FLUID RESERVOIR HAVING AN OPTIONALLY INSERTABLE INNER BAG

Abstract

A fluid reservoir for a spray gun, which fluid reservoir has a material outlet configured for the direct and/or indirect connection to the spray gun. The fluid reservoir includes a material container and a cover arrangement for closing the material container in a detachable manner. An inner bag is arranged in the material container and can be filled with coating material. The fluid reservoir is configured in such a manner that it can be filled with coating material optionally with or without the inner bag and can be used for dispensing the coating material via the material outlet to the spray gun. A flow cup arrangement includes a flow cup and an inner bag. The inner bag can be used with different flow cups.

Claims

1-23. (canceled)

24. A flow cup for a spray gun, which flow cup has a material outlet that is designed to be directly and/or indirectly connected to the spray gun, wherein the flow cup has a material container and a lid arrangement that detachably closes the material container, wherein an inner bag can be arranged in the material container and can be filled with coating material, wherein the coating material with which the inner bag has been filled can be supplied to the spray gun via the material outlet, wherein the flow cup is designed such that the flow cup can be filled with coating material, and used so as to dispense the coating material via the material outlet to the spray gun, either with or without the inner bag.

25. The flow cup as claimed in claim 24, wherein the flow cup has a ventilation device that can be installed and/or manually actuated by the user, wherein the ventilation device has at least one ventilation opening via which pressure equalization for the interior of the material container is possible when the coating material emerges from the flow cup via the material outlet when the flow cup is used with and without the inner bag, wherein the ventilation device can, at least in one operating state, prevent liquid from emerging from the interior of the material container through the ventilation opening.

26. The flow cup as claimed in claim 24, wherein the flow cup comprises a ventilation device that is arranged on the lid arrangement.

27. The flow cup as claimed in claim 24, wherein the detachable connection between the material container and the lid arrangement is configured such that, when the flow cup is used with the inner bag, the inner bag can be clamped between the material container and the lid arrangement.

28. The flow cup as claimed in claim 24, wherein the detachable connection between the material container and the lid arrangement is configured such that the connection is fluid-tight when the flow cup is used with and without the inner bag.

29. The flow cup as claimed in claim 24, wherein the detachable connection between the material container and the lid arrangement is configured such that the lid arrangement is fastened with a sufficient holding force to the material container when the flow cup is used with and without the inner bag.

30. The flow cup as claimed in claim 24, wherein the fluid-tight seal between the lid arrangement and the material container is realized by means of an axial and/or radial seal when the flow cup is used with the inner bag and is realized by means of an axial and/or radial seal when the flow cup is used without the inner bag.

31. The flow cup as claimed in claim 24, wherein the connection between the lid arrangement and the material container is designed such that the lid arrangement and the material container are connected to one another in fluid-tight fashion in a first position if the inner bag is clamped between the lid arrangement and the material container and are connected to one another in fluid-tight fashion in a second position if no inner bag is clamped between the lid arrangement and the material container.

32. The flow cup as claimed in claim 24, wherein the connection between the lid arrangement and the material container is designed such that, when the flow cup is used with the inner bag, the inner bag is clamped in a radial annular gap between the lid arrangement and the material container, wherein, when the flow cup is used without the inner bag, the lid arrangement and the material container bear radially directly against one another, or are spaced apart from one another, in the region of the radial annular gap.

33. The flow cup as claimed in claim 24, wherein the connection between the lid arrangement and the material container is designed such that, when the flow cup is used with the inner bag, an edge of the inner bag is clamped in an axial annular gap between the lid arrangement and the material container, wherein, when the flow cup is used without the inner bag, the lid arrangement and the material container bear axially directly against one another, or are spaced apart from one another, in the region of the axial annular gap.

34. The flow cup as claimed in claim 24, wherein the lid arrangement is equipped with a receiving groove for an edge region of the material container, wherein a central region, adjoining the receiving groove, of the lid arrangement is designed as a continuation of at least a predominant part of an inner limb of the receiving groove.

