Pneumatic tube conveyor system

A pneumatic tube conveyor system comprises at least two dispatching stati (13) for dispatching conveying cases and at least two receiving stations (22) for receiving the conveying cases. Pneumatic tube lines connect the dispatching stations and the receiving stations. An intermediate store (25) is provided within the tube lines. The tube lines are associated with a plurality of gates (21, 26, 33). Control means serve for connecting any dispatching station selectively to any receiving station or to the intermediate store, and for connecting the intermediate store to tube lines leading to any receiving station.

The present invention relates to a pneumatic tube conveyor system having a 
plurality of dispatching stations for dispatching conveying cases, a 
plurality of receiving stations for receiving the conveying cases, a tube 
system which connects the dispatching stations and the receiving stations 
and which comprises a plurality of gates, and control means for connecting 
any dispatching station selectively to any receiving station. 
A pneumatic tube conveyor system of the described type is generally known. 
Pneumatic tube conveyor systems are generally used for transporting 
lightweight articles. A typical application of pneumatic tube conveyor 
systems is the transportation of in-house mail within a factory plant, 
i.e., the transportation of papers between a plurality of stations which 
are at the same time dispatching stations and receiving stations. Further, 
pneumatic tube conveyor systems are employed in hospitals for distributing 
papers, but also small-size articles, such as medicines, within the 
hospital. Finally, another typical application of pneumatic tube conveyor 
systems is found in credit institutions where the counters, which are 
accessible to the public, are connected to the central money deposit by a 
pneumatic tube conveyor system so that large amounts of cash need not be 
kept the very counters which are accessible to the public. 
It is also known that systems for distributing articles and machine 
elements are required in industrial enterprises where assembly operations 
have to be performed, for example on special machines. Such machine 
elements include, on the one hand, large machine components that can be 
moved only by heavy implements, such as machine chassis or complete 
pre-assembled units, and on the other hand, at the other end of the 
dimensional scale, medium-sized and small parts such as screws, nuts, 
bolts, pins, seals, hoses, valves, and the like. 
Until now, such materials or parts were generally distributed manually, by 
a shop hand who collected the required parts at a materials issue counter 
using an electric truck or sometimes only a portable box. Such a 
distribution system obviously is very labor-intensive, and, thus, 
expensive. This is particularly true when the materials have to be 
distributed in a large assembly shop having a length of several hundred 
meters, because then the distances to the materials issue counter get so 
long that on the one hand a considerable amount of labor is required and, 
on the other hand, rapid access to the store is virtually impossible if, 
for example, a specific part is required immediately for a given assembly 
job. If the assembly shop is large, it may absolutely take a quarter of an 
hour or even more until the required part has arrived at the assembly 
position from the materials issue counter. This may lead to the condition 
that the whole assembly process must be stopped during the waiting time, 
and such a stoppage may lead to considerable consequential costs. 
Now, it is the object of the present invention to improve a pneumatic tube 
conveyor system of the type described above in such a way that it can be 
used for distributing assembly materials or the like so that the 
distribution of materials can be effected in less time and with reduced 
labor input. 
The invention achieves this object by the fact that the pneumatic tube 
dispatching stations take the form of order picking positions of a parts 
store, forming together with the latter a materials distribution center, 
that the pneumatic tube receiving stations are distributed over an 
assembly shop, that the assembly shop is subdivided into a predetermined 
number of areas, and that the materials distribution center is equipped 
with a number of pneumatic tube lines corresponding to the predetermined 
number, each such line being assigned to one of the areas. 
This solves the problem underlying the present invention fully and 
perfectly because the use of a conventional pneumatic tube conveyor system 
for distributing assembly materials, and the like, ensures in this manner 
a materials distribution procedure which is not only quick, but also 
minimally labor-intensive. This is true all the more because it is 
possible according to the invention to subdivide a large assembly shop 
under management aspects into different assembly areas which are 
conveniently selected in such a way that each of the areas has an 
approximately equal demand for parts, by volume and weight. If in this 
case the several areas are served by a plurality of parallel pneumatic 
tube conveyor lines, then a parallel or multiplex operation is obtained 
which guarantees particularly quick materials distribution and full 
surface coverage. 
According to a particularly preferred embodiment of the pneumatic tube 
conveyor system of the invention, the pneumatic tube lines are equipped 
with an intermediate store. 
This feature provides the advantage that buffering is rendered possible 
between the materials distribution center and the lines which are 
distributed over the assembly shop. This is important because the filled 
conveying cases are loaded into the system at the order picking positions 
of the materials disttibution center in irregular intervals, depending on 
how long it takes until the person handling an order has filled the 
respective conveying case. Considering in addition that the dispatching 
rate from the materials distribution center is already irregular because 
different travelling times through the lines of the assembly shop have to 
be allowed for, this situation can be corrected by the provision of the 
intermediate store, it being now possible for the intermediate store on 
the one hand to accept filled conveying cases which are dispatched at the 
order picking positions at irregular intervals, and on the other hand to 
dispatch conveying cases at irregular intervals, without this leading to a 
backlog or to unacceptable idle times. 
