Abstract:
A device for presorting separated thin postal items to sorting final position areas of a postal item sorting machine according to the read distributing information and to the assigned sorting final position area includes at least two inputs for streams of postal items and at least two outputs each leading to a sorting final position area. All connecting paths with intersections are provided in a multiple manner between each respective input and each respective output. The postal items are distributed via corresponding switches to the multiple connecting paths from an input to an output in such a manner that, at the intersections, gaps develop that are required for postal items in the intersecting path and in the junctions.

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to a device for presorting separated thin postal items, of which the distributing information has been successfully read, to sorting final position areas featuring sequentially arranged sorting final positions of a postal item sorting machine corresponding to the read distribution information and to the assigned sorting final position area, with a number of entries for the postal item streams and a number of exits leading to a sorting final position area in each case, with the entries being connected to the exits by connecting paths in each case. 
   To increase the throughput of sorting machines for flat postal items, although the transport speed cannot simply be increased and the spacings between the postal items (item gaps) in the stream of postal items cannot be reduced below a minimum spacing, handling the items in parallel offers an obvious solution. In such a case two material entries create two streams of postal items which are fed to two segments of the sorting machine which can each process the throughput of one material entry. A prerequisite for the parallelization is that each postal item of the two item streams can reach each destination address of the two segments of the sorting machine which for transport in one plane can be made possible by an intersection of the two postal item streams for example. In such cases the overall throughput is reduced since a correspondingly large gap must be created in one of the postal item streams if two postal items from the two postal item streams are intended for one segment at the same time. In addition the overall throughput is reduced, because, to avoid a collision in one of the postal item streams, a correspondingly large gap must be created if two postal items were to be located in the intersection area at the same time, which would each have be transported into the “other” segment of the sorting machine connected by the intersection. 
   To avoid these disadvantages an intersection-free transport of the postal items from one material entry in each case to the segment located beyond the other material entry in two transport planes is proposed. 
   In addition a connecting path is provided from one material entry to the segment beyond the other material entry which intersects with a connecting path from the other material entry to the segment arranged after the first material entry at an intersection (U.S. Pat. No. 4,615,446). 
   A sorting device is described in EP 0 613 730 A2 in which a number of connecting paths are possible from a specific entry to a specific exit. The connecting paths are formed by transport units located on turntables, arranged in a hexagonal grid structure, which are aligned in accordance with the entries and exits to be connected. In this case however only connecting paths which do not cross each other are ever active at a specific time, with the topology of the paths also being variable over time. Therefore there is also no merging of a number of path sections to a single path section in which collisions between postal items can occur. Because of the many controlled rotatable transport units required, this apparatus has a high level of mechanical complexity. 
   SUMMARY OF THE INVENTION 
   The object of the invention is to create a device for presorting separated postal items with a number of material entries, from which the postal items are able to be transported with little effort to each segment of the sorting machine in a transport plane over intersecting connecting paths. 
   In accordance with the invention the object is achieved by a device for presorting separated thin postal items to sorting final position areas of a postal item sorting machine according to the read distributing information and to the assigned sorting final position area having at least two inputs for streams of postal items and at least two outputs each leading to a sorting final position area. All connecting paths with intersections are provided in a multiple manner between each respective input and each respective output. The postal items are distributed via corresponding switches to the multiple connecting paths from an input to an output in such a manner that, at the intersections, gaps develop that are required for postal items in the intersecting path and in the junctions. 
   In this case the intersecting connecting paths of a defined topology feature intersections which are always passable in the intersecting directions. All connecting paths with intersections between one entry and one exit respectively are embodied as multiple paths and the postal items are distributed via the corresponding switches to the multiple connecting paths from an entry to an output in such a way that at the intersections, gaps develop that are required for postal items in the intersecting path and in the junctions. 
   The supplied postal item streams are divided up and joined again in each case with the “other” postal item streams one after the other, with the postal item streams passing through a number of intersections. The “empty spaces” arising in the postal item stream through the division can be occupied by the postal items of the parallel postal item stream, which means that an obstacle-free intersection area is produced. 
