DEVICE FOR DISPENSING A FLOWABLE MEDIUM

Description

[0001] The present invention relates to a device for dispensing a flowable medium, wherein the flowable medium is preferably an adhesive, in particular a hot melt adhesive or melt adhesive.

[0002] Such devices are used, for example, to apply a flowable medium to a substrate in portions. The application of the flowable medium is controlled, and the device has a dispensing opening for dispensing the flowable medium. This dispensing opening can be opened and closed by means of a sealing section of a rod movable by an actuator. In this respect, the device has a closable valve.

[0003] Devices for dispensing a flowable medium are known, for example, from DE 10 2015 000 630 B3, EP 2 308 602 B1, US 7 617 955 B2 and US 8 333 307 B2.

[0004] With regard to devices for dispensing a flowable medium of the aforementioned type, a particular problem is preventing the flowable medium from entering the actuator area. Seals are used to seal the actuator from the flowable medium, particularly from a cavity containing the flowable medium. Two different types of seals are generally known for this purpose.

[0005] One is a so-called "dynamic seal," in which the seal or sealing element is formed or arranged between two surfaces that move relative to each other during operation of the device. A disadvantage of this type of seal is that during long-term operation of the device, the dynamic seal becomes worn and, as a result, the seal loses its sealing effect, which can lead to unwanted penetration of fluid into the actuator area.

[0006] Furthermore, so-called "bellows seals" are known from the prior art. In contrast to a dynamic seal, with a bellows seal, the seal does not occur between two surfaces moving relative to each other. Instead, the bellows seal is statically connected to the rod element by a first section and statically connected to another element of the device by a second section, with the rod moving relative to the second element of the device. The movement of the rod relative to the element of the device is absorbed by a deformation of the bellows seal. This ensures very high tightness even during long-term operation of the device, since only low frictional forces occur at the seal.

[0007] Devices for dispensing a flowable medium, which have a bellows seal for the purpose of sealing an actuator, are known, for example, from DE 10 2015 000 630 B3, EP 2 308 602 B1, US 7 617 955 B2 and US 8 333 307 B2. EP 2 308 602 B1 has the features of the preamble of patent claim 1. Specifically, the device has a head section and a base body section, wherein the device has a cavity for receiving the flowable medium. The head section has a dispensing opening opening into the cavity for dispensing the flowable medium. Furthermore, the device has a rod displaceable in an axial direction between a first end position and a second end position, wherein a first end section of the rod has a sealing section.In the first end position, the sealing section is arranged at a distance from the dispensing opening and thus enables dispensing of the adhesive in the first end position. In the second end position, the sealing section of the rod closes the dispensing opening on a side facing the cavity. A second end section of the rod extends out of the cavity and is coupled to an actuator, specifically to a piston of a compressed air cylinder. The device has a seal for sealing a region of the device receiving the second end section of the rod from the cavity. The seal is arranged in the region of the cavity, wherein the seal circumferentially encloses the rod in the region of the cavity.The seal is designed as a bellows seal, wherein the seal has a first sealing section and a second sealing section, wherein the first sealing section is stationary in sealing engagement with the rod with respect to the rod, and is thus stationary connected to the rod. Due to the stationary connection of the first sealing section to the rod, the first sealing section follows any movement of the rod. The second sealing section lies stationary against a wall defining the cavity. Between the first sealing section and the second sealing section, the seal has an elasticity region in order to compensate for or absorb the relative movement of the rod with respect to the cavity, specifically with respect to the wall defining the cavity, against which the second sealing section lies. EP 2 308 602 B1 further provides for the seal to be compressed or compressed in the axial direction.

[0008] Compressing or compressing the seal has the disadvantage that a relatively high force must be applied to open the dispensing opening, since the opening of the dispensing opening counteracts the spring force of the seal due to the compression. This adversely affects the force required by the actuator and the time required for opening and closing.

[0009] Furthermore, US 6 343 721 B1 discloses a dispensing device for dispensing a flowable material, which has the features of the preamble of patent claim 1. US 4 798 314 A discloses further prior art.

