Abstract:
An automated warehouse system row cart includes a lifter that uses cams to raise and lower pallets. Three symmetrical cam lobes are cut into a hollow cylinder. Three matching cam lifters ride these lobes and are attached to an elevator plate. A stepper motor running in one direction is used to raise and lower the elevator plate by virtue of the action between the cam lobes and lifters.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to automated storage and retrieval systems (AS/RS), and more particularly to material handling systems for storing and accessing palletized material in large multi-story automated warehouse buildings.  
         [0003]     2. Description of Related Art  
         [0004]     Automated warehouses and automated storage and retrieval systems (AS/RS) can reduce costs, pilferage, and damage because far fewer workers are needed for otherwise similar operations.  
         [0005]     U.S. Pat. No. 6,652,213, which is incorporated herein by reference, describes an automated storage module system. Elevators operate within exterior fixed elevator shafts amongst many floors in multi-story automated warehouse. A number of corresponding aisleways at each level of the warehouse each connect to the elevators on every level. A number of rows on each level are orthogonal to each aisleway, and allow palleted material on uniform-sized pallets to be warehoused. One aisle cart per aisleway provides a piggyback parking space on its top that can be aligned to each of the number of rows on its respective level. A row cart that is able to run along any of the number of rows on its respective level and, when aligned, it can park on the piggyback parking space on the top of any intersecting aisle cart. Such provides for independent operation by being umbilical or battery powered, and it can shuttle the palleted material along a row and aboard the intersecting aisle cart. A computer system provides for movement control of the elevators, aisle carts, and row carts with the aid of strategically placed position sensors for the carts and identity tags for the palleted material.  
         [0006]     The row carts need to be able to lift up the pallets loaded on their backs to match the heights of shelves and elevator floors they visit. Typically, a lift of 3-5 inches is enough. Prior art lifting devices on row carts have proven to be complex, bulky, and unreliable in being able to lift straight. Combinations of lift bars and hydraulics have all been tried, often with poor results in heavy use, and even product damage. One such row cart used four jacking screws that demanded a lot of maintenance and wore rapidly.  
       SUMMARY OF THE INVENTION  
       [0007]     An object of the present invention is to provide an automated storage and retrieval system that is economical to install and operate.  
         [0008]     Another object of the present invention is to provide a simple lifting device that can keep pallets level as they are risen.  
         [0009]     A further object of the present invention is to provide a lifting device in a warehouse automation system that is simple and requires little maintenance.  
         [0010]     Briefly, an automated warehouse system row cart embodiment of the present invention includes a lifter that uses cams to raise and lower pallets. At least three symmetrical cam lobes are cut into a hollow cylinder. Matching cam lifters ride these lobes and are attached to an elevator plate. A stepper motor running in one direction is used to raise and lower the elevator plate by virtue of the action between the cam lobes and lifters.  
         [0011]     An advantage of the present invention is that a system is provided that efficient, robust, and requires little maintenance.  
         [0012]     The above and still further objects, features, and advantages of the present invention will become apparent upon consideration of the following detailed description of specific embodiments thereof, especially when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a perspective, exploded assembly view diagram of a warehouse system row cart embodiment of the present invention;  
         [0014]      FIG. 2  is a perspective, exploded assembly view diagram of a lifter embodiment of the present invention that can be used in the warehouse system row cart of  FIG. 1 ;  
         [0015]      FIG. 3  is a perspective view of a warehouse system embodiment of the present invention, and uses the row cart of  FIG. 1 ;  
         [0016]      FIG. 4  is a perspective view of the internal material-transfer and storage portion of the warehouse system of  FIG. 3 ;  
         [0017]      FIG. 5  is a perspective view of the unloading elevator and material-output portion of the warehouse system of  FIG. 3 ; and  
         [0018]      FIG. 6  is a perspective view of a rail trolley or aisle cart used in the warehouse system of  FIG. 3 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]      FIG. 1  illustrates a warehouse system row cart embodiment of the present invention, referred to herein by the reference numeral  100 . The row cart  100  comprises a top tray  102  mounted to a rail car  104 . A lifter  106  is mounted inside the rail car  104  and can smoothly lift the top tray  102  as much as a few inches higher. A set of rail wheels  108 - 111  is shown and a similar set is out of view on the opposite side.  
         [0020]      FIG. 2  illustrates a lifter embodiment of the present invention, referred to herein by the reference numeral  200 . The lifter  200  comprises an elevator plate  202  that rides on a triple-lobe cam  204 . Such are operated by a transmission  206  driven by a stepping motor  208 . Four lobe configurations are possible, but the lobe ramping angles become so high that a great deal of torque is required to be delivered by motor  208 . The torque that is required with three lobes is made practical by the high gear ratios of ring and worm gear transmissions.  
