drum outer boundary 206 to facilitate onboarding and offboarding of components of the belt 102 that engage with and disengage from the outer boundary 206, such as the belt support rod inner ends 111 or belt link tabs 129, respectively. As such, the system 100 with a ribless drum cage additionally includes transition elements, such as entrance and / or exit rings, at points along the drum outer boundary 206 that are vertically separated from one another to enable smooth onboarding of the belt 102 at the infeed section 220 and urge the belt 201 away from the cage 210 at the outfeed section 221.

[0095] FIG. 18 is a perspective view of a ribless transition element. FIG. 18 shows a ribless transition element 250 having bar couples 215 for attachment to cage bars 212 (not shown). In some embodiments, the cage bars 212 are fabricated as ribless transition elements 250 and do not need to be connected to the underlying cage bars 212. In some embodiments, including the one illustrated in FIG. 18, the ribless transition element 250 is connected to the cage bars 212 with bar couples 215. In some embodiments, the transition element 250 does not have cap grooves 214. In some embodiments, the transition element 250 includes cap grooves 214. The transition element 210 is fabricated with a beveled inclined surface 227, i.e., not parallel to any other surface of the element 250, as illustrated in FIG. 18. The beveling of the inclined surface 227 distributes belt tension along the belt inner edge 105 as the belt 102 transitions into the drum outer boundary 206, which is formed in part by the plurality of transition elements 250. Edge bevels 255 may be formed on transition elements 250, cage bars 212, bar caps 213, entrance ring 256, exit ring 257, or other surfaces of components disposed on drum 200 to encourage engagement with and disengagement from drum 200, or both engagement and disengagement of belt 102 with drum 200. In some embodiments, ramps 227 and bevels 255 are formed directly from cage bars 212 rather than by bar caps 213. For example, in some embodiments of system 100, bar caps 213 and belt 102 do not interact solely with the plurality of cage bars 210 at features formed by bars 210 (including, in some embodiments, ramps 227 and edge bevels 255). In some embodiments, elements 250 also include a ledge 253 bordering recess 254, to which entrance ring 256 may be attached. In some embodiments, bevels 255 are disposed on exit ring 257. In some embodiments, the exit ring 257 and / or the entrance ring 256, individually or in any combination, are directly coupled to the cage bars 212.

[0096] Many configurations of the bevel 255 are within the scope of the disclosure described herein. For example, in some embodiments, the bevel 255 has the same width as the transition element 250 or the cage bar 212. In some embodiments, the bevel 255 tapers to a radius smaller than the radius of the drum 200. In some embodiments, the bevel 255 does not extend to the discharge section 221. In some embodiments, the bevel 255 is made from a different material than the cage bar 212. For example, the bar 212 is made from steel, another metal, or metal alloy, and the bevel 255 is made from a plastic polymer. In some embodiments, the transition element 250 is made entirely from a plastic polymer. In some embodiments, the plastic is nylon. In some embodiments, the plastic is polyethylene. In some embodiments, the transition element 250 is directly coupled to the entrance ring 256, the exit ring 257, or both the entrance ring 256 and the exit ring 257. In some embodiments, the plurality of transition elements 255 disposed around the periphery of the drum 200 may be spaced apart at a distance equal to or slightly less than the shortened pitch of the belt inner edge 105 to facilitate transfer of the belt 102 from the transition elements 250 to the cage bars 212. In some embodiments, the transition elements 250 may engage and drive the belt 102 at a different link tab 129 or rod inner end 113 than another link tab 129 or rod inner end 113 driven by an adjacent cage bar 212. In some embodiments, an exit ring 257 is formed in a segment positioned on the drum 200 between adjacent cage bars 212, bar caps 213, or transition elements, alone or in any combination without limitation.

