Abstract:
A device for emptying a mail item container that is open at the top and serves for transporting mail items. The mail item container has sidewalls and a container underside. The device has a lifting device for moving the mail items relative to the sidewalls. In order to enable postal articles, such as, for example, letter mail items, to be emptied from a mail item container in an ergonomically favorable and efficient manner without adversely affecting its mechanical stability to too great an extent, it is proposed that the lifting device is provided for passing through the underside of the container.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a mail item container for transporting mail items, said mail item container having side walls, an open top side and a container underside that has a pass-through for a lifting means for lifting up the mail items, and having a base that is movable relative to the sidewalls in the direction of the top side. 
     For the purpose of sorting mail items in sorting systems, for example letters according to addresses, the mail items are brought to the sorting system in plastic containers. In order to sort the mail items, said containers must be unloaded and the mail items must be supplied to a singulating means, called a feeder. For this purpose it is known to position the containers filled with mail items close to a conveying means, e.g. a conveyor belt, and to remove the mail items from the containers stack by stack, one container at a time, place them onto the conveying means, and there form a singulating stack. This gripping operation is ergonomically unfavorable because the container walls are higher than the average mail item center of mass and as a result the operator is obliged to reach into the containers and lift the mail items out of the container. 
     EP 1 100 629 B1 discloses a device for emptying mail item containers wherein the mail item containers are emptied automatically in that a lifting comb engages laterally into a sidewall of the mail item container, the sidewall being slotted from above, moves under the mail items and lifts them out of the mail item container. However, the open recesses in the mail item container that are necessary for the lifting comb result in the mail item container being mechanically unstable. 
     The published unexamined German patent application DE 23 04 331 describes a mail item container in the form of a magazine into which a stack carrier engages from below through an opening in the base of the mail item container for the purpose of lifting and lowering mail items. 
     A mail item container having a plurality of slots arranged adjacent to one another and behind one another in the mail item container base to allow stack carriers to be passed through is known from DE 102 34 516 A1. 
     A further solution for unloading mail items from a mail item container is known from the published unexamined German patent application DE 26 09 106. Described therein is a mail item container that has a movable base and can be raised by means of bars that are guided through the container base in such a way that the mail items are lifted above the top edge of the mail item container. 
     BRIEF SUMMARY OF THE INVENTION 
     It is therefore the object of the invention to disclose a mail item container for transporting mail items which is mechanically stable and easy to empty. 
     In order to explain the invention a device for emptying a mail item container for transporting mail items is described, said mail item container being open at the top and having sidewalls and a container underside, also having a lifting means for passing through the underside of the container and for moving the mail items relative to the sidewalls. The sidewalls can remain without recesses that are open on both sides, as a result of which the mail item container remains stable against twisting and deforming. With the aid of the lifting means the mail items can be lifted up, with the result that an ergonomically unfavorable reaching into the mail item container and an energy-consuming and difficult lifting-out of the mail item stack that is movable per se is no longer necessary or necessary only to a lesser degree. 
     The sidewalls can remain without recesses that are open on both sides, as a result of which the mail item container remains stable against twisting and deforming. With the aid of the lifting means the mail items can be lifted up, with the result that an ergonomically unfavorable reaching into the mail item container and an energy-consuming and difficult lifting-out of the mail item stack that is movable per se is no longer necessary or necessary only to a lesser degree. 
     A mechanical loading of the container base in the event of a deformation of the mail item container toward a lozenge shape can be compensated by a sufficient number of and sufficiently wide ridges in the container base which allow sufficient possibilities for allowing the lifting means to pass through. The lifting means can be provided for raising the mail items relative to stationary sidewalls. The lifting means can equally well be provided for raising the mail items that are lifted from the mail item container relative to descending sidewalls, in which case they are stationary relative to the rest of the environment, such as e.g. a stand or a control unit of the device. The device can have an automatic drive for moving the lifting means or, as the case may be, lowering at least one sidewall. A device that is advantageous in terms of ease of manufacture can be created if the device is provided to allow a manual actuation of the lifting means or, as the case may be, to allow the pressing-down of the sidewalls. 
