Abstract:
An apparatus and method for using same relates generally to automated conveying and sorting of items such as packages from one or more loading sites to a variety of output destinations, and more particularly relates to a conveying system which can eject packages to either side of a conveyor path onto designated output chutes, bins or subsequent conveyors under a particular means of control. This control provides a means for speeding up the sorting conveyor when there is no unloading or loading occurring. The main sorting conveyor can be sped up for more rapid loading when the time interval before discharging the next article is within a predetermined range.

Description:
TECHNICAL FIELD 
     This invention relates generally to automated conveying and sorting of items such as packages from one or more loading sites to a variety of output destinations, and more particularly relates to a conveying system which can eject packages to either side of a conveyor path onto designated output chutes, bins or subsequent conveyors under programmed or manual control, which is efficient in its use of “idle time”. 
     BACKGROUND OF THE INVENTION 
     Modern high volume package delivery systems often include package conveying systems that accept packages from one or more loading stations, and transport the packages to a variety of output destinations such as chutes, bins, and subsequent conveyor systems. 
     One of the most conventional types of conveyors is a belt conveyor, which includes the use of an endless flexible belt which passes over at least two cylindrical rollers, one of which is a drive roller. Packages are placed atop the upwardly-directed “working” surface of the belt conveyor, and are transported in a generally straight direction from end of the conveyor to the other. Another type of conveyor is a “roller” conveyor which con include powered or idling rollers which contact, support, and in certain instances propel the bottom of the package along its path. 
     Such prior art conveying systems tend to have a substantially fixed capacity which is a function of their operating speed. This translates to a certain number of cells or trays or linear feet of belt which pass a reference point. The higher the number the higher the capacity. 
     However, the effect of inertia limits conveyor speeds; the faster the conveyor speeds the more likely inertia will negatively affect discharge accuracy. At very high speed reliable control of the packages is very difficult due to the effect of inertia. A desired property of any automated system is operation accuracy which is very difficult to achieve at high constant speed. System mistakes are bound to be very costly to a user since it can lead to mis-deliveries of parcels which must be rectified at the carrier&#39;s expense. 
     Various prior art methods and apparatuses have been developed to convey items. 
     U.S. Pat. No. 3,799,319 to Cutler et al. discloses an article-aligning apparatus having a variable speed feed conveyor for providing articles to trays of a main sorting conveyor. The articles are aligned on the trays once they are placed on the sorting conveyor. 
     U.S. Pat. No. 4,765,456 to Bower discloses a variable speed belt conveyor with a drive system designed to share the load at any speed of operation. 
     U.S. Pat. No. 5,170,877 to Francioni discloses an automatic conveyor system. The conveyor system includes a main conveyor system and a plurality of branch conveyors. If a stoppage is detected at one of the branch conveyors and articles begin to accumulate on the other branch conveyors, the other branch conveyors begin to operate at a faster speed. The speed of advance of conveyor portion of a branch conveyor is varied in order to prevent overcrowding of articles on the conveyor. 
     U.S. Pat. No. 4,792,033 to Iwata et al. discloses an apparatus for supplying articles to a conveyor. The speed of the conveyor is varied so that articles are uniformly spaced on the conveyor. The conveyor speed is increased to produce space on the conveyor sufficient to receive a predetermined number of additional articles. 
     Therefore it may be seen that variable speed sorting conveyors are known in the art. Furthermore, increasing the capacity of a main sorting conveyor by increasing the speed of input conveyors is known. It is also known to accumulate articles at a particular location for entry onto the main sorting conveyor by varying the speed of a conveyor. 
     However, a need still exists in the art for an improved sorting conveyor. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes deficiencies in the prior art by providing a method and apparatus for providing same for speeding up a sorting conveyor when there is no unloading occurring. The main sorting conveyor can be sped up for more rapid loading when the time interval before discharging the next article is within a predetermined range. 
     Generally described, the present invention is directed towards a method of transporting a plurality of parcels from one destination from another atop a conveyor having a speed control, the method including determining the time until the next package of the plurality of parcels is to be discharged from the conveyor, the determination establishing a remaining conveying time, comparing the remaining conveying time to a predetermined threshold, and increasing the conveyor transport speed during a portion of the remaining conveying time during which no parcels are discharged. 
     Therefore it is an object of the present invention to provide an improved conveying apparatus. 