[0010] The object of the present invention is to further develop or modify a device for dispensing a flowable medium, which has the features of the preamble of patent claim 1, in such a way that it nevertheless has the necessary sealing effect and fatigue strength while overcoming the aforementioned disadvantages.

[0011] This object is achieved by a device having the features of patent claim 1.

[0012] To achieve the above-mentioned object, it is provided that the seal is stretched or extended in the axial direction in the second end position of the rod compared to a basic state of the seal.

[0013] Accordingly, the elastic region of the seal is stretched in the state in which the dispensing opening is closed, and the movement of the rod for opening the dispensing opening, i.e. for transferring the rod from the second end position to the first end position, is thus supported by the pretension of the elastic region of the seal, whereby the force to be applied by the actuator is reduced or the seal as such supports the movement of the rod from the second end position to the first end position.

[0014] Due to the fact that the liquid medium present in the cavity is typically under pressure and thus acts accordingly on the seal, the forces present in the seal due to the expansion or stretching of the seal are preferably partially compensated so that a very high fatigue strength can be achieved.

[0015] In particular, it is provided that the extension or elongation of the seal is designed in such a way that, at a known pressure of the flowable medium present during operation of the device, the forces acting in the axial direction in the seal disappear in the second end position of the rod.

[0016] This can increase the fatigue strength and thus the service life of the seal.

[0017] In a preferred embodiment of the device, the first sealing section is integrally connected to the rod.

[0018] It is considered particularly advantageous if, without the application of an external force to the rod and / or the seal, the rod is in the first end position or is between the first end position and the second end position. Thus, a force must be exerted on the rod in the direction of the second end position in order to close the dispensing opening.

[0019] It is considered particularly advantageous if the device comprises means that exert an external force on the rod toward the second end position, in particular, if the rod is displaced toward the first end position counter to the force of the means. The means can, for example, comprise a spring or be formed by a spring. It is considered particularly advantageous if the rod is in the second end position without any action of the actuator on the rod.

[0020] Preferably, the means comprise a stop, wherein the stop is mounted axially displaceably in the base body section and interacts with the rod and / or the actuator. The means further comprise a return means that interacts with the stop, wherein a displacement of the stop toward the first end position of the rod occurs counter to the return force of the return means. The return means can be designed, for example, as a spring.

[0021] The second sealing section is preferably connected in a form-fitting and / or force-fitting and / or material-fitting manner to the wall delimiting the cavity.

[0022] In a preferred embodiment of the device, the second sealing section of the seal is arranged between the head section and the base body section, in particular held in a clamping manner.

[0023] To ensure a particularly good sealing effect, it is considered advantageous if the seal has a circumferential bead in the area of ​​the second sealing section. The bead is formed, in particular, on a side facing the actuator and thus protrudes in the axial direction.

[0024] Any manufacturing tolerances that may occur can also be compensated for by the circumferential bead.

[0025] Furthermore, a bead facilitates the non-destructive absorption of the forces occurring when the second sealing section is clamped between the head section and the base body section during the clamping process by the second sealing section.

[0026] The device has at least one inlet opening opening into the cavity for supplying the flowable medium into the cavity. With regard to a particularly homogeneous distribution of the flowable medium in the cavity or a particularly homogeneous supply of the flowable medium into the cavity, a particularly preferred embodiment provides for the device to have a plurality of inlet openings opening into the cavity, wherein the inlet openings are arranged circumferentially around the rod.

[0027] Preferably, the inlet openings are arranged regularly, in particular equidistantly.

[0028] It is considered particularly advantageous if the angular distance between the inlet openings is 360° divided by the number of inlet openings.

[0029] The device preferably has an odd number of inlet openings. An odd number of inlet openings has proven particularly advantageous with regard to ensuring the most homogeneous supply possible. The device particularly preferably has five inlet openings.

[0030] In order to supply the flowable medium particularly homogeneously and thus also to stress the seal particularly homogeneously or to exert pressure on it, a preferred embodiment provides that the inlet openings are arranged along a circumference of a circle, wherein a circular plane of the circle is formed perpendicular to the axial direction.