     The lifting means can have an elongate pusher arranged transversely with respect to the lifting direction for the purpose of lifting up the mail items. The pusher can be guided through the underside and placed directly in contact with the mail items, with many mail items being able to be lifted up simultaneously by means of a pusher shape that is, for example, plate-like, elongate transversely with respect to the lifting direction and narrow in cross-section, and with only a narrow slot being necessary in the base of the mail item container. 
     The mail items can in each case be lifted up by a plurality of pushers and a reliable lifting achieved thereby if the lifting means has a plurality of pushers offset transversely with respect to a longitudinal direction of the mail items that are stacked in the mail item container for the purpose of lifting up the mail items, in particular by means of a direct contact with the mail items. Advantageously, the lifting means comprises a plurality of pushers offset longitudinally with respect to a longitudinal direction of the mail items that are stacked in the mail item container. As a consequence of this arrangement the pushers can be distributed over the longitudinal direction of the container base, as a result of which the container base retains a high degree of stability. 
     The mail items in the mail item container can be lifted up particularly reliably with the aid a movable base in the mail item container. For that purpose the lifting means is beneficially provided for moving a container base that is movable relative to the sidewalls. 
     The object directed to the mail item container is achieved by means of a mail item container of the type cited in the introduction which, according to the invention, has two opposing sidewalls that are secured to the movable base and are movable together with the movable base. By means of said sidewalls the mail items can be prevented from falling down from the raised base. The sidewall secured to the base is beneficially an additional inner sidewall within an outer sidewall affording the mail item container its stability. It can be arranged in the stacking direction or transversely with respect thereto and be a longitudinal or narrow sidewall. Advantageously, the sidewall secured to the base is movable in the raised state of the base from a sidewall position into a position exposing the contents of a container. The mail items initially held by the sidewall can be released and thus easily taken hold of by an operator without the sidewall interfering with the seizing action. Movability, e.g. into the releasing position, can be achieved particularly easily if the sidewall secured to the base can be tilted relative to the base. 
     The sidewalls of the mail item container can remain without recesses that are open on both sides, as a result of which the mail item container remains stable against twisting and deforming. Furthermore, the mail items can be lifted up from below with the aid of the lifting means, with the result that an ergonomically unfavorable reaching into the mail item container and an energy-consuming and difficult lifting-out of the mail item stack that is movable per se is no longer necessary or necessary only to a lesser degree. The pass-through can be a hole- or slot-like opening in a container base. Equally, a larger open area is possible, e.g. for raising a movable base which forms the container base and is supported only at its edges. 
     A high degree of stability of the mail item container can be afforded if it has a container base disposed on the underside of the container and having elongate slots to allow the lifting means to be guided through. If the container base comprises a plurality of elongate slots offset with respect to one another in the transverse direction, the mail items can be reliably lifted up by means of a plurality of pushers simultaneously. With a plurality of elongate slots offset with respect to one another in the longitudinal direction, a slot running under all the mail items can be avoided and a high degree of stability of the mail item container achieved. 
     In an advantageous development of the invention the sidewalls include at least one elongate recess for accommodating the lifting means. An undercut can be achieved which counteracts a jamming of mail items in a slot between a sidewall and the lifting means. The recesses can be a slot or a groove and be embodied in particular for guiding the lifting means. 
     Good stackability of the mail item container can be achieved if at least one sidewall includes an upper wider and lower narrower area. Good protection against jamming of the mail items can be achieved in this case if the recess runs completely through the narrower area at least as far as the wider area. In order to counteract a possibility that the mail items will slip off from the lifting means during a lifting operation in the wide area, the wider area advantageously includes a blocking means for the purpose of preventing the mail items from extending completely into the wider area. The blocking means can be a molding of a sidewall inward, in particular around a handle of the mail item container. 
     By means of the movable base the mail items can be reliably lifted up and the lifting means can be implemented in a simple manner. In order to prevent the movable base from being lost, it is advantageously fixed at least indirectly to the sidewalls. It can be secured directly to the sidewalls, for example in a groove which is closed at the top and in which a molding of the base can run. A retaining means which changes its shape during a movement of the base, such as, for example, in the manner of a concertina, an accordion or lazy tongs, is particularly reliable and resistant to jamming. A stop advantageously limits an upward movement of the base. 