   Advantageous embodiments of the invention are set down in the subclaims. 
   So that the throughput loss is as low as possible, it is advantageous for the number of intersecting connecting paths from one entry to one exit in each case to correspond to at least the larger value of the number of the entries or of the exits. 
   It is also advantageous, for a device with two entries, for the postal item streams and two exits leading to a sorting final position area in each case, to connect each entry via two consecutive switches arranged in a connecting path to the downstream exit at the end of this connecting path and via the two switches by means of two further connecting paths and corresponding junctions with the connecting path from the other entry to its downstream exit, with the two further connecting paths leading from an entry to the exit downstream from the other entry in each case intersect with the two further connecting paths from the other entry. The postal items to be directed from one entry to the connecting path connecting the other entry with the downstream exit in each case are directed to create the gaps alternately into the two connecting paths following each other. 
   So that the gaps formed in the postal item streams are sufficient for all postal items in the range of postal items, it is advantageous, for the gaps of the front edges and rear edges of the postal items from each other to correspond to at least the length of the longest postal item plus the minimum gap and for the chronological sequence of the postal items in the item stream and the transport lengths to be selected so that the postal items from the two entries pass through the intersection areas without obstructing each other. 
   To adapt the gaps formed to the lengths of the postal items and thereby to increase the throughput in relation to the solution presented in the previous paragraph, it is advantageous if, to implement the intersections, first sections of the intersecting connecting paths coming from the switches in the connecting paths without intersections come out into a junction in each case and if in each case, in a link following the junction, a braking and acceleration module is arranged for controlled displacement of postal items in the postal items stream or for temporary storage of the postal items. A switch is then located at the end of the common link in each case to distribute the postal items to further parts of the intersecting connecting paths. 
   To reduce the length required for the presorting device with two entries and exits the second switches in the transport direction located in the connecting paths are advantageously arranged before the junctions in the relevant connecting paths with the first further connecting paths, so that the remaining sections of the first further connecting paths additionally intersect twice with the first sections of the second further connecting paths. A further braking and acceleration module is arranged in each connecting path between the two switches for collision-free joining and crossing of the postal item streams. 
   It is further advantageous, if each non-intersecting connecting path from an entry to an exit features one or more parallel subsections each with a braking and acceleration module for temporary storage of postal items for the case in which the respective postal item is to be directed at the same time as a postal item of another entry into the same exit. The buffered postal item is then forwarded, as soon as the exit involved is free. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The invention is explained below in an exemplary embodiment with reference to the drawing. 
     The figures show 
       FIG. 1  a schematic diagram of a presorting device with 3 entries, 3 exits and a total of 6 intersections, 
       FIG. 2  a schematic diagram of a presorting device with two entries and exits and two intersection areas displaced into each other, 
       FIG. 3  a schematic diagram of a presorting device according to  FIG. 2  with four additional braking and acceleration modules, 
       FIG. 4  a schematic diagram of a presorting device according to  FIG. 3  with two further braking and acceleration modules, 
       FIG. 5  a schematic overhead view of an intersection. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The presorting device in  FIG. 1  has three entries E 1 , E 2 , E 3  and three exits A 1 , A 2 , A 3 . Entry E 1  is connected via three switches W 11 , W 12 , W 13  and three junctions Z 11 , Z 12 , Z 13  to exit A 1  for the sorting segment  1 , entry E 2  is connected via three switches W 21 , W 22 , W 23  and three junctions Z 21 , Z 22 , Z 23  to exit A 2  for sorting segment  2  and entry E 3  is likewise connected via three switches W 31 , W 32 , W 33  and three junctions Z 31 , Z 32 , Z 33  to exit A 3  for sorting segment  3 . The cross connections, i.e. those to direct postal items from entry E 1  to exit A 2  or A 3 , are implemented as follows: 
   The entries E 1 , E 2 , E 3  are followed in the connecting path in each case by switches W 11 , W 21 , W 31  which connect the postal items either in the direction of the directly following exit or to intersection junctions KZ 1  and KZ 4  between the connecting paths, which connect the entry E 1  with the exit A 1 , the entry E 2  with the exit A 2  and the entry E 3  with the exit A 3 . The switches W 11  and W 31  located in the outer connecting paths switch between two directions, whereas the switch W 21  arranged in the central connecting path after the entry E 2  is switchable in three directions, i.e. either to the left to intersection junction KZ 1 , straight ahead in the direction of exit A 2  or to the right to intersection junction KZ 4 . 
