Patent Publication Number: US-2022212873-A1

Title: Active Direct Drive Spiral Conveyor Belt Systems and Methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 17/004,560 filed on Aug. 27, 2020, which claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 62/893,496 filed on Aug. 29, 2019, the entire contents of which are incorporated herein by reference. 
    
    
     STATEMENT CONCERNING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     Not applicable. 
     TECHNICAL FIELD 
     The present disclosure is described in the context of spiral conveyor belt systems and methods. More specifically, the present disclosure relates to direct drive spiral conveyor belts configured to transition between a linear portion and a direct drive spiral portion. 
     BACKGROUND 
     Spiral conveyor belt systems are designed to provide a large amount of belt carry surface within a relatively small footprint, such as on a manufacturing plant floor. This makes spiral conveyor belt systems well suited for applications, such as freezing, cooling, proofing, cooking, etc. Many spiral conveyor belt systems incorporate a “low-tension” frictional drive that utilizes a rotating drum composed of multiple vertical uprights. The vertical uprights of the rotating drum drive the belt forward by imparting a friction and traction force against the inside belt edge as the drum rotates, thereby driving the belt forward and along the vertical helix of the spiral conveyor belt system. Such systems, however, also impart a high tension throughout the belt, which can contribute to a reduced service life of the belt. 
     Other spiral conveyor belt systems incorporate a direct drive. A direct drive arrangement utilizes a positive engagement between a belt drive feature often positioned near the inside belt edge (e.g., formed ends of an exposed cross-rod/pin of the belt) and drive members of the drum that are often positioned along the vertical uprights (e.g., vertical ribs included on caps that attach to select vertical uprights). Although this type of system generally lowers overall belt tension once the belt is fully engaged, the initial engagement between the belt and the drive members can be challenging to achieve in consistent, efficient, and structurally sound manners. For instance, controlling and/or accounting for the interaction between the variable pitch of a conveyor belt (e.g., the dynamic distance between belt drive features) as it begins to collapse and fully engage with the spaced drive members (e.g., vertical ribs) of the rotating drum presents unique challenges, including aspects of maintaining desired tension in the belt as it engages, rides along, and disengages the drive members. In addition, variations in belt properties and dimensions (e.g., such as a result of wear and environmental influence) introduce additional considerations to address, particularly to the initial engagement between the belt and the drive members in either an up-go spiral or a down-go spiral. 
     Therefore, a need exists for improved spiral conveyor belt systems and methods that maintain and enhance the conventional features and benefits, while addressing various deficiencies associated with the interaction between the belt and the drive members during transition between linear and spiral portions of a direct drive spiral conveyor belt system. 
     SUMMARY 
     In one embodiment, an active drive conveyor belt system includes a drum configured to rotate about a drum axis, a plurality of modules, a plurality of cross-rods joining together the plurality of modules, and an infeed system. The drum can include a plurality of drive bars, each with a drive member extending therefrom, and spaced an arc length. At least some of the plurality of cross-rods and/or modules can include a drive end configured to engage with the drive members. The plurality of modules can be configured to be collapsible relative to each other and the plurality of cross-rods. The infeed system can be configured to collapse the spacing between adjacent drive ends prior to transiting into engagement with a cooperating drive member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the invention. Given the benefit of this disclosure, skilled artisans will recognize the examples provided herein have many useful alternatives that fall within the scope of the invention. 
         FIG. 1  is a simplified side elevation view of an example direct drive spiral conveyor belt system in accordance with an embodiment. 
         FIG. 2  is a top plan view of the example direct drive spiral conveyor belt system shown in  FIG. 1  with an attached linear segment. 
         FIG. 3  is a more detailed isometric view of a section of another example of a direct drive spiral conveyor belt system in accordance with an embodiment. 
         FIG. 4  is a top plan view of a portion of the direct drive spiral conveyor belt system shown in  FIG. 3 . 
         FIG. 5  is an isometric view of a drive rib plate attached to a vertical bar in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     The following discussion is presented to enable a person skilled in the art to make and use embodiments of the invention. Given the benefit of this disclosure, various modifications to the illustrated embodiments will be readily apparent to those skilled in the art and the underlying principles herein can be applied to other embodiments and applications without departing from embodiments of the invention. Thus, embodiments of the invention are not intended to be limited to embodiments shown but are to be accorded the widest scope consistent with the principles and features disclosed herein. 