     It is a further object of the present invention to provide an improved conveying method. 
     It is a further object of the present invention to provide an improved conveying method and apparatus which provides improved efficiency features. 
     It is a further object of the present invention to provide an improved conveying method and apparatus which provides improved safety features. 
     It is a further object of the present invention to provide an improved conveying method and apparatus which provides improved reliability features. 
     It is a further object of the present invention to provide an improved conveying method and apparatus which provides improved loading features. 
     It is a further object of the present invention to provide an improved conveying method and apparatus which provides improved discharge features. 
     It is a further object of the present invention to provide an improved conveying method and apparatus which provides improved transport features. 
     Other objects, features, and advantages of the present invention will become apparent upon reading the following detailed description of the preferred embodiment of the invention when taken in conjunction with the drawing and the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top illustrative view of a simple conveying system including a linear main conveyor  20  (such as a belt conveyor) which is loaded by an input station  10  and is unloaded by a discharge station  30 . The input station  10  is a distance  40  along conveyor  20  from the discharge station  30 . The main conveyor  20  also includes an input end  21  and a discharge end  22 , configured for accepting and discharging parcels, respectively. 
     FIG. 2 is a top illustrative view of a second conveying system including a linear main conveyor  100  (such as a belt conveyor) which is loaded by a first input station  101  and a second input station  102 , and is unloaded by a first discharge station  111  and a second discharge station  112 . The first input station  101  is a first distance  150  along conveyor  100  from the first discharge station  111 , and the second input station is a second distance from the second discharge station  112 . The linear main conveyor  100  also includes an input end  103  and a discharge end  104 . 
     FIG. 3 is a top plan view of an endless oval-shaped conveyor system  200 , which includes a plurality of input stations  210  and a plurality of output stations. Such a configuration is generally shown in U.S. Pat. No. 5,433,311, incorporated by reference. The input stations  210  are shown introducing parcels or other items from the outside of the oval-shaped conveying path, although introduction from within the oval-shaped conveying path is contemplated without departing from the spirit and scope of the present invention. Similarly, the output stations are shown receiving parcels or other items from both sides of the oval-shaped conveying path, although introduction from only one side of the oval-shaped conveying path is contemplated without departing from the spirit and scope of the present invention. It should be understood that such an oval-shaped conveying path could be used with a belt conveyor system having side notches as shown in FIG. 4, or could be used with a “tilt-tray” configuration as shown in FIG.  5 . 
     FIG. 4 is a top plan view of a conveyor belt configuration  300  which includes slotted sides to allow for an oval-shaped path as shown in U.S. Pat. No. 5,894,918, incorporated herein by reference, or further can be serpentine-shaped as shown further in U.S. Pat. No. 5,894,918. This configuration  300  includes input stations  325 P, output stations  326 , a flexible belt conveyor including segments  311 , all for transporting parcels  320 . 
     FIG. 5 is a pictorial view of an endless oval-shaped conveyor system  400  as generally shown in U.S. Pat. No. 5,433,311. This configuration  400  includes a plurality of upper tiltable trays  420 U, a plurality of lower tiltable trays  420 L, upper input stations  410 U, lower input stations  410 L, upper discharge stations  430 U, and lower discharge stations  430 L. Reference is made to U.S. Pat. No. 5,433,311 for the specifics of operation of this configuration, but generally described, the configuration  400  defines a generally oval-shaped endless conveying path which allows for parcel loading to the upper tiltable trays  420 U via the upper input stations  310 U, and parcel unloading therefrom via upper discharge stations  430 U. Parcel loading to the lower tiltable trays  420 L is done via the lower input stations  410 L, and parcel unloading therefrom via lower discharge stations  430 L. The trays are allowed to tilt to discharge the parcels. 
     FIGS. 6A-6C are sequential illustrative view of parcels being conveyed under a first conveying scenario. 
     FIGS. 7A-7C are sequential illustrative views of parcels being conveyed under a second conveying scenario. 
     FIGS. 8A-8B are sequential illustrative views of parcels being conveyed under a third conveying scenario. 
     FIGS. 9A-9C are sequential illustrative views of parcels being conveyed under a fourth conveying scenario. 
     FIG. 10 is an illustrative control diagram which illustrates the interaction of a typical Processor  1000  according to the present invention, which accepts data from a Data Input Source  1100 , and controls the speed of a Conveyor Drive Motor  1200  according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference is now made in more detail to the drawings, in which like numerals refer to like parts throughout the several views. 
