Fluid reservoir for a paint spray gun with screw cap and screw cap or material container of such a fluid reservoir
Patent Information
- Application Number
- EP2024703976
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-03-23
- Filing Date
- 2024-02-07
- Publication Date
- 2026-01-28
AI Technical Summary
Existing flow cups for paint spray guns face issues with sealing effectiveness due to material pairings that cause stick-slip effects and increased friction, particularly when both parts are made of polypropylene, leading to unreliable connections and potential for paint residue spattering during assembly and disassembly.
A flow cup design featuring a circumferential sealing element that forms a flat contact between the screw cap and material container, with a sealing element width greater than its height, and a contact area that is wider than the sealing element height, providing improved sealing and reduced friction, thus enhancing the screwing behavior and fluid-tight connection.
The design ensures a functionally reliable seal even under excess pressure, reduces the effort required for screwing, and prevents unwanted deformations during demolding, resulting in a more stable and efficient connection between the screw cap and material container.
Smart Images
Figure EP2024053039_26092024_PF_FP
Abstract
Description
[0001] Gravity cup for a paint spray gun with screw cap and screw cap or material container of such a gravity cup
[0002] The invention relates to a flow cup for a paint spray gun, which has a material outlet which is designed for direct and / or indirect connection to a paint spray gun, wherein the flow cup has a material container with an inner material container surface and a screw cap closing the material container as well as a flow cup longitudinal axis, wherein during the detachable and fluid-tight connection of the material container and the screw cap to form a screw connection, an upper edge region of the material container is to be arranged in a receiving groove on the screw cap.
[0003] Furthermore, the invention relates to a screw cap or a material container of such a flow cup.
[0004] A gravity feed cup of the type mentioned above is disclosed, for example, in DE102020120226 A1. The cup described therein comprises a material container and a lid with which the material container can be closed. In order to use the cup with a paint spray gun, the material container is first filled with a coating material to be applied. The material container filled with the coating material is then closed using the lid. For this purpose, the lid is placed on the material container, with the upper edge of the material container being inserted into a receiving groove in the lid. The gravity feed cup known from DE102020120226 A1 is a cup with a screw lid, i.e. the lid is mounted on the material container by a rotating movement.A screw connection holds the lid on the material container, creating a fluid-tight connection between the material container and the lid after screwing.
[0005] The gravity-feed cup has a material outlet. In the case of DE102020120226 A1, the material outlet is located on the lid. This is a so-called upside-down gravity-feed cup, which is mounted on the paint spray gun with the lid facing down. Due to the effect of gravity, the coating material flows from the material container through the material outlet on the lid into the paint spray gun. In compressed air-atomizing paint spray guns, the coating material is additionally drawn from the cup to the nozzle by a vacuum created at the atomizing nozzle.
[0006] In this context, it is also advantageous that the lid is designed as a screw cap, since, unlike a snap-on connection, a screw connection is characterized by its high robustness against transverse forces caused by impacts or very rapid pivoting movements. Furthermore, the assembly and disassembly of a snap-on lid causes vibrations in the lid and the material container, which in turn increases the risk of uncontrolled, sudden detachment of paint residue from the surface of the lid or material container and the associated splashing. A screw cap, on the other hand, can be repeatedly and smoothly assembled and removed without vibration.
[0007] The present invention aims to improve the screwing behavior between the screw cap and the material container.
[0008] The problem is solved by a gravity cup having the features of claim 1.
[0009] The flow cup according to the invention for a paint spray gun has a material outlet which is designed for direct and / or indirect connection to a paint spray gun. The flow cup has a material container with a screw cap closing the material container and a flow cup longitudinal axis. During the detachable and fluid-tight connection of the material container and screw cap, forming a screw connection, an upper edge region of the material container is arranged in a receiving groove on the screw cap. The flow cup according to the invention is characterized in that a circumferential sealing element is provided which protrudes from the upper edge region of the material container and comes into flat, sealing contact with a sealing surface of the screw cap.
[0010] It is known from the prior art that sealing elements are provided on the screw cap, forming one or more narrow, circumferential sealing lines between the screw cap and the material container. It is known that the sealing effect deteriorates when the sealing surface between two difficult-to-deform materials is enlarged, which is why experts in such cases typically use sealing elements with a narrow sealing line.
[0011] It has been shown that negative effects occur when sealing elements with a narrow sealing line known from the prior art are used in different material pairings between the screw cap and the material container. Such material pairings therefore had to be avoided until now, even if they were advantageous for other reasons. Because the sealing element according to the invention is designed to form a flat contact between the screw cap and the material container, such negative side effects of unsuitable material pairings can be avoided. For example, so-called stick-slip effects can be prevented, which occur with different material pairings and / or increased friction between the screw cap and the material container can be prevented, as can be the case, for example, when both parts are made of polypropylene.
[0012] A gravity feed cup according to the invention for a paint spray gun can be designed as a conventional gravity feed cup, which has the material outlet on the underside of the material container and is closed on its top with the screw cap. Such a conventional gravity feed cup is filled with material to be atomized when the gravity feed cup is mounted on the paint spray gun. Alternatively, the gravity feed cup can be designed as a so-called upside-down gravity feed cup, which has its material outlet on the screw cap and preferably an air valve for air equalization on the opposite cup base. Such upside-down gravity feed cups are placed on a base with the underside of the material container facing up for filling, after which the material container is filled and the screw cap is mounted.Next, the paint spray gun is turned with its cup connection on top so that the cup connection is facing down. The paint spray gun is then connected to the cup connection on the screw cap. The paint spray gun, with the gravity feed cup installed, is then turned so that the upside-down gravity feed cup is on top of the paint spray gun.
[0013] Preferably, the sealing element protrudes from the inner surface of the material container and forms a flat, sealing contact with an outward-facing sealing surface of the screw cap. Because the sealing element is located on the inner surface of the material container, the screw cap is spread open during installation on the material container, resulting in a functionally reliable seal between the screw cap and the material container, which also functions reliably in the event of overpressure developing in the gravity feed cup. Furthermore, an injection-molded part with such a positioned seal can be forced demolded particularly easily.
