Patent Publication Number: US-2017349383-A1

Title: Diverting conveyor using a diverting belt with actuated rollers

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of International Patent Application No. PCT/US2017/021998, filed Mar. 13, 2017, which claims the benefit of U.S. Provisional Patent Application No. 62/314,458, filed Mar. 29, 2016. The disclosures of those applications are incorporated into this application by reference. 
    
    
     BACKGROUND 
     The invention relates to power-driven conveyors and more particularly to conveyor lines intersected by diverting belts with linear-motor-actuated rollers. 
     A tire-sorting conveyor system using a roller-top conveyor belt crossing and intersecting a conveyor line to selectively sort tires off either side of the line is disclosed in U.S. Pat. No. 7,306,086, which issued on Dec. 11, 2007. The roller-top belt is selectively started and stopped. When running, the belt travels in a direction of belt travel perpendicular to the length of the conveyor line. The rollers in the belt are freely rotatable on axles parallel to the direction of travel of the belt. Tires that are not to be sorted off the conveyor line transfer across the stopped roller-top belt from the upstream portion of the conveyor line to the downstream portion. When a tire that is to be sorted off the conveyor line is received on the running roller-top belt, an actuator raises the belt above the plane of the conveyor line so that the tire is supported only by the belt, which can then sort the tire off a side of the line. But problems can arise if the actuator raises the roller-top belt before a tire reaches the belt. If that occurs, the tire will be blocked by the belt and will not be sorted off. Sensors along the conveyor line are used to indicate that a tire is in position for the belt to be raised. But the timing of the raising of the belt is important in preventing premature raising that can block tires and tardy raising that can cause tires to cross the roller-top belt without being sorted off the side of the conveyor line. 
     SUMMARY 
     A conveyor system embodying features of the invention comprises a main conveyor line having an infeed portion and an outfeed portion and conveying articles in a conveying direction and a diverting conveyor belt intersecting the main conveyor line between the infeed portion and the outfeed portion. The diverting conveyor belt, which is advanceable in a diverting direction transverse to the conveying direction, includes an upstream edge adjacent the infeed portion, an opposite downstream edge adjacent the outfeed portion, and an outer side. Article-supporting rollers protrude from the outer side of the belt and include electrically conductive or magnetic material. The rollers are arranged to rotate in the conveying direction. A linear-motor stator disposed under the diverting conveyor belt produces an electromagnetic wave that interacts with the rollers to actuate the rollers to rotate in the conveying direction. A controller selectively advances the diverting conveyor belt in the diverting direction and unpowers the linear-motor stator to deactuate the rollers and divert articles from the main conveyor line and stops the diverting conveyor belt and powers the linear-motor stator to actuate the rollers to rotate in the conveying direction to transfer articles across the diverting conveyor belt from the infeed portion to the outfeed portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view, partly cut away, of a conveyor system embodying features of the invention; 
         FIG. 2  is a side elevation view, partly cut away, of the conveyor system of  FIG. 1 ; 
         FIG. 3  is a top plan view of the conveyor system of  FIG. 1 ; 
         FIG. 4  is a cross section of the conveyor system of  FIG. 1  taken along lines  4 - 4  of  FIG. 3 ; 
         FIGS. 5A and 5B  are cross sections of the conveyor system of  FIG. 1  taken along lines  5 - 5  of  FIG. 3  showing the diverting conveyor belt in pass-through and tilted diverting positions; 
         FIG. 6  is a block diagram of a control system for the conveyor system of  FIG. 1 ; 
         FIG. 7  is a flowchart of a programmed control routine executed by the controller of  FIG. 6 ; and 
         FIGS. 8A-8C  are top plan, front elevation, and side elevation views of a portion of a conveyor system as in  FIG. 1  with linear-motor-driven rollers in the diverting belt. 
