EP0672355B1 - Method and apparatus for transporting filter rods - Google Patents

Abstract

The transport system has a pneumatic feed line, to which the cigarette filters are fed individually from a supply reservoir, via axis parallel reception pockets (2) in a rotary transfer wheel (1). The pockets are indexed past an ejection zone, in which the filter is displaced along its axis by pressurised air, for input to the pneumatic line. The longitudinal movement of the filter in the ejection zone is monitored, with a fault signal supplied when the filter fails to be ejected from the pocket in a given time interval, pref. defined between the entry of the pocket into the ejection zone and the exit of the pocket from the ejection zone.

Description

The invention relates to a method according to the preamble of claim 1 and an apparatus according to the preamble of claim 7.

The transport of the filters from filter production to further processing, for example in A filter attachment machine is usually carried out via a pneumatic delivery line on the input side to a transmitting station and on the output side to one with the magazine of the Processing machine connected receiving station is connected. In the Transmitting station, the filter rods are rotating in successive shots Transfer conveyor (transmission drum) transaxially from a supply to a launch position brought, in which they are aligned with the pneumatic conveyor line. In the launch position they are moved longitudinally axially into the delivery line using compressed air, in which they are then pneumatically conveyed to the receiving station at the processing machine. During the axial movement of a filter rod from the holder into the delivery line the transfer conveyor continues to rotate, so that the filter rod in question at the same time is moved axially. To pinch the filter between the rotating transfer conveyor and to avoid the stationary mouth of the pneumatic delivery line, the launch zone has an extension in the direction of rotation of the transfer conveyor, on the axial and cross-axial speed of the filters at launch is coordinated. The mouth of the pneumatic delivery line has been expanded accordingly and runs funnel-shaped towards the conveyor pipe (GB 2 068 325 A). This GB 2 068 325 A describes a pneumatic conveyor system that uses five filter manufacturing machines pneumatic conveyor lines with five magazine groups of filter processing machines connects. The conveyor lines connect two transmission stations in pairs above described type with a magazine of a processing machine. This will make a Magazine fed via two conveyor lines each, which is a significant improvement the security of supply of the magazines with filters means. This system has one Series of sensors for detecting fault conditions and for generating fault signals on. This controls whether the sealing shoe or sealing block is opened, whether the Coupling disengages due to overload, whether the stock in the magazine is replenished, whether rods in enter the delivery line or whether there is a backlog in the delivery line.

When a transmitting station is operating properly, a filter is accommodated in the transfer conveyor leave when this shot moves out of the launch zone, so that the transfer conveyor unhindered the next intake in the launch zone can move.

If a filter remains when it is fired, so that it does not completely leave its holder, while it is in the launch zone, the filter collides between the stationary mouth of the conveyor line and the rotating transfer conveyor is pinched. Because the transfer conveyor is moving at high speed moves and because it has a high shear force on the face of the stationary mouth of the delivery line exerted on the pinched filter, this can be partially sheared off, whereby part of the filter gets into the conveyor line and the other in the receiving of the transfer conveyor remains. This leads to a malfunction that occurs when the facility is at a standstill must be remedied. GB 2 068 325 neither addresses nor offers this problem a solution for it.

The invention has for its object a method and a device of the beginning to further improve the described type. In particular, the aim is to prevent sheared off Parts of a filter through the pneumatic conveyor line in the further production process get there and cause major interference.

In a method of the type specified at the outset, this object is achieved according to the invention solved in that the movement of the recording through the launch zone longitudinal axial movement of the filter from the intake into the delivery line is monitored and that an interference signal is generated if a filter within the recording in question has not completely left a predetermined time interval. When an interference signal occurs immediately the transverse axial movement of the conveyor stopped.

In a further development of the invention, the entry of a Admission to the launch zone and exit from the launch zone detected. The time of entry gives the start and the time of exit before the end of the time interval, in which a filter on launching its inclusion in the transfer conveyor must have left the error-free Transport the filter from the intake to the delivery line guarantee. According to a preferred embodiment of the Method according to the invention when firing a filter successively the transition of the front and the rear End of filter from the intake in the delivery line and corresponding transition signals are formed, and there is an interference signal formed if not the times of both transition signals within the time interval specified for the launch lie. This is a particularly practical way to the longitudinal axial movement of the filter when fired into the delivery line with its transverse axial movement through the launch zone to compare and occurring errors and arising Record faults immediately. The Stopping the conveyor happens before one is not complete filter that entered the delivery line from the rotating one Transmission drum can be sheared off. To get a jammed To release filters, the transmitter drum will stop after stopping preferably turned back a little. The filter can then be easily be removed from the transition area. This will avoid that filter fragments through the delivery line in the further Production process. Claims 4 and 5 contain Troubleshooting measures to achieve that filters stuck when fired quickly and safely be removed from the conveyor.