[0097] In some embodiments, any one or more of the transition elements 250, cage bars 212, and / or bar caps 213 present a substantially flat surface without any belt-engaging features, such as grooves, ribs, or other protrusions relative to the belt 102. In some embodiments, the spacing between the cage bars 212, bar caps 213, or other adjacent belt-driving elements disposed on the drum 200 and forming the outer boundary 206 is configured to provide vertical support to the belt 201. In some embodiments, the belt 102 traveling along the helical path 101 on the drum 200 equipped with the transition elements 250 may include tabs 129 or other drum-engaging features that increase the spacing between adjacent belt-driving elements by using one or more links without tabs 129 or other elements for engaging the drum 200.

[0098] In some embodiments, the exit ring 257 is positioned at a larger drum radius than the plurality of cage bars 212 and is configured to urge the belt 102 off the cage bars 212. In some embodiments, the exit ring 257 includes an edge bevel 255.

[0099] Figure 19A is a cutaway top view of an arc section of a drum having ribless transition elements interleaved with cage bar caps. Figure 19A shows a drum 200 having a plurality of cage bars 212 arranged around the arc section at the outer boundary 206 of the drum 200, interleaved 1:1 with a corresponding plurality of ribless transition elements 250. In some embodiments, the ribless transition elements 250 are connected to the cage bars 212 with bar couples 215. An inlet skin 256 is shown connected to the plurality of transition elements 250.

[0100] Figure 19B is a perspective cross-sectional view of an arcuate portion of a drum having ribless transition elements alternating with cage bar caps. Figure 19B shows a drum 200 having a plurality of cage bars 212 arranged around the arcuate portion at the outer boundary 206 of the drum 200, alternating 1:1 with a corresponding plurality of ribless transition elements 250. An inlet ring 256 is shown coupled to the plurality of transition elements 250 at the location where the belt 102 reaches the infeed section 220 (not shown) and transitions into engagement with the drum 200.

[0101] FIG. 20 is a side view of an arcuate portion of a drum having ribless transition elements interleaved with cage bar caps. FIG. 20 shows a plurality of ribless transition elements 250 disposed around the outer boundary 206 (not shown in FIG. 20) of the drum 200 and connected to a corresponding plurality of cage bars 212 that form the outer boundary 206. FIG. 20 additionally shows an inlet ring 256 connected to the plurality of transition elements 250 within a recess 254 (hidden by the ring 256). Also shown is a ramp 227 of the transition element 250. In some embodiments, such as the example shown in FIG. 20, an edge chamber 255 is disposed with and contiguous to the ramp 227. In some embodiments, the ramp 227 extends a greater length along the transition element 250 than the edge bevel 255.

[0102] 19B, 22A-22B, and 23, in some embodiments, the cage drum 200 includes an inner ring 202. The inner ring 202 adds additional structural strength to the cage drum 200. In some embodiments, a plurality of transition elements 250 are coupled to and supported by the inner ring 202 at their upper sides.

[0103] Figure 21 is a perspective view of an arcuate portion of a drum having only ribless transition elements and no cage bar caps. Figure 21 shows a drum 200 having an outer boundary 206 made up of multiple transition elements 250. It should also be noted that in some embodiments, such as the example shown in Figure 21, edge bevels completely replace the angled surfaces 227 on the transition elements 250.

[0104] Figure 22A is a perspective view of an arcuate portion of a drum having only ribless transition elements and no cage bar caps. Figure 22A shows an exemplary embodiment of a ribless cage drum 200 having alternating transition elements 250 and cage bars 212. An entrance ring 256 is connected to the plurality of transition elements 250, where a belt 201 (not shown) moves over the entrance ring 256 into engagement with the transition elements 250. As the belt moves upward along the helical path 101 (not shown) of the outer boundary 206 of the drum 200, the belt inner edge 213 moves down the plurality of inclined surfaces 227 and rests on the outer boundary 206 formed only by the plurality of cage bars 212.

