Abstract:
A universal cross belt sorter system ( 1 ) consisting of four major components: a monorail track ( 26 ), a drive car ( 20 ), multiple cross belt cars ( 24 ) and system controls. The drive cars ( 20 ) pull multiple cross belt cars ( 24 ) along the track ( 26 ). The cross belt cars ( 24 ) are typically loaded with material, which is then discharged into outlets. An outlet may be a chute, a bin, a conveyor, a truck, etc. Sortation systems are typically used to consolidate material according to selected parameters, such as zip code, customer order, to replenish a specific store and many other identifying information. The cross belt cars ( 24 ) are loaded with material at induction areas ( 3 ). The types or methods of inducting material onto the cross belt cars ( 24 ) range from manual to semi-automatic to fully automatic.

Description:
[0001]    This application is a continuation of U.S. application Ser. No. 10/531,322, filed Apr. 12, 2005, now U.S. Pat. No. 7,559,282, which was the national stage entry of PCT/US03/32703, filed Oct. 16, 2003, which claimed priority from provisional application Ser. No. 60/418,795, filed Oct. 16, 2002, the disclosures of which applications are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates generally to sortation systems and more particularly to monorail sortation systems. 
         [0003]    Automated material handling and sortation systems are known for receiving, transporting and discharging goods among various stations in large scale sortation operations, for example warehousing, distribution, postal sortation and handling of mail and packages, and airport baggage handling, to name a few. Whatever the operation, goods typically originate from one location within the facility and must be sorted and transported to several different locations for further handling, or originate from several locations within a facility and must be transported to a single location such as a shipping dock. The manner in which the goods are sorted and selectively distributed among various stations in a facility of course depends on the nature of the operation. 
         [0004]    One known sortation and delivery method involves using powered belt or roller conveyers to transport individual items or sorted loads of items to various destinations within a facility. When goods from multiple sources must be delivered to a single station, associated take away conveyors must be merged onto a main conveyor or discharge point. This requires careful coordination of each item as it arrives to prevent jams or damage. Each merge point on such a conveyor system would accordingly require a complex system of sensors, start/stop controls, actuators, power supply lines, etc. Similarly, when items must be delivered to multiple destinations or stations in a facility, a main conveyor must be provided with diverter apparatus to direct individuals items or batches of items to either continue or be diverted at various points. Each diverter apparatus would require an additional closed system including sensors, actuators, control mechanisms, wiring and power supply to accomplish the diverting operation and track and identify the items being diverted. 
         [0005]    The disadvantages of conveyor-type systems have led to the development of tracked systems. In one known type of system, a closed loop track carries cars propelled by a continuous belt or chain drive. The cars are equipped with open trays which can be loaded from chutes, and subsequently tilted to unload their carloads into bins which are located around the track. These cars are often termed “dumb” because they do not initiate any sorting actions, but rather respond to stimuli from the induction stations to discharge their load. For example, car speed is controlled by a track-side motor which circulates the belt or train drive, and car dumping is controlled by track-side dumping mechanisms. Such systems are designed for long term installations which sort and transport large volumes of goods. Although these closed loop track systems are an improvement over conveyor-type systems, the complexity of their track, drive and tilting mechanisms makes it a major undertaking to set them up or rearrange their sortation layout. They must be shut down for nearly all maintenance tasks. 
         [0006]    The foregoing illustrates limitations known to exist in present sortation systems. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter. 
       SUMMARY OF THE INVENTION 
       [0007]    In one aspect of the present invention, this is accomplished by providing a sortation system comprising: a longitudinally extending monorail track; a plurality of interconnected cars, at least one car being a drive car, and at least one car being an article conveying car. 