35. The flow cup as claimed in claim 24, wherein the lid arrangement is equipped with a receiving groove for an edge region of the material container, which receiving groove is adjoined, radially to the inside, by a compensating ring groove.

36. The flow cup as claimed in claim 24, wherein the connection between lid arrangement and material container is designed as a screw connection.

37. An inner bag for a flow cup, wherein the inner bag has, at an open end side, an encircling edge from which a peripheral wall leads away, which peripheral wall at the opposite end side, is closed or has an outlet projection.

38. The inner bag as claimed in claim 37, wherein the inner bag is produced in a deep-drawing process from plastics material.

39. The inner bag as claimed in claim 37, wherein the inner bag is equipped with at least one fold line, owing to which a vacuum in the interior or an emergence of coating material from the interior of said inner bag causes the inner bag to contract so as to assume a reduced vacuum and/or reduced residual volume.

40. The inner bag as claimed in claim 37, wherein the inner bag is equipped with at least one fold line which results from shaping and/or weakening of the bag wall along the at least one fold line.

41. The inner bag as claimed in claim 37, wherein the inner bag is equipped with at least one fold line which runs in annularly closed or spiral-shaped fashion on the peripheral wall of the inner bag.

42. The inner bag as claimed in claim 37, wherein the inner bag is equipped with multiple annularly closed fold lines which have equal spacings, or spacings which increase or decrease in a longitudinal direction of the inner bag, to one another.

43. The inner bag as claimed in 37, wherein the inner bag is of bellows-like design.

44. The inner bag as claimed in claim 37, wherein the inner bag, opposite the open end side, is closed with a smooth base or is equipped with a funnel-like outlet projection.

45. A flow cup arrangement comprising the flow cup as claimed in claim 24 and an inner bag, wherein the inner bag has, at an open end side, an encircling edge from which a peripheral wall leads away, the peripheral wall at an opposite end side is closed or has an outlet projection.

46. A flow cup arrangement comprising the flow cup as claimed in claim 24, wherein the flow cup arrangement further comprises a replacement element which can be clamped between the lid arrangement and the material container instead of an inner bag in order for the flow cup to be used without an inner bag.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The invention will be discussed below on the basis of exemplary embodiments. In the figures:

[0073] FIG. 1 shows a sectional illustration of a spray gun with a flow cup arrangement according to a first exemplary embodiment of the invention,

[0074] FIG. 2 shows a side view of an optionally insertable inner bag for the flow cup as per FIG. 1,

[0075] FIG. 3 shows a side view of an annular sealing element that can be inserted instead of the inner bag as per FIG. 2 in a flow cup as per FIG. 1,

[0076] FIG. 4 shows a sectional illustration of a flow cup arrangement according to a second exemplary embodiment of the invention,

[0077] FIG. 5 shows a sectional illustration of an optionally insertable inner bag for the flow cup as per FIG. 4,

[0078] FIGS. 6 and 7 show an enlarged sectional illustration of the connection of lid arrangement and material container of the flow cup as per FIGS. 1 and 4 with and without inner bag clamped therein, and

[0079] FIGS. 8 to 10 show schematic side views for illustrating variants of optionally insertable inner bags for the flow cup as per FIG. 4.

DETAILED DESCRIPTION

[0080] FIG. 1 shows a handheld spray gun 1 for atomizing and applying a flowable coating material with the assistance of compressed air. The spray gun 1 may be configured for example as a so-called high-pressure, compliant or HVLP spray gun 1. The spray gun 1 has a cup attachment 2 and a nozzle head 3, at which coating material supplied to the spray gun 1 via the cup attachment 2 is atomized and emerges in the form of a spray jet.

[0081] The spray gun 1 furthermore comprises a handle 4, a trigger 5 for actuating a material needle 10 arranged in the interior of the spray gun 1, a setting mechanism 6 for the stroke of the material needle (material flow rate regulation), an air pressure setting device 7 (micrometer), a round/flat jet setting device 8, and a compressed air attachment 9. The round/flat jet setting device 8 can be used to vary the distribution of the supplied compressed air between, for example, atomizing and transport air, on the one hand, and horn air for forming a flat jet, on the other hand.