   Such a three-directional switch can obviously also be implemented by two two-directional switches arranged after each other. 
   The two intersection junctions KZ 1 , KZ 4  are each followed by an intersection switch KW 1 , KW 4 . Each intersection junction KZ 1 , KZ 4  forms an intersection area together with the immediately following intersection switch KW 1 , KW 4 . 
   This enables postal items to be directed as required also from entry E 1  via switch W 11 , intersection junction KZ 1 , intersection switch KW 1  and junction Z 21  to the connecting path between entry E 2  and exit A 2 , or also accordingly from entry E 2  to the connecting path between entry E 1  and exit A 1 . In the same manner an intersection area is arranged between the connecting path from entry E 2  to exit A 2  and the connecting path from entry E 3  to exit A 3 , consisting of the intersection junction KZ 4  and an immediately following intersection switch KW 4 , with the exits of the intersection switch KW 4  being connected to the connecting paths between entry E 2  and exit A 2  and between entry E 3  and exit A 3 . 
   In this case postal items can also be transported from the entries E 2  or E 3  to the exits A 3  or A 2 . 
   Following this described connecting path structure with intersection areas between the connecting paths from entry E 1  to exit A 1 , from entry E 2  to exit A 2  and from entry E 3  to exit A 3  are arranged another two identical connection structures between the connecting paths from entry E 1  to exit A 1 , from entry E 2  to exit A 2  and from entry E 3  to exit A 3 . 
   Each structure likewise has two intersection areas, consisting in each case of an intersection junction KZ 2 , KZ 5  as well as KZ 3 , KZ 6  and an intersection switch KW 2 , KW 5  as well as KW 3 , KW 6 , which are likewise routed via switches W 12 , W 22 , W 32 , W 13 , W 23 , W 33  and intersections Z 12 , Z 22 , Z 32 , Z 13 , Z 23 , Z 33  on the connecting paths from entry E 1  to exit A 1 , from entry E 2  to exit A 2  and from entry E 3  to exit A 3 . As can be easily seen, there is thus the option of implementing the intersecting connections of each entry at least twice with the corresponding exits, so that gaps are created for intersecting postal items in the intersecting areas and in the junctions and collisions are thereby avoided. The option is thus provided for example of transporting a postal item at entry E 1  via the intersection areas KZ 1 -KW 1  and KZ 5 -KW 5  or KZ 2 -KW 2  and KZ 6 -KW 6  to exit A 3  or transporting a postal item at entry E 3  via the intersection areas KZ 4 -KW 4  and KZ 2 -KW 2  or KZ 5 -KW 5  and KZ 3 -KW 3  to exit A 1 . If the postal items are to be directed from an entry to an exit adjacent to the intersection-free following exit, then, as can be seen, there are even three possible intersecting paths. 
     FIG. 2  shows a presorting device with two entries E 1 , E 2  and two exits A 1 , A 2  to provide improved clarity. 
   This device essentially corresponds to a part of the device shown in  FIG. 1  (only two entries and exits E 1 , E 2 , A 1 , A 2 , and two connecting path structures described in  FIG. 1 ). Since the second connecting path structure is displaced to shorten the length to the entries by comparison with the structures shown in  FIG. 1 , i.e. the switches W 12 , W 22  of the second connecting path structure are located in the direction of transport before the intersections Z 11 , Z 21  of the first connecting path structure, the connecting paths leading from the intersection areas KZ 1 -KW 1  and KZ 2 -KW 2  to the junctions Z 11 , Z 21  or to the switches W 12 , W 22  intersect additionally in the additional intersections K 1 , K 2 . The postal items shown are intended to illustrate that the black postal items are to be routed from entry E 1  to exit A 2  and the white postal items from E 2  to exit A 1 . At the frontmost switches W 11  and W 21  each second postal item is directed to the intersection areas KZ 1 -KW 1 , KZ 2 -KW 2 , which means that in the two paths leading on from the switches W 11 , W 21  streams of postal items are transported with large gaps between the postal items. 
