Coating system and pig for use in a coating system

Abstract

A coating system (1) for coating an object with a coating material, comprising a piggable pipeline system (14) for supplying a pickup point (8) with the coating material, in which the pipeline system (14) has a number of pig parking stations (22) for temporarily receiving a pig (20) guided in the pipeline system (14), is designed for the gentlest possible handling of the pig (20) in order to extend its service life. According to the invention, each pig parking station (22) is provided with a guide pair (34) in combination with the pig (20), which, when the pig (20) is fully inserted into a parking space (26) in the parking station (22), ensures a predetermined rotational orientation of the pig (20) relative to the parking station (22).

Description

[0001] The invention relates to a coating system for coating an object with a coating material, comprising a piggable line system for supplying a discharge point with the coating material. The line system has a number of pig parking stations, also referred to as sending stations, starting stations, or exchange stations, for temporarily accommodating a pig guided in the line system. It further relates to a pig for use in such a coating system.

[0002] Such coating systems with so-called "piggy-able" piping systems are used in a wide variety of applications for coating objects such as vehicle bodies, particularly as paint shops. Pigging systems allow the separation of directly adjacent coating materials and can also be used for cleaning and / or inspecting the piping system. In coating technology, it is well known to use a pig to transport coating material through a pipe, for example, from a supply source to another location, especially to an application facility. The pig can also be moved alone, for example, to clean the pipe.

[0003] Corresponding pig-based processes and systems are used particularly in paint shops where, in a conventional manner, a paint reservoir is connected to a gun or atomizer unit. The pig is usually an approximately circular-cylindrical object with a waist in the middle that tightly fills the pipe cross-section and is pressed through the supply line by a thrust medium, pushing the medium to be expressed in front of it. Pigging technology requires not only the pig but also locks built into the system through which the pig can be inserted into and removed from the pipes. Such locks can be part of so-called parking stations, also called sending or receiving stations, in which the pig can temporarily remain motionless until it is inserted into the pipe system via the lock.

[0004] The working medium can be, for example, paint or cleaning agent, which is present on one side of the pig within the supply line. Compressed air is typically used as the thrust medium, which is applied to the pig on the other side. However, a liquid medium can also serve as the thrust medium.

[0005] Pigging technology makes it possible to use different paint types and colors within a supply line. These are each introduced into the supply line via lateral, valve-controlled supply lines from a paint reservoir or drawn accordingly for delivery to the application unit. In painting systems, different colors can thus be used in rapid succession during series production. The so-called paint recovery technology is often used here. This means that the supply line is filled with the corresponding paint color, and after the painting process is completed, the remaining paint in the supply line is returned to the corresponding paint reservoir using the pigging technology described above.

[0006] When moving a pig into or out of the respective parking station, a number of criteria and boundary conditions must be observed to ensure reliable operation that meets higher demands, particularly with regard to processing speed. On the one hand, a pig is usually stopped when removed from the supply line from a comparatively high transport speed, namely that of the respective thrust medium within the supply line, and brought to a rest position in the parking station. This can lead to a comparatively hard mechanical impact on the end surface of the parking space intended for the pig, which serves as the stop surface, resulting in correspondingly harsh and wear-intensive stress on the pig.On the other hand, in the opposite direction, i.e., when removing the pig from its parking position, a suitable "pushing" of the pig is first necessary to properly convey it into the supply line. To do this, the pig's breakaway force must first be overcome using a suitable actuator or drive medium, such as compressed air in the form of a pressure pulse, in order to set it in motion from its parking position. This, as well as the subsequent controlled and guided movement of the pig in the line system, requires a sufficiently tight seal between the pig's front face and the inner wall of the line system. In particular, targeted and secure guidance of the pig may be desirable to enable reliable pushing of the pig even with limited working pressure of the drive medium.

[0007] The invention is therefore based on the object of providing a coating system of the aforementioned type that allows particularly reliable and controlled handling when using a pig. Furthermore, a pig particularly suitable for use in such a system is to be provided.

[0008] With regard to the coating system, this object is achieved according to the invention in that the or each pig parking station in combination with the pig is provided with a guide pair which, when the pig is completely inserted into a parking space provided for it in the parking station, effects a predetermined rotational orientation of the pig relative to the parking station.

[0009] Advantageous embodiments of the invention are the subject of the subclaims.