         [0008]    In a second aspect of the present invention, this is accomplished by providing a sortation system comprising: a longitudinally extending monolithic monorail track comprising: an upper wheel engaging section; a lower wheel engaging section; and a power section, the upper section being connected to an upper portion of the power section and the lower section being connected to a lower portion of the power section; a multi-conductor power bus mounted within the power section; two longitudinally extending mounting flanges, each mounting flange having a U-shape, one side of the mounting flange U-shape being coincident with a portion of one side of one of the upper wheel engaging section and the lower wheel engaging section; and one side of the mounting flange U-shape being coincident with a portion of one side of the power section, wherein the upper wheel engaging section and the lower wheel engaging section are spaced apart, the track having a closed side being closed by the power section and an open side opposite the power section, the open side being between the upper wheel engaging section and the lower wheel engaging section; a plurality of interconnected cars, at least one car being a drive car, and at least one car being an article conveying car, the at least one drive car and the at least one article conveying car each have a brush assembly slidably engaging the power bus. 
         [0009]    In a third aspect of the present invention, this is accomplished by providing a sortation system comprising: a longitudinally extending monorail track; a plurality of interconnected cars, at least one car being a drive car, and at least one car being an article conveying car, each car includes two wheel assemblies, each wheel assembly engaging the track, each wheel assembly comprising: a plurality of spaced apart side wheels, the side wheels rotating about a vertical axis; and an end wheel, the end wheel rotating about a horizontal axis, the end wheel being a caster, the caster swiveling about a vertical axis. 
         [0010]    In a fourth aspect of the present invention, this is accomplished by providing a track comprising: a longitudinally extending monolithic monorail track having an upper wheel engaging section; a lower wheel engaging section; and a power section, the upper section being connected to an upper portion of the power section and the lower section being connected to a lower portion of the power section; a multi-conductor power bus mounted within the power section, wherein the upper wheel engaging section, the lower wheel engaging section and the power section each have a U-shape, wherein the upper wheel engaging section U-shape has its open side facing downward, the lower wheel engaging section U-shape has its open side facing upward, and the power section U-shape has its open side facing horizontally; and the upper wheel engaging section U-shape open side, the lower wheel engaging section U-shape open side and the power section U-shape open side all facing towards a common center; and a plurality of interconnected cars, at least one car being a drive car, and at least one car being an article conveying car. 
         [0011]    In a fifth aspect of the present invention, this is accomplished by providing a drive car adapted for drivingly engaging a track comprising: a frame; a plurality of wheel assemblies attached to the frame; and a motor and drive wheel assembly attached to the frame, the motor and drive wheel assembly being vertically movable relative to the frame, the drive wheel being adapted to drivingly engage the track. 
         [0012]    In a sixth aspect of the present invention, this is accomplished by providing a drive car adapted for drivingly engaging a track comprising: a frame; a two wheel assemblies attached to the frame, each wheel assembly comprising: a plurality of spaced apart side wheels, the side wheels rotating about a vertical axis; and an end caster wheel, the end caster wheel rotating about a horizontal axis, the drive car having a forward direction of travel, one wheel assembly having the end wheel at an upper end of the wheel assembly and being forward of the other wheel assembly, the end wheel of the other wheel assembly being at a lower end of the wheel assembly; and a motor and drive wheel assembly attached to the frame, the motor and drive wheel assembly being vertically movable relative to the frame, the drive wheel being adapted to drivingly engage the track, the motor and drive wheel assembly comprising: a cantilever bar attached to a rear part of the motor and drive wheel assembly, a portion of the cantilever bar distal from the motor and drive assembly being attached to the frame; and a slide assembly mounted between the rear part of the motor and drive wheel assembly and the frame, the slide assembly comprising a slide slidably fitting within a slotted member, the slide assembly permitting the motor and drive wheel assembly to move vertically relative to the frame, the drive wheel being positioned between the wheel assemblies. 
         [0013]    In a seventh aspect of the present invention, this is accomplished by providing an article conveying car adapted for movably engaging a track comprising: a frame; an endless movable belt; at least three rotatable rollers attached to the frame, the movable belt being positioned about the rollers; and at least one of the rollers being translatably moveable relative to the movable belt. 