[0014] In a particularly preferred embodiment, the circumferential sealing element has a sealing element width that runs in the direction of the gravity cup longitudinal axis and along the inner surface of the material container. Furthermore, the sealing element has a sealing element height by which the sealing element protrudes from the inner surface of the material container in the radial direction to the gravity cup longitudinal axis. In this case, the sealing element width is greater than the sealing element height. Particularly preferably, the sealing element width is at least 1 / 3 greater than the sealing element height; in particular, the sealing element width is at least twice the sealing element height. In this case, the sealing element width is smaller than the length of a sealing element setback by which the sealing element is set back from the front side of the upper edge region of the material container.Appropriate dimensioning allows for a particularly rigid geometry of the sealing element, resulting in easier demolding and tighter manufacturing tolerances in the sealing area. This improves the sealing situation between the material container and the screw cap, as fewer unwanted deformations of the sealing element occur during forced demolding, which would negatively affect the sealing behavior.
[0015] Insofar as the sealing element height is concerned, the sealing element height is understood to be the extension of the sealing element in the radial direction to the gravity cup longitudinal axis from the inner surface of the material container up to the point at which the outer surface is at its maximum distance from the adjacent inner surface of the material container in the radial direction to the gravity cup longitudinal axis. Insofar as the sealing element width is concerned, the sealing element width is understood to be the width of the sealing element at the base of the sealing element. It is therefore the longitudinal extent over which the sealing element extends in the direction of the gravity cup longitudinal axis along the inner surface of the material container, with the beginning and end of the sealing element being formed by the transition between the inner surface of the material container and the flanks of the sealing element which are inclined thereto. In this area, the sealing element extends over its maximum length in the direction of the gravity cup longitudinal axis.
[0016] It is particularly advantageous if the sealing element has a contact area where the sealing element rests against the sealing surface of the screw cap. The width of the contact area in the direction of the gravity cup's longitudinal axis is greater than the sealing element's height. In particular, the width of the contact area is greater than 1.5 times the sealing element's height. Such a ratio between the width of the contact area and the sealing element's height results in a larger contact area compared to a conventional sealing element while simultaneously ensuring high stability of the sealing element in the direction of the gravity cup's longitudinal axis. This improves the sliding properties and the sealing effect between the screw cap and the material container.Due to the improved sliding properties, the screw cap can be screwed onto the material container with significantly less force than is the case with conventional gravity feed cups, which have a particularly small contact area between the screw cap and the material container.
[0017] With regard to the contact area, the contact area is understood to be the area in which the sealing element rests against the opposite sealing surface of the screw cap when the screw cap is screwed fluid-tight onto the material container. The contact area can be either flat or curved in such a way that only the elasticity of the materials used creates a correspondingly large contact area between the sealing element or the contact area of the sealing element and the sealing surface of the screw cap. The width of the contact area in the direction of the gravity feed cup's longitudinal axis is understood to be the extent of the contact area in the direction in which the sealing element of the material container and the sealing surface of the screw cap actually touch.
[0018] Advantageously, the sealing element has a contact area against which the sealing element rests on the screw cap, which is designed to be so flat that the width of the contact area in the direction of the gravity cup longitudinal axis, in which the sealing element comes into contact with the sealing surface when the material container and screw cap are connected in a fluid-tight manner, is greater than 1 / 3 of the sealing element width in the direction of the gravity cup longitudinal axis. Particularly preferably, the width of the contact area is smaller than the sealing element width, in particular smaller than half the sealing element width. Such a length ratio between the contact area and the sealing element width leads to a particularly large contact surface in relation to the sealing element width, wherein the flanks of the sealing element, which extend between the contact area and the inner surface of the material container, have a particularly advantageous bevel that can be easily demolded.
[0019] Preferably, the angle of inclination of the tangent of a sealing element outer surface facing the gravity cup longitudinal axis over the sealing element width relative to the material container inner surface in a region of at least 1 / 3, in particular at least 1, of the sealing element width is less than 15°, in particular less than 7°. In this case, the sealing element outer surface can extend in the direction of the gravity cup longitudinal axis over a larger area than the contact area. In this case, the sealing element outer surface can, for example, have a convex curvature which has a larger radius of curvature in the central region relative to the gravity cup longitudinal axis than in the outer regions of the sealing element outer surface. In a further embodiment, the sealing element outer surface can also be designed in the form of a flat plane in the central region and essentially parallel to the material container inner surface in the direction of the gravity cup longitudinal axis.In this embodiment, the outer regions can be convex or concave, or even in the form of a flat plane that connects the contact area to the inner surface of the material container. Such a configuration also results in an enlarged contact area between the sealing element and the sealing surface of the screw cap, thus also improving sliding behavior between the material container and the screw cap. Preferably, the region in which the pitch angle is below 15° or below 7° is located in the central region of the sealing element relative to the longitudinal axis of the gravity cup, adjacent to which outer regions with a different pitch angle adjoin on both sides.
[0020] Insofar as the angle of inclination of the tangent relative to the longitudinal axis of the gravity cup is referred to, this is to be understood as the acute angle between the inner surface of the material container and a tangent lying in the same plane as the longitudinal axis of the gravity cup, whereby the tangent is applied in the manner of a curve discussion to the outer surface of the sealing element over the course of the outer surface of the sealing element in the direction of the longitudinal axis of the gravity cup and thus changes over the course of the outer surface of the sealing element in the direction of the longitudinal axis of the gravity cup, since the sealing element protrudes from the inner surface of the material container as intended.If an area of the sealing element outer surface is designed parallel to the material container inner surface in the direction of the gravity cup longitudinal axis, the pitch angle in this area is 0° and only changes at the transition to the outer areas if these are designed in the form of a flat surface, or within the outer areas if these are concave or convex.
[0021] In a particularly preferred embodiment, the sealing element outer surface has a contact area, a sealing element upper flank connected to the contact area in the direction of the material outlet, and a sealing element lower flank connected to the contact area in the opposite direction. The pitch angle of the tangent of the sealing element lower flank along its path in the direction of the gravity cup longitudinal axis is smaller than the pitch angle of the sealing element upper flank. The sealing element lower flank and the sealing element upper flank form the previously described outer regions of the sealing element outer surface. Particularly preferably, the sealing element upper flank is smaller in the direction of the gravity cup longitudinal axis than the length of the sealing element lower flank. Such a configuration allows for particularly easy forced demolding of the sealing element due to the reduced slope of the sealing element lower flank.