[0010] The invention is based on the idea that, fundamentally, in order to increase the durability and reduce stress on the pig, a controlled and guided influence on its movements within the pipeline system should be sought. Especially during the phases of discharge from the pipeline system and insertion into the parking station, or conversely, during removal from the parking station and insertion into the pipeline system, the pig can be exposed to very intense changes in its state of motion and high accelerations, for example, when impacting the end face in the parking station. Therefore, it is precisely during these phases, i.e., in connection with the interaction of the pig with the parking station, that particular emphasis should be placed on guided and, if possible, controlled movement.In one aspect of the invention, this point is taken into account by incorporating, in addition to the usual position data and parameters of the pig, its rotational orientation, i.e., its positioning relative to its longitudinal axis, into the guide. This allows, for example, small irregularities in its cross-sectional contour and the associated effects on sealing to be compensated for, while also intensifying access to and mechanical contact with the pig.

[0011] Advantageously, the system for providing the corresponding element of the guide pair provides the respective pig parking station with a suitably contoured and dimensioned guide surface for the pig in the area of ​​the end surface of the parking space for the pig. According to one aspect of the invention, the guide surface can have a suitably selected number of conical surfaces on the pig itself, adapted to the corresponding element of the guide pair. These conical surfaces are inclined and, as a whole, taper from the free end to the end surface of the parking space, thus being arranged in a "funnel-like" manner. The term "conical surface" is to be interpreted broadly and is intended to describe essentially a funnel-shaped or funnel-like basic form.These can be "true" conical surfaces, i.e. conical surfaces in the mathematical sense, or other funnel-shaped surface contours, such as funnel-shaped spherical surface elements.

[0012] These guide surfaces, commonly referred to as conical surfaces, thus catch the pig as it enters the parking space and, in conjunction with the corresponding structural elements of the pig, ensure that the pig rotates around its longitudinal axis until it reaches the correct rotational orientation, allowing it to fully enter the parking space and reach its end stop. This also slightly slows the pig down so that it does not hit the docking surface at full speed.

[0013] With regard to the pig, which is considered to be independently inventive, for use in a coating system intended for coating an object with a coating material, in particular according to the design described above, the stated object is achieved by providing the pig with a contoured guide end segment on one of its end faces. This segment is intended in particular to provide the pig-side element of the guide pair and is therefore, according to one aspect of the invention, suitably adapted in its contour and spatial shape to the corresponding element in the parking station.

[0014] In an advantageous embodiment, the guide end segment has a non-circular cross-section whose radius assumes a local maximum value in a number of main directions. Furthermore, and according to one aspect of the invention, the radii of the main directions of the cross-section of the end segment can be at least approximately equal in length, and the angular distance between any two adjacent main directions can be approximately equal, so that the guide end segment has a multi-fold symmetry in cross-section. This allows the pig to be fully inserted into its final parking position in a number of rotational positions corresponding to the number of symmetry.

[0015] In a further advantageous embodiment, considered to be independently inventive, the pig has a number of contour fingers separated by gaps in the region of its guide end segment, wherein a number of channel surfaces arranged in the region of the gaps of the pig's end segment, when the pig is fully inserted into the parking space, each in combination with an associated channel surface arranged in the region of the guide surface, forms an overflow channel for a drive medium for the pig. In this way, the ensemble of the pig's end segment and the end surface of the parking space, in their combination, can be designed in a particularly simple manner for the formation of overflow channels for the drive medium or compressed gas when the pig is in the parking station.By providing such overflow channels, it is possible to ensure that a pressure pulse applied to the end face of the pig not only impacts the front part of the pig that protrudes into the pressure line, but also that the pressure pulse is introduced into an annular space below it in the parking space, where additional contact surfaces are provided for the pressure pulse. Overall, this allows a significantly larger front face of the pig to be subjected to the pressure pulse to "push" the pig, reliably overcoming the breakaway force when the pig is released from its parking position.

[0016] An embodiment of the invention is explained in more detail with reference to a drawing. In the drawing: Fig. 1 a schematic diagram of a coating system, Fig. 2 a pig parking station of the coating system according to. Fig. 1 in longitudinal section, Fig. 3 a pig of the coating system according to Fig. 1 in side view, Fig. 4 the newt after Fig. 3 in perspective view, Fig. 5 the newt after Fig. 3 in frontal view, Fig. 6the newt after Fig. 3 in longitudinal section, Fig. 7 a section of the parking space of the newt parking station according to. Fig. 2 in longitudinal section, Fig. 8 the parking space after Fig. 7 in perspective view, Fig. 9the parking space after Fig. 7 introduced newt after Fig. 3 in a view from the assigned borehole to the pig end, and Fig. 10 a pig introduced into the parking space after Fig. 3 in enlarged longitudinal section.