[0105] Figure 22B is a close-up view of an arcuate portion of a drum having ribless transition elements alternating with cage bar caps. Figure 22B shows a drum 200 configured as a ribless cage drive having multiple cage bars 212 alternating with transition elements 250 distributed around the periphery of the drum 200. As shown, an inlet ring 256 is shown coupled to multiple transition elements 250. In this example, as well as in some other embodiments, the transition elements 250 include both angled surfaces 227 and edge chambers 255 that connect to each angled surface 227 along a distance less than the entire length of the angled surfaces 227.

[0106] FIG. 23 is a perspective view of an arcuate portion of a drum having alternating ribless transition elements and cage bar caps and an entrance ring. FIG. 23 shows a drum 200 with multiple parallel ribless transition elements 250 arranged alternately between adjacent cage bars 212. An entrance ring 256 is also shown coupled to the underside of the multiple transition elements 250. In some embodiments, as shown, the transition elements 250 include a sloped surface 227. In this and some other embodiments, the ribless transition elements 250 include a sloped surface 227 but do not include a chamber 255. This is illustrative and not intended to be limiting. In this and some other embodiments, multiple engagement features (not shown) of the belt 102 will first contact the outer boundary 206 of the drum 200 at the entrance ring 256 on the lower side of the drum 200 as shown, and then move progressively inward along the sloped surface 227 until they engage a cage bar 212 or bar cap 213 (not shown). At the top of the plurality of ramps 227, the outermost surfaces of the transition elements 225 are inward of the outermost surfaces of the cage bars 212 and engage the ramps 227 to smoothly transition the components of the belt 102 passing over the ramps 227 onto the outer surfaces of the plurality of cage bars 212. In other words, the drum outer boundary 206 (not shown) transitions from the ramps 227 to the cage bars 212.

[0107] FIG. 24 is a cutaway top view of an arcuate portion of a drum having ribless transition elements alternating with cage bar caps and entrance or exit rings connected to the transition elements. FIG. 24 shows multiple parallel transition elements 250 without bevels 255 arranged on the drum 200, alternating between adjacent cage bars 212. As shown, an entrance ring 256 is connected to the multiple transition elements 250. It is easy to see how the belt 102 moves progressively upward from the entrance ring 256 along a helical path 101 across the drum outer boundary 206, then moves up an inclined surface 227 (not shown) in a tapered radial helical path, and finally creeps onto the cage bar 212 (or bar cap 213 in some embodiments) to engage the outer boundary 206 of the drum 200.

[0108] FIG. 25 is a top view of a portion of a belt with clevis links engaged on a ribless belt drum. FIG. 25 shows a drum 200 with multiple parallel transition elements 250. As shown, tabs 129 located on clevis links 121 are driven by ribless transition elements 250 connected to alternating cage bars 212. The transition elements 250 hold the drum-engaging feature (tabs 129 in this example) outward and away from the cage bars 212. In some embodiments, as the belt passes up the transition elements 250 along the helical path 101, the tabs 129 (or other belt-engaging feature) move inward up the ramp 227 until the engagement of the tabs 129 with the drive drum 200 shifts from the transition elements 250 to the cage bars 212 (or bar caps 213).

[0109] Figure 26 is a top view of a portion of a belt with row links engaged on a ribbed belt drum. Figure 26 is similar to Figure 25, except that the engagement of the drum 200 is with the belt 102 with row links 131. As shown, each row link 131 includes a tab 129.

[0110] Figures 27A-27C are enlarged side views of a cage drum with an exit ring. Figure 27A shows a side view of the exit ring 257 attached to the cage bar 212 of the drum 200. The tabs 129 on the links following two adjacent courses of the helical path 101 are illustrated, with the upper link tabs 129 urged outward up the inclined surface 227 of the transition element 250 toward the exit ring 257, thereby disengaging from the drive drum 200. Figure 27B shows the tabs 129 of the links 1212 resting on the transition element 250. In this (and some other) embodiments, the exit ring 257 is not present, and as in the example illustrated in the drawings, the tabs 129 or other drive drum engagement features of the belt 102 pass through the drum 200 by adjacent recessed bar caps 213 attached to the underlying cage bar 212. FIG. 27C shows an alternative embodiment that also has a recessed bar cap 213, whereby the rod link 121 with the drive drum engagement feature of the tab 129 is urged away from the drum 200 by the edge bevels 255 on both the leading and trailing edges of the bar cap 213.