[0022] Preferably, the material container is formed in the upper edge region by a fold-over section, which has an inner fold-over leg located radially inward relative to the longitudinal axis of the gravity cup and an outer fold-over leg located radially outward relative to the longitudinal axis of the gravity cup. The inner fold-over leg and outer fold-over leg are connected to one another at the end face of the upper edge region via a radially extending connecting web, with the opposite side of the fold-over section being open. Preferably, the inner fold-over leg and outer fold-over leg are connected to one another along their circumference several times by stiffening ribs extending radially relative to the longitudinal axis of the gravity cup, which extend from the connecting web toward the upper edge region of the material container.The stiffening ribs can be connected to the inner roll-over leg or the outer roll-over leg over a different length in the direction of the gravity cup's longitudinal axis. Accordingly, the underside of the stiffening ribs, which faces away from the screw cap, is designed at an angle to the radial direction of the gravity cup's longitudinal axis, preferably at an angle greater than 45° to the radial direction. This design stabilizes the upper edge area of the material container, while the inner roll-over leg and the outer roll-over leg remain decoupled from each other in such a way that both can move independently of each other.
[0023] It is particularly advantageous if the stiffening ribs are connected to the inner leg of the fold-over section over a shorter length in the direction of the longitudinal axis of the gravity cup than to the outer leg of the fold-over section. It is particularly advantageous if the stiffening ribs on the inner leg of the fold-over section end before the area in which the sealing element is provided on the inner surface of the material container, thus forming a stiffening rib clearance. Thus, the stiffening ribs extend from the connecting web toward the sealing element on the inner side of the fold-over section facing the outer leg of the fold-over section, with the stiffening ribs ending before the area in which the sealing element is located on the outer side of the fold-over section, viewed in the radial direction, and thus on the inner surface of the material container.In practice, it has been shown that injection-molding-related deformations occur in the area of the sealing element when the stiffening ribs extend into this area. These injection-molding-related deformations can lead to the sealing element not fully contacting the sealing surface of the screw cap. By providing such stiffening rib clearance, such injection-molding-related deformations can be prevented, thus improving the sealing situation.
[0024] Advantageously, the stiffening ribs extend radially from the inner side of the outer leg facing the inner leg to the outer leg where the outer thread of the material container is located. This ensures that the sealing element is not negatively influenced during injection molding, while still ensuring that the forces acting on the thread during the screwing process can be optimally dissipated. The described design allows the upper edge area of the material container to be maximally reinforced during the screwing process with a minimal material wall thickness, without the sealing element and thus the sealing situation being negatively influenced during injection molding.
[0025] It is particularly advantageous if the stiffening ribs in the upper edge area of the material container are distributed at equal spacing along the circumference. Preferably, at least 8 and a maximum of 25 stiffening ribs are provided, which are evenly distributed along the circumference. In a particularly preferred embodiment, at least 10 and a maximum of 16 evenly distributed stiffening ribs are provided. Particularly preferred are 12 evenly distributed stiffening ribs.
[0026] In a further embodiment, the sealing element has a substantially trapezoidal cross-section. In particular, the sealing element has the cross-section of a non-isosceles trapezoid. The shorter base of the trapezoid forms the contact area of the sealing element. This type of sealing element design is easy to demold and, thanks to its flat contact area, offers particularly good sliding properties between the sealing element of the material container and the sealing surface of the screw cap, thus requiring less force to create a fluid-tight connection between the screw cap and the material container.
[0027] Preferably, the receiving groove on the screw cap is formed on its inner side relative to the gravity cup longitudinal axis by an inner leg extending opposite the material outlet and in the direction of the gravity cup longitudinal axis. This inner leg has the sealing surface on its outer side facing opposite the gravity cup longitudinal axis. In this case, the sealing element is set back from the front side of the upper edge region of the material container in the form of a sealing element setback over at least half, in particular over more than 60%, of the inner leg length with which the inner leg extends in the direction of the gravity cup longitudinal axis. This setback of the sealing element relative to the front side of the upper edge region ensures that the sealing element only comes into contact with the sealing surface of the screw cap when the screw cap is almost completely screwed onto the material container.Thus, the sealing element only influences the assembly of the screw cap over a short distance, which reduces the force required when assembling the screw cap.
[0028] Preferably, the inner surface of the material container and the outer side of the inner leg have a flat guide area extending in the direction of the gravity cup's longitudinal axis, which extends from the sealing element or a contact surface of the sealing element on the screw cap in the direction of the gravity cup's longitudinal axis and toward the material outlet, at least over the length by which the sealing element is set back from the front side of the upper edge region of the material container. Such a guide area allows for precise centering between the material container and the screw cap before the sealing element comes into contact with the sealing surface during assembly of the screw cap.
[0029] In a preferred embodiment, the inner circumference of the sealing element in the contact area and the outer circumference of the sealing surface in the contact area are designed in such a way that the end face of the upper edge area and the groove base of the receiving groove are spaced apart from one another in the direction of the gravity cup's longitudinal axis in such a way that a free space is formed between the end face of the upper edge area and the groove base. The screw cap and the material container are accordingly designed in such a way that the end face of the upper edge area does not abut the groove base, but rather a distance is provided between the groove base and the end face of the upper edge area even in the assembled state.Such clearance can be used to compensate for manufacturing tolerances, as the upper edge area does not touch the groove base. This would prevent a fluid-tight connection between the screw cap and the material container from being created if the inner circumference of the sealing element was too large in the contact area due to manufacturing tolerances, or if the screw cap was manufactured too small in the area of the outer circumference of the sealing surface. Thus, the clearance ensures a fluid-tight connection between the material container and the screw cap.