     
    
    
     DETAILED DESCRIPTION 
     A sorting conveyor system embodying features of the invention is shown in  FIG. 1 . The conveyor system  10  comprises a main conveyor line  12  having an upstream infeed portion  14  conveying articles in a main conveying direction  16  toward a downstream outfeed portion  18 . Crossing and intersecting the main conveyor line  12  is a roller-top conveyor belt  20 . The roller-top belt  20  advances in a direction of belt travel  22  transverse—perpendicular in this example—to the main conveying direction  16  to selectively divert articles off the side of the main conveyor  12  and onto a discharge conveyor  24 . Articles not diverted off onto the discharge conveyor  24  transfer across the diverting roller-top belt  20  from the upstream portion  14  to the downstream portion  18  of the conveyor line  12 . Although the infeed, outfeed, and discharge conveyors  14 ,  18 ,  24  are shown as conveyor belts, each could alternatively be realized as a roller conveyor or a chute. And although the main conveyor line is represented as a pair of belts forming the upstream  14  and downstream  18  portions, the main conveyor line could alternatively be constructed of a single conveyor belt whose path detours under the roller-top belt  20 . The roller-top belt  20  and the main conveyor line  12  are supported in a frame  26 . A position sensor, such as an optical transmitter  28  and receiver  29  (or transmitter/receiver  28  and reflector  29 ) mounted on the frame  26  on the upstream infeed portion  14  of the conveyor line  12 , senses the presence of an article at that position along the length of the line. 
     The roller-top belt  20  has rollers  30  mounted on axles that define axes of rotation  32  parallel to the direction of belt travel  22 . The rollers  30  are freely rotatable in the main conveying direction  16  of the conveyor line  12 . With the level of the tops of the rollers  30  at about the level of the plane of the infeed and outfeed conveyor portions  14 ,  18 , articles conveyed down the conveyor line  12  ride the rollers across the roller-top belt  20  to the outfeed portion of the line without being diverted onto the discharge conveyor  24 . 
     As shown in  FIG. 2 , the roller-top belt  20  is supported in a gap  34  between the upstream and downstream portions  14 ,  18  of the main conveyor line. A belt support  36  is pivotably mounted to the conveyor frame  26  at a pivot  38  at the upstream end of the support. The pivot  38  includes a pivot bar that extends across the width of the main conveyor line. The pivot allows the downstream end of the roller-top belt  20  to tilt upward as indicated by the clockwise arrow  40 . A motor-driven timing belt  41  trained around two toothed pulleys  42 ,  43  is used to drive an eccentric camshaft  44  that tilts the roller-top belt&#39;s support  36  in one version of a tilt actuator for the sorter belt  20 . 
       FIG. 3  shows a diverting roller-top belt  20  intersecting and crossing the conveyor line between the infeed and outfeed portions  14 ,  18 . The belt support  36  has an overhanging upstream lip  46  between the upstream edge  48  of the belt  20  and the upstream conveyor portion  14  to minimize the gap over which articles must pass in transferring onto the roller-top belt. The support  36  has a similar downstream lip  47  at the downstream edge  49  of the roller-top belt  20 . The end  50  of the sorter belt  20  extends past the conveyor frame  26  in close proximity to the discharge conveyor  24 . 
     The roller-top belt  20  is shown in  FIG. 4  as a center-driven, bidirectional belt. The belt  20  is trained around idle sprocket sets  52 ,  53  at opposite ends of the belt run. A drive sprocket set  54  and snubber rollers  56 ,  57  engage the belt  20  in the lower run. The drive sprocket is mounted on a drive shaft  58  driven by a motor ( 60 ,  FIG. 1 ). Alternatively, the belt could be driven in only one direction if all sorting is to one side as in  FIG. 1 . In that case the belt  20  need not be center-driven. Instead, the drive motor could be connected to the shaft  62  of the sprocket set  52  closer to the discharge end of the belt, and the center-drive sprocket set  54  and snubber rollers  56 ,  57  could be replaced with support rollers or shoes in the lower belt-return run.  FIG. 4  also shows a servomotor  64  whose shaft is coupled to the lower pulley  42  ( FIG. 2 ) that drives the timing belt  41  ( FIG. 2 ) in the sorter-belt tilt actuator. The tilt actuator&#39;s eccentric camshaft  44  is elongated in the direction of travel  22 , i.e., the diverting direction. Cam followers  66  mounted at opposite ends of the belt support  26  ride on the camshaft  44 . 