[0111] FIG. 28 is a partial view of a belt link engaging and disengaging with a cage drum having an entrance ring and transition element. FIG. 28 shows both the entrance ring 256 and the exit ring 257 of the drum 200. Two adjacent cage bar caps 213 are shown without other structure of the drum 200 for clarity. A series of links 121 on several adjacent and non-adjacent courses of the belt 102 are shown sequentially engaging and disengaging with the drive drum 200. Starting near the bottom of FIG. 28, the tab 129 of the link 121 contacts the entrance ring 256. The tab 129 or other drum-engaging feature provided by the belt 102 moves upward with each revolution of its helical path along the inclined surface 227 toward the transition element 250. As the link 121 moves progressively inward along the inclined surface 227, the tab 129 comes into engagement with the bar cap 213. Similarly, tab 129 contacts angled surface 227 of exit ring 257 near the upper end of drum 200 in the upper portion of FIG. 28, urging link 121 away from cage bar cap 213, resulting in belt 102 disengaging from drive drum 200. Careful consideration of FIG. 28 will show that the outer surface of exit ring 257 extends beyond the outer belt-facing engagement surface of bar cap 213. Note also that in this and some other embodiments, exit ring 257 is discontinuous, positioned along outer boundary 206 (not labeled) of drum 200 between cage bar cap 213 and / or cage bars 212. Similarly, in some embodiments, entrance ring 256 may be continuous, as shown, or discontinuous, like exit ring 257 in this exemplary embodiment.

[0112] FIG. 29 is a top perspective view of a recessed exit ring mounted on a cage drum. FIG. 29 shows the exit ring 257 connected to two cage bars 212. Additional cage bars 212 and other components forming the drum 200 have been omitted for ease of understanding. As shown, the exit ring 257 is recessed relative to the cage bars 212, thereby disengaging the links 121, of which only one representative one is shown for ease of understanding, from the cage bars 212. In some embodiments, disengagement occurs when the plurality of links 121 and the support rod inner ends 113 forming the inner edge 105 of the belt 102 traveling around the helical path 101 exit the drum 100 at the top end of the helical path 101 in successive stages.

[0113] It is important to note several aspects of the drum 200 that include transition elements 250 to facilitate onboarding and offboarding of the belt 102. The exit ring 257 may have a radius smaller than the cage radius (the radius of the drum outer boundary of the cage bars 212 or bar caps 212 that are positioned between the exit ring 257 and the entrance ring 256 at a distance offset from the exit ring) to facilitate the transition from the cage bars 212 or bar caps 213 to the exit ring 257. In some embodiments, the exit ring 257 may be positioned over multiple cage bars 212 or bar caps 213, thereby creating a larger radius of the drum outer boundary 206 up to the exit ring 257. In some embodiments, the exit ring 257 has a radius larger than the radius of the cage bars 212. In some embodiments, the exit ring includes a bevel 255 that guides the belt 102 into the larger radius of the exit ring 257. As described herein and illustrated in some of the figures, the exit ring 257 may be segmented and positioned between the cage bars. In some embodiments, an engaging element of the belt 102, such as a link tab 129 or an inner rod end 113, is spaced from the cage bar 212 or bar cap 213 by a distance equal to or slightly less than one or more shortened pitches to facilitate the transition of the belt 102 from the transition bar 250 to the cage bar 212.