     In addition let a system be described having a mail item container that is open at the top and a device for emptying the mail item container which, according to the invention, has a lifting means for passing through an underside of the container for the purpose of moving the mail items relative to the sidewalls. An ergonomically favorable lifting of the mail items out of a stable mail item container can be achieved. The mail item container advantageously has a shape corresponding to the lifting means. The lifting means can engage e.g. in a positive locking manner into the base and reliably raise it. 
     The invention is explained in more detail with reference to exemplary embodiments that are illustrated in the drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  shows a mail item container having slot-shaped pass-throughs through its container base, 
         FIG. 2  shows the mail item container from  FIG. 1  having a manual device for emptying the mail item container, 
         FIG. 3  shows a mail item sorting system having an automated emptying device with plate-shaped pushers, 
         FIG. 4  shows a mail item container having round pass-throughs through its container base, 
         FIG. 5  shows the mail item container from  FIG. 4  having an inserted movable base, 
         FIG. 6  shows a device for emptying the mail item container from  FIG. 5  with a mail item container, 
         FIG. 7  shows the device from  FIG. 6  with lowered mail item container, 
         FIG. 8  shows a section of a mail item feeder system having an emptying device and a mail item container, 
         FIG. 9  shows the mail item container from  FIG. 8  with sidewalls fixed to the raised base and folded down and with mail items held by two retaining means, and 
         FIG. 10  shows a schematic sectional view through the mail item container from  FIG. 9  with secured movable base. 
     
    
    
     DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a mail item container  2  having sidewalls  4 ,  6 , a container base  8  and an open top side. The container base  8  is joined in a single piece to the sidewalls  4 ,  6  and contains a plurality of elongate, slot-shaped pass-throughs  10  whose longitudinal direction runs in a stacking direction  12  of mail items  14  that are shown schematically in  FIG. 2 . The pass-throughs  10  are arranged—referred to their long extension direction—adjacent to one another in both the transverse direction and the longitudinal direction and have different lengths. Pass-throughs  10  adjoining the sidewalls  6  transition into recesses  16  in the sidewalls  6  which run completely through a lower narrower area  18  as far as an upper wider area  20  of the mail item container  2 . The recesses, though embodied as outward-facing pass-throughs in  FIG. 1 , can also be implemented as grooves at least partially closed toward the outside and open toward the inside. The upper wide area  20  has handles  22  which are incorporated into inwardly offset blocking means  24  for the purpose of preventing lifted-up mail items  14  from extending completely into the wider area  20 . 
       FIG. 2  shows a manual device  26  for emptying the mail item container  2 . It has a base  28  and a level support  30  onto which the mail item container  2  can be placed. The support  30  is pressed upward by a spring device  32  having a compression spring as far as a support plate  34  and can be pressed downward against the spring force by pressure exerted by an operator onto a supported mail item container  2 , as shown in  FIG. 2 . The support  30  has pass-throughs which are shaped analogously to the pass-throughs  10  in the mail item container  2 . The support  30  is part of a lifting means  36  having several plate-shaped pushers  38  that are elongate in the lifting direction and shaped so as to correspond to the pass-throughs  10 . The pushers  38  of the lifting means  36  are rigidly joined to the base  28 . 
     When the support  30  with the mail item container  2  placed thereon is lowered, the plates  38  engage through the pass-throughs of the support  30  and the pass-throughs  10  of the mail item container  2  and lift up the mail items  14  relative to the sidewalls  4 ,  6  during a corresponding downward movement of the mail item container  2  until they are essentially lifted completely out of the mail item container  2 , as can be seen in  FIG. 2 . A stop  40  prevents the support  30  and the mail item container  2  from descending further. The mail items  14  can now be easily grasped by an operator without the latter having to lift the mail items  14  out of the mail item container  2 . An undercut is formed in the sidewalls  6  by means of the lifting means  36  extending into the recesses  16  or, as the case may be, the pushers  38 , said undercut preventing a jamming of mail items  14  in a slot between a sidewall  6  and the lifting means  36 . 
