Mail flow compensating device

Abstract: A mail flow compensating device (1) wherein a straight horizontal conveyor belt (3) is supplied with a stream (19) of overlapping flat mail items (20). The flow compensating device (1) comprises a stop wall (5) sloping in relation to the belt (3) and presenting a bottom end portion (33) facing the belt (3). When the height (H) of the stream (19) exceeds a maximum value (D), the mail items contact and accumulate against the stop wall (5) to form a group of superimposed mail items (20). The flow compensating device (1) also presents an optical sensor (34) for detecting the limit contour of the group of mail items, generating a full-flow-compensating-device signal, and cutting off supply to the conveyor belt (3).

Description: The present invention relates to a mail flow compensating device. Mail sorting machines are known wherein a flow forming device provides for forming a stream of overlapping mail items (letters and postcards), which is fed by a conveyor belt to a user, e.g. separating, device. Under stationary operating conditions, the output of the flow forming device substantially equals the input of the separating device, so that the stream of mail items is substantially orderly. When the number of mail items fed to the output of the flow forming device, however, is greater than that withdrawn by the separating device, the mail items are subjected to forces affecting the initial arrangement. More specifically, the bottom portion of the mail items moves at substantially the same speed as the conveyor belt, whereas the items themselves are subjected to the reaction exerted by the items accumulating at the input of the separating device. As a result, each mail items rotates about its bottom edge, and is lifted off the surface of the belt and on to the foregoing item closer to the separating device, so that the height of the stream gradually increases to such a point as to result in fallout of the mail items. It is an object of the present invention to provide a flow compensating device fittable along a conveyor belt of the aforementioned type, and which provides for compensating for any difference between the output stream generated by the flow forming device and the input stream to the user device. Document US-3,236,355 discloses a mail handling device provided with a flow compensating device as defined in the preamble of claim 1 According to the present invention, there is provided a flow compensating device for mail items as defined in claim 1. A preferred non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a schematic side view of a flow compensating device in accordance with the teachings of the present invention; Figure 2 shows the Figure 1 flow compensating device in a different operating condition. Number 1 in Figure 1 indicates a flow compensating device comprising a horizontal conveyor belt 3 and a shaped stop wall 5 located over belt 3. Conveyor belt 3 comprises a straight flat top portion 7 extending between two pulleys 8 and 9 and defining at each end the input 13 and output 14 of belt 3. More specifically, input 13 communicates with the output 15 of a second horizontal conveyor belt 16 extending between an idle pulley (not shown) and a drive pulley 18 facing pulley 8. Belt 3 is driven from pulley 8 to pulley 9 by a direct-current motor 8a (shown schematically), while pulley 18 is driven by a motor 18a. The second conveyor belt 16 is supplied by a postal machine (not shown), e.g. a flow forming device, which provides for forming on belt 16 a stream 19 of overlapping mail items 20 (letters and postcards). Output 14 of belt 3 communicates with the input 21 of a conveyor device 22 forming part of a user device, e.g. a separating device (not shown), for receiving mail items 20 from belt 3. More specifically, conveyor device 22 comprises a top belt 24 having, when viewed from the side, a substantially triangular contour and supported on three pulleys 28 driven by an electric motor (not shown). Conveyor device 22 also comprises a substantially straight bottom belt 25 supported on three drive pulleys 30 and having a mid portion contacting a bottom portion of belt 24. The portions of belts 24 and 25 facing belt 3 define the input 21 of conveyor device 22. Stop wall 5 comprises a first flat portion 5a sloping in relation to portion 7, converging with the traveling direction of belt 3, and extending between a top end 31 and a bottom end 33 blending with a second upward-bent portion 5b. Bottom end 33 of wall 5 is located facing belt 3, and is separated from portion 7 by distance D. Wall 5 is made of transparent material (e.g. plexiglass) and is connected to an optical sensor 34 comprising a photoemitting device 35 and photodetecting device 36 defining an optical path 37 which intersects wall 5 and extends parallel to and at a distance F from flat portion 7. Optical sensor 34 is connected to a central processing unit 40 (shown schematically) and provides for generating a full-flow-compensating-device signal when optical path 37 is cut off. Flow compensating device 1 also presents a second optical sensor 44 comprising a photoemitting device 45 and photodetecting device 46 defining an optical path 47 parallel to path 37 and separated from flat portion 7 by a distance E less than distance F. Optical sensor 44 is connected to central processing unit 40 (shown schematically) and provides for generating an empty-flow-compensating-device signal when optical path 47 is not cut off. By means of respective lines 41 and 42, processing unit 40 controls motors 8a and 18a driving conveyor belts 3 and 16. In actual use, and under stationary operating conditions, the mail items 20 fed by the flow forming device (not shown) on to conveyor belt 16 substantially equal those fed by belt 3 to the separating device (not shown), so that stream 19 extends from the flow forming device (not shown) to input 21, and presents substantially constant geometric characteristics by virtue of items 20 overlapping one another and forming an angle of a few degrees with the surface of belt 16. More specifically, height H of stream 19 is less than distance D, so that stream 19 is fed by belts 16 and 3 underneath wall 5. Conversely, in the event the supply of items 20 on to conveyor belt 16 by the flow forming device (not shown) is greater than that to input 21 of the separating device (not shown), stream 19 is subjected to forces affecting its initial arrangement. In this case, in fact, the bottom portion of items 20 travels at substantially the same speed as belts 3 and 16, while items 20 themselves are subjected to the reaction exerted by the items 20 accumulating against input 21. As a result, each item 20 rotates about its bottom edge and is lifted off the surface of belts 16 and 3 and on to the foregoing item 20 closer to input 21, so that the height of stream 19 increases. When the height of stream 19 exceeds distance D, items 20 contact wall 5 (Figure 2) and pile up one on top of the other into a group 50. The height of group 50 increases gradually until an item 20 in the group eventually intercepts optical path 37, at which point, central processing unit 40 stops conveyor belt 16; conveyor belt 3 transfers the items 20 accumulated in device 1 to conveyor device 22; and flow compensating device 1 thus disposes of the accumulated items 20 so that the height of group 50 gradually decreases. Upon the height of group 50 falling below optical path 47 (indicating device 1 is substantially empty), belt 16 is started up again, and stream 19 transferred continuously by the flow forming device (not shown) to the separating device (not shown). Flow compensating device 1 thus clearly provides for compensating for any difference between the output of the flow forming device and the input to the user device. By means of repeated start and stop cycles of belt 16, flow compensating device 1 provides for ensuring the stream of mail items supplied to input 21 of the separating device (not shown) is substantially constant and not noticeably distorted. To those skilled in the art it will be clear that changes may be made to the flow compensating device as described and illustrated herein without, however, departing from the scope of the present invention as defined by the claims. For example, the functions of the second sensor 44 may be performed by a timing circuit (not shown) of processing unit 40, designed to receive the full-flow-compensating-device signal generated by sensor 34, and, following stoppage of belt 16, to re-start belt 16 after a given time interval T (sufficient for unloading flow compensating device 1).