     General Recognitions 
     The inventor has recognized that merely transporting the package between charge and discharge can be done at very high speed without adverse effect on the parcel due to the absence of the manifestation of the interial forces during that time. 
     The experience of the inventor also has resulted in a recognition that it is easier to charge a system at high speed then to discharge without loss of control on the package. 
     General Conveyor Operation and Construction 
     The method according to the present invention is based on the random distribution between all parcels on the system and their respective destinations. 
     Generally described, the present invention comprises a variable speed control for transporting packages between loading and unloading stations at varying rates of speed. Although the system must run relatively slowly to discharge packages, packages may be loaded at higher rates of speed. If no discharging is in progress, the system may speed up significantly above its normal speed until time for discharging a package. Since the sorting system knows the distance and time until the next package is unloaded, the conveyor may speed up if the smallest time interval before discharge is within a predetermined window of time. Upon approaching the designated unloading station, the conveyor will resort to its normal speed for discharging the package. 
     Reference is now made to FIG. 1, which is a top illustrative view of a simple conveying system including a linear main conveyor  20  (such as a belt conveyor) which is loaded by an input station  10  and is unloaded by a discharge station  30 . The input station  10  is a distance  40  along conveyor  20  from the discharge station  30 . The main conveyor  20  includes an input end  21  and a discharge end  22 , configured for accepting and discharging parcels such as  12 . 
     It should be understood that a configuration such as shown in FIG. 1 includes two input stations, the input station  10  and the input end  21  of the conveyor  20 . The configuration such as shown in FIG. 1 likewise includes two discharge (a.k.a. “output”) stations, the discharge station  30  and the discharge end  22  of the conveyor  20 . 
     FIG. 2 is a top illustrative view of a second conveying system including a linear main conveyor  100  (such as a belt conveyor) which is loaded by a first input station  101  and a second input station  102 , and is unloaded by a first discharge station  111  and a second discharge station  112 . The first input station  101  is a first distance  150  along conveyor  20  from the first discharge station  111 , and the second input station is a second distance from the second discharge station  112 . The linear main conveyor  100  includes an input end  103  and a discharge end  104 . 
     It should be understood that a configuration such as shown in FIG. 2 includes three input stations, the input stations  101  and  102 , and the input end  101  of the conveyor  100 . The configuration such as shown in FIG. 2 likewise includes three discharge (a.k.a. “output”) stations, such as discharge stations  111 ,  112  and the discharge end  102  of the conveyor  100 . 
     Reference is now briefly made to FIGS. 3-5, which show alternate conveyor layouts which differ from the straight belt conveyor shown in FIGS. 1 and 2. 
     FIG. 3 is a top plan view of an endless oval-shaped conveyor system  200 , which includes a plurality of input stations  210  and a plurality of output stations. Such a configuration is generally shown in U.S. Pat. No. 5,433,311, incorporated by reference. The input stations  210  (which could be input conveyors) are shown introducing parcels or other items from the outside of the oval-shaped conveying path, although introduction from within the oval-shaped conveying path is contemplated without departing from the spirit and scope of the present invention. Similarly, the output stations are shown receiving parcels or other items from both sides of the oval-shaped conveying path, although introduction from only one side of the oval-shaped conveying path is contemplated without departing from the spirit and scope of the present invention. It should be understood that such an oval-shaped conveying path could be used with a belt conveyor system having side notches as shown in FIG. 4, or could be used with a “tilt-tray” configuration as shown in FIG.  5 . 
     FIG. 4 is a top plan view of a conveyor belt configuration  300  which includes slotted sides to allow for a oval-shaped path as shown in U.S. Pat. No. 5,894,918, incorporated herein by reference, or further can be serpentine-shaped as shown further in U.S. Pat. No. 5,894,918. This configuration  300  includes input stations  325 P, output stations  326 , a flexible belt conveyor including segments  311 , all for transporting parcels  320 . 