[0017] Identical parts are provided with the same reference numerals in all figures.

[0018] The Fig. 1 The coating system 1 shown as a schematic diagram, a painting system in the illustrated embodiment, comprises a supply line 2 for conveying a working medium, which in the embodiments described here is paint. Connected to the supply line 2 are, on the one hand, a number of different paint reservoirs 4, each containing paint of different colors, and, on the other hand, a number of removal points 8, each comprising a paint applicator (not shown in detail), for example an atomizer. The paint reservoirs 4, like the removal points 8, are each connected to the interior of the supply line 2 via a feed line 10. Feed pumps 12 are connected to the feed lines 10 as needed to convey the paint from the respective paint reservoir 4 into the supply line.

[0019] In principle, all supply lines 10 can be provided with such feed pumps 12 and / or with suitable shut-off valves for shutting off the respective supply line 10; these are Fig. 1 However, this is not shown. Especially when transporting paints of different colors or otherwise different qualities through the supply line 2 or segments thereof, an intermediate cleaning step may be provided or required between such transports in order to reliably prevent the alternating contamination of individual paint batches. Fig. 1 The system 1 shown is specifically designed for paint recovery technology suitable for frequently used paints. The supply line 2 is filled with the corresponding paint color from one of the paint reservoirs 4, and after the painting process is completed, the remaining paint in the supply line 2 is returned to the corresponding paint reservoir 4.

[0020] In order to enable the necessary passage of a suitable cleaning agent through the supply line 2 or generally the passage of various media through the supply line 2 and also the aforementioned media change at an acceptable cost, the transport of various coating agents, varnishes or other substances and their separation from one another is usually carried out by means of the so-called pigging technology, i.e. by means of suitable separating or blocking means, commonly also referred to as a "pig". The line system 14 formed by the aforementioned components is accordingly designed as a piggable line system 14. Such a pig 20 intended for use in the piggable line system 14, as shown in Fig. 1 in the embodiment shown as a pig package 20 with two pigs 20a, 20b, is an object which can be moved within the supply line 2, is basically approximately circular-cylindrical in shape and is tapered in the middle, which tightly fills the line cross-section and is pressed through the supply line 2 by means of a pushing medium or also by means of a subsequent coating medium and in the process pushes the medium to be expressed in front of it.

[0021] To enable the use of such a pig 20 within the supply line 2 and to be able to insert the pig 20 into the supply line 2 for the purpose of media separation, for example, between two media columns within the supply line 2, a number of catching or parking stations 22 for the pig 20 are connected to the supply line 2. These serve as locks through which the pig 20 can be inserted into and removed from the supply line 2. On the inlet side, the parking stations 22 can each be connected to a reservoir 23 for a thrust medium via supply lines 10 equipped with feed pumps 12.

[0022] Such a parking station 22 for a newt 20, as shown in longitudinal section in Fig. 2 shown, comprises a parking space 26 arranged within a housing 24 for the pig(s) 20. In Fig. 2 a state is shown in which two pigs 20, which together form a pig package, are located in the parking space 26. The parking space 26 is in turn connected to the interior of the supply line 2 via a feed channel 28, so that the pig(s) 20 can be introduced into or removed from the supply line 2 via the feed channel 28. The parking space 26, like the associated feed channel 28, has the same internal cross-section, both in terms of shape and size, as the supply lines 2 of the coating system 1, so that the pig 20 can seal off all of these channels without any problem. Media or control channels can also be incorporated into the housing 24, via which corresponding media flows can be set, for example for handling the pigs 20.In particular, a pressure line 29 is arranged in the housing 24 for supplying a thrust or drive medium, in particular in the form of a pressure pulse, into the parking space 26, with which a pig 20 located in the parking space 26 can be transported into the feed channel 28 and via this into the connected supply line. The pressure line 29 has a smaller inner diameter than the parking space 26, so that an annular end or stop surface 30 for the pig 20 is formed at the point where the pressure line 29 enters the parking space 26.