[0114] In some embodiments, a belt system 100 including a helical path 101 and a drum 100 having ribless transition elements 250 includes belt-engaging features such as tabs 129 or rod inner ends 113, and the spacing between adjacent belt-engaging features is increased by using one or more standard links between links having drive elements, such that drive elements are placed only on every third, fourth, or other integer number of belt links 121. In some embodiments, a plurality of transition elements 250 distributed around the drum 200 form a drum outer boundary 206 having an initial radius equal to the radius of the inlet ring 256 and greater than the drum radius formed by the plurality of cage bars 212 or bar caps 213. In some embodiments, the transition elements 250 do not extend to the height of the drum 200 in the discharge section 221.

[0115] The plurality of cage bars 212 in any embodiment having transition elements 250 may, in some embodiments, have cage bar caps 231. In some embodiments, the cage bar caps 213 are ribless bar caps. In some embodiments, the bar caps 213 include cap grooves 214. In some embodiments, the bar caps 213 are ribless and grooveless. In some embodiments, the bar caps 213 and transition elements 250 contact drive features of the belt 102, such as cap 129 or inner rod end 113, on a radial surface. The cage bars 213, bar caps 212, and transition elements 250, alone or in any combination, may support the weight of the belt 102 on a circumferential surface.

[0116] The components of the spiral belt system 100 are not limited and may be made from any suitable material known in the art. For example, the drum 200, the belt 102, and the listed components comprising the drum 200 and the belt 102 may be made from metals such as steel, stainless steel, aluminum, and other metal alloys. In some embodiments, these components may be made from heat-stable plastics and other polymers known in the art. In some embodiments, combinations of metals, metal alloys, and plastic polymers are used. Because the spiral conveyor system 100 is intended for use in a wide range of industrial applications, a variety of materials and combinations of components made from different materials are within the scope of the disclosure and teachings herein.

[0117] The embodiments and examples described herein are presented to best explain the invention and its practical application and to thereby enable those skilled in the art to make and use the invention. However, those skilled in the art will recognize that the foregoing description and examples have been presented for purposes of illustration and illustration. The description set forth is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the teachings herein.

Claims

1. a belt formed from a plurality of segments and configured to move along a helical path, the belt having a belt width, an inner edge and an outer edge, the inner edge translating along the helical path having an inner radius and the outer edge translating along the helical path having an outer radius; Each of the plurality of segments is at least one rod having an elongated shape with a central portion and terminating in an inner end and an outer end, the inner end of each rod including an angle; and a belt comprising at least one link connected to the at least one rod, each segment being movably connected to two adjacent segments; a drum generally formed as a cylinder having a central longitudinal axis coaxial with said helical path and an outer boundary, said drum configured to rotate about said central longitudinal axis and to releasably interact with each of said plurality of segments at said outer boundary; the belt moves along the helical path due to continuous interaction between the outer boundary of the drum and the belt segments as the drum rotates; the drum includes a plurality of cage bars disposed about the outer boundary, each cage bar configured to simultaneously releasably engage a plurality of inner ends of the belt rods; the plurality of cage bars are connected to a corresponding plurality of cage bar caps, the cage bar caps reversibly interacting with an inner edge of the belt; each of the plurality of cage bar caps includes a groove; The spiral conveyor system, wherein the groove forms a non-orthogonal angle with the central longitudinal axis and is configured to releasably interact simultaneously with two belt segment support rod ends bent at corresponding non-orthogonal angles.

2. The system of claim 1 , wherein the link comprises a first leg and a second leg, the first leg and the second leg being generally parallel.

3. The system of claim 2 , wherein the first leg comprises at least one circular opening and at least one semicircular opening, and the second leg comprises a slotted opening.

4. The system of claim 1 , wherein the rod central portion is not connected to a link.

5. 2. The spiral conveyor system of claim 1, wherein each of said plurality of cage bar caps is ribless.