[0082] A flow cup arrangement 11 is connected by means of a material outlet, in the form of an outlet connector 12, to the cup attachment 2 of the spray gun 1. For this purpose, the outlet connector 12 is equipped with attachment means in the form of a bayonet fastener, which comprise a clamping wedge element 13 that projects radially from the outlet connector 12. The clamping wedge element 13 engages into a corresponding receiving groove 14 on the spray gun 1. The outlet connector 12 seals axially, for example by way of its end surface 15, against the cup attachment 2 (optionally via a clamping ring on the inner bag, FIG. 2) and/or radially by way of two encircling radial sealing lips 16 (scarcely visible in FIG. 1 owing to the proportions).

[0083] The flow cup arrangement 11 comprises a flow cup 17 and an inner bag 18 arranged in the flow cup 17. The flow cup 17 has a material container 19, on the base of which the outlet connector 12 is formed. The flow cup 17 furthermore comprises a lid arrangement, in the form of a screw-type lid 20, which closes the material container 19.

[0084] FIG. 2 shows the inner bag 18 once again on its own. Said inner bag is produced for example from plastics material in a deep-drawing process.

[0085] An edge 21 of the inner bag 18 is clamped between the screw-type lid 20 and the material container 19. A tubular peripheral wall 22, which lines the interior of the material container 19, extends from the edge 21 of the inner bag 18. At the side opposite the edge 21, the peripheral wall 22 transitions into a funnel-shaped outlet projection 23, which is adapted in terms of shape to the material passage of the outlet connector 12 and which lines and is led through said outlet connector. The open end of the outlet projection 23 is equipped with an encircling clamping ring 24, by means of which the outlet projection 23 is fixed to the end surface 15 of the outlet connector 12.

[0086] It can be seen from FIG. 1 that a disk-shaped screen element 25 is inserted in the interior of the inner bag 18, through which screen element the coating material must pass before it can exit the inner bag 18 via the outlet connector 12. As an alternative to the disk-shaped screen element 25, a tubular screen element may be used which is inserted into the outlet connector 12 on the cup and/or is inserted into the cup attachment 2 on the gun.

[0087] The flow cup 17 as per FIG. 1 is designed as a standard flow cup. It can be filled with coating material either with or without the inner bag 18 and used for dispensing the coating material via the material outlet to the spray gun 1.

[0088] This is made possible in particular by virtue of the fact that the detachable connection 26 between material container 19 and screw-type lid 20 is configured such that, when the flow cup 17 is used with inner bag 18, the inner bag 18 is clamped between the material container 19 and the screw-type lid 20, wherein the screw-type lid 20 is fastened with a sufficient holding force to the material container 19 and the connection is fluid-tight. The connection is however additionally firm and fluid-tight even when the flow cup 17 is used without inner bag 18.

[0089] FIG. 3 shows an annular sealing element 27 that can be installed between screw-type lid 20 and material container 19 instead of the inner bag 18 in order to ensure that the connection between screw-type lid 20 and material container 19 is fluid-tight even when the inner bag 18 is not used. The sealing element 27 corresponds in terms of shape to the edge portion of the inner bag 18. Said sealing element comprises an identically configured edge 28 and a sealing collar 29, which in FIG. 3 projects downward.

[0090] In the case of the flow cup 17 as per FIG. 1, it is however advantageously not necessary to install the annular sealing element 27 during use without inner bag 18, because the screw-type lid 20 and the material container 19 are designed so as to also be connectable directly to one another in fluid-tight fashion. The design of the connection 26 between the screw-type lid 20 and the material container 19 will be discussed in more detail further below on the basis of FIGS. 6 and 7.

[0091] It can be seen from FIG. 1 that a central region 30 of the screw-type lid 20 is equipped with a ventilation device. The ventilation device is designed as a cartridge valve 31.