In a device of the type specified in the object underlying the invention solved with the characterizing features of claim 6.

Training and advantageous refinements of the device according to the invention are specified in subclaims 7 to 15. Claims 7 and 8 contain preferred arrangements of the monitoring means by which the longitudinal axial movement the filter from the recordings in the delivery line is monitored becomes. The arrangement of the monitoring means in the sealing block is particularly beneficial because it is very accurate in this way in the transition area between the rotating transmission drum and the mouth of the delivery line can be installed. The Claims 9 to 11 contain features of an embodiment of the Device with which the movement of the individual recordings through the launch zone and that for the axial movement the time interval available for the filter rods during firing is specified. Claims 12 to 15 relate to Features of the device proposed according to the invention, the enable advantageous use of the interference signals that occur. This makes shearing insufficiently shot Filter rods avoided and it is achieved that in the transition between the transfer conveyor and the mouth of the conveyor line stuck filters are automatically removed.

The main advantage of the invention is that in disturbances occurring at the transmitting station can be detected immediately and they can be remedied automatically. It is through the return rotation of the transfer conveyor when it occurs Disorder ensured that a rotating between the Transfer conveyor and the stationary mouth of the line jammed filter is released and easily blown out can be. The quick detection and elimination of faults ensures a high transfer rate of the pneumatic Funding arrangement. This ensures that none are sheared off Filter parts get into the delivery line and the operation of the following machines. That will be with little technical effort achieved.

Figur 1

in einer teilweise geschnittenen Seitenansicht ein Ausführungsbeispiel einer Vorrichtung nach der Erfindung,

Figur 2

einen Schnitt in der Ebene B-B der Figur 1,

Figuren 3 und 4

zwei verschiedene Positionen einer Aufnahme des Überführungsförderers in der Abschußzone,

Figur 5

ein Schema der Steuerungsanordnung und der Druckluftversorgung der Vorrichtung nach der Erfindung und

Figur 6

verschiedene Signalverläufe der Sensoren bzw. Detektoren der Vorrichtung.

The invention will now be explained in more detail with reference to the drawing. Show it

Figure 1

in a partially sectioned side view an embodiment of a device according to the invention,

Figure 2

2 shows a section in the plane BB of FIG. 1,

Figures 3 and 4

two different positions of a transfer conveyor intake in the launch zone,

Figure 5

a diagram of the control arrangement and the compressed air supply of the device according to the invention and

Figure 6

different signal profiles of the sensors or detectors of the device.

The in Figures 1 and 2 as an embodiment of the invention Conveying device shown has a transfer conveyor in the form of a front or transmission drum 1, the is provided with receiving troughs 2 for filter rods 3. With Suction holes 4 provided and limited by webs 6 Receiving troughs 2, also referred to as shots below, run parallel to the axis of rotation 7 of the conveyor drum 1 and are open radially outwards. The conveyor drum 1 is from a motor 8 via gears 9 and 11 by means of a shaft 12 continuously drivable in the direction of an arrow 13. The Conveyor drum 1 borders a filter rod magazine on its upper side 14 with front and rear boundary walls 16 and 17 where the recordings pass through a removal area 18. Here, the recordings 2 are oriented one after the other axially parallel Open filter rods from magazine 14 and transport them them transversely axially in the direction of arrow 13 into one on the underside the delivery zone 1 arranged launch zone Z. This launch zone Z is aligned axially with one in a control ring 19 provided mouth 22 of a pneumatic conveyor line 21.