6. a belt formed from a plurality of segments and configured to move along a helical path, the belt having a belt width, an inner edge and an outer edge, the inner edge translating along the helical path having an inner radius and the outer edge translating along the helical path having an outer radius; Each of the plurality of segments is At least one rod having an elongated shape with a central portion and terminating in inner and outer ends; and a belt comprising at least one link connected to the at least one rod, each segment being movably connected to two adjacent segments; a drum generally formed as a cylinder having a central longitudinal axis coaxial with said helical path and an outer boundary, said drum configured to rotate about said central longitudinal axis and to releasably interact with each of said plurality of segments at said outer boundary; the belt moves along the helical path due to continuous interaction between the outer boundary of the drum and the belt segments as the drum rotates; the drum includes a plurality of cage bars disposed about the outer boundary, each cage bar configured to simultaneously releasably engage a plurality of inner ends of the belt rods; the plurality of cage bars are connected to a corresponding plurality of cage bar caps, the cage bar caps reversibly interacting with an inner edge of the belt; the system further includes an infeed section and an outfeed section, wherein the interaction between the drum and the segments occurs along a length of the drum central longitudinal axis beginning at the infeed section and ending at the outfeed section; the drum has a first radius between the infeed section and the outfeed section, the first radius extending from the longitudinal axis to the outer boundary; the drum has a second radius projecting from the longitudinal axis to the outer boundary at the infeed section; the second radius is greater than the first radius; each of the cage bar caps includes a ramped surface disposed at the outer boundary such that the second radius transitions to the first radius along the ramped surface, the ramped surface configured to move the belt inwardly from the infeed section to the first radius; Spiral conveyor system, wherein the inclined surface is rib-free.

7. 7. The system of claim 6, wherein the ramped surface further comprises a bevel that distributes belt tension along the inner edge of the belt as the belt transitions to the outer boundary of the drum.

8. The system of claim 6 , wherein each of the plurality of cage bar caps is entirely ribless.

9. The system of claim 6 , wherein the bevel is angled rearward relative to belt travel.

10. The system of claim 6 , wherein each of the plurality of cage bar caps includes a groove configured to engage the belt.

11. A belt having a plurality of segments and configured to move along a helical path, the belt having a belt width, an inner edge and an outer edge, the inner edge translating the helical path along an inner radius and the outer edge translating the helical path along an outer radius; a belt, each of the plurality of segments comprising at least one rod having an elongated shape with a central portion and terminating at inner and outer ends, and at least one link connected to the at least one rod; 1. A spiral conveyor system comprising: a rotatable drum having a plurality of cage bars arranged about a central longitudinal axis to form a cage; and a plurality of cage bar caps attached to some or all of the plurality of cage bars, the cage bar caps defining an outer boundary of the drum; the drum is configured to rotate about the central longitudinal axis coaxial with the helical path and to releasably interact with each of the plurality of segments at the outer boundary; the belt moves along the helical path due to continuous interaction between the outer boundary of the drum and the belt segments provided by the rotating drum; The system further comprises: a plurality of intermediate cage bars disposed between the plurality of cage bars, the intermediate cage bars extending partway from the infeed portion of the drum toward the discharge portion of the drum; a plurality of intermediate cage bar caps connected to the plurality of intermediate cage bars; the intermediate cage bar includes an inclined surface extending from a first radius at the infeed section to a second radius at an outer boundary of the drum between the infeed section and the outfeed section, the first radius being greater than the second radius; Spiral conveyor system, wherein the inclined surface is rib-free.

12. 12. The system of claim 11, wherein the ramped surface includes a bevel that distributes belt tension along the inner edge of the belt as the belt transitions to the outer boundary of the drum.

13. The system of claim 11 , wherein each of the intermediate cage bar caps is ribless.

14. The system of claim 11 , wherein the bevel is angled rearward relative to belt travel.

15. The system of claim 11 , wherein each of the plurality of cage bar caps comprises a groove.

Images