According to a particular preferred further development of this embodiment 
of the invention, the intermediate store is followed by a gate for 
connecting the outlets of the intermediate store individually and 
selectively to the pneumatic tube lines leading to particular receiving 
stations, or to a buffer store. 
It is the advantage of this feature that any conveying cases, which are not 
to be dispatched, can be separated out from the intermediate store. This 
may become necessary, for example, when the receiving station signals that 
due to some malfunction it is temporarily not in a position to receive 
another conveying case, and when at that time a filled conveying case 
intended for this station has already been introduced into the tube system 
at a dispatching station. If this should occur, then the conveying case 
which was initially to be dispatched and which now is to be retained, can 
be separated out via a gate upon leaning the intermediate store, and can 
be transferred to the buffer store from where it can be retrieved and 
reintroduced into the tube system after the malfunction of the receiving 
station has been corrected. 
According to another preferred embodiment of the invention, each of the 
dispatching stations connects to a predetermined number of pneumatic tube 
lines and a pre-sorting device which allocates the conveying cases to be 
dispatched to the different pneumatic tube lines. 
This feature provides the advantage that each receiving station can be 
addressed from each dispatching station as the person handling an order 
can feed each conveying case into each of the pneumatic tube lines. Thus, 
the conveying cases are sorted and distributed over the individual 
pneumatic tube lines at the dispatching station. This simplifies the 
arrangement of the tube network in the area of the dispatching stations 
considerably. 
Other advantages of the invention will appear from the specification and 
the attached drawing. 
It is understood that the features that have been described before and will 
be explained hereafter may be used not only in the described combinations, 
but also in any other combination, or individually, without departing from 
the scope and intent of the present invention.

In FIG. 1, the pneumatic tube conveyor station is located within an 
assembly shop 10 of the type used, for example, in a manufacturing plant 
for assembling special machines. Assembly shops of this kind include a 
plurality of assembly work places positions where complete machines are 
assembled by fitters from parts supplied to these positions. As regards 
the parts required for this purpose, one usually distinguishes between 
different dimensional classes, the heaviest parts, for example machine 
frames or completely pre-assembled units, being distributed in the 
assembly shop 10 by means of cranes or trolleys, while a distribution 
system using electric trolleys or fork trucks is used for parts of medium 
weight. 
The present invention deals with a distribution system for small mechanical 
components or parts, such as screws, nuts, pins, bolts or other parts 
having weights of up to approximately 15 kg, either individually or 
grouped by orders. 
In the case of FIG. 1, the described parts are kept ready for use in the 
conventional manner in a parts store 11 in the assembly shop 10. Conveyor 
systems 12a to 12f provide the possibility to call off the parts 
individually or by orders from the parts store 11. This is done by workers 
working at order picking positions 13 where individual orders of parts 
required at the assembly positions in the assembly shop 10 are prepared 
for dispatch from the parts arriving from the parts store 11. 
In the case of the present invention, the order picking positions 13 are 
designed as dispatching stations of a pneumatic tube conveyor system. 
Consequently, the order picking positions 13 are part of a materials 
distribution center 14 which serves to supply the assembly positions in 
the assembly shop 10 with parts of the before-mentioned weight range. 
The pneumatic tube conveyor system 14 is connected, via a data line 16, to 
control means designed as a computer 15 which serves first to ensure that 
the required parts are supplied from the parts store 11. The computer also 
establishes, in the manner that will be described in more detail below, a 
connection between one of the dispatching stations 13a to 13f and one of 
the receiving stations 22. 
The assembly shop 10 is subdivided into a predetermined number of areas, 
the number and location of the areas being selected in such a way that 
each area has approximately the same demand for parts, by number and/or 
volume. In the case of the illustrated example, the assembly shop 10 is 
subdivided into three areas A, B and C. 
One end of a conveyor tube system 18 communicates with a plurality of 
pneumatic tube lines 20, the number of these lines corresponding to the 
number of areas. In the case of the example illustrated in FIG. 1, 
therefore, three lines 20A, 20B and 20C are provided, which are assigned 
to the areas A, B and C, respectively. 
As illustrated by way of example for the area A in FIG. 1, the line 20A 
leads to a first gate or plurality of gates 21 so that the line can be 
connected to any one of a number of receiving stations 22. By operating 
the gates 21 in a suitable manner over a plurality of operational 
positions, it is thus possible, by means of the computer 15, to connect 
the lines 20A, 20B, 20C to any of the receiving stations 22, each such 
receiving station 22 being assigned to an assembly position in the 
assembly shop 10. 
Now, it is the function of the pneumatic tube conveyor system to connect 
each dispatching station 13a to 13f selectively to any receiving station 
22 in any area A, B or C, in order to transport conveying cases filled 
with parts from the dispatching stations 13a to 13f to the receiving 
stations 22. 