In the area of the launch zone Z are the receptacles 2 of the conveyor drum 1 with a sealing block 23 radially outwards to the surroundings locked up. The sealing block has one of the circular arc Path of the conveyor drum 1 adapted sealing surface 24th and extends along the circumference of the conveyor drum 1 over the shooting zone 2 adjacent to the shooting zone 2. in the employed state, the sealing block 23 is supported exclusively sealing at its two ends with its sealing surface 24 on two stationary arranged concentrically to the conveyor drum 1 Support bushings 19 and 26, the outer radius of the radius corresponds to the sealing surface 24, but is slightly larger than the outer radius of the conveyor drum 1. This gives a game and thus a non-contact employment between the drum peripheral surface formed by the webs 6 and the sealing surface 24 of the sealing block 23. The front support bush 19 is designed as a control ring, in which one with a vacuum source 27 connected and the front into one Control slot 28 opening vacuum line 29 runs. The Control slot 28 corresponds to in the conveyor drum 1 Axially parallel suction air bores 31 for the vacuum supply of the suction bores 4 in the receptacles 2.

The shaft 12 of the conveyor drum 1 1 is through the support bushings 19th and 26 passed through and outside the support bushings in fixed Housing walls 32 and 33 mounted radially without play. The Support bushings 19 and 26 themselves carry a 34 via traverse members stationary mounting plate 36. The mounting plate takes two vertically arranged parallel guides 37 for the movement of the Sealing block 23 and two compressed air cylinders 38 for two compressed air pistons 39 for vertical up and down movement of the sealing block 23 on.

The sealing block 23 is in two parts in the embodiment shown educated. It consists of an external shape the conveyor drum 1 adapted sealing body 41 and a support body 42. The support body 42 is also a supply plate in which one with a pressure source 43 connected compressed air line 44 runs. To initiate the Compressed air from the compressed air line 44 into the in the launch zone Z located 2 of the conveyor drum 1 are a Cross bore 46 in the sealing body 41 and control slots 47 in a control flange 48 of the conveyor drum 1 is provided. The Conveyor drum 1 has a separate one for each receptacle 2 Control slot 47 on that with an axially parallel Bore 49 is connected. The compressed air comes out of the Pressure source 43 via a connecting line 51, through the compressed air line 44, the transverse bore 46 and the control slot 47, that of the receptacle 2 that is currently in the launch zone Z is assigned through the axially parallel bore 49 as a shot or Conveying air into the mouth 22 of the pneumatic conveying line aligned recording 2.

In the transition area between the downstream end face the rotating conveyor drum 1 and the stationary control ring 19 is a sensor 52 in the sealing body 41 of the sealing block 23 for example in the form of a reflection light barrier, arranged, the movement of a filter rod 3 during the Shot in the delivery line 21 detected. This sensor 52 5, is connected to a control arrangement 53, which can be the machine control.

The conveyor drum 1 are, as in Figure 2 schematically as an embodiment shown, two position detectors 54 and 56, for example in the form of proximity initiators, which can also be integrated in the sealing block Position detectors 54 and 56 are also in accordance with FIG Control arrangement 53 connected.

Figure 1 shows in the area of the inlet end of the conveyor line 21 a compressed air connection connected to the compressed air source 57, for introducing blow-back air into the delivery line serves.

Figure 1 shows the sealing block in its working position, in the its sealing surface 24 rests on the support bushings 19 and 26 and thereby the recordings 2 located in the launch zone Z Seals conveyor drum 1 to the outside. With a dashed line Line 58 is the bottom position, the maintenance position, of the Sealing block 23 indicated. On the sealing surface of the in the Maintenance position of the lowered sealing block is a cleaning nozzle 59 aligned with the pressure source 43 connected is.

As FIG. 5 shows, the conveying air connection 51 is the Compressed air connection 57 and the cleaning nozzle 59 via valves 61 to 63 connected to the compressed air source, so that the corresponding Compressed air supply is controllable. It should be noted that electrical connection lines in the scheme of Figure 5 with a simple line and pneumatic lines are marked with double lines. The free ending arrows at valves 61 to 63 make the connections to the Consumers 51, 57 and 59.

If the conveyor device is started, the sealing block becomes 23 from its lower, for example for cleaning reasons Maintenance position 58 raised to its working position, in which its sealing surface, as shown in FIGS. 1 and 2, bears sealingly against the support bushings 19 and 26. To do this the air cylinder 38 actuated so that the pressure stamp 39th move the sealing block 23 upwards against the support bushings. The Zugtraversen 34 catch the support bushings 19 and 26 applied pressure and bending forces and brace the System in itself. Because of the smaller drum diameter Conveyor drum 1 remains between the peripheral surface of the Conveyor drum 1 and the sealing block 23 a defined free space, so that smooth and therefore wear-free operation of the Conveyor device is possible.