[0030] Preferably, the contact surface against which the sealing element rests when a fluid-tight connection is established between the screw cap and the material container is provided in the area of one end of the inner leg of the receiving groove that faces away from the material outlet. This design facilitates the assembly of the screw cap, as the sealing element only engages with the material container shortly before the screw cap is fully assembled and thus does not affect the previous screwing path.
[0031] In a preferred embodiment, a circumferential stiffening ring extending substantially radially inward relative to the gravity cup's longitudinal axis adjoins the end of the inner leg, supporting the end of the inner leg against a force directed toward the gravity cup's longitudinal axis. Such a stiffening ring can reduce the elasticity of the screw cap in the area of the contact surface, thereby ensuring a fluid-tight connection between the screw cap and the material container.
[0032] Preferably, the material container has outwardly directed fastening means in the upper edge region, in particular in the form of an external thread on the material container, and the screw cap has inwardly directed counter-fastening means, in particular in the form of an internal thread on the screw cap. Such fastening means can ensure a functionally reliable attachment of the screw cap to the material container.
[0033] In a particularly preferred embodiment, the sealing element, the material container, and the material container's external thread, as well as the screw cap and the screw cap's internal thread, are each designed as a single-piece injection-molded part. This design reduces the number of required parts, thereby saving manufacturing costs.
[0034] Preferably, the material container and screw cap are injection-molded from polypropylene, or the material container is injection-molded from polypropylene (PP) and the screw cap is injection-molded from high-density polyethylene (HDPE). If both the material container and the screw cap are made of polypropylene, both parts can be designed to be particularly transparent, allowing the contents of the gravity feed cup and its fill level to be clearly seen from the outside. If the material container is made of polypropylene and the screw cap is made of high-density polyethylene, a beneficial material combination can be created between the screw cap and the material container, as this material combination can minimize friction between the screw cap and the material container.
[0035] The invention is further realized by a screw cap or a material container designed for use as part of a gravity feed cup having the features described above and below.
[0036] Both the features described above and those described below
[0037] Features, even those from different embodiments, can be combined with one another, resulting in synergistic interactions that go beyond the sum of their individual effects. Furthermore, the different embodiments are also considered inventions in their own right, even if this is not explicitly stated. This also applies to the combination of different features of the individual embodiments.
[0038] The invention is explained below using various exemplary embodiments. The figures show:
[0039] Fig. 1 is a sectional view of a paint spray gun with a gravity feed cup according to a first embodiment,
[0040] Fig. 2 is a sectional view of a flow cup according to a second
[0041] embodiment,
[0042] Fig. 3 is a sectional view of a screw cap for a flow cup according to the second embodiment of Fig. 2,
[0043] Fig. 4 is a perspective view of a material container for a
[0044] Flow cup according to the second embodiment of Fig. 2,
[0045] Fig. 5 a detailed view of the screw cap according to the second
[0046] Embodiment of Fig. 2, which shows the area marked as B in Fig. 3,
[0047] Fig. 6 a detailed view of the flow cup according to the second
[0048] Embodiment of Fig. 2, which shows the area marked as A in Fig. 2,
[0049] Fig. 7 a detailed view of the flow cup according to the second
[0050] Embodiment from Fig. 2, which shows the area marked as A in Fig. 2 in an alternative embodiment, Fig. 8 is a detailed view of the material container according to the alternative embodiment of the paint cup from Fig. 2 shown in Fig. 7 in the area of the sealing element without screw cap,
[0051] Fig. 9 is a detailed view of the material container according to the alternative embodiment of the paint cup from Fig. 2 shown in Fig. 7 in the area of the sealing element,
[0052] Fig. 10 is a detailed view of the material container according to the alternative embodiment of the paint cup from Fig. 2 shown in Fig. 7 in the area of the sealing element,
[0053] Fig. 11 is a detailed view of the material container according to the alternative embodiment of the paint cup from Fig. 2 shown in Fig. 7 in the region of the sealing element according to an alternative embodiment of the sealing element.
[0054] Fig. 12 a detailed view of the flow cup according to the second
[0055] Embodiment of Fig. 2, which shows the area marked as A in Fig. 2 in an alternative embodiment,
[0056] Figure 1 shows a handheld paint spray gun 1 for the compressed air-assisted atomization and application of a flowable coating material. The paint spray gun 1 can be designed, for example, as a so-called high-pressure, compliant, or HVLP spray gun 1. The paint spray gun 1 has a cup connection 2 and a nozzle head 3, at which coating material supplied to the paint spray gun 1 via the cup connection 2 is atomized and exits in the form of a spray jet. Furthermore, a trigger guard 4 for actuating the paint spray gun 1 and for controlling the amount of coating material exiting the nozzle head 3, as well as a handle 5, by which the user holds the paint spray gun 1, are provided.
[0057] Figure 1 also shows a gravity feed cup 10 for a paint spray gun 1, which has a material outlet 21 which is designed for direct and / or indirect connection to the paint spray gun 1. The gravity feed cup 10 has a material container 30 with an inner material container surface 31 and a screw cap 20 closing the material container 30. Also shown is a gravity feed cup longitudinal axis 12 of the gravity feed cup 10. For the detachable and fluid-tight connection of the material container 30 and the screw cap 20, a screw connection 11 is provided in the upper edge region 32 of the material container 30, wherein the material container 30 is arranged in a receiving groove 22 on the screw cap 20, which has on its outer side a screw cap internal thread 29 which is shown in more detail in the following figures.The flow cup 10 shown is a conventional flow cup 10 in which the material outlet 21 is provided directly on the material container 30, wherein the screw cap 20 carries a cover valve 52 for pressure equalization.
[0058] On the material container inner surface 31, a circumferential sealing element 33 is provided, which is shown in more detail in the following figures and protrudes relative to the material container inner surface 31 and which comes into flat sealing contact with an outwardly facing sealing surface 23 of the screw cap 20.
[0059] Figure 2 shows a further embodiment of a gravity feed cup 10 according to the invention, wherein this gravity feed cup 10 is an upside-down gravity feed cup, which carries its material outlet 21 on the screw cap 20 and a bottom valve 46 is provided on the underside of the material container 30. Furthermore, section A is shown, which is shown enlarged in Figure 6.