     An automated device  42  for emptying a mail item container  2  is shown in  FIG. 3 . The following descriptions are in each case restricted essentially to the differences from the preceding exemplary embodiments, to which reference is made in relation to features and functions that remain the same. Essentially unchanged components are basically numbered using the same reference signs. The device  42  is part of a mail item sorting system  44  having a mail item feeder system  46  which includes the emptying device  42 . The mail item feeder system  46  has a container conveyor  48  having a two-part conveyor belt  50 —a multi-part conveyor belt is equally well conceivable—between whose two belts arranged in parallel is a space through which plate-shaped pushers  38  of a lifting means  52  can be moved upward and guided through the pass-throughs  10  of the container base  8  of the mail item containers  2  as far as the mail items  14 . The pushers  38  are arranged along the entire conveyor belt  50  underneath and between the two belts and can be activated individually or in groups by a control unit  54  according to the position of the mail item container  2  requiring to be emptied. For reasons of better illustration only, only one group of pushers  38  is shown activated—in other words in the raised position—in  FIG. 3 , where there is no mail item container  2 . In an alternative exemplary embodiment, the pushers  38  can be movable along the conveyor belt  50 , i.e. between the two belts of the conveyor belt  50 , such that it is always the same pushers  38  that lift up the mail items  14 . 
     In order to unload the mail item containers  2 , the latter are moved along the conveyor belt  50  as far as a sensor  56  and stopped there. The pushers  38  arranged under the frontmost mail item container  2  are then moved upward in a controlled manner by the control unit  54  and guided through the container base  8  such that they lift up the mail items  14  and raise them partially or completely out of the mail item container  2 . The raised mail items  14  are taken hold of by an operator and placed on a conveyor means  58  which transports the mail items  14  to a feeder means  60 , where they are singulated in order to be sorted into compartments  62  in a subsequent sorting process. Gradually, all of the mail item containers  2  are now emptied, with the control unit  54  also keeping a count of the emptied mail item containers  2  and so always activating the lifting means  52  at the right position. Generally the kinematic reversal is also possible, such that the pushers  38  remain stationary in the vertical direction and the mail item container  2  that is to be emptied is moved downward, as has been described with reference to  FIGS. 1 and 2 . 
       FIGS. 4 and 5  show an alternative mail item container  64  having a plurality of round pass-throughs  66  which are covered by a movable base  68 , shown in  FIG. 5 , which is inserted between the sidewalls  4 ,  6  and rests on top of and in contact with the container base  8 . Alternatively to the pass-throughs  66 , the container base  8  can have a single large pass-through, such that the container base  8  is restricted to a supporting edge for the purpose of supporting the movable base  68  downward or even has only a small number of bearing elements projecting inward from the sidewalls  4 ,  6 . In this case the base of the mail item container  2  is formed by the movable base  68 . 
       FIGS. 6 and 7  show a device  70  for emptying a mail item container  64  as illustrated in  FIG. 5 , said device comprising a base  72  and a lifting means  74  for moving a movable base  68 ,  76 . The lifting means  74  is implemented analogously to the lifting means  36  and comprises a support  78  and pushers  80  for raising the movable base  76  which has a shape corresponding to the pushers  80  into which the pushers  80  can engage, for example. The mail items  14  on the base  76  are held by means of two sidewalls  82  secured to the base  76  such that they do not fall down when the base  76  is raised and do not insinuate themselves between the base  76  and the sidewall  6  and become jammed there when the base  76  is lowered. The mail items  14  raised relative to the sidewalls  4 ,  6  can now be taken hold of by an operator and placed on a conveying means  58  for further processing. 
       FIG. 8  shows a section of a mail item feeder system  84  having a device  86  for emptying a mail item container  88 . The device  86  comprises a support  30  onto which the mail item container  88  is placed by an operator. Inserted into the mail item container  88  is a movable base  90  to which two movable sidewalls  94  are secured by means of hinges  92 . Pushers  98  of a lifting means  100  that are held by a carrier  96  project from below through the support  30  and through an underside of the mail item container  88 , such that they can be brought into contact with the movable base  90 . In a starting position the support  30  is raised and essentially aligned flush with a conveying means  102 . 