During operation, it takes over the shaft 12 with constant Speed driven conveyor drum 1 in the removal area 18 filter rods 3 from the magazine 14 in their receiving troughs 2, in which they with the through the suction air holes 4, the axially parallel bores 31, the control slot 28, the Vacuum line 29 created by the vacuum source 27 Suction air are held. Enter the axially parallel holes 31 of the conveyor drum 1 when rotating in the conveying direction 13 from the angular range of the control slot 28, so causes the centrifugal force that the filter rods to the outer Set up the limit of the recordings 2 and move along them become. This outer boundary is above the sealing block from a cover plate 64 and in the area of the sealing block from whose sealing surface 24 is formed. In the illustration in FIG. 2 are only shown in the filter 3 recordings, while the im Stock 14 contained filters were omitted. The filter rods 3 are in the receptacles 2 from the conveyor drum 1 the removal area 18 transferred to the launch zone Z, in which align the filter rods with the delivery line. Flees the filter rod with the pneumatic delivery line 21 or with its stationary mouth 22, the compressed air source 43 through the lines 51 and 44 and through the transverse bore 46 and the relevant control slot 47 compressed air the receptacle 2 aligned with the delivery line, which the filter rod 3 located therein in the direction of a Arrow 66 moves axially from the receptacle into the delivery line. As the conveyor drum moves during this longitudinal axial movement the filter rods 3 continues to rotate, the filter rods are simultaneously thus also moved axially. To give them one anyway enable trouble-free entry into the delivery line, is the mouth 22 of the delivery line 21 in the direction of the transverse axial Movement expanded, which can be seen in Figures 2 to 4 is.

Figure 2 shows schematically a section approximately along the line B-B of Figure 1. Figures 3 and 4 show enlarged sections of the same cross-section in the area of the launch zone Z.

In FIG. 2, the section through the conveyor drum 1 is on two places have broken out so that there is a view of the Front side of the support bush or the control ring 19 is free. In this way, a piece of the control slot becomes in the upper part 28 visible, the for supplying the suction air with the Suction air holes 31 in the conveyor drum 1 corresponds. in the lower broken out area of the drum is the one in the Support bushing 19 provided opening 67 of the pneumatic Recognize the delivery line. The figure is dashed the receptacle just aligned with this mouth opening 67 2 of the conveyor indicated, in which one in the delivery line filter rod to be fired can be seen. The right dashed line 68 the rear flank surface of the preceding web and the left dashed line 69 the front flank surface of the subsequent web 6.

During the operation of the conveyor, the Firing a filter rod 3 from a receptacle 2 of the conveyor can begin when the recording is relative to the mouth opening 67 of the pneumatic delivery line that shown in Figure 3 relative position. At that moment, cursed the filter rod 3 with the mouth opening and can freely from the Recording 2 can be moved into the mouth opening 67. The longitudinal axial Movability of a filter rod 3 ends when the recording 2 of the rotating conveyor relative to the mouth opening 67 has reached the position shown in FIG. 4, in which a filter rod that has not yet completely left the recording has between the rotating conveyor drum and the mouth the stationary delivery line is pinched. The one there forces acting on the filter rod are so great that the Filter rod can be sheared off, creating corresponding parts of the filter rod into the delivery line and further into the subsequent one Production can get where there is significant disruption can cause. For this reason it is provided that the longitudinal axial movement of the filter rod from the inclusion in monitors the delivery line at launch and the rotational movement the conveyor drum 1 is stopped when a filter rod did not leave his admission in time at the launch.

For this purpose, the two initiators 54 and 56 specify a time interval T (FIG. 6), in which a receptacle 2 is aligned with the opening 67 of the conveying line during the rotation of the conveying drum 1 so that a longitudinally axial movement of the filter rod into the conveying line is possible. The initiators are set on the front flank surface 69 of the webs 6. When this flank surface 69 is detected by the initiator 54 at time t1, which is shown in FIG. 3, it forms a first position signal P1, which indicates that a receptacle 2 with the filter rod 3 conveyed therein is now aligned with the opening 67 of the delivery line and the launch can take place. If the same flank surface 69 is detected by the second initiator 56 at time t ₂ , it forms a second position signal P ₂ , which indicates that the recording has now emerged from the firing zone Z to such an extent that a further longitudinal axial movement of the filter rod is no longer possible . Between time t _{1 of} the first and time t _{2 of} the second position signal lies the time interval T (FIG. 6a) in which the longitudinal axial movement of the filter from the holder into the delivery line is possible.