[0060] Figure 3 shows a screw cap 20 of a gravity feed cup 10, as shown in Figure 2. Furthermore, section B is shown, which is shown enlarged in Figure 6.
[0061] Also shown is a guide region 51 extending in the direction of the gravity cup longitudinal axis 12, which is located on the inner leg outer side 25 of the receiving groove 22, shown enlarged in Figure 5. In the guide region 51, the inner leg outer side 25 is flat, wherein the guide region 51 extends from a contact surface 27 of the sealing element 33, against which the sealing element 33 of the material container 30 rests, in the direction of the gravity cup longitudinal axis 12 and towards the material outlet 21 over the length by which the sealing element 33 is set back from the end face of the upper edge region 32 of the material container 30. The length of the guide region 51 on the material container inner surface 31 in the direction of the gravity cup longitudinal axis 12 is between 2 mm and 10 mm, in particular between 3 mm and 4 mm.
[0062] Figure 4 shows a material container 30 of the gravity feed cup 10 shown in Figure 2. The material container 30 carries on its material container inner surface 31 the sealing element 33, which is set back from the end face of the upper edge region 32 of the material container 30 in such a way that a flat guide region 51 is formed which runs in the direction of the gravity feed cup longitudinal axis 12 and extends from the sealing element 33 in the direction of the gravity feed cup longitudinal axis 12 and towards the end face of the upper edge region 32 over the length in which the sealing element 33 is set back from the end face of the upper edge region 32.The inner circumference 44 of the sealing element 33 is designed in the contact area 38, in which the sealing element 33 comes into contact with the sealing surface 23 of the screw cap 20, such that the end face of the upper edge area 32 and the groove base 24c of the receiving groove 22 are spaced apart from one another in the direction of the gravity cup longitudinal axis 12 when the material container 30 and the screw cap 20 are connected in a fluid-tight manner in such a way that a free space 13 shown in Figure 6 is formed between the end face of the upper edge area 32 and the groove base 24c to compensate for manufacturing tolerances.
[0063] Figures 5 and 6 show the enlarged details, which are labeled A and B in Figures 2 and 3. The receiving groove 22 on the screw cap 20 is formed, on its inner side relative to the gravity feed cup longitudinal axis 12 shown in the previous figures, by an inner leg 24a extending opposite the material outlet 21 and in the direction of the gravity feed cup longitudinal axis 12, and on the inner leg outer side 25 of said inner leg, facing opposite the gravity feed cup longitudinal axis 12, the sealing surface 23 is provided. The sealing element 33 shown in Figure 6 is set back from the end face of the upper edge region 32 of the material container 30 in the form of a sealing element setback 37 over at least half, in the case shown over more than 60%, of the inner leg length 26, with which the inner leg 24a extends in the direction of the gravity feed cup longitudinal axis 12.The inner leg length 26 in the direction of the gravity feed cup's longitudinal axis 12 is between 3 mm and 10 mm, in particular between 5 mm and 7 mm. The sealing element offset 37 forms a guide area 51 that centers the screw cap 20 and the material container 30 relative to one another before the sealing element 33 comes into contact with the sealing surface 23 during assembly of the screw cap 20. The sealing element offset 37 relative to the end face of the upper edge area 32 of the material container 30 is between 2 mm and 7 mm, in particular between 3 mm and 5 mm, in the direction of the gravity feed cup's longitudinal axis 12. In the radial direction to the longitudinal axis 12 of the flow cup, the outer leg 24b sits opposite the inner leg 24a, wherein the inner leg 24a and the outer leg 24b are connected to one another via the annular groove base 24c which runs in the radial direction to the longitudinal axis 12 of the flow cup.
[0064] Both the material container inner surface 31 and the inner leg outer side 25 have a flat guide region 51 running in the direction of the gravity cup longitudinal axis 12, which extends from the sealing element 33, or the contact surface 27 of the sealing element 33 on the screw cap 20, in the direction of the gravity cup longitudinal axis 12 and towards the material outlet 21, at least over the length in which the sealing element 33 is set back from the front side of the upper edge region 32 of the material container 30.
[0065] As can be seen from Figures 5 and 6, the inner circumference 44 of the sealing element 33 shown in Figure 4 and the outer circumference of the sealing surface 23 in the region of the contact surface 27 are designed such that the end face of the upper edge region 32 and the groove base 24c of the receiving groove 22 are spaced apart from one another in the direction of the gravity cup longitudinal axis 12 such that in the state shown in Figure 6, in which the material container 30 and screw cap 20 are connected to one another in a fluid-tight manner, a free space 13 is formed between the end face of the upper edge region 32 and the groove base 24c, which serves to compensate for manufacturing tolerances, in particular on the inner circumference 44 of the sealing element 33 or the contact region 38 and / or on the outer circumference of the contact surface 27.
[0066] Figures 5 and 6 also show that the contact surface 27, against which the sealing element 33 rests in the case of a fluid-tight connection between the screw cap 20 and the material container 30, is located in the region of one end 24d of the inner leg of the receiving groove 24a, which end faces away from the material outlet 21. Adjoining the end 24d of the inner leg 24a is a circumferential stiffening ring 28 which extends essentially radially inward relative to the longitudinal axis 12 of the gravity cup, supports the end 24d of the inner leg 24a against a force directed towards the longitudinal axis 12 of the gravity cup and runs essentially parallel to the groove base 24c of the receiving groove 22. The stiffening ring 28 extends in the radial direction to the longitudinal axis 12 of the gravity cup between 3 mm and 7 mm, in particular between 4 mm and 5 mm, from the end 24d of the inner leg.
[0067] The material container 30 has outwardly directed fastening means 45 in the upper edge region 32, in particular in the form of a material container external thread 45, and the screw cap 20 has inwardly directed counter-fastening means 29, in particular in the form of a screw cap internal thread 29. The sealing element 33, the material container 30 and the material container external thread 45, as well as the screw cap 20 and the screw cap internal thread 29, are each designed as a single-piece injection-molded part.