Claims: A flow compensating device (1) for mail items (20), comprising a straight conveyor device (3) driven by first drive means (8a); said conveyor device (3) presenting an input (13) supplied with a stream (19) of overlapping flat mail items (20) presenting a substantially constant height (H) under stationary supply conditions; said conveyor device (3) presenting an output (14) for expelling said stream (19) of mail items (20); and a stop wall (5) located a predetermined distance (D) from said conveyor device (3) and designed to intercept said mail items (20) upon the height (H) of said stream (19) exceeding a maximum value (D), characterized by the fact that it comprises first sensor means (34) for detecting an upper clearance of the group (50) of said mail items accumulated against said wall (5); said sensor means (34) being designed to emit a full-flow-compensating-device signal for cutting off supply of mail items to said conveyor device (3). A device as claimed in Claim 1, characterized by the fact that it comprises second sensor means (44) for detecting a lower clearance of said group (50) of said mail items contained in said flow compensating device (1); said second sensor means (44) being designed to emit an empty-flow-compensating-device signal, for reactivating supply to said conveyor device (3). A device as claimed in Claim 1 or 2, characterized by the fact that said first and/or second sensor means (34, 44) comprise optoelectronic sensors defining an optical path (37, 47) for intercepting an end portion of said group (50) of mail items. A device as claimed in Claim 3, characterized by the fact that said wall (5) is made of transparent material, and is intersected by said optical path (37, 47). A device as claimed in any one of the foregoing Claims, characterized by the fact that it comprises a conveyor belt system (16) driven by second drive means (18a) and supplied with said stream (19) of mail items (20); said conveyor belt system (16) presenting an output (15) adjacent to and communicating with said input (13) of said conveyor device (3). A device as claimed in Claim 5, characterized by the fact that it comprises an electronic control unit (40) communicating with said first sensor means (34) and said second drive means (18a); said unit (40) arresting said second drive means (18a) upon reception of said full-flow-compensating-device signal. A device as claimed in Claim 6 dependent on Claim 2, characterized by the fact that said electronic control unit (40) communicates with said second sensor means (44); said unit (40) re-starting said second drive means (18a) upon reception of said empty-flow-compensating-device signal. A device as claimed in Claim 1, characterized by the fact that said stop wall (5) slopes in relation to said conveyor device (3), and converges with its traveling direction; said wall (5) presenting an end portion (33) facing the conveyor device (3). A device as claimed in Claim 1, characterized by the fact that said conveyor device (3) comprises at least one conveyor belt (3) having at least one straight flat portion (7); said stop wall (5) sloping in relation to said straight flat portion (7), with said end portion (33) separated from the flat portion (7) by said predetermined distance (D).

Inventors: LEVARO MAURO, SOFIA GIUSEPPE, LEVARO, MAURO, SOFIA, GIUSEPPE
Applicants: ELSAG SPA
Application year: 1993
Main classification: B07C1
IPC codes: B07C1