To monitor whether a filter in the depending on the Position signals P1 and P2 of the initiators 54 and 56 from the Control arrangement 53 predetermined time interval T its inclusion 2 actually leaves completely and the conveyor drum Bring the next shot into the launch zone Z without interference can, the sensor detects 52 (Figure 1), the transition from the transversely axially moving receptacle 2 to the stationary mouthpiece 22 of the Delivery line 21 is assigned, the longitudinal axial movement of the Filters 3 at launch. It creates the beginning and the end the filter passage through the detection range of the sensor indicating transition signal S, its timing and duration checked by the control arrangement 53 relative to the time interval T. becomes. The normal case is shown in FIG. 6b and in FIG. that the 3 operation runs smoothly. The longitudinal axial Filter movement from the receptacle past the sensor 52 into the Delivery line, which is indicated by the transition signal S lies fully in the time interval T; the filter leaves the recording completely while the shot passes through the launch zone Z.

Figures 6c and 6d show the signal curves in the event of a fault.

If the transition signal S of the sensor 52 is not completely in predetermined time interval T (Figure 6c), it means that the filter is still in the transition area between the recording and the mouth 22 of the delivery line 21 is when the Recording leaves the launch zone Z (see also Figure 4). In in this case, the control arrangement 53 emits an interference signal which momentarily stops the drum drive 8 and the conveyor drum 1 before the drum and Clogged filter mouth of the delivery line is sheared and filter fragments get into the delivery line. Immediately afterwards the control arrangement 53 controls the motor 3, whereby the Transmitter drum is turned back by a small angle and releases the jammed filter. If the filter is OK, he can now continue from the recording flowing conveying air can be moved into the conveying line 21 (Figure 6c), which eliminates the problem quickly. Let yourself if the filter does not convey any further (FIG. 6d), the control arrangement switches 53 the valves 61 and 62, so switches the Conveying air from and the blow-back air through port 57, so that the filter is moved back into the holder. The sealing block 23 is moved into the lowered maintenance position 58 and its sealing surface 24 by means of a compressed air flow from the Blown cleaning nozzle 59, with the filter blown out be dropped into a collecting container, not shown. The Actuation of the sealing block drives 38 and switching the Cleaning air valves 63 are also dependent from the interference signal by the control arrangement 53.

Then all valves are switched back, the Sealing block 23 is brought into its upper working position and the operation is started again as described above.

Claims (15)