[0092] The cartridge valve 31 allows pressure equalization in the interior of the flow cup 17 when coating material flows out of the flow cup 17 via the outlet connector 12 or the outlet projection 23 of the inner bag 18. In the case of this flow cup arrangement 11, it is not necessary for the inner bag 18 to contract when coating material is dispensed to the spray gun 1.

[0093] The cartridge valve 31 has a manually actuatable closure element in the form of a closure cap 32, by means of which a ventilation opening 33 in the terminating wall 34 of the screw-type lid 20 can be closed. The closure cap 32 is movable perpendicularly with respect to the terminating wall 34 between an open position and a closed position. In the open position, air can flow through the ventilation opening 33 into the interior of the flow cup 17. In the closed position, a closure plug on the closure cap 32 closes the ventilation opening 33, such that air cannot enter the flow cup 17, nor can coating material emerge from the flow cup 17, via the ventilation opening 33.

[0094] The closure cap 32 can be installed or uninstalled by a user in accordance with requirements.

[0095] FIG. 4 shows a second exemplary embodiment of a flow cup arrangement 11 with a flow cup 17 and an inner bag 18 arranged therein. Overall, the flow cup 17 according to the second exemplary embodiment is, by contrast to the flow cup 17 as per FIG. 1, designed as an upside-down flow cup. The screw connection 26 between screw-type lid 20 and material container 19, the cartridge valve 31 and the attachment means on the outlet connector 12 are however of identical design to the corresponding components of the flow cup arrangement 11 as per FIG. 1.

[0096] By contrast to the first exemplary embodiment, the outlet connector 12 is arranged on the screw-type lid 20, and the cartridge valve 31 is arranged on the base 37 of the material container 19. A screen element receptacle 36 for a flat, disk-like screen element (not shown) similar to the screen element 25 shown in FIG. 1 is provided in the screw-type lid 20. As an alternative to a flat screen element, a tubular plug-in screen may be used which may be fastened in the outlet connector 12 or, on the spray gun, in the cup attachment 2.

[0097] FIG. 4 illustrates the cartridge valve 31 in a closed position. Before the flow cup 17 is used with an inner bag 18, the cartridge valve 31 must be opened in order that air can flow into the space between inner bag 18 and material container 19 whilst the inner bag 18 contracts as a result of coating material emerging from the interior thereof. The closure cap 32 of the cartridge valve 31 may also be uninstalled entirely beforehand.

[0098] It can be seen from FIG. 4 that the base 37 is, on the inside, substantially smooth with an inward bulge extending uniformly across the entire base 37. This measure is advantageous in particular for unhindered and complete mixing of coating material in the flow cup 17. That point on the inwardly bulged base 37 which projects furthest to the inside owing to the inward bulge has an offset or a depth in relation to the outer edge region of the base 37 of 1% to 4%, more specifically of 2% to 3%, of the diameter of the base 37. In the exemplary embodiment shown, the diameter is for example d=84.6 mm, and the offset is for example V=2.0 mm.

[0099] The inwardly bulged base 37 is adjoined by a peripheral wall 38 of the material container 19. The peripheral wall 38 is of conical design, specifically to such an extent that the base 37 (despite the bulge) adjoins the peripheral wall 38 at an angle of greater than 90°. In the exemplary embodiments shown, there is an angle of approximately 92°.

[0100] The inner bag 18 is designed analogously, and is shown once again separately in FIG. 5. Like the inner bag 18 as per FIG. 2, the inner bag 18 has an edge 21 by means of which said inner bag can be clamped between the screw-type lid 20 and material container 19. The peripheral wall 22 and the base 39 of the inner bag 18 are designed to replicate the material container 19, such that the inner bag 18, when installed in the interior, substantially fully lines the interior space of the material container 19 and bears closely against the walls of the material container 19. The base 39 of the inner bag 18 is consequently likewise equipped with an inward bulge that extends uniformly across the entire base 39. The peripheral wall 22 widens (slightly) in conical fashion from the base 39 to the edge 21.