[0068] Figure 7 shows an alternative design of the upper edge region 32 of the
[0069] Material container 30, in which the material container 30 is formed in this area by a fold-over, which encloses a material recess 47 between the part of the fold-over carrying the material container external thread 45 and the material container inner surface 31 carrying the sealing element 33. The fold-over saves material during production by means of plastic injection molding, the material container 30 is designed to be more elastic in this area for better sealing towards the screw cap, and material accumulations are avoided, which leads to fewer manufacturing tolerances.
[0070] Figure 8 shows the sealing element from Figure 7 in detail, with the sealing element 33 of the other previously described figures being designed in the same way. The only difference is the presence of the material recess 47. The sealing element outer surface 41 has a contact area 38, a sealing element upper flank 43 connected to the contact area 38 in the direction of the material outlet 21, and a sealing element lower flank 42 connected to the contact area 38 in the opposite direction.
[0071] Figure 9 shows the sealing situation between screw cap 20 and material container 30 in detail. The sealing element 33, which runs around the inner surface 31 of the material container, has a sealing element width 34 that extends in the direction of the longitudinal axis 12 of the gravity feed cup, shown, for example, in Figure 2, and along the inner surface 31 of the material container. The sealing element further has a sealing element height 35, by which the sealing element 33 protrudes from the inner surface 31 of the material container in the radial direction to the longitudinal axis 12 of the gravity feed cup. In this case, the sealing element width 34 is greater than the sealing element height 35. In particular, the sealing element width 34 is at least 1 / 3 greater than the sealing element height. In a further embodiment, the sealing element width 34 can be twice the sealing element height 35 or more.
[0072] Figure 9 further shows that the sealing element 33 has a contact area 38, at which the sealing element 33 rests against the sealing surface of the screw cap 20 and the width 36 of the contact area 38 in the direction of the gravity cup longitudinal axis 12 is greater than the sealing element height 35. In the present case, the width 36 of the contact area is 1.5 times the sealing element height 35, whereby the width 36 of the contact area can also be twice or three times the sealing element height 35.
[0073] In the embodiment shown here, the sealing element 33 has a contact area 38, against which the sealing element 33 rests on the screw cap 20, which is designed to be so flat that the width 36 of the contact area 38 in the direction of the gravity cup longitudinal axis 12, in which the sealing element 33 comes into contact with the sealing surface 23 when the material container 30 and the screw cap 20 are connected in a fluid-tight manner, is greater than 1 / 3 of the sealing element width 34 but smaller than the sealing element width 34 in the direction of the gravity cup longitudinal axis 12. Alternatively, the sealing element can also be designed such that the width 36 of the contact area 38 is half or 2 / 3 of the sealing element width 34.
[0074] As can be seen from Figure 9, the sealing element 33 has a substantially trapezoidal cross-section, wherein in the case shown it is a non-isosceles trapezoid, the leg of which shown in Figure 8 and referred to as the sealing element upper flank 43 is shorter than the leg referred to as the sealing element lower flank 42.
[0075] Figures 10 and 11 show two different embodiments of a sealing element according to the invention. What these different embodiments have in common is that the contact area 38 is designed so flat that the sealing element 33 rests flatly against the sealing surface 23 of the screw cap 20. Obviously, further embodiments are possible, which fall within the scope of protection due to the wording of the patent claims.
[0076] Figures 10 and 11 illustrate that certain geometries can be derived, taking into account which a sealing element 33 with the advantages described above can be created. As can be seen, such sealing elements 33 can have both a flat contact area 38 and a curved contact area 38. The sealing element lower flank 42 and / or the sealing element upper flank 43 can also be curved, as shown in Figure 11. In both cases, the contact area 38 rests against the sealing surface 23 (not shown here) of the screw cap 20 or the contact surface 27 of the sealing surface 23, whereby the improvements described above can be achieved. As an alternative to the configuration shown in Figure 10, curves can also be provided between the contact area 38 and the sealing element lower flank 42 and / or the sealing element upper flank 43, by means of which the areas merge into one another.
[0077] The figures show that the pitch angle 39 of the tangent 40 of the sealing element outer surface 41, which faces the gravity cup longitudinal axis 12 (not shown here), is less than 15° across the sealing element width 34 and relative to the material container inner surface 31 in a region of at least 1 / 3 of the sealing element width 34. Alternatively, the pitch angle 39 can also be less than 7°. The region in which the corresponding pitch angle 39 lies below the said values can also extend over more than half the sealing element width 34. As can be seen from the figures, in this geometric consideration, the acute angle between the material container inner surface 31 and the pitch angle 39 is to be considered and not the obtuse angle, which must be below 15° or below 7°. Both exemplary embodiments meet the said minimum requirements.In the embodiment of Figure 10, the pitch angle 39 across the width 36 of the contact area 38 is always 0°, since the contact area runs parallel to the material container inner surface 31 in the direction of the gravity cup longitudinal axis 12. The width 36 of the contact area 38 is 37% of the sealing element width 34. In the embodiment of Figure 11, the area in which the pitch angle 39 of the tangent 40 of the sealing element outer surface 41 is less than 15° extends over more than half the sealing element width 34. The values of the pitch angles 39 are as follows: 39a = 0°; 39b = 28°; 39c = 48°; 39d = 7°; 39e = 49°.
[0078] Both exemplary embodiments show that the sealing element outer surface 41 has a contact area 38, a sealing element upper flank 43 connected to the contact area 38 in the direction of the material outlet 21, and a sealing element lower flank 42 connected to the contact area 38 in the opposite direction, wherein the pitch angle 39 of the tangent 40 of the sealing element lower flank 42 over its course in the direction of the gravity cup longitudinal axis 12 is smaller than the pitch angle 39 of the sealing element upper flank 43. The transition between the contact area 38 and the sealing element lower flank 42 or the sealing element upper flank 43 takes place at the point at which the pitch angle 39 of the tangent 40 increases above the aforementioned value of 15° or 7°.Since the pitch angle 39 of the sealing element upper flank 43 is greater than the pitch angle 39 of the sealing element lower flank 42, it follows that the length of the sealing element lower flank 42 in the axial direction is greater than the length of the sealing element upper flank 43.