     Some of the discussion below describes direct drive spiral conveyor belt systems that can be incorporated into new and/or retrofit into existing direct drive spiral conveyor belt system arrangements. The context and particulars of this discussion are presented as examples only. For instance, embodiments of the disclosed invention can be configured in various ways, including other shapes and arrangements of elements. Similarly, embodiments of the invention can be used with other types of conveyor belts or assemblies (e.g., metal mesh, modular plastic, etc.) in addition to those expressly illustrated or described herein and, for instance, may be incorporated into an up-go and/or down-go conveyor system. 
     A conveyor belt is typically an endless belt driven in a direction of travel. In instances where a large amount of belt carry surface within a relatively small footprint is desired, for instance, on a manufacturing plant floor supporting applications, such as freezing, cooling, proofing, cooking, etc., spiral conveyor belt systems are well suited. In a conveyor belt arrangement incorporating a direct drive spiral conveyor belt system, the conveyor belt includes a generally linear segment that merges (e.g., somewhat tangentially) along a transitional zone with a generally helical spiral segment to achieve positive engagement between a belt drive feature often located near the inside edge of the belt and a cooperating drive member rotating with the drum. 
     A simplified depiction of a portion of an example direct drive spiral conveyor belt system  100  is shown and described with reference to  FIGS. 1-4 . In addition to having a belt  110 , the example direct drive spiral conveyor belt system  100  has a plurality of vertical bars  134  that generally form a drum  130 , which rotates about a drum axis  132  (shown in  FIGS. 1 and 2 ). The rotation of the drum  130  can be implemented via conventional means, such as one or more electric motors, power transmissions, and controllers. 
     The belt  110  can have a plurality of modules, shown in one embodiment as rows of pickets  120 , interconnected by a plurality of cross-rods  116 . Each of the plurality of pickets  120  is slidable relative to each other and the respective cross-rods  116  allowing the spacing of the plurality of pickets  120  and the interconnecting cross-rods  116  to compress and expand. For example, as the belt  110  traverses a generally helical spiral segment  102 , the plurality of pickets  120  can compress together along an inside portion  112  and expand away from each other along an outside portion  114 . In some embodiments, each of the cross-rods  116  can have a drive end  118  on the end nearest the inside portion  112 , as shown in  FIGS. 3 and 4 . The number, pattern, spacing, and form factor of the drive ends  118  can be adapted to accommodate application-specific designs and requirements, such as load carrying capacity and cost targets. In other forms, the drive ends can be separate and independent from the cross-rods (e.g., integrally molded with a plastic module). 
     As shown, a first number of the plurality of vertical bars  134  may have a drive cap  140  attached thereto (e.g., clipped, adhered, bolted, etc.) (shown best in  FIG. 3 ). The drive cap  140  can have a planar portion  142  along a length  144  of the drive cap  140 . The example drive cap  140  defines a drive member in the form of a rib  146 . The example rib  146  extends away from the planar portion  142  and may extend along the entire length  144  of the drive cap  140 . The drive member may comprise various other form factors configured to mate with and establish positive engagement with a cooperating belt drive feature formed, for example, on at least a portion of the inner edge of the belt  110 . 
     The ratio and pattern of vertical bars  134  about the drum  130  having drive members (e.g., ribs  146 ) can be adapted to address application-specific requirements (e.g., based on dimensions of the drum  130 , load capacity specifications, throughput and velocity specifications, etc.). In some examples, drive caps  140  with ribs  146  are provided on consecutive vertical bars  134  (shown in  FIGS. 3 and 4 ). 
     The example ribs  146  on the drive cap  140  may be integrally formed with the planar portion  142  and configured to, for instance, contact and engage with drive ends  118  of one of the cross-rods  116  on the inside edge of the example belt  110  (shown in  FIGS. 3 and 4 ). As the drum  130  and the vertical bars  134  rotate about the drum axis  132 , the drive caps  140  ultimately engage and drive the belt  110  along the conveyor belt system  100 . 
     An infeed system  150  is preferably provided in a transitional zone  106  in which the conveyor belt  110  transitions from the linear segment  104  to the helical spiral segment  102 , or vice versa. The infeed system  150  can include a motor M (e.g., a variable speed electric motor) and one or more sprockets  152  that engage the cross-rods  116  from beneath the belt  110 . The belt  110  can be actively over-driven within the transitional zone  106  by the infeed system  150  to cause sequential pickets  120  of the belt  110  to at least partially collapse (i.e., compress) together prior to reaching the helical spiral segment  102  and before the drive caps  140  on the vertical bars  134  engage the drive ends  118  of the cross-rods  116 . As the belt  110  moves upward (or downward) through the helical spiral segment  102 , the drive ends  118  of the cross-rods  116  can engage with the ribs  146  on the drive caps  140  while the pickets  120  of the belt  110  are at least partially collapsed together. 