     Other details of the tilt actuator are shown in  FIGS. 5A and 5B  in connection with a description of the operation of the sorter. The belt support  36  is shown in  FIG. 5A  in a pass-through position, in which the tops of the rollers  30  at the upper outer side  68  of the belt  20  are generally coplanar with the conveying surfaces  70 ,  71  of the infeed and outfeed conveyors  14 ,  18 . The eccentric camshaft  44  forms a lobe  72  that is in a downward position relative to the shaft&#39;s axis  74  to lower the belt support  36  to the level, pass-through position. When the cam followers  66 , which are mounted to the belt support  36  below the downstream edge  49  of the diverting belt  20 , sit on the non-lobe portion of the camshaft  44 , the belt is not tilted relative to the conveyor line. With the belt  20  in that position, articles transfer across the freely rotatable rollers  30  from the upstream conveyor portion  14  to the downstream portion  18  without being diverted. When the roller-top belt  20  is in the untilted position, it is also typically stopped. In that way there is no sidewise force applied to the articles, and they pass directly across on the stationary and freely rotatable belt rollers  30 . 
     Just before an article selected to be diverted off the side of the conveyor line reaches the diverting conveyor belt  20 , a controller sends a tilt signal to the servomotor ( 64 ,  FIG. 4 ) to drive the tilt actuator&#39;s timing belt ( 41 ,  FIG. 2 ) to rotate the upper pulley ( 43 ,  FIG. 2 ) and the camshaft  44  180° . The cam follower  66  is lifted by the rotating camshaft  44  until the timing belt stops with the cam lobe  72  facing upward as shown in  FIG. 5B . The cam follower&#39;s movement on the eccentric camshaft  44  pivots the belt support  36  on the pivot bar  38  about a pivot axis  74  parallel to the diverting direction (into the page in  FIG. 5B ). The pivot bar  38  resides below the upstream edge  48  of the roller top belt  20 . With the cam lobe  72  facing up, the roller-top belt  20  is at a maximum tilt angle α of 30° or less relative to the plane of the infeed and outfeed conveyors  14 ,  18 . When the roller-top belt  12  is in the tilted, diverting position, it is also driven in the diverting direction (into the page is  FIG. 5B ). Articles selected for diverting are prevented from contacting the outfeed conveyor portion  18  and are diverted off the side of the conveyor line by the tilted diverter belt  20 . If the next article is not to be diverted, the servomotor precisely advances or reverses the camshaft  44  another 180° until the cam lobe is downward as in  FIG. 5A , and the belt motor ( 60 ,  FIG. 1 ) is stopped. 
     Another version of a diverting conveyor embodying features of the invention is shown in  FIGS. 8A-8C . The diverting conveyor  90  has article-supporting belt rollers  92  that include electrically conductive or magnetic material. The rollers protrude from the top face  94  of a diverting conveyor belt  96 . The rollers shown are elongated perpendicular to the conveying direction  16  more than the belt rollers  30  in  FIG. 1 , which could alternatively include electrically conductive or magnetic material and be used. The rollers  92  rotate on axles providing axes of rotation perpendicular to the conveying direction  16 . A linear-motor stator  98  is mounted below the top run of the diverting conveyor belt  96  between the infeed portion  14  and the outfeed portion  18 . The stator  98  propagates an electromagnetic wave through the conveyor belt  96  parallel to the conveying direction  16  that induces currents in rollers  92  that include electrically conductive material. The induced currents create a secondary electromagnetic field that interacts with the stator wave to produce a force that actuates the rollers  92  to rotate in the conveying direction  16 . Thus, the electrically conductive rollers  92  each form a linear-induction motor with the stator  98 . Rollers  92  that include magnetic material create magnetic fields that interact with the stator wave to produce a force that actuates the rollers to rotate in the conveying direction. Thus, the magnetic rollers  92  each form a linear-synchronous motor with the stator  98 . In either case, when the conveyor belt  96  is stopped to allow an article to transfer across from the infeed portion  14  to the outfeed portion  18  without being diverted, the rollers  92  are actuated to aid the transfer and prevent stranding. Sensors and the tilt actuator of  FIGS. 1-5B  may be used with the diverting conveyor of  FIGS. 8A-8C . And the conveyor belt may be operated bidirectionally in opposite diverting directions  22  to divert articles onto discharge conveyors  24 ,  24 ′ on either side. 