         [0014]    In an eighth aspect of the present invention, this is accomplished by providing a n article conveying car comprising: a frame comprising two side plates connected by a plurality of cross bars; three rollers rotatably attached to the frame, the three rollers being arranged in a triangle; an endless movable belt about the rollers; two wheel assemblies attached to the frame, each wheel assembly comprising: a plurality of spaced apart side wheels, the side wheels rotating about a vertical axis; and an end wheel caster at a lower end of the wheel assembly, a wheel of the end wheel caster rotating about a horizontal axis; a bi-direction position controllable belt drive attached to the frame and operably connected to one of the rollers; and an interconnection adapted to connect one article conveying car to one of a drive car and another article conveying car, the interconnection including a mechanical connection and an electrical connection. 
         [0015]    In a ninth aspect of the present invention, this is accomplished by providing an article conveying car comprising: each article conveying car comprising: a frame comprising two side plates connected by a plurality of cross bars, and a reduced friction plate having a groove therein; three rollers rotatably attached to the frame, the three rollers being arranged in a triangle, each roller having a groove therein; an endless movable belt about the rollers, the belt having a rib extending therefrom, the belt rib tracking in at least one of the reduced friction plate groove and the roller grooves; two wheel assemblies attached to the frame; and a bi-direction position controllable belt drive attached to the frame and operably connected to one of the rollers. 
         [0016]    The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0017]      FIG. 1  is a plan view of a monorail sortation system according to the present invention; 
           [0018]      FIG. 2  is an end view of a monorail track for use with the sortation system shown in  FIG. 1 ; 
           [0019]      FIG. 3  is a perspective view of the monorail track shown in  FIG. 2 , illustrating the power bus; 
           [0020]      FIG. 4  is a second perspective view of the monorail track shown in  FIG. 2 , illustrating the mounting flanges; 
           [0021]      FIG. 5  is an end view of a section of the monorail track shown in  FIG. 2 , illustrating the engagement of a wheel assembly with the track; 
           [0022]      FIG. 6  is a perspective view of the tow car shown in  FIG. 1 ; 
           [0023]      FIG. 7  is a perspective view of the tow car shown in  FIG. 6 , without a cover; 
           [0024]      FIG. 8  is a side view of the tow car shown in  FIG. 6 ; 
           [0025]      FIG. 9  is a side view of the lower portion of the tow car shown in  FIG. 6 ; 
           [0026]      FIG. 10  is a perspective view showing the details of the motor and drive wheel assembly; 
           [0027]      FIG. 11  is a perspective view of the cross belt car shown in  FIG. 1 ; 
           [0028]      FIG. 12  is a perspective view of the cross belt car shown in  FIG. 11 , with the cross belt removed; 
           [0029]      FIG. 13  is second perspective view of the cross belt car shown in  FIG. 11 , with certain components removed; and 
           [0030]      FIG. 14  is an end view of the cross belt car shown in  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION 
       [0031]      FIG. 1  shows a sortation system  1  according to the present invention. In this sortation system  1 , a continuous loop monorail track  26  supports a continuous train of interconnected tow or drive cars  20  and cross belt or article conveying cars  24 . In one embodiment, a drive car  20  can pull about  24  article conveying cars. Although the drawings show a cross belt type car  24 , other types of article conveying cars, such as a tilting car, can be used with the present invention. In addition to providing support for the cars  20 ,  24 , the monorail track  26  also provides electrical power through a power bus  36  attached to the track  26  to the cars  20 ,  24 . In the preferred embodiment, DC power at 80 volts for the drive motors and 24 volts for electronics is supplied through power bus  36 . Preferably, a wireless communication system is used to provide control signals from a central control system to the cars  20 ,  24 . Alternatively, a wired communication system could be included in the power bus  36 . 
         [0032]    Sortation system  1  includes multiple induction stations  3  where packages or articles are loaded onto article conveying cars  24 . Multiple bins  5  accept the packages from the article conveying cars  24 . When a package is loaded onto to an article conveying car  24 , the control system is updated with information about the package, such as its destination, and associates that package with that particular article conveying car  24 . As the article conveying car  24  approaches the appropriate bin  5  for that package, the control system signals the article conveying car  24  to unload the package into the appropriate bin  5 . Alternatively, the control system informs the article conveying car  24  of the location of the appropriate bin. The article conveying car  24  keeps track of its location relative to the appropriate bin  5  and unloads the package into the appropriate bin. 