     The belt  110  is dynamically/actively over-driven when the velocity of the belt  110  within the transitional zone  106  is relatively greater than the velocity of the belt  110  that has transitioned generally into the helical spiral segment  102 . In the example embodiment, this relative velocity difference is achieved as a result of the operational differences between the belt velocity allowed by the rotating drum  130  (and the associated drum drive system) and the belt velocity allowed by the infeed system  150  (and the associated motor M). In this arrangement, the combined over-drive and downstream backpressure results in the momentary collapse of sequential pitches of the belt  110  within the transitional zone  106 . In other embodiments, this momentary collapsing may be achieved by other techniques that establish a velocity difference between the belt  110  in the relevant operational segments. 
     The distance between adjacent drive ends  118  after leaving the transitional zone  106  defines a substantially arcuate drive-end distance  160 . The extent to which the pickets  120  and the cross-rods  116  of the belt  110  are collapsed by the infeed system  150  is, in some embodiments, preferably a whole-number factor of the rib arc length  148  between adjacent ribs  146  to maximize cooperation between available drive ends  118  and ribs  146 . The amount of collapse effectuated can vary from none to full collapse, depending on application-specific requirements, such as desired belt tension, belt width, drum diameter, load-carrying requirements and the like. 
     The drive-end distance  160  also directly corresponds to the amount of edge tension within the belt  110 , which, depending on the application-specific requirements (e.g., load rating on the belt  110 , radius of the helical spiral segment  102 , width of the belt  110 , conveyor speed, etc.), more or less tension may be preferred. The drive-end distance  160  can be adjusted to match the desired belt tension. One example includes varying the rib arc length  148  between the ribs  146  and/or the placement of drive ends  118 . Another example includes varying the amount the belt  110  is over-driven by the infeed system  150  and thus the amount the belt  110  is collapsed between pickets  120  and the cross-rods  116 . 
     As the belt  110  traverses the helical spiral segment  102 , the drive-end distance  160  between adjacent drive ends  118  at the inside portion  112  of the belt  110  is mostly maintained, while the distance between the cross-rods  116  at the outside portion  114  is generally the distance between adjacent cross-rods  116  in the belt  110  in a fully-extended state (uncollapsed distance  162 ) because typically some tension in the outside portion  114  of the belt  110  is preferable to maintain the contact between the drive ends  118  and the ribs  146 . The smaller the drive-end distance  160  is relative to the uncollapsed distance  162 , the more the belt  110  is inherently curved and the less tension is induced into the belt  110  at the outside portion  114  as it traverses the helical spiral segment  102 . 
     As explained herein, a unique auxiliary belt drive is disclosed that achieves a properly functioning direct drive spiral conveyor by utilizing an active engagement system between the belt and the rotating drum. Instead of using a passive system that relies on the inside belt edges gradually engaging the vertical ridges through a decreasing inside drum radius, the belt is positively over-driven at the infeed section to cause sequential pitches/modules/rows of belt to momentarily collapse on the conveyor just prior to reaching the tangential engagement point with the rotating drum. As the belt gradually moves upward (or downward) through the spiral helix, the inside edge of the belt engages with vertical drive ridges while the belt is still in its partially collapsed state. The extent that the belt is collapsed ultimately influences the edge tension carried by the belt throughout the remainder of the spiral stack. Some tension on the outer edge of the belt may persist in order to maintain contact between the inside belt edge and the rotating drum that propels the belt (and product load) forward. In some embodiments, the amount of overdrive of this belt section can be varied in order to adjust the amount of belt that collects within this location. In this way, the amount of “excess belt” that is captured between the positive engagement points on the rotating drum can be varied to match the desired belt tension setting on the spiral conveyor overall. This active direct drive system concept is relatively efficient to install and maintain, and can provide a convenient retrofit option for existing low-tension systems, such as during a belt change-out. The system is also capable of operating on either an up-go spiral or a down-go spiral conveyor. 