[0079] Figure 12 shows an alternative embodiment of the upper edge region 32 of the material container 30, in which the material container 30 is formed in this region by a fold-over portion 48, analogous to the embodiment in Figure 7, which fold-over portion 48 encloses a material recess 47 between the part of the fold-over portion 48 carrying the material container external thread 45 and the material container inner surface 31 carrying the sealing element 33. The fold-over portion 48 runs along the entire upper edge region 32 of the material container 30. The fold-over portion 48 is shown in dashed lines here, as it is concealed by a stiffening rib 49 in this sectional view. The fold-over inner leg 53 and the fold-over outer leg 54 are connected to one another along their circumference several times by the stiffening ribs 49 running radially relative to the longitudinal axis 12 of the gravity feed cup.The stiffening ribs 49 extend from the connecting web 55 toward the sealing element 33 on the inner side 57 of the inner leg 53 facing the outer leg 54, wherein the stiffening ribs 49 end before the region in which the sealing element 33 is located, viewed in the radial direction, on the outer side of the inner leg 53 and thus on the material container inner surface 31. The stiffening ribs 49 extend from the inner side 58 of the outer leg 54 facing the inner leg 53, viewed in the radial direction, into the region where the material container external thread 45 is provided on the outer side 59 of the outer leg 54. Several stiffening ribs 49 are provided in the upper edge region 32 of the material container 30, which are distributed at equal distances from one another along the circumference.In the example shown, 12 stiffening ribs are provided, with advantageously at least 8 and a maximum of 25 stiffening ribs being provided. The stiffening ribs 49 are connected to the inner turn-up leg 53 and the outer turn-up leg 54 in the direction of the gravity cup's longitudinal axis 12 over a different length. Thus, the underside 50 of the stiffening ribs 49, which faces away from the screw cap 20, is formed obliquely to the radial direction of the gravity cup's longitudinal axis 12. In the embodiment shown, the underside 50 of the stiffening ribs is inclined to the radial direction such that the angle between the underside 50 of the stiffening ribs and the radial direction is greater than 45°. In actual practice, the angle is between 60° and 80°.
[0080] As can also be seen from Figure 12, the stiffening ribs 49 are connected to the inner turn-up leg 53 over a shorter length in the direction of the flow cup's longitudinal axis 12 than to the outer turn-up leg 54, thereby forming a stiffening rib clearance 56 that extends between the stiffening rib underside 50 and the inner turn-up leg 53. The stiffening ribs 49 on the inner turn-up leg 53 end in front of the area where the sealing element 33 is provided. Thus, the stiffening rib clearance 56 on the inner turn-up leg 53 extends into the area where the sealing element 33 is provided.In the example shown, the stiffening rib clearance 56 ends in a region which, in the direction of the flow cup longitudinal axis 12 and towards the end face of the upper edge region 32, is spaced by more than half of the sealing element setback 37 from the region at which the sealing element 33 is provided on the material container inner surface 31.
[0081] Figures 1 to 12 described above show a gravity feed cup 10 whose material container 30 and screw cap 20 are injection-molded and made of polypropylene (PP). This has the advantage that both parts can be designed transparently and both parts exhibit the advantageous properties of polypropylene. Pairing two identical materials, particularly with polypropylene, generally leads to unwanted side effects that negatively impact the screw connection 11 between screw cap 20 and material container 30. For example, a high frictional force develops between the two parts, which must be overcome when assembling and disassembling the screw cap 20. This is particularly the case when the surfaces that rub against each other are very small. A type of stick-slip effect also arises, which also negatively impacts the screw connection.Such negative effects can be reduced or prevented by a previously described design of a flow cup 10, whereby at the same time a fluid-tight connection between screw cap 20 and material container 30 can be ensured.
[0082] The solution described above can also improve the screwing behavior of the screw connection 11 with material pairings other than between two parts made of polypropylene. For example, the screw cap 20 can also be made of high-density polyethylene (HDPE) and the material container 30 of polypropylene. With such a combination, the material pairing does not have as negative an effect on the screwing behavior as with the material pairing between PP and PP, since HDPE has good sliding properties when paired with other plastics. However, the design of the gravity feed cup 10 explained above can also improve the screwing behavior with this material pairing, while at the same time ensuring a fluid-tight connection between the screw cap 20 and the material container 30.
[0083] The gravity feed cup 10 according to the invention and the paint spray gun 1 equipped therewith are suitable for atomizing and applying a wide variety of materials. A primary area of application is automotive refinishing, where topcoats, fillers, and clearcoats are used, placing very high demands on atomization and the properties of the spray jet. However, a variety of other materials can also be processed using the gravity feed cup 10 and a possibly modified spray gun 1. The crucial requirement is that the materials are flowable and at least to a certain extent sprayable.
Claims
Claims 1. A gravity feed cup (10) for a paint spray gun (1), having a material outlet (21) designed for direct and / or indirect connection to a paint spray gun (1), wherein the gravity feed cup (10) has a material container (30) with a screw cap (20) closing the material container (30), and a gravity feed cup longitudinal axis (12), wherein, when the material container (30) and the screw cap (20) are releasably and fluid-tightly connected to form a screw connection (11), an upper edge region (32) of the material container (30) is to be arranged in a receiving groove (22) on the screw cap (20), characterized in that the upper edge region (32) of the material container (30) has a protruding, circumferential sealing element (33) which comes into flat, sealing contact with a sealing surface (23) of the screw cap (20).
2. Flow cup (10) according to claim 1, characterized in that the sealing element (33) protrudes from an inner surface (31) of the material container and comes into flat sealing contact with an outwardly facing sealing surface (23) of the screw cap (20).
3. Flow cup (10) according to claim 1 or 2, characterized in that the circumferential sealing element (33) has a sealing element width (34) which runs in the direction of the flow cup longitudinal axis (12) and along the material container inner surface (31), and has a sealing element height (35) in which the sealing element (33) protrudes from the material container inner surface (31) in the radial direction to the flow cup longitudinal axis (12), wherein the sealing element width (34) is greater than the sealing element height (35), in particular the sealing element width (34) is at least 1 / 3 greater than the sealing element height or is at least twice the sealing element height (35).