     FIG. 5 is a pictorial view of an endless oval-shaped conveyor system  400  as generally shown in U.S. Pat. No. 5,433,311. This configuration  400  includes a plurality of upper tiltable trays  420 U, a plurality of lower tiltable trays  420 L, upper input stations  410 U, lower input stations  410 L, upper discharge stations  430 U, and lower discharge stations  430 L. Reference is made to U.S. Pat. No. 5,433,311 for the specifics of operation of this configuration, but generally described the configuration  400  defines a generally oval-shaped endless conveying path which allows for parcel loading to the upper tiltable trays  420 U, via the upper input stations  310 U, and parcel unloading therefrom via upper discharge stations  430 U. Parcel loading to the lower tiltable trays  420 L is done via the lower input stations  410 L, and parcel unloading therefrom via lower discharge stations  430 L. The trays are allowed to tilt to discharge the parcels. 
     The Idling Threshold Concept 
     Regardless which of the above conveyor types is being used, at times a loaded system may run for some time without any parcel being discharged. This period can vary between seconds to minutes. During that time the parcels are merely transported by the system on their way to their proper destinations. 
     The present invention contemplates that during the “idle time”, the system be automatically switched to a much higher speed since there is less danger of adverse effect on the discharge. 
     Several different scenarios will now be discussed. It should be noted that the use of these scenarios should not be construed as limiting but are for purposes of example only. 
     When describing the following scenarios, a threshold will be assumed. This threshold is as follows: the conveyor must go through a period when all of its parcels idle at the same time through at least three consecutive segments. Another way of describing this is that all parcels on the conveyor must go through at least three consecutive “idle stations” at the same time to meet the threshold. 
     Although the above threshold is proposed at three consecutive segments, it should be understood that different thresholds may be used, and may differ depending on the type of system in use. 
     First Scenario (FIGS. 6A-6C) 
     Under the first scenario, parcels P 1  and P 2  are input at the same time at locations I 1  and I 2 , respectively, and are both to be discharged at discharge location D 1 . Under this scenario, parcel P 2  is the first to be discharged after “idling” through two distance segments prior to being discharged from the third segment as shown in FIG.  6 B. After parcel P 2  is discharged, parcel P 1  idles through one distance segment, and is then discharged from the last segment to discharge location D 1  as shown in FIG.  6 C. 
     Under this scenario, conveyor speed does not change, because the “idling threshold” is not met.(*claim generally) As may be seen, parcel P 2  only idles though two consecutive space segments between its discharge and its discharge. Parcel P 1  idles through four segments before its discharge, but since parcels P 1  and P 2  (all the parcels on the conveyor) only idle through two consecutive segments at the same time, the threshold is not met. Thus no speed change is made. 
     Second Scenario (FIGS. 7A-7C) 
     Under Scenario 2, the two parcels P 1 , P 2 , are input at station I 1 , I 2 , as before. However, this time parcel P 1  is discharged at station D 2 . Under this scenario both parcels go though two consecutive idle stations until P 2  is discharged at D 1 . Parcel P 1  then goes through three consecutive idle stations until it is discharged at D 2 . 
     Under this scenario, conveyor speed does change, at a time between the discharge of parcel P 2  and the discharge of parcel P 1 . This is because the assumption is met that the conveyor must to through a period when all of its parcels idle through at least three consecutive segments at the same time. Another way of describing this is that all parcels on the conveyor must go through at least three consecutive idle stations at the same time. As noted above, parcel P 2  only idles though two space segments between its discharge and its discharge. Parcel P 1  idles through six segments between its input and discharge, but this idling period is broken up by the discharge of Parcel P 2 , as shown in FIG.  7 B. However, after Parcel P 2  is discharged, Parcels P 1  is the only parcel on the conveyor, and thus is “all” of the parcels on the conveyor. Thus since at that point Parcel P 1  idles through three segments after Parcel P 2  is discharged, “all” of the parcels idle through at least three segments at the same time, and thus the threshold is just met. This causes the conveyor to speed up during this idling time. 
     It should be understood that the idle stations as defined above are conceptualized in terms of distance along the conveying path, namely whether all packages are conveyed along a conveying path for a given distance in an “idling” mode (no discharge or input). However, such stations could also be conceptualized in terms of time, namely whether all packages are conveyed along a conveying path for a given time in an “idling” mode. Since the processing controller is assumed to “know” the location of all of the parcels on the conveyor, the distinction between time and space is somewhat academic, because knowing one results in the knowledge of the other. 