     It is further contemplated that there may be a feedback control system  170  ( FIG. 2 ) configured to maintain the desired engagement relationship (e.g., between the ribs  146  and the drive ends  118 ) that can be, for example, correlated to the drive-end distance  160 . The feedback control system  170  can include a feedback device F, such as sensors, strain gauges, optical sensors, and other belt monitoring equipment to monitor the engagement relationship (e.g., via the drive-end distance  160  upon entering or exiting the infeed system  150 ). This engagement relationship may also be monitored, for instance, via an optical device that provides driving engagement data (e.g., percentage of drive ends  118  being engaged by ribs  146 ) and/or via a strain gauge that provides general belt tension data (e.g., tension along the inside/outside/middle of the belt, the linear segment  104 , the transitional zone  106 , and/or the helical spiral segment  102 ). The feedback control system  170  can provide indications (e.g., audio, visual, and/or electronic text notifications) to an operator if the measured values are outside of the predetermined parameters. In one example embodiment, the infeed system  150  and the feedback control system  170  can include two synchronized motor drives (e.g., motor M and a separate motor configured to drive rotation of the drum  130 ), each motor drive can include an encoder and be configured to establish and maintain a desired over-drive and prescribed collapse of the belt  110 . In one form, the motors are synchronized to collapse the belt  110  a prescribed amount by advancing a metered amount of belt  110  from, for instance, a take-up/slack loop assembly as the drum  130  rotates at a substantially fixed velocity. The feedback control system  170  can also make dynamic, near real-time adjustments to the infeed system  150  as necessary to maintain a predetermined parameter, such as drive-end distance  160 , including adjusting the speed of the motor M (and/or of the drum  130 ) or upon command if an adjustment to the engagement relationships (e.g., drive-end distance  160 ) is desired. In some embodiments, the feedback control system  170  can include sensors (e.g., inductive sensors) configured to move (e.g., translate) in concert with the take-up/slack loop assembly, such as inductive sensors positioned on an adjustable take-up belt loop assembly wherein the position of the assembly is indicative of the relative tension. The example inductive sensors can comprise a high sensor and a low sensor positioned to sense the dynamic relative proximity to a fixed high-side reference member and a fixed low-side reference member positioned/spaced to establish acceptable over-drive variation, such that changes in belt tension (e.g., due to temperature and/or wear effects on belt properties) can be inferred within the take-up/slack loop and thus inform appropriate alterations to the relative motor controls (e.g., adjusting the speed of motor M to increase or decrease belt collapse and the associated system properties). Given the benefit of this disclosure, one skilled in the art will appreciate the variety of application-specific infeed system and feedback control system configurations available. 
     Additionally, or alternatively, as shown in  FIG. 5 , a drive rib plate  240  can be attached to a side  138  of the vertical bar  134  (e.g., clipped, adhered, bolted, etc.). In  FIG. 5 , the drive rib plate  240  extends outward past the radially outward face  136  of the vertical bar  134  to engage with the drive ends  118  of the cross-rods  116 . The example drive rib plate  240  is sandwiched between a plate  242  and the vertical bar  134  with at least one fastener, here shown as a bolt  244 , securing the plate  242  and the drive rib plate  240  thereto. The drive rib plate  240  can be secured to either the leading side or the trailing side of the vertical bar  134  or a set of drive rib plates  240  can be secured to each of the leading and trailing sides of the vertical bar  134 . The drive rib plate  240  can, for instance, be formed from nylon and is configured to be conveniently removable and replaceable by removing/replacing the plate  242 , which can be made of a stainless steel material. In some embodiments, the vertical bar  134  may include a drive cap (similar to the ribless drive caps  140  shown in  FIG. 1 ) that is made of an ultra-high molecular weight plastic. 
     It will be appreciated by those skilled in the art that while the invention has been described above in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications, and departures from the embodiments, examples, and uses are intended to be encompassed by the claims attached hereto. For example, the spacing, size, gauge, form-factor, and other features may vary based on application-specific requirements (e.g., product to be conveyed, environmental factors, speed of conveyance, operational envelope limitations, etc.). In addition, while the embodiments have been described in context of a metallic construction, it is contemplated that other materials (e.g., polymers) or composite constructions (e.g., a metallic base with a plastic overmold) are possible. Other types of conveyor belt systems (e.g., plastic modular conveyors) may also benefit from the incorporation of aspects of the invention. 
     Various features and advantages of the invention are set forth in the following claims.