     In order to empty the mail item container  88  the latter is placed onto the support  30  by the operator and pressed downward. In the process the support  30  travels downward, as shown in  FIG. 8 , in which case the pushers  98  remain stationary and raise the base  90  relative to the descending sidewalls  4 ,  6 . With the container in the raised state, the operator can now fold down the sidewalls  94 , as shown in  FIG. 9 , such that they are moved from a position holding the mail items  14  to a position releasing the mail items  14 . The mail items  14  can then be taken hold of by the operator and pushed onto the conveying means  102  which is embodied for example as a conveyor belt and transports the mail items  14  to a feeder means  60 . This operation can be assisted by means of retaining means  104  ( FIG. 9 ), implemented for example as separating blades, which are positioned laterally against the stack of mail items  14  and hold it together. The retaining means  104  run in a guide  106  and can be moved in concert by the operator. An assistance can be achieved by means of a motorized drive of the retaining means  104  in the guide  106 , as a result of which the mail items  14  can be automatically pulled onto the conveying means  102 . The sidewalls  94  are subsequently folded into an upright position again, the mail item container  88  is raised and can be removed from the emptying device  86  in order to make room for a next full mail item container  88 . 
     In a further embodiment, the emptying of the mail item container  88  can be assisted using automated means. After the operator has placed the mail item container  88  onto the support  30  as shown in  FIG. 8 , he or she actuates an input means  108 , a button for example, which sends a signal to a control unit  54  which controls a raising of the carrier  96  by way of a drive  110 . By this means the pushers  98  lift up the base  90  and with it the mail items  14  as far as the position shown in  FIG. 8 , in which the base  90  is positioned above a top edge of the sidewalls  4 ,  6  and aligned flush with the top edge of the conveying means  102 . In this case, too, the kinematic reversal is a beneficial alternative exemplary embodiment in which the pushers  98  remain stationary and the mail item container  88  is moved vertically. 
     If a base  68  without sidewalls  82 ,  94  is used, control of the lifting movement by way of an input means  112  which leaves the hands of the operator free, e.g. a foot-operated switch, is beneficial. The operator&#39;s hands are free for holding the mail items  14  emerging from the mail item container  88  without the mail items  14  falling out of the mail item container  88 . Control of the speed of movement of the carrier  96  by way of the input means  108 ,  112  is advantageous, for example in that a speed is dependent on a pressure applied to the input means  108 ,  112 . 
     An even further automated device  86  for emptying the mail item containers  88  comprises a second conveying means  114  for transporting mail item containers  88  by means of which the mail item containers  88  are transported in from the left and pushed onto the support  30  that is raised in its home position. In this case the support  30  is aligned flush with a top edge of the conveying means  102  embodied as a conveyor belt. With the carrier  96  in the raised position—triggered automatically or manually—the support  30  is now lowered such that the sidewalls  4 ,  6  of the mail item container  88  are moved downward. The mail items  14  can then be unloaded, as described with reference to  FIGS. 8 and 9 . Subsequently, the support  30  is raised again and the empty mail item container  88  can be removed by the operator so that a next full mail item container  80  can be moved into position. Fully automated emptying can be achieved if the emptied mail item container  80  is transported away by means of a further conveying means for example at a lower level under the second conveying means  114 . 
       FIG. 10  shows the empty mail item container  88  in a sectional view. The movable base  90  is indirectly secured to the sidewalls  4 ,  6  by way of a container base  126  in a captive manner by two securing means  116  which are implemented as what are termed lazy tongs having members  120  connected by means of articulated joints  118 . The two securing means  116  are in each case arranged directly adjacent to the sidewalls  6  and run by means of rollers  122  in corresponding rails  124  of the container base  126  and of the movable base  90  in which they are secured. When the base  90  is lowered, the securing means  116  come to rest under the base  90  in such a way that they are kept clear of the mail items  14 . 
     A mail item within the meaning of the invention can be postal articles of any kind.