[0101] The flow cups 17 according to the first and second exemplary embodiments are preferably produced from plastics material in a plastics material injection molding process, wherein the screw-type lids 20 and the material containers 19 are in each case formed as a single piece, aside from the closure cap 32 and the screen elements 25. Alternatively, the components may also be assembled from multiple components, and in particular, the material outlet (outlet connector 12) may be produced as a separate component and inserted into the rest of the lid arrangement or the rest of the material container.

[0102] In an exemplary embodiment which is not shown, one or more closure caps and/or one or more screen elements may also be produced as a single piece with the screw-type lid 20 or the material container 19. For example, they may be attached at any desired location by means of tearable webs, lugs, film hinges etc. that can be severed in order for the elements to be installed at some other location.

[0103] The material containers 19 are for example produced from polypropylene (PP), and the screw-type lids 20 are for example produced from hard polyethylene or high-density polyethylene (HDPE) or polypropylene (PP). The closure cap 32 is for example likewise produced from hard polyethylene or high-density polyethylene (HDPE) or polypropylene (PP).

[0104] The flow cups 17 according to the invention are preferably extremely thin-walled products. For example, the wall thickness of the material container 19 lies in the range from 0.55 mm to 0.65 mm, and is specifically approximately 0.60 mm, and the wall thickness of the screw-type lid 20 lies in the range from 0.50 mm to 0.85 mm, and is specifically 0.60 mm. The only exceptions are material accumulations at local locations, for example for the purposes of forming thread flanks, detent and grip edges, or at the outlet connector 12, in particular for the purposes of forming the clamping wedge element 13.

[0105] Preferably, the screw-type lid 20 of the first exemplary embodiment and the material container 19 of the second exemplary embodiment are produced in an injection-molding process in which the gate point of the components is situated in each case as centrally as possible on the inwardly bulged terminating wall (base 37, central region 30). In order to make this possible, the ventilation device is arranged in a slightly eccentric position. Said ventilation device is arranged with an offset with respect to the center of the terminating wall of more than 5% but less than 10% of the diameter of the terminating wall 34.

[0106] In FIG. 4, the gate point on the base 37 of the material container 19, which simultaneously corresponds to the location at which the inward bulge is at a maximum, is situated adjacently to the left of the ventilation opening 33 and is denoted by the reference designation 40. In the exemplary embodiment shown, the offset between the eccentric ventilation opening 33 and central gate point 40 is 5.50 mm, which corresponds to 6.50% in the case of a diameter of the base 37 of 84.6 mm.

[0107] The screw connection 26 between the screw-type lid 20 and the material container 19 will be described in more detail below on the basis of FIGS. 6 and 7. FIGS. 6 and 7 show an enlarged detail of the structurally identical connecting point both of the flow cup 17 as per FIG. 1 and of the flow cup 17 as per FIG. 4.

[0108] FIG. 6 shows the connection 26 with the inner bag 18 clamped therein. The screw-type lid 20 and the material container 19 assume a first rotational position relative to one another. FIG. 7 shows the connection 26 without an inner bag 18 clamped therein. The screw-type lid 20 and the material container 19 assume a second rotational position relative to one another.

[0109] The edge region of the material container 19 is equipped with a turned-over portion 41 which is stiffened by means of multiple radial transverse ribs. The transverse ribs end approximately flush with the outer edge of the turned-over portion 41. The turned-over portion 41 has an outer limb, a middle connecting web, and an inner limb. The inner limb transitions into the peripheral wall 38 of the material container 19. FIGS. 6 and 7 show a section through a radial transverse rib that is formed as a single piece with the outer and inner limbs and with the middle connecting web. The dashed lines in FIGS. 6 and 7 indicate the course of the outer and inner limbs and of the middle connecting web. Four thread elements in the form of thread webs 42 are provided on the outer side of the outer limb of the turned-over portion 41.

[0110] The edge region of the screw-type lid 20 has a receiving groove 43, which is likewise formed by an outer limb, a middle connecting web, and an inner limb. When the flow cup 17 is in the closed state, the receiving groove 43 encompasses the turned-over portion 41 in the edge region of the material container 19.