[0031] In order to ensure a particularly uniform flow to the seal, it is considered advantageous if the inlet openings have a different cross-sectional area.

[0032] In a particularly preferred embodiment of the device, the device has an annular channel for supplying the flowable medium to the multiple inlet openings. In particular, it is provided that the annular channel surrounds the rod all the way around. However, the annular channel does not necessarily have to be closed; it is certainly conceivable for the annular channel to only partially surround the rod, for example, enclosing the rod over an angular range of 270°.

[0033] With regard to a particularly simple supply of the flowable medium into the channel, it is considered advantageous if the device has a supply line accessible from the outside, wherein the supply line opens into the annular channel.

[0034] The supply line can in particular have a connection for connecting a hose for supplying the flowable medium.

[0035] It is considered particularly advantageous if the channel in the direction of flight of the supply line is free of inlet openings leading into the cavity.

[0036] In a design with multiple inlet openings, it is considered particularly advantageous if the cross-sectional area of ​​an inlet opening that is closer to the supply line than another inlet opening is smaller than the cross-sectional area of ​​the other inlet opening. This promotes the most homogeneous flow possible to the seal.

[0037] The second sealing section of the seal is designed as a flange. This allows for particularly easy installation of the seal while providing a particularly good sealing effect.

[0038] The seal is preferably designed as a bellows seal. The bellows seal may well be a convoluted bellows seal.

[0039] In a preferred embodiment, at least a portion of the elastic region of the seal is arranged radially spaced from the rod. This prevents frictional contact and thus frictional forces that negatively impact the service life of the seal.

[0040] In an advantageous further development, the seal has a constant wall thickness in the elastic range. Such a seal is particularly simple and cost-effective to manufacture and, due to the special design of the device—namely, the seal is stretched or extended in the axial direction compared to the seal's basic state—still exhibits the necessary fatigue strength.

[0041] It is considered particularly advantageous if the elasticity region exhibits a curvature in a flat cross-section of the seal parallel to the axial direction. In this context, the term "flat cross-section" refers to a section along a plane. In this respect, the term "flat cross-section" is used to distinguish it from a stepped cross-section, also known as a step section. In particular, it is intended that the curvature of the elasticity region can be described by a center line of the cross-section of the elasticity region, with a curvature of the center line being continuous. The continuous curvature of the center line ensures that changes in stress in the seal also behave continuously. This ensures a particularly long service life of the seal. The shape of the center line can be described, in particular, by a section of a quadratic sine function.

[0042] Preferably, the seal has an axis of symmetry, and the aforementioned cross-section runs through the axis of symmetry of the seal. The axis of symmetry of the seal preferably runs through the rod of the device.

[0043] In a particularly advantageous development, it is provided that the rod is designed in at least two parts, wherein a first rod part has the sealing section, wherein the first rod part has a receptacle for a second rod part, wherein the second rod part is arranged in the receptacle and wherein the first sealing section is connected to the first rod part.

[0044] Preferably, the first sealing section is connected to the first rod part and / or to the second rod part in a force-fitting and / or form-fitting and / or material-fitting manner.

[0045] In a particularly advantageous further development, it is provided that the first sealing section is clamped between the first rod part and the second rod part.

[0046] In order to achieve a particularly long service life, it is provided that the elasticity region adjacent to the first sealing section has a first contact section and the rod has a first sliding section, wherein the first contact section contacts the first sliding section and / or the elasticity region adjacent to the second sealing section has a second contact section and the device has a wall section surrounding the rod all the way around, wherein the wall section has a second sliding section, wherein the second contact section contacts the second sliding section on a side facing away from the rod. During actuation of the rod and the simultaneous elastic deformation of the seal, sliding may occur in the corresponding sliding sections. The sliding sections also prevent damage to the seal during assembly and initial commissioning.In particular, it is provided that the respective sliding section has a coating and / or a lower roughness compared to a region of the rod adjacent to the first sliding section in order to reduce occurring frictional forces.