         [0021]     The elevator plate  202  includes three fixed cam lifters  210 - 212  that surround an outer collar  214 . This mates with an inner collar  216  on the triple-lobe cam  204 . Three identical cam lobes  218 - 220  match the distribution of the distribution cam lifters  210 - 212 . The triple-lobe cam  204  is intended to rotate relative to the elevator plate  202 , and this rotation will cause elevator plate  202  to smoothly rise and fall. The three fixed cam lifters  210 - 212  provide a three-point support to maintain the parallel plane alignment of the top surface of elevator plate  202  with a base  222 .  
         [0022]     A pair of bearings  224  and  226  allow the triple-lobe cam  204  to turn with very little wobble on a shaft  228 . The base  222  is attached to a ring gear  230  turned by a worm gear  232 , a driveshaft  234 , and a stepping motor coupler  236 . The symmetrical shaping of cam lobes  218 - 220  allows the lifter  200  to operate without requiring stepping motor reversals for up and down elevator actions. The stepping motor  208  can be operated in one direction and simply stopped when the elevator plate  202  is at a desired height. Sensors to detect the position of elevator plate  202  would normally be included in the stepping motor control system for stepping motor  208 . Keys or slots are used to prevent the rotation of elevator plate  202  as stepping motor  208  is operated.  
         [0023]     The multiple-lobe cam and cam lifters can mutually provide flat spots on which to rest at minimum and maximum heights of elevation of the elevator plate.  
         [0024]     In an alternative embodiment, the elevator plate  202  is the mirror image of, and fits over, triple-lobe cam  204 . The lobes of each set ride over the other matching set.  
         [0025]      FIG. 3  partially illustrates a warehouse system embodiment of the present invention, referred to herein by the reference numeral  300 . Such includes the row carts  100  ( FIG. 1 ) and lifters  00  ( FIG. 2 ). The warehouse system  300  is preferably installed in a high profile warehouse building with at least one freight elevator. A product  302  on a standard pallet  304  is lifted and retracted into a loading elevator shaft  305  by a rotating forklift  306 . A uniform pallet size is desired for a specific system. For example, a “standard” pallet in a grocery application would be a Grocery Manufacturers Association (GMA) 40″×48″ pallet with four way entry. An elevator car  308  supports a turntable  310  and the rotating forklift  306  which is mounted inside. The rotating forklift  306  can extend its forks to reach out and bring in or drop off product loaded on a standard pallet. A scissors mechanism  311  allows an adequate reach to bring pallets in and out of the elevator car  308 .  
         [0026]      FIG. 3  shows three each of such rotating forklifts  306 , elevator cars  308 , and turntables  310 , but in actual use only one such set would be present. These three sets are shown in  FIG. 3  to illustrate the different phases of use that occur over time. The bottom set demonstrates incoming material being received. The middle set demonstrates the material being spun around and reoriented to face the warehouse system interior. The top set demonstrates the unloading of the elevator car and staging for transfer to the aisle cart.  
         [0027]     Once the pallet  304  and product  302  are inside the loading elevator shaft  305 , the rotating forklift  306  is spun around on the turntable  310  to face the interior levels of the warehouse system. When the pallet  304  and product  302  are transported and arrive at a particular level, the rotating forklift  306  extends out and deposits the product and pallet on a temporary support. An empty temporary pallet support  312  is shown on the bottom level as two opposing L-angle steel sections. A loaded temporary pallet support  314  is shown at the top level, also as two opposing L-angle steel sections, just below a product  316  and its pallet  318 . Such pallet supports  312  and  314  allow the elevator to drop off its incoming load, and then go on to another task. The corresponding outgoing pallet supports ( FIG. 2 ) allow the aisle carts to drop off their outgoing loads, and then return to a designated location for another task. It should be understood that the previous two functions can be accomplished with one universal elevator.  
         [0028]     A set of three aisle railways  320 ,  322 , and  324  are shown for the three levels visible in  FIG. 3 . These railways run between the loading elevator shaft  305  to a corresponding unloading elevator shaft ( FIG. 3 ) on the same level. Where only a single or universal elevator is used, then these railways run from the elevator to the far end of the system. Each level has one aisle cart  326 ,  328 , and  330  that shuttles along the aisle railways  320 ,  322 , and  324  between the temporary pallet supports  312  and  314  for the elevator. Perpendicular to each aisleway are several parallel row rails, e.g., an upper-level row rail  332 , a middle-level row rail  334 , and a lower-level row rail  336 . Each level will typically have more than one row and row rail,  FIG. 3  shows only one set for each level so the illustration does not become cluttered and hard to read. The aisle carts  326 ,  328 , and  330  carry battery powered piggyback or row carts that run back and forth along a row. A battery powered row cart  338 , similar to row cart  100  ( FIG. 1 ), is shown docked atop its aisle cart  326 . An empty row cart  340  is shown docked atop its aisle cart  330 .  