         [0033]    Although there are many ways for the sortation system  1  to track the article conveying cars  24  relative to the appropriate bin  5 , one method used for the present sortation system uses photo sensors (not shown) on the article conveying cars  24 . When a package is loaded onto an article conveying car  24 , the control system tells the car  24  to unload the package XX flags from the loading station  3 . Placed about the system  1  are flags that are sensed by the photo sensors. For example, a package going to Minneapolis is loaded onto car  24 . The bin  5  for Minneapolis packages is positioned 27 flags from the loading station  3 . The article conveying car photo sensor senses the car  24  passing the flags. As the car  24  approaches the 27th flag, a controller on the article conveying car  24  operates an unloading mechanism or belt  100  to unload the package into the Minneapolis bin. ID tags, preferably bar codes,  54  are provided on each car  20 ,  24 . A bar code sensor is used by the control system to determine which car  24  is being loaded with what package so that the appropriate destination commands can be sent to the right article conveying car  24 . 
         [0034]      FIGS. 2 through 5  show the features of monorail track  26  and the engagement of cars  20 ,  24  with track  26 . Preferably track  26  is formed from multiple sections of either straight or curved monolithic extruded track. Track  26  is preferably an aluminum alloy. Track  26  includes an upper section  30  attached to a power section  34  that has a lower section  32  attached to it. Above and below the power section  34  are two longitudinally extending mounting flanges  38 . A power bus  36 , such as power conductors supplied by Vahle Electrification Inc. is mounted in power section  34 . Each car  20 ,  24  includes a removable brush assembly  52  that slidably engages the power bus  36  so that power can be transferred to the cars  20 ,  24 . 
         [0035]    Mounting flanges  38  have two purposes. First, the flanges  38  are used to attach the track  26  to building structures, such as floors, walls or ceilings. Mounting brackets  44  are used to secure track  26  to whatever additional framework is needed to attach the track  26  to the appropriate structure. The second purpose of mounting flanges  38  is to secure one section of track  26  to an adjacent section of track  26  (See  FIG. 3 ). Where two sections of track  26  are joined, jointers  42  are placed in the mounting flanges  38  of the two sections of track  26 . The jointers  42  extend between the two sections of track  26  and are secured with fasteners or other mounting hardware. 
         [0036]    Both types of cars  20 ,  24  use similar wheel assemblies  80  to attach the cars  20 ,  24  to the track  26 . Each wheel assembly  80  consists of a center member  82  that is removably attached to a wheel assembly support  50 . Wheel assembly support  50  is then attached to car  20 ,  24 . Rotatable side wheels  84  are attached to the ends of center member  82 . Side wheels  84  roll against the sides of track upper and lower sections  30 ,  32 . End wheel(s)  88  are attached to either end, or both ends, of center member  82 . Preferably, end wheel  88  uses a caster mount  86  that allows end wheel  88  to swivel as car  20 ,  24  moves through a section of curved track. Preferably, each car  20 ,  24  uses two wheel assemblies  80 . In one embodiment, both end wheels  88  on an article conveying car  24  are at the lower end of the wheel assemblies  80 . In another embodiment of a drive car  20  (see  FIG. 9 ), one end wheel  88  is at the lower end of one wheel assembly  80  and one end wheel  88  is at the upper end of the other wheel assembly  80 . The forward wheel assembly (relative to the direction of travel as shown by arrow  90 ) has the end wheel  88  at the upper end of wheel assembly  80 . The forward wheel assembly  80  can optionally have a second end wheel  88  at its lower end, as shown in  FIG. 9 . 