4. Flow cup (10) according to one of the preceding claims, characterized in that the sealing element (33) has a contact area (38) on which the sealing element (33) rests against the sealing surface of the screw cap (20) and the width (36) of the contact area (38) in the direction of the flow cup longitudinal axis (12) is at least 2 / 3 of the sealing element height (35), in particular the width (36) of the contact area (38) is greater than the sealing element height (35), in particular greater than 1.5 times the sealing element height (35).
5. Flow cup (10) according to one of the preceding claims, characterized in that the sealing element (33) has a contact area (38) against which the sealing element (33) rests on the screw cap (20), which is designed to be flat such that the width (36) of the contact area (38) in the direction of the gravity cup longitudinal axis (12), in which the sealing element (33) comes to rest on the sealing surface (23) when the material container (30) and the screw cap (20) are connected in a fluid-tight manner, in the direction of the gravity cup longitudinal axis (12) is greater than 1 / 3 of the sealing element width (34).
6. Flow cup (10) according to one of the preceding claims, characterized in that the pitch angle (39) of the tangent (40) of a sealing element outer surface (41) facing the flow cup longitudinal axis (12) over the sealing element width (34) relative to the material container inner surface (31) in a region of at least 1 / 3, in particular at least 1 / 2, of the sealing element width (34) is less than 15°, in particular less than 7°.
7. Flow cup (10) according to one of the preceding claims, characterized in that the sealing element outer surface (41) has a contact area (38), a sealing element upper flank (43) connected to the contact area (38) in the direction of the material outlet (21) and a sealing element lower flank (42) connected to the contact area (38) in the opposite direction, wherein the pitch angle (39) of the tangent (40) of the sealing element lower flank (42) over its course in the direction of the flow cup longitudinal axis (12) is smaller than the pitch angle (39) of the sealing element upper flank (43).
8. Flow cup (10) according to one of the preceding claims, characterized in that the material container (30) is formed in the upper edge region (32) by a turn-up (48), the turn-up inner leg (53) and the turn-up outer leg (54) of which are connected to one another along their circumference several times by stiffening ribs (49) extending radially relative to the flow cup longitudinal axis (12), wherein the stiffening ribs (49) are connected to the turn-up inner leg (53) or the turn-up outer leg (54) in the direction of the flow cup longitudinal axis (12) over a different length.
9. Flow cup (10) according to one of the preceding claims, characterized in that the stiffening ribs (49) are connected in the direction of the flow cup longitudinal axis (12) over a shorter length to the inner turn-up leg (53) than to the outer turn-up leg (54), whereby a stiffening rib clearance (56) is formed between the inner turn-up leg (53) and Stiffening rib underside (50) is formed, in particular the stiffening rib free space (56) extends on the inner turn-up leg (53) into the area in which the sealing element (33) is provided.
10. Flow cup (10) according to one of the preceding claims, characterized in that the sealing element (33) has a substantially trapezoidal cross-section, in particular a non-isosceles trapezoid.
11. Gravity cup (10) according to one of the preceding claims, characterized in that the receiving groove (22) on the screw cap (20) is formed on its inner side relative to the longitudinal axis (12) of the gravity cup by an inner leg (24a) extending opposite the material outlet (21) and in the direction of the longitudinal axis (12) of the gravity cup, on the inner leg outer side (25) of which facing opposite the longitudinal axis (12) of the gravity cup the sealing surface (23) is provided, wherein the sealing element (33) is set back from the end face of the upper edge region (32) of the material container (30) in the form of a sealing element setback (37) over at least half, in particular over more than 60%, of the inner leg length (26) with which the inner leg (24a) extends in the direction of the longitudinal axis (12) of the gravity cup.
12. Flow cup (10) according to one of the preceding claims, characterized in that the material container inner surface (31) and the inner leg outer side (25) have a flat guide region (51) running in the direction of the flow cup longitudinal axis (12), which extends from the sealing element (33), or a contact surface (27) of the sealing element (33), on the screw cap (20) in the direction of the flow cup longitudinal axis (12) and towards the material outlet (21) at least over the length in which the sealing element (33) is set back from the end face of the upper edge region (32) of the material container (30).
13. Flow cup (10) according to one of the preceding claims, characterized in that the inner circumference (44) of the sealing element (33) in the contact area (38) and the outer circumference of the sealing surface (23) in the area of the contact surface (27) are designed in such a way that the end face of the upper edge area (32) and the groove base (24c) of the receiving groove (22) are spaced apart from one another in the direction of the flow cup longitudinal axis (12) in such a way that a free space (13) is formed between the end face of the upper edge area (32) and the groove base (24c), which in particular compensates for manufacturing tolerances.
14. Flow cup (10) according to one of the preceding claims, characterized in that the contact surface (27) against which the sealing element (33) rests in the case of a fluid-tight connection between the screw cap (20) and the material container (30) is located in the region of an end (24d) of the inner leg of the receiving groove (24a) which is facing away from the material outlet (21).
15. Flow cup (10) according to one of the preceding claims, characterized in that a circumferential stiffening ring (28) extending substantially radially inwards relative to the flow cup longitudinal axis (12) is connected to the end (24d) of the inner leg (24a), which stiffening ring supports the end (24d) of the inner leg (24a) against a force directed towards the flow cup longitudinal axis (12).
16. Flow cup (10) according to one of the preceding claims, characterized in that the material container (30) has an outwardly directed material container external thread (45) in the upper edge region (32) and the screw cap (20) has an inwardly directed screw cap internal thread (29).
17. Flow cup (10) according to one of the preceding claims, characterized in that the sealing element (33), the material container (30) and the material container external thread (45), as well as the screw cap (20) and the screw cap internal thread (29), are each designed as a one-piece injection-molded part.
18. Flow cup (10) according to one of the preceding claims, characterized in that the material container (30) and the screw cap (20) are injection-molded from polypropylene, or the material container (13) is injection-molded from polypropylene (PP) and the screw cap (15) is injection-molded from high-density polyethylene (HDPE).
19. Screw cap (15) or material container (13) of a flow cup (10) according to one of the preceding claims.