[0023] When inserting or removing a pig 20 into or from the parking station 22, a number of criteria and boundary conditions must be observed to ensure reliable operation that meets higher demands, particularly with regard to processing speed. On the one hand, when a pig 20 is removed from the supply line 2, i.e., corresponding to the feeding into the parking station 22, it is usually stopped from a comparatively high transport speed, namely that of the respective thrust medium within the supply line 2, and brought into a rest position in the parking station 22. This can lead to a comparatively hard mechanical impact on the end surface 30 of the parking space 26, which is provided as a stop surface, which can cause correspondingly hard and wear-intensive stress on the pig 20, especially in the region of its end surface 32 facing the end surface 30.On the other hand, in the opposite direction, i.e., when inserting the pig 20 from its parking position in the parking station 22 into the supply line 2, a suitable "pushing" of the pig 20 is first necessary to properly convey it into the supply line 2. To do this, the breakaway force of the pig 20 must first be overcome by means of a suitable actuator or drive medium supplied via the pressure line 29, for example, compressed air in the form of a pressure pulse, in order to set it in motion from its parking position. This, as well as the subsequent controlled and guided movement of the pig 20 in the line system, requires a sufficiently tight seal between the end face 32 of the pig 20 and the inner wall of the line system in the area of ​​the end face 30.

[0024] In order to meet these requirements and thus enable high operational reliability of the overall system with a long service life of the components, the coating system 1 as a whole and in particular with regard to the pig 20 used therein is suitably designed according to one aspect of the invention. According to one aspect of the invention, a guide pair 34 is provided between the parking space 26 and the pig 20, which, when the pig 20 is introduced into its parking position and thus shortly before contact with the end face 30, ensures that the pig 20 is centered and rotationally correctly aligned relative to the surrounding housing 24 in its parking position. This ensures that the incoming pig 20, even at high initial speed, strikes the end face 30 in the parking space 26 with a guided movement and thus under controlled conditions, and the resulting load can thus be introduced in a targeted manner.On the other hand, the pig 20 can also be brought into its parking position in such a defined manner that a reliable application of pressure sufficient to overcome the breakaway force, for example with a pressure pulse for discharging from the parking position, can be easily ensured.

[0025] The guide pair 34 is formed by two interacting guide surfaces, one of which is mounted in the area of ​​the end surface 30 of the parking space 26 in the parking station 22 and the other, interacting with the first, on the end surface 32 of the pig 20.

[0026] For further explanation, the Molch 20, which is considered to be independently inventive, is shown in Fig. 3 in side view, in Fig. 4 in perspective view, in Fig. 5 in frontal view and in Fig. 6 shown in longitudinal section. The pig 20 has, as can be seen from the side view in Fig. 3 As can be clearly seen, the connecting line 2 has a waisted base body 40 in which the central constriction 42 forming the waist is surrounded, viewed in the longitudinal direction, by two circumferential annular beads 44, 46 at the ends. The annular beads 44, 46, which are preferably made of sufficiently elastic material, have an approximately circular outer contour in cross-section and are adapted in their dimensions to the inner cross-section of the connecting line 2 in order to ensure the tightest possible seal.

[0027] In the area of ​​its end face 32, which faces the end face 30 of the parking space 26 during operation, the pig 20 is provided with a contoured guide end segment 50, which forms a component of the aforementioned guide pair 34 and is accordingly designed to interact with a corresponding element in the parking station 22. According to one aspect of the invention, the guide end segment 50 has a non-circular cross-section, the radius of which assumes a local maximum value in a number of main directions.

[0028] In cooperation with a corresponding contour in the area of ​​the end surface 30 of the parking station 22, the pig 20 with such an end segment 50 can be fully inserted into the parking position in the manner of a "key-lock configuration" only in a rotationally correctly aligned position relative to the housing 34 of the parking station 22, so that a safely guided positioning is possible.