   The same then also applies for the paths leading from the rear switches W 12 , W 22  to intersection area KZ 2 -KW 2  and to the paths leading away from the intersection areas KZ 1 -KW 1 , KZ 2 -KW 2 . If the two postal item streams are synchronized to each other at entries E 1 , E 2 , the postal items directed into the intersecting paths are offset from each other by one postal item and the gaps of the front edges and rear edges of the postal items to each other in the postal item streams at the entries E 1 , E 2  correspond to at least the length of the longest postal item plus the minimum gaps functionally necessary for distribution, with the same lengths of the corresponding paths and symmetrical circumstances it is guaranteed for the connecting path structures that the postal items of the other stream in each case will move into the gaps arising, so that presorting runs without any conflicts. 
   Since however the average length of the postal item is smaller than the maximum item length, the above solution leads to throughput losses. To reduce these throughput losses with smaller gaps between the postal items, braking and acceleration modules BB 1 -BB 4  are arranged before the possible collision points in the connecting paths, which displace a postal item in each case in relation to the adjacent items of the respective item stream so that the gap necessary for the respective intersecting postal item is created. To avoid collisions at the first intersection junction KZ 1  the material entries creating the postal item streams at the entries E 1 , E 2  are controlled accordingly. 
   The braking and acceleration modules are located before the switches W 12 , KW 1 , W 22  and thus ensure that there are suitable gaps in the intersections K 1 , K 2  and in the junctions Z 11 , Z 21 , KZ 2 . Furthermore a fourth braking and acceleration module BB 4  is located before switch KW 2  of the intersection area KZ 2 -KW 2 , which creates the necessary gaps for the junctions Z 12 , Z 22 . The structure with the intersection areas KZ 1 -KW 1 , KZ 2 -KW 2  has been selected in order to obtain the necessary space for the braking and acceleration modules BB 2  and BB 4  before the junctions Z 11 , Z 21  and Z 12 , Z 22 . If two postal items must be directed almost at the same time from the two postal item streams at the entries E 1 , E 2  to an exit A 1  or A 2 , a correspondingly large gap must be created for the additional postal item to be inserted in the postal item stream leading to this exit. This can be achieved, in accordance with  FIG. 4 , by connecting a braking and acceleration module BB 5  in parallel to braking and acceleration module BB 1  via the switch W 11  and the junction Z 11  and by connecting a braking and acceleration module BB 6  in parallel to braking and acceleration module BB 3  via the switch W 21  and the junction Z 21 . These switches and junctions thus divide the stream into three directions or join it from three directions. This means that, together with the remaining braking and acceleration modules BB 1 -BB 4 , there are sufficient controlled storage locations to partly eliminate the statistically unequal distributions. 
     FIG. 5  shows a typical intersection K 1 , K 2  in greater detail. The transport paths are formed in the known way by covered belt systems. In this system the outer covered belts of the two feeding covered belt systems DZ 1 , DZ 2  are diverted in each case via a deflection roller R 1 , R 2  and then run on at the exit of the intersection as the outer covered belt of the outgoing covered belt system DA 1 , DA 2  of the respective intersecting path. The other covered belts of the incoming and outgoing covered belt systems DZ 1 , DZ 2 , DA 1 , DA 2  are deflected to the entries and exits of the intersection via further deflection rollers R 3 -R 6 . Two corresponding guide elements L 1 , L 2  are arranged to guide the postal items in the crossing, which guide the postal items over the intersection from the incoming into the outgoing covered belt system. 
   It should be stressed that these examples do not represent any restriction. Presorters with a greater number of entries and exits can naturally also be implemented with the inventive teaching, in which case the number of entries and exits do not have to match.