         [0037]      FIGS. 6 through 10  shows the details of drive car  20 . Drive car  20  includes a frame formed from two side plates  60  and two cross bars  58 . The article conveying car  24  uses a similar frame. A motor and drive wheel assembly  62  is attached to the rear of drive car  20 . The motor and drive wheel assembly consists of a DC servo or positionable controllable motor  92  connected to a friction drive wheel  64  through a reducer and right angle drive  94 . Drive wheel  64  engages the upper surface of track  26 . Motor and drive wheel assembly  62  is suspended from the rear of car  20  by a cantilever arm  96  and a slide assembly  98 . Cantilever arm  96  is attached to the reducer and right angle drive  94 . The free end of cantilever arm  96  is attached to the frame of car  20 . Slide assembly  98  consists of a slide on the reducer and right angle drive  94  that fits within, and slides within, a corresponding slotted block attached to the frame of car  20 . This attachment arrangement for the motor and drive wheel assembly  62  suspends all the weight of the motor and drive wheel assembly  62  from the rear of car  20 , allows the motor and drive wheel assembly  62  to move vertically, and thereby increases the downward force on drive wheel  64 . Having all the weight at the rear of car  20  causes car  20  to tip up slightly in the front, see  FIG. 8 . Therefore, the forward wheel assembly  80  has the end wheel  88  at the upper end of the wheel assembly so that the end wheel  88  can ride against the inside top surface of the upper section of track  26 . 
         [0038]    Drive car  20  includes a wireless control signal receiver or modem  66  for receiving control signals from the central control system. The modem  66  can also be used for sending status information and error messages regarding the sortation systems cars back to the central control system. Modem  66  is connected to a computer  68  that in turn is connected to a DC servo controller  70 . Depending upon the modem  66  and the DC servo controller  70  being used, modem  66  could be directly connected to the DC servo controller  70  thereby eliminating the computer  68 . Car  20  includes a DC/AC inverter  72  that takes power from the power bus  36  via brush assembly  52  to supply AC power to any electronic components requiring AC power. A power supply  74  is provided to provide appropriate power to computer  68 . 
         [0039]    In operation, the central control system uses RF signals to broadcast control signals to drive cars  20  and to article conveying cars  24 . Wireless modem  66  receives the control signals for both drive cars  20  and article conveying cars  24  and passes them to the computer  68 , which then passes the control signals to the DC servo controller  70 . DC servo controller  70  has two functions. First, it uses the control signals to send the appropriate control signals to DC servo motor  92  to move car  20 . Second, it passes the control signals for the article conveying cars  24  through interconnection  56  to the other cars. Drive car  20  and article conveying car  24  use a CAN® bus network for inter-car communication. Interconnection  56  includes both a physical connection (see  FIG. 8 ) and an electrical connection (see  FIG. 7 ). Depending upon the characteristics of the controller  70  and the computer  68 , the location where these functions are performed could change. 
         [0040]    For a continuous sortation system, as shown in  FIG. 1 , the control of the multiple drive cars  20  has to be coordinated to evenly drive the continuous system. In one embodiment, the central control system sends commands to a lead drive car and the lead drive car coordinates the operation of the other drive cars. Alternatively, the central control system can coordinate the operation of all the drive cars and send individual commands to each drive car. 
         [0041]      FIGS. 11 through 14  show the details of the article conveying car  24 . Car  24  includes a frame formed from side plates  60  connected by two cross bars  58 , similar to the frame for a drive car  20 . Rotatable rollers  102 ,  106  are mounted on the cross bars  58 . One roller  102  is a drive roller. The other roller  106  is preferably non-driven. A third roller  104  is positioned below rollers  102 ,  106  such that the three rollers form a triangle. Roller  104  is vertically movable and can be adjusted by threaded adjuster  110 . A belt  100  is placed about the three rollers  102 ,  104 ,  106 . Roller  104  is then adjusted to achieve the desired tension on belt  100 . Belt  100  is preferably formed from a UHMW (Ultra High Molecular Weight) polymer, preferably a reduced friction polymer. A reduced friction UHMW polymer plate  120  is placed below the upper horizontal extent of belt  100 . Plate  120  provides support for belt  100  when a package has been placed on car  24 . Belt  100  includes a rib  122  extending below the belt. Rib  122  is essentially co-extensive with the length of belt  100 . Corresponding grooves  118  are formed in the three rollers,  102 ,  104 ,  106  and plate  120 . Tracking of the belt  100  is maintained by rib  122  tracking in grooves  118 . This eliminates the need for side plates  60  to extend above belt  100  to maintain proper tracking of belt  100 . It also eliminates the need for any roller adjustment mechanisms to adjust the tracking of belt  100 . Without raised sides extending above belt  100 , a large or long package can span two article conveying cars  24 . 