[0047] The actuator is preferably a pneumatically actuated piston. The piston is preferably sealed within a cylinder, with the piston dividing the cylinder into a first cylinder section and a second cylinder section, each cylinder section having a connection for supplying compressed air. To open the dispensing opening, one connection is supplied with compressed air, and to close the dispensing opening, the other connection is supplied with compressed air.

[0048] In a particularly advantageous development, it is provided that the cylinder interior is sealed with a further seal, wherein an overflow channel is provided in the device between the cavity and the further seal, wherein the overflow channel is arranged downstream of the seal which serves to seal the area of ​​the device receiving the second end section of the rod against the cavity. The overflow channel is formed in the area of ​​the device receiving the second end section and serves to divert misdirected media which penetrate into this area of ​​the device and reach this area despite the seal, for example as a result of damage to the seal or wear to the seal or damage and / or wear to the connection between the seal and the rod.The overflow channel and the additional seal prevent, in particular, misdirected media from entering the area of ​​the actuator. Character description

[0049] In the following figures, the invention is illustrated using an exemplary embodiment, without being limited thereto.

[0050] They show: Fig. 1 a device for dispensing a flowable medium, in a sectional view, Fig. 2 a portion of the device according to Fig. 1 , in a sectional view, Fig. 3 the device according to Fig. 1 , in a first perspective view, Fig. 4 the device according to Fig. 1 , in a second perspective view.

[0051] The Fig. 1 to 4show a first embodiment of the device 1 for dispensing a flowable medium, in this case for dispensing a hot melt adhesive. The device 1 has a head section 2 and a base body section 3. The head section 2 is inserted into the base body section 3 and screwed to the base body section 3 at the end by means of four screws 35. For the purpose of sealing, a sealing ring 32 is arranged between the base body section 3 and the head section 2. The device 1 has a cavity 4, which serves to receive the flowable medium. The cavity 4 is formed in the head section 2 in this case. The head section 2 has a dispensing opening 5 opening into the cavity 4 for dispensing the flowable medium, in this case the hot melt adhesive.Furthermore, the device 1 has a rod 7, 8, wherein the rod 7, 8 in this case is designed in two parts, namely a first rod part 7 and a second rod part 8, wherein the first rod part 7 has a receptacle for the second rod part 8, wherein the second rod part 8 is arranged in the receptacle. In the present case, the second rod part 8 has an external thread, wherein the first rod part 7 in the region of the receptacle has an internal thread corresponding to the external thread of the second rod part 8. For the purpose of connecting the first rod part 7 to the second rod part 8, the second rod part 8 is screwed into the thread of the first rod part 7 and preferably additionally glued to the first rod part 7.

[0052] The rod 7, 8 is movable between a first end position and a second end position in an axial direction Z. These two positions are shown in the Fig. 1 and 2shown, wherein the left half of the respective figure shows the rod 7, 8 or the device 1 in the first end position of the rod 7, 8 and the right half of the respective figure shows the rod 7, 8 or the device 1 in the second end position of the rod 7, 8.

[0053] The rod 7, 8 has a first end portion, which in this case is formed by the first rod part 7. The first end portion has a sealing portion 9, which serves to tightly close the dispensing opening 5 in the second end position of the rod 7, 8.

[0054] In the first end position of the rod 7, 8, the sealing section 9 is arranged at a distance from the dispensing opening 5, and in the second end position, the sealing section 9 closes the dispensing opening 5 on a side facing the cavity 4. The axial distance of the sealing section 9 in the first end position from the position of the sealing section 9 in the second end position is designated by the reference symbol Δ. The distance Δ is identical to the stroke of the lifting movement of the rod 7, 8. To move the rod 7, 8, a second end section of the rod 7, 8, which in this case is formed by the second rod part 8, is led out of the cavity 4 and coupled to an actuator 10, in this case a piston of a pneumatic cylinder 23, in this case mounted in the piston 10.The cylinder 23 has two cylinder sections separated by the piston 10, with a first port 24 opening into the cylinder section facing the head section 2 and a second port 25 opening into the cylinder section facing away from the head section 2. To transfer the rod 7, 8 from the second end position to the first end position, the first port 24 is pressurized with compressed air. To transfer the rod 7, 8 from the first end position to the second end position, the second port 25 is correspondingly pressurized with compressed air.