[0029] In the exemplary embodiment, the end segment 50, as shown in Fig. 4 and in particular the frontal view according to Fig. 5 can be seen, has five main directions. Furthermore, and according to one aspect of the invention, the radii of the main directions of the cross section of the end segment 50 are at least approximately the same length, and the angular distance between any two adjacent main directions is the same, so that in the illustrated embodiment, the end segment 50 has a fivefold symmetry. Generally speaking, according to one aspect of the invention, the cross-sectional geometry of the end segment 50 is designed with multifold symmetry. This means that the pig 20 can be fully inserted into its final parking position in a number of rotational positions corresponding to the number of symmetry.By appropriately selecting further geometric parameters, for example the width of the contour fingers 52 extending along the main directions in relation to the width of the gaps 54 located between the contour fingers 52, it can also be ensured according to further aspects of the invention that the contour fingers 52 can be suitably guided and rotationally aligned in the parking station 22 in any rotational orientation of the pig 20, i.e. in the event of "accidental impact" upon contact with the corresponding counter contour.

[0030] As shown in the longitudinal section in Fig. 6 can be removed, the base body 40 of the pig 20 is itself designed in several parts in a design considered to be independently inventive and comprises two cover or end components 56, 58 as housing parts, which are mounted on both sides in a central, waisted casing body 60. The end component 56 is provided with the aforementioned end segment 50 for providing the aforementioned element of the guide pair 34. In their interior, the plugged-together housing parts 56, 58, 60 enclose an interior space 64 in which suitable functional components of the pig 20 can be reliably accommodated.

[0031] In the exemplary embodiment, according to one aspect of the invention, an RFID chip 66 is arranged in the interior 64 of the pig 20. According to one aspect of the invention, the RFID chip 66 serves to identify the pig 20; the corresponding identifiers can be read out, for example, in an associated reading unit of the coating system 1. This means that in such a configuration, the read-out identifier of the pig 20 can also be used, for example, in a logging format to document and, if necessary, archive the use of the pig 20 or its usage cycles, and, if necessary, to detect or predict a need for replacement.

[0032] Furthermore, a magnet 68 is arranged in the interior 64 of the pig 20. This magnet can be detected by corresponding sensors in the coating system 1 and thus used to determine the position of the pig 20 within the coating system 1.

[0033] On the outside, in the area of ​​the respective connection point of the end components 56, 58 with the casing body 60, there is a circumferential sealing ring 70 made of a solvent-resistant material that is softer than the housing components 56, 58, 60, in this example TPE or rubber. The dimensions of the sealing rings 70 are adapted to the internal cross-sections of the respective lines in the coating system 1, so that they seal against their inner surface without, however, offering excessive frictional resistance that would hinder the process due to excessive deformation, and form the annular beads 44, 46. In this respect, the sealing rings 70 are also suitably profiled and, in a roof-like configuration, have a comparatively pointed maximum point 72 in their cross-section.

[0034] In addition to and corresponding to the contoured end segment 50 of the pig 20, the end surface 30 of the parking station 26 is designed according to one aspect of the invention to form the aforementioned guide pair 34. As can be seen from the partial representation in longitudinal section of the respective line segment in Fig. 7 and the perspective representation in Fig. 8 can be removed, the end surface 30 is provided with a suitably contoured and dimensioned guide surface 80 to provide the corresponding element of the guide pair 34. The guide surface 80 comprises a number of conical surfaces 82 adapted to the number of contour fingers 52 of the pig 20, which are inclined and tapered as a whole from the free end to the end surface 30 of the parking space 26. The conical surfaces 82 thus catch the pig 20 as it enters the parking space 26 and, in cooperation with the contour fingers 52 of the pig 20, ensure a rotation of the pig 20 about its longitudinal axis until it reaches a correct rotational alignment in which it can enter the parking space completely and up to the end stop. This state is shown in Fig. 9 removable.

[0035] In the exemplary embodiment, according to one aspect of the invention, the conical surfaces 82 are adapted in the contouring of their (concave) surfaces to the corresponding (convex) end surface regions of the contour fingers 52 of the pig 20, so that the pig 20, with correct rotational alignment, rests with the end surface regions of its contour fingers 52 on the corresponding conical surfaces 82 of the end surface 30. According to a further aspect of the invention, which is considered to be independently inventive, the ensemble comprising the end segment 50 of the pig 20 and the end surface 30 of the parking space 26, in their combination, is designed to form overflow channels for the drive medium or compressed gas when the pig 20 is located in the parking station 22.