In order to ensure that this function can be properly performed, certain 
arrangements are made in the pneumatic tube conveyor system which will be 
discussed in detail below. 
FIG. 2 shows an intermediate store 25 connected between the lines 20A, 20B 
and 20C, which store comprises a plurality of outlets and a plurality of 
storage positions 25A, 25B and 25C, with an outlet and a storage position 
provided for each of the lines 20A, 20B and 20C. 
The intermediate store 25 is followed by a second gate 26, comprising a 
plurality of operational positions by means of which each outlet of the 
intermediate store can be connected to the pneumatic tube line 20A, 20B or 
20C leading to a particular receiving station, or to a buffer store 27, 
comprising a plurality of storage positions 27A, 27B and 27C. 
This measure serves the following purpose: 
At the order picking positions 13a to 13f, conveying cases are filled and 
dispatched at irregular intervals. This is due to the fact that picking 
the different orders may take different lengths of time, depending on the 
particular type of order. On the other hand, it is, however, desirable to 
have the lines 20A to 20C utilized as uniformly as possible so that the 
greatest possible number of conveying cases can be conveyed per unit of 
time. The intermediate store 25, therefore, acts as a buffer store which 
ensures that conveying cases can be dispatched to the areas A, B and C 
from the outlet of the intermediate store 25 in the manner determined by 
the computer 15 and that no backlog will build up due to the irregular 
loading of cases by the order preparing personnel. 
In addition, it is rendered possible by the intermediate store 25 to affect 
the dispatch of conveying cases, for example if information should be 
received that some trouble exists at one of the receiving stations 22 so 
that no cases can be received at that moment by the particular station, 
for example because the operator has failed to unload the preceding 
conveying cases from the receiving buffer at that location so that the 
latter is full and not in a position to accept additional conveying cases. 
If such a condition occurs, the gate 26 is actuated via the control line 
28, connecting the line 20A, 20B or 20C to the buffer store 27. One 
ensures in this way that if it is determined that a conveying case placed 
in any of the lines 20A to 20C cannot be received at the envisaged 
receiving station 22, the respective conveying case will not cause any 
problems in the area of the receiving station 22 and will also not delay 
the dispatch of other conveying cases waiting behind it in the lines 20A 
to 20C. 
The conveying cases separated out in this way can then be removed from the 
buffer store 27 manually and can be dispatched once more from any of the 
dispatching stations 13a to 13f, for example after the fault conditions at 
the receiving station 22 have been removed and the station has been 
released again. 
Considering that the flow of parts in an assembly shop 10 can neither be 
predicted nor pre-sorted at reasonable expense, it is provided in the case 
of the pneumatic tube conveyor system according to the invention that each 
of the dispatching stations 13a to 13f can route cases to any receiving 
station 22 in any area A to C. 
FIG. 3 shows in this connection an installation within, e.g., dispatching 
station 13a for presorting complete conveying cases which provides means 
for identifying a destination receiving station for each conveying case 
and means for directing each conveying case to the pneumatic tube line 
connecting to the destination station for that conveying case. The 
operator handling the respective order has filled a conveying case with 
the desired parts, the conveying case having a self-adhesive label 
preferably printed by a printer, which label contains a machine-readable 
destination code representative of the respective receiving station 22. 
The conveying case filled and prepared in this manner is now introduced by 
the operator into a loading position 30 at the dispatching station 13a, as 
indicated by arrow 31 in FIG. 3. 
Starting from the loading position 30, the conveying case first passes a 
reading position 32 where the destination coordinates of the conveying 
case appearing on the label are read by a suitable scanner. The signals so 
scanned are converted into a control command which is supplied, via a 
control line 34, to a third gate 33 between the dispatching stations and 
the pneumatic tube lines 20A to 20C. 
The gate 33, operating over a plurality of operating positions, connects 
any of the dispatching stations selectively to any of as many outlet tube 
sections 20a to 20f as lines 20 are provided in the pneumatic tube 
conveyor system. In the illustrated example, the gate 33 connects with 
three outlet tube sections 20a, each of which communicates via the 
conveyor tube system 18 with one of the lines 20A to 20C, thereby 
directing each conveying case into a line 20 connecting to the appropriate 
destination receiving station for that conveying case. 
The lines 20A to 20C are designed as bidirectional lines, as indicated by 
the double arrows in FIG. 1. 
FIG. 4 shows that each conveying case leaving the intermediate store 25 for 
being dispatched is diverted by the gate 26 by 180.degree., and is then 
dispatched to the area for which it is intended, via the lines 20A to 20C. 
In the case of one practical example of a pneumatic tube conveyor system, 
an assembly shop which has a length of 560 m and which is subdivided into 
three areas, is supplied with a total of approximately 2300 dispatched 
cases during 15 hours, with a reserve of 30%. The conveying cases may have 
a total weight of up to 7 kg. The forwarding tube has a nominal width of 
160 mm, so that a loading diameter of 110 mm and a loading length of 400 
mm is obtained for the conveying cases. The conveying cases travel at a 
speed of approximately 6 m/s.