[0111] In the interior of the receiving groove 43, more specifically on the inner side of the outer limb, there are formed four thread webs 44 which, together with the thread webs 42 on the material container 19, form the multi-threaded screw connection 26. All four thread webs 44 begin approximately at the lower edge of the outer limb and transition into the middle connecting web that forms the base of the receiving groove 43. The thread webs 44 therefore partially overlap in a peripheral direction but are offset axially with respect to one another in the region of overlap.

[0112] With a clamped inner bag 18 (FIG. 6), the fluid-tight seal is realized between screw-type lid 20 and material container 19 by way of encirclingly sealing radial and axial contact in the interior of the receiving groove 43. Specifically, the radial seal is realized by virtue of the peripheral wall 22 of the inner bag 18 being clamped in a radial annular gap 48 between the outer side of the inner limb of the receiving groove 43 and the inner side of the inner limb of the turned-over portion 41 of the material container 19.

[0113] The axial seal is realized by virtue of the edge 21 of the inner bag 18 being clamped in an axial annular gap 49 between the top side of the middle connecting web of the turned-over portion 41 and the bottom side of the middle connecting web of the receiving groove 43, whereby an end stop for the screw-type closing movement between screw-type lid 20 and material container 19 is also formed. In FIG. 6, the screw-type lid 20 and the material container 19 assume a first position relative to one another defined by said end stop, in which first position the fluid-tight seal and a sufficient holding force between said screw-type lid and material container, in the presence of a clamped inner bag 18, are ensured.

[0114] Without a clamped inner bag 18 (FIG. 7), the fluid-tight seal is likewise realized between screw-type lid 20 and material container 19 by way of encirclingly sealing radial contact in the interior of the receiving groove 43. Specifically, the radial seal is realized by virtue of the outer side of the inner limb of the receiving groove 43 and the inner side of the inner limb of the turned-over portion 41 being pressed directly against one another with sealing action.

[0115] In the exemplary embodiment shown, an axial seal is additionally realized by virtue of the top side of the middle connecting web of the turned-over portion 41 and the bottom side of the middle connecting web of the receiving groove 43 being pressed sealingly against one another, whereby an end stop for the screw-type closing movement between screw-type lid 20 and material container 19 is also formed. In FIG. 7, the screw-type lid 20 and the material container 19 assume a second position relative to one another defined by said end stop, in which second position the fluid-tight seal and a sufficient holding force between said screw-type lid and material container, without a clamped inner bag 18, are ensured.

[0116] An important aspect of the exemplary embodiment shown is that the thickness of the edge 21 of the inner bag 18, the thickness of the peripheral wall 22, the conicity of the upper cup edge of the material container 19 and the conicity of that portion of the screw-type lid 20 which interacts therewith are coordinated with one another such that a sufficient axial 49 and radial annular gap 48 for receiving the inner bag 18 between the screw-type lid 20 and the material container 19, and also a fluid-tight seal, are formed during use with inner bag 18, and it is nevertheless the case that a fluid-tight seal is likewise formed between the screw-type lid 20 and the material container 19 without inner bag 18.

[0117] In an exemplary embodiment which is not shown, the additional axial seal may be omitted. In this case, it is for example possible for the top side of the middle connecting web of the turned-over portion 41 to nevertheless come into contact with the bottom side of the middle connecting web of the receiving groove 43 without forming an encirclingly fluid-tight seal, but with the contact still forming an end stop for the screw-type closing movement between screw-type lid 20 and material container 19.

[0118] By way of example, FIGS. 6 and 7 show three encircling sealing ribs 47, which are formed on the outer side of the inner limb of the receiving groove 43 and which lead to a further intensification of the sealing action. Furthermore, the sealing action is improved by virtue of the inner diameter of the material container 19 in the upper edge region being selected such that, as the screw-type lid 20 is installed, the material container 19 is spread open at least in the region of the turned-over portion 41, thus resulting in a particularly intense and lasting radial pressing action between the screw-type lid 20 and material container 19, which is further intensified during use with inner bag 18.