         [0029]     In operation, each aisle cart  326 ,  328 , and  330  is positioned in front of a designated row along the aisleway, and the row cart (e.g.,  338 ) delivers, deposits, and retrieves product on pallets along the rows. Storage supports are provided along both sides of each row for storing the product and pallet at a designated position.  
         [0030]     The movement of the aisle carts, row carts, elevators, turntables, extending forklifts, etc., is preferably computer controlled. This allows applications software to be in charge of all the material handling. This application software works in conjunction with inventory control software, such as AIM software available from TRW.  
         [0031]      FIG. 4  illustrates another portion of the warehouse system  400 , especially that part concerned with transferring material on pallets between aisles and rows on multiple levels. The warehouse system  400  allows a product  402  on a standard pallet  403  to be carried along a row by a row cart  404  after it undocks from its position on top of an aisle cart  405 . Row cart  404  is similar to row cart  100  ( FIG. 1 ) and uses lifter  200  ( FIG. 2 ).  
         [0032]     In one embodiment of the present invention, a pair of pallet support rails  406  above and outside of a pair of row rails  408  allows the row cart  404  to drop off or pick up the product  402  and pallet  403 . When the row is empty, the first unit of product  402  and pallet  403  is taken and deposited at the back position of the row. The next unit of product  402  and pallet  403  is deposited at the next position, and so on until the row is full of the same product. Each row can have from one to ten or more positions. The pair of pallet support rails  406  are parallel and spaced such that they will support the pallet  403  between them. The row cart rolls off the aisle cart, proceeds to the proper position on the row and stops. The lifting device then retracts so that the pallet is now supported on the support rails  406 . When retrieving the product  402  and pallet  403 , the row cart  404  positions itself under the pallet and load, and then lifts the product  402  and pallet  403  up off the pallet support rails  406  before returning to its docking position on the aisle cart  405 , which then moves toward an elevator and, for description purposes, becomes aisle cart  416 .  
         [0033]     In  FIG. 4 , a product  410  on a pallet  412  is being carried by a row cart  414  docked on top of an aisle cart  416 . Such is brought to an unloading elevator  418  and deposited on a temporary support  420  by retraction of the row cart  414 . The aisle cart  416  can then proceed to another assignment with the row cart  414  on top thereof. The product  410  and pallet  412  are positioned on the temporary support for an extending forklift  422  to reach out and retrieve product and pallet into the unloading elevator  418 . The extending forklift  422  is attached to a rotating base  424 , which is in turn supported on a turntable  426  and elevator car  428 .  
         [0034]      FIG. 5  illustrates another portion of the warehouse system  500 , especially that part concerned with unloading material on pallets out of the system. An unloading elevator  502  includes an elevator car  504  that transports product and pallet to the various levels. A rotating forklift  506  is carried on a turntable  508  on the elevator car  504 . A row cart  510  on top of an aisle cart  512  rides on aisle rails  514 ,  516 ,  518 , or  520 , to deliver product on pallets to the unloading elevator  502 . Row cart  510  is similar to row cart  100  ( FIG. 1 ) and uses lifter  200  ( FIG. 2 ). Once the product on pallets is retrieved onto the elevator car  504  by the rotating forklift  506 , the turntable is spun around 90° to 180° so that loaded pallets can be presented to the dock staging system for shipment to any desired destination.  
         [0035]      FIG. 6  represents an aisle cart  600  similar to those shown in  FIGS. 1-3 . The aisle cart  600  includes a set of four wheels  601 - 604 . These are attached with axles to a lower chassis  606  and ride on the aisle rails, e.g.,  320 ,  322 , and  324  ( FIG. 3 ). A pair of electric stepping motor and gear units  608  and  610  are mechanically connected to the four wheels  601 - 404  to drive the unit back and forth along the aisleways. A pair of rail sections  612  and  614  allow a row cart to roll on and off the top to one side or the other, albeit only when properly aligned with a row.  
         [0036]     Although particular embodiments of the present invention have been described and illustrated, such is not intended to limit the invention. Modifications and changes will no doubt become apparent to those skilled in the art, and it is intended that the invention only be limited by the scope of the appended claims.