     Third Scenario (FIGS. 8A and 8B) 
     Under scenario 3, as shown in FIG. 8A, the parcels P 1  and P 2  are simultaneously placed on the conveyor at locations I 1  and I 2 , but this time P 1  is discharged at D 1  and D 2  is discharged at D 2 . Therefore, both of the parcel go through five idling stations at idle at the same time until being commonly discharged as shown in FIG.  8 B. As such, they can be conveyed at a higher speed through said stations until the conveyor is slowed down when they both need to be commonly discharged. Therefore the threshold is met and in fact surpassed. This causes the conveyor to speed up during this idling time. 
     Fourth Scenario (FIGS. 9A-9B) 
     Under Scenario 4, the sortation is similar to that of Scenario 3, except that a parcel P 0  is known to be introduced at I 0  after parcels P 1  and P 2  have gone through two stations at idle. Under this scenario, the computer will recognize that the conveyor will not have more than three adjacent idle stations and no high speed conveying will be conducted. 
     Variations on Speed 
     It should be understood that under the embodiments of the present invention described above, the conveyor will consider input to break the idle mode. Under another embodiment, the computer will consider input not to break the idle mode. Such a configuration may be particularly applicable in the situation when a inputting conveyor of conveyor set is used which readily accelerates parcels onto the leading edge of a belt conveyor. 
     In another embodiment of the present invention, the conveyor is capable of being operated at three speeds, one “low” speed for loading, an “intermediate” speed high than the low speed but slow enough to suitably handle input, and a high speed suitable for delivering the parcels at idle. 
     The Motor 
     The drive motor will either have two or more speeds or controlled by an inverter capable of controlling its speed. 
     Control 
     As noted above, the speed of the conveyor can be varied by use of a variable speed drive motor, which can be an electric, pneumatic, or other type as known in the art. 
     FIG. 10 is an illustrative control diagram which illustrates the interaction of a typical Processor  1000  according to the present invention, which accepts data from a Data Input Source  1100 , and controls the speed of a Conveyor Drive Motor  1200  according to the present invention. 
     The Data Input Source  1100  provides information to the Processor  1000  regarding when the next parcel will be entering the conveyor, so that if needed the Conveyor Drive Motor  1200  can be slowed down to accommodate same. 
     Therefore the Processor  1000  could be thought of as tracking all packages on the system and “knows” the relative destination discharge chute of every single package. The computer could be programmed to switch the motor to double its normal speed when the time elapsed before the next discharge time, which could be for example five (5) seconds at the given speed, at which time the motor will revert to its normal discharge speed. This can be readily converted to distance since conveyor speed is known. 
     The Input and Discharge Stations 
     It should be understood that the input stations such as  10 , in FIG. 1 can be belt conveyors, push members, or other means known in the art. The discharge stations such as  30  can likewise be provided by belt conveyors, push members, or other means known in the art. 
     Results 
     The results might be that over a given time (such as an hour) the system would have run a total of, for example, ten (10) minutes at say double or triple its normal speed. Therefore the average speed of the system can be computed as: 
     
       
         300+(600/6)=400 FPM 
       
     
     or 
     
       
         300+(900/6)=450 FPM 
       
     
     The extra speed could conceivably reach a magnitude of 25% which means that the parcels will reach their destination that much sooner for loading or further processing. All that can be done without actually discharging parcels at a higher speed and risking the parcel to overshoot its destination bin. 
     This method will derive high benefit during “wrap-up” time when the flow on the system is light and the time before system shutdown is short. 
     Since all such systems have a commercial application and the laws of physics are immutable, even a small advantage in capacity/speed may represent a significant advantage from a return on investment point of view. 
     Since the method is totally automatic it requires no intervention from an operator at all. 
     Conclusion 
     Therefore it may be seen that the present invention overcomes deficiencies in the art by providing an improved conveying method and apparatus which includes variable speed control for transporting packages between loading and unloading stations at varying rates of speed. Although the system must run relatively slowly to discharge packages, packages may be loaded at higher rates of speed. If no discharging is in progress, the system may speed up significantly above its normal speed until time for discharging a package. Since the sorting system knows the distance and time until the next package is unloaded, the conveyor may speed up if the smallest time interval before discharge is within a predetermined window of time. Upon approaching the designated unloading station, the conveyor will resort to its normal speed for discharging the package. 
     While this invention has been described in specific detail with reference to the disclosed embodiments, it will be understood that many variations and modifications may be effected within the spirit and scope of the invention as described in the appended claims.