[0119] It is self-evident that further sealing ribs, lips or beads may alternatively or additionally also be formed at some other location in order to intensify the ceiling action. Alternatively, it is for example also possible for only one axial or only one radial seal to be realized between screw-type lid 20 and material container 19.

[0120] The central region 30 of the screw-type lid 20 is designed as a continuation of the inner limb of the receiving groove 43. FIGS. 6 and 7 show only an outer portion of the central region 30. In particular, the inner limb is followed by a first annular portion, which extends at least approximately perpendicularly with respect to the receiving groove 43. The annular portion is followed by a second annular portion which runs at least approximately parallel to the inner limb of the receiving groove 43, specifically such that a compensating ring groove 45 is formed which is open in the opposite direction in relation to the receiving groove 43. For example, manufacturing tolerances of the components can be compensated by means of the compensating ring groove 45, in particular in order to ensure the functionality, strength and sealing action of the screw connection 26. Furthermore, desired support or rigidity of the inner limb of the receiving groove 43 can be defined by way of the dimensioning of the compensating ring groove 45.

[0121] Modified embodiments of the inner bag 18 for the flow cup 17 as per FIG. 4 will be discussed on the basis of FIGS. 8 to 10. The inner bag 18 may advantageously be equipped with at least one fold line 46, owing to which the inner bag 18 contracts, so as to assume a reduced vacuum and/or reduced residual volume, when a vacuum prevails in the interior of said inner bag or coating material emerges from the interior of said inner bag. The fold line 46 or multiple fold lines 46 may be introduced for example by way of a material variation (by thermal, mechanical or chemical means). For example, the wall thickness of the inner bag 18 may be reduced along the fold line 46.

[0122] FIG. 8 shows an inner bag 18 equipped with encirclingly closed fold lines 46. By way of example, four fold lines 46 are illustrated which are introduced by means of deformations in the peripheral wall 22, with the specific form of the deformation being slightly different in each case. In preferred variants, multiple fold lines 46 which are however of the same type are provided on an inner bag 18.

[0123] In FIG. 8, further fold lines 46 are depicted merely by dashed lines in order to illustrate how fold lines 46 may be provided in a manner distributed along the peripheral wall 22. In the example shown, the fold lines 46 are spaced apart equidistantly. The spacings of the fold lines 46 may however increase or decrease from bottom to top in FIG. 8.

[0124] FIG. 9 shows an inner bag 18 equipped, by way of example, with one spiral-shaped fold line 46. Finally, FIG. 10 illustrates a variant of an inner bag 18, the peripheral wall 22 of which is designed as a paper-lantern-like tube owing to criss-crossing rhomboidal fold lines 46. The base (not shown) is for example closed and smooth. The edge 21, connected to the peripheral wall 22, of the inner bag 18 is indicated merely by dashed circles in FIG. 10.

[0125] The edges 21 of all inner bags 18 shown have a wall thickness of 0.5 mm to 0.7 mm. The wall thicknesses of the peripheral walls 22 are 0.1 mm to 0.3 mm. All inner bags 18 shown are collapsible in a flexible manner but have sufficient intrinsic rigidity that they nevertheless stand in a stable manner, that is to say do not collapse or buckle in the absence of external forces. The inner bags 18 are produced from a fluid-tight, in particular solvent-resistant plastics material. Preferably, the inner bags are produced from a deep-drawable plastics material film and/or from PE (for example LDPE), PP, PET, a similar plastics material or a mixture of these plastics materials.

[0126] Aside from the inner bag 18 as per FIG. 10, all illustrated inner bags 18 are substantially rotationally symmetrical with respect to their longitudinal axis.

[0127] The flow cup 17 according to the invention, and the spray gun 1 equipped therewith, are suitable for atomizing and applying a very wide range of different materials. A main field of use is painting in the automobile repair sector, in which finishing paint, filler and clear lacquer are used, and in which the atomization and the properties of the spray jet are subject to very stringent requirements. It is however also possible for numerous other materials to be processed using the flow cup 17 and a possibly modified spray gun 1. It is essential that the materials are flowable and are sprayable at least to a certain extent.