         [0042]    Car  24  includes a bi-directional DC servo motor  112  that is connected to drive roller  102  by drive belt  114 . Preferably, both DC servo motor  112  and drive roller  102  include drive sprockets  116  and drive belt  114  is a grooved or ribbed timing belt. In one embodiment, roller drive sprocket  116  is cut into the end of roller  102 . Car  24  includes a DC servo controller similar to the DC servo controller  70  for drive car  20 . The DC servo controller receives commands from the central control system through interconnection  56  via a drive car  20  and any article conveying cars  24  between the DC servo controller and the drive car  20 . In one embodiment, car  24  includes a photo sensor (not shown) that counts flags (not shown) to determine the position of car  24 . When the designated number of flags have been counted, the DC servo controller operates DC servo motor  112  to move belt  100  causing a package to be moved from car  24  into a bin  5 . When a large or long package has been placed on two adjacent article conveying cars  24 , the DC servo controller for the lead or forward car operates its belt  100  first causing the package to turn towards bin  5 . Next belt  100  on the following car is operated ejecting the turned package into bin  5 . Where bin  5  is large enough to accept a long package without it being turned first, belts  100  on both cars  24  are operated together to eject the long package into bin  5 . 
         [0043]    An intercar plate  124  is attached to the leading edge of car  24 . Plate  124  extends across the gap between adjacent cars  24  and under the belt  100  on the leading car  24  (See  FIG. 12 ). Plate  124  generally has a rectangular shape. In the preferred embodiment, plate  124  is formed of Lexan® polycarbonate resin. 
         [0044]    In an alternate embodiment of sortation system  1 , the drive cars  20  and article conveying cars  24  are combined into combination drive and article conveying cars. Preferably, this is accomplished by using a linear induction motor. 
         [0045]    Linear electric motors belong to a special group of electrical machines that convert electrical energy directly to mechanical energy in translational motion. While all electric motors operate based on principles of electromagnetic interactions, there are different types of motors. Polyphase synchronous motors and induction motors both use alternating current as input electricity source. Direct current motors are normally used for small horsepower applications. Conceptually, any rotary motor has a linear counterpart. There are linear synchronous motors (with permanent magnet or wound field), linear induction motors, and linear direct current motors. 
         [0046]    A linear electric motor is perhaps best understood by imagining the stator of an ordinary electrical motor being cut, unrolled and stretched lengthwise. An appropriate conductive material like copper, aluminum, or other material is positioned next to the unrolled stator. The alternating current in the unrolled stator provided by conventional techniques magnetically interacts with the conductive material to create a moving field of magnetic force acting on both the stator and the conductive material. The vehicle may be slowed down or stopped by reversing the polarity of that moving field. 
         [0047]    A linear induction motor (LIM) consists of a primary and a secondary. When powered by three-phase alternating current, a moving flux is produced in the primary winding. Current induced in the secondary reacts with the flux, producing a mechanical force. Both the primary and the secondary of LIMs are flat structures. The interaction of flux and current moves the secondary linearly. A linear synchronous motor (LSM) has a similar structure, except that its secondary must be either a permanent magnet or a wound field with a direct current. The word “synchronous” comes from the fact that the primary magnetic field and the secondary magnetic field in a LSM move at the same speed. 
         [0048]    A mount  108  is provided in side plates  60  to mount a reaction plate (aluminum and mild steel plates sandwiched together) bolts to each car  24 . Linear motors bolt to the track parallel to the reaction plate with a small air gap. An AC drive powers the linear motor coils to propel the article conveying cars  24 .