[0036] These overflow channels are formed by channel surfaces 84 arranged in the area of ​​the gaps 54 of the end segment 50 of the pig 20 on the one hand and, in addition, by channel surfaces 86 arranged in the end surface 30 between the conical surfaces 82 on the other hand. When the pig 20 is brought into the parking position in the correct rotational alignment, these channel surfaces 84, 86 in combination create a gas-side connection between the pressure line 29 and the end area of ​​the parking space 26. As can be seen in particular from the enlarged longitudinal section in Fig. 10 This ensures that a pressure pulse supplied via the pressure line 29 not only impacts the front part of the pig 20 protruding into the pressure line 29, but that the pressure pulse is also introduced into the annular space 88 of the parking space 26 located on this side of the first sealing ring 70. Overall, this allows a significantly larger front surface of the pig 20 to be subjected to the pressure pulse to "push" the pig.

[0037] In Fig. 10 For the sake of clarity, the pig 20 located in the parking station 22 is shown in its end segment 50 in six-fold (and thus even-numbered) symmetry, namely in Fig. 10a in longitudinal section in a sectional plane in which the gaps 54 and thus the overflow channels formed by the channel surfaces 84 arranged in their area from the pressure line 29 into the annular space 88 are visible. In contrast, Fig. 10bthe pig 20 located in the parking station 22 in longitudinal section in a sectional plane in which the contour fingers 52 of the end segment 50 abutting the end surface 30 are visible.

[0038] As has been discovered quite surprisingly, this design enables significantly improved deployment of the pig 20 from its parking position. In particular, the breakaway force of the pig 20 when pushed from its parking position can be overcome much better and more controllably. Depending on the contour and dimensioning of the sealing rings 70, possibly with a comparatively high oversize compared to the free internal cross-section of the parking space 26, these can have a comparatively strong preload in the bore of the parking station due to deformation. In conventional systems, when accelerating the pig, the resulting comparatively strong static friction must be overcome by a suitably strong pressure pulse. The pressure may then have to be reduced in order to keep the transport speed within the desired range.In contrast, with the above-described design, which is considered to be independently inventive, a reliable sealing contour with comparatively low oversize can be provided by partially transferring the pressure pulse into the aforementioned annular space 88 and the resulting effectively enlarged effective area of ​​the pressure pulse, which does not exhibit particularly strong static friction during start-up. Under these conditions, the pig 20 can be accelerated and transported at constant pressure. List of reference symbols

[0039] 1Coating system 2Supply line 4Paint reservoir 8Take-off point 10Feed line 12Feed pump 14Pipe system 20Pig 22Pig parking station 24Housing 26Parking space 28Feed channel 29Pressure line 30End face 32End face 34Guide pair 40Base body 42Constriction 44, 46Annular bead 50End segment 52Contour finger 54Gap 56, 58End component 60Shell body 64Interior 66RFID chip 68Magnet 70Sealing ring 72Maximum point 80Guide surface 82Conical surface

Claims

1. Coating system (1) for coating an object with a coating material, with a piggable line system (14) for supplying a take-off point (8) with the coating material, wherein the line system (14) has a number of pig parking stations (22) for temporarily receiving a pig (20) guided in the line system (14), and wherein the or each pig parking station (22) in combination with the pig (20) is provided with a guide pair (34) which, when the pig (20) is fully inserted into a parking space (26) in the parking station (22), effects a predetermined rotational orientation of the pig (20) relative to the parking station (22).

2. Coating system (1) according to claim 1, wherein the or each pig parking station (22) has a guide surface (80) for the pig (20) in the region of the end surface (30) of the parking space (26).

3. Coating system (1) according to claim 2, whose guide surface (80) is formed by a number of conical surfaces (82).

4. Pig (20) for use in a coating system (1) intended for coating an object with a coating material, comprising a piggable line system (14) for supplying a removal point (8) with the coating material, in particular according to one of claims 1 to 3, which is provided on one of its end faces (32) with a contoured guide end segment (50).

5. Pig (20) according to claim 4, whose guide end segment (50) has a non-circular cross-section, the radius of which assumes a local maximum value in a number of main directions.

6. Pig (20) according to claim 4 or 5, whose guide end segment (50) has a multi-fold symmetry in cross section.

7. A pig (20) according to any one of claims 4 to 6, wherein the guide end segment (50) of the pig has a number of contour fingers (52) separated by gaps (54), wherein a number of channel surfaces (84) arranged in the region of the gaps (54) of the end segment (50) of the pig (20) when the pig (20) is fully inserted into the parking space (26) each in combination with an associated channel surface (86) arranged in the region of the guide surface (80) each form an overflow channel for a drive medium for the pig (20).

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