1. A method of conveying filters (3) for cigarettes from a store (14) into a pneumatic conveying line (21), in which the filters (3) are transferred individually in succession from the store (14) into axially parallel receiving means (2) of a conveyor (1), the receiving means (2) are moved transversely axially with the filters (3) into an ejection zone (Z) orientated towards the pneumatic conveying line (21) and the filter (3) held in the receiving means (2) passing through the ejection zone (Z) is ejected longitudinally axially from the receiving means into the conveying line (21) by means of compressed air, characterized in that the longitudinally axial movement of the filter (3) from the receiving means (2) into the conveying line is monitored during the movement of the receiving means (2) through the ejection zone (Z), and an error signal is generated if a filter (3) has not completely left the respective receiving means (2) within a pre-set period of time, and when an error signal occurs the transversely axial movement of the conveyor (1) is immediately halted automatically.
2. A method according to Claim 1, characterized in that the entry of a receiving means into the ejection zone and its exit from the ejection zone is detected, and the moment of entry sets the beginning and the moment of exit sets the end of the period of time.
3. A method according to Claim 1 or 2, characterized in that during the ejection of a filter the passage of the front and the rear filter end from the receiving means into the conveying line is detected in succession and a corresponding transition signal is produced, and an error signal is produced if the moments of the two transition signals are not within the period of time pre-set for the ejection.
4. A method according to one of Claims 1 to 3, characterized in that in accordance with an error signal the receiving means is opened, and the filter which has not completely entered the conveying line is removed from the ejection zone.
5. A method according to Claim 4, characterized in that in accordance with an error signal a filter which has not completely entered the conveying line is blown out of the conveying line and the ejection zone by reversing the compressed air.
6. A device for conveying filters (3) for cigarettes from a store (14) into a pneumatic conveying line (21), having a circulating transfer conveyor (1) which is provided with receiving means (2) for transversely axially conveying filters (3), a removal area (18) in which the receiving means of the conveyor (1) for taking up filters adjoin the store (18) and are open towards the latter, an ejection zone (Z) in which the receiving means (2) are sealed off towards the outside and one respective receiving means is orientated axially towards the conveying line (21), and a device (43 to 51) for introducing conveying air into the receiving means (2) passing through the ejection zone (Z) in each case in order to move the filter (3) contained in the receiving means into the conveying line (21), characterized in that monitoring means (52) for monitoring the longitudinally axial movement of a filter (3) from a receiving means into the conveying line (21) and for generating monitoring signals (S) dependent upon the filter movement are associated with the receiving means (2) in the ejection zone (Z), and the monitoring means (52) are attached to an evaluation device (53) which emits an error signal if the monitoring signals (S) do not appear within a pre-set period of time (T), a drive means (8) is provided for the circulating movement of the transfer conveyor (1), and the evaluation device (53) is designed so as to halt the said drive means (8) in accordance with an error signal.
7. A device according to Claim 6, characterized in that the monitoring means (52) is associated with the ejection zone (Z) in the transition region from the receiving means (2) to the open end (67) of the conveying line (21).
8. A device according to Claim 6 or 7, characterized in that a sealing plug (23), which is adapted to the external shape of the conveyor (1) and which closes the receiving means (2) radially towards the outside, is provided for sealing the receiving means (2) radially in the region of the ejection zone (Z), and at least one sensor detecting the presence of a filter (3) is incorporated as a monitoring means (52) in the sealing plug in the region adjacent to the conveying line (21).
9. A device according to one of Claims 6 to 8, characterized in that at least one position detector (54, 56) for detecting the ejection position of a receiving means in the ejection zone (Z) and for generating corresponding position signals (P₁, P₂ ) is associated with the transfer conveyor (1), and the position detector is attached to an evaluation device (53) which determines the duration of the passage of a receiving means (2) through the ejection zone (Z) in accordance with the position signals (P₁, P₂ ) and pre-sets the period of time (T) for the proper movement of a filter (3) from the receiving means (2) into the conveying line (21).
10. A device according to Claim 9, characterized in that two position detectors (54, 56) are associated with the transfer conveyor (1) at a mutual distance corresponding to the transversely axial width of the ejection zone (Z), the first position detector (54) detects the complete entry of a receiving means (2) into the ejection zone (Z) and generates a first position signal, the second position detector (56) detects the starting exit of the receiving means (2) out of the ejection zone (Z) and generates a second position signal (P₂ ), the attached evaluation device pre-sets a period of time (T) in accordance with the first and the second position signals, and it generates an error signal if the monitoring signal (S) of the monitoring means (52) detecting the longitudinally axial movement of the filter (3) does not end within the period of time (T).
11. A device according to Claim 10, characterized in that the first position detector (54) is arranged at the upstream boundary of the ejection zone (Z) with respect to the transversely axial conveying movement, the second position detector (56) is mounted in the ejection zone (Z) approximately at a distance of a filter diameter from the downstream end of the ejection zone, and the two position detectors are set so as to detect the rear boundary (69) of each receiving means (2) passing the ejection zone.
12. A device according to one of Claims 6 to 11, characterized in that a drive means (8) is provided for the circulating movement of the transfer conveyor (1), and the evaluation device (53) is designed so as to halt the said drive means (8) in accordance with an error signal and to rotate it backwards by a slight angular amount.
13. A device according to one of Claims 6 to 12, characterized in that a drive device (38, 39) is provided for moving the sealing plug (23) from its sealing position sealing the receiving means (2) of the transfer conveyor (1) in the ejection zone (Z) into a maintenance position (58) opening the receiving means towards the outside, the drive device is connected to the evaluation device (53), and the evaluation device is designed so as to control the drive device if an error signal occurs with respect to the movement of the sealing plug (23) from its sealing position into the maintenance position (58).
14. A device according to one of Claims 6 to 13, characterized in that a blow-back line (57) connected to a pressure source (43) by way of a blow-back valve (61) is attached to the pneumatic conveying line (21) in the region of its upstream end, and the evaluation device (53) opens the blow-back valve (61) in accordance with an error signal to blow free the beginning of the line.
15. A device according to Claim 13 or 14, characterized in that a cleaning nozzle (59) attached to a pressure source (43) by way of a valve (62) is provided, the nozzle is orientated towards the sealing face (24) of the sealing plug (23) in the maintenance position (58) thereof, and the cleaning-air valve (62) is controllable by the evaluation device (53) in accordance with an error signal to blow free the sealing face.

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