     A block diagram of a control system for a diverting conveyor as in  FIG. 1  or  FIGS. 8A-8C  is shown in  FIG. 6 . A controller  76 , such as a programmable logic controller or other programmable computing device receives a sensor input signal or signals  78  from one or more sensors, such as one or more of the position sensors  28  or a barcode reader or other indicia-reading sensor  79 , on the upstream conveyor portion. From the sensor signal or signals, the controller  76  determines a characteristic of the article, such as the leading edge, length, size, shape, or identity of the article passing the sensor&#39;s sensing position. With knowledge of the sensor&#39;s sensing position along the length of the conveyor line, the controller  76  knows the position of the article at the time the sensor signal is received. The system may also use another position sensor  89  mounted at the diverting belt to send a signal  88  indicating the presence of an article entering or about to enter the diverting belt. From the characteristic information provided by the sensor or sensors  28 ,  79 ,  89  the controller  76  decides whether the article should pass through or should be diverted from the conveyor line. The controller  76  controls the run speed (and direction if a bidirectional motor is used) of the roller belt with a diverting motor signal  80  to the belt&#39;s motor  60 . The controller  76  controls the tilting of the roller belt by sending a tilt signal  82  to the tilt actuator&#39;s servomotor  64 . For the conveyor of  FIGS. 8A-8C , the controller  76  controls the linear motor stator  98  to actuate or deactuate the belt rollers with a linear-motor signal  99 . And the controller  76  may also be used to control the speed of the main conveying line with a conveyor motor signal  84  to the conveyor-line motor or motors  86 . 
     The controller  76  is programmed to operate the diverting conveyor according to the exemplary flowchart of  FIG. 7 . First, the controller determines the position and a characteristic, such as the length, shape, or identity of an article on the upstream infeed conveyor portion of the conveyor line from the sensor signal. From the characteristic of the article, the controller decides whether the article is to be diverted or passed through. In a system with more than one diverting conveyor belt along the length of the line, the controller determines the divert destination of each article to be diverted and allows it to pass through all divert locations upstream of the divert destination. With knowledge of the speed of the infeed conveyor, the controller can estimate the article&#39;s arrival time at the diverting belt. Alternatively, a position sensor near the entrance to the diverting belt can be used to signal the controller of the impending entrance of the article onto the diverting belt. The upstream sensor may include a barcode reader or an optical sensor, such as a laser sensor or a visioning system, or both. If a visioning system or a multi-sensor optical or laser system is used, the computed size will include information on the article&#39;s shape. 
     If, upon reaching a divert location, the article is to be passed through, the controller stops the diverting conveyor belt with the motor signal  80  to the diverting belt&#39;s motor  60  ( FIG. 6 ). And the controller untilts the diverting belt by sending an untilt command in the tilt signal  82  to the tilt actuator  64  ( FIG. 6 ) to return the diverting conveyor belt to the untilted first position. For the linear-motor conveyor of  FIGS. 8A-8B , the controller actuates the rollers  92  by powering the stator  98  to transfer the articles across the belt. The acceptable article then passes over the roller-top belt and onto the downstream outfeed conveyor. 
     If, on the other hand, the article to be diverted reaches its divert destination, the controller sends a tilt command in the tilt signal to the tilt actuator to tilt the diverting conveyor belt to the tilted second position and a run command in the motor signal to the diverting belt&#39;s motor to advance the belt toward the discharge conveyor. And for the conveyor of  FIGS. 8A-8C , the controller deactuates the rollers  92  by unpowering the stator  98 . 
     The controller&#39;s control software routine described by the flowchart of  FIG. 7  resides in the controller&#39;s program memory and runs whenever an article is detected at the sensor&#39;s position on the upstream infeed conveyor. Or the individual blocks may be divided into individual tasks or interrupt routines that run on different schedules as determined by a task manager and interrupt handler in the controller software. 
     The tilting of the diverting conveyor belt  20  shown in  FIG. 5B  does not raise the upstream edge  48  of the diverting belt above the plane of the infeed conveyor  14 . As shown the upstream edge  48  is at the same level whether the diverting belt  20  is in the tilted or the untilted position. Because of that, the articles, which are typically singulated and spaced apart along the length of the infeed conveyor  14 , are not blocked from advancing onto the diverting belt  20  as they would be if the diverting belt were merely lifted vertically. So the timing of the tilting of the diverting belt is not critical as with a diverting belt that lifts vertically. 
     Although the invention has been described by reference to an exemplary version, other versions are possible. For example, the tilt actuator could be realized instead with a linear actuator powered by hydraulics, pneumatics, or electromagnetics or with a gear system, such as a rack-and-pinion system. As another example, if the diverting conveyor belt is narrow enough, i.e., narrower than the length of the conveyed articles, it could be a belt with a rollerless, low-friction, flat top surface across which pass-through articles can slide easily.