[0055] To limit the stroke of the rod 7, 8 and thus of the sealing section 9, a stop 28 is used. The stop 28 is arranged in a cover 31, wherein the cover 31 is in turn screwed to the base body section 3 at the end by means of screws 35. The stop 28 is displaceably mounted in the cover 31, wherein a displacement of the stop 28 in the opening direction of the rod 7, 8 occurs counter to the restoring force of a restoring means 29 designed as a spring. In this respect, the stop 28 and the restoring means 29 form means that exert an external force on the rod 7, 8 in the direction of the second end position. When the device 1 is depressurized, the rod 7, 8 is pressed by the stop 28 in the direction of the second end position of the rod 7, 8. This prevents flowable medium, in this case adhesive, from escaping from the outlet opening 5 in a depressurized state.Another advantage is that no air humidity can enter the cavity 4. This means that when a reactive adhesive such as PUR is used, it cannot harden. The position of the stop 28 and thus the stroke of the rod 7, 8 can be changed by means of the adjusting means 30 designed as an adjusting screw by screwing it further or closer into the cover 31 or into the base body section 3. By means of the adjusting means 30, manufacturing tolerances can be compensated and a fine adjustment of the stroke movement of the rod 7, 8 can be made. To prevent the adjusting means 30 from turning loose, the adjusting means 30 is secured with a lock nut 33.

[0056] In order to seal an area of ​​the device 1 receiving the second end section and thus also the actuator 10 against the cavity 4, the device 1 has a seal 11, which in the present case is designed as a bellows seal.

[0057] This seal 11 is arranged in the region of the cavity 4 and circumferentially encloses the rod 7, 8 in the region of the cavity 4. The seal 11 has a first sealing section 12 and a second sealing section 13, wherein the first sealing section 12 is fixedly and sealingly connected to the rod 7, 8, in this case the first rod part 7, and wherein the second sealing section 13 is fixedly and sealingly abuts a wall delimiting the cavity 4.

[0058] The seal 11 prevents, in particular, hot melt adhesive from entering the intermediate region 40 between the seal 11 and the rod 7, 8 and from there into the region of the device 1 receiving the second end section.

[0059] Due to the fixed connection of the first sealing section 12 with the rod 7, 8 relative to the rod 7, 8, the first sealing section 12 follows the movement of the rod 7, 8.

[0060] In the present case, the second sealing section 13 is designed as a flange, wherein the second sealing section 13 is clamped between the head section 2 and the base body section 3.

[0061] To ensure a good seal even in the event of manufacturing tolerances, the second sealing section 13 has a circumferential bead 36, wherein this circumferential bead 36 is formed on a side facing the actuator 10. Furthermore, the bead 36 facilitates the non-destructive absorption of the forces occurring on the second sealing section 13 when the head section 2 is screwed to the base body section 3.

[0062] The seal 11 has an elastic region 14 between the first sealing section 12 and the second sealing section 13. This elastic region 14 serves to compensate for the change in the distance between the first sealing section 12 and the second sealing section 13, which occurs when the rod 7, 8 is displaced to transfer the rod 7, 8 from the first end position to the second end position and vice versa.

[0063] In the present case, the seal 11 or the arrangement of the seal 11 in the device 1 is designed such that in the second end position of the rod 7, 8, the seal 11 is stretched or extended in the axial direction Z compared to a basic state of the seal 11.

[0064] In the present embodiment, it is provided that the first sealing section 12 is integrally connected to the rod 7, 8. The first rod part 7 has, on the connecting surface with the first sealing section 12, a plurality of preferably circumferential undercuts 39 spaced apart in the axial direction Z in order to better absorb the axial forces occurring in this area, which are caused by the applied adhesive pressure and by the actuating forces of the rod 7, 8.

[0065] The device 1 has a plurality of inlet openings 6 opening into the cavity 4, specifically five inlet openings 6. These inlet openings 6 are arranged circumferentially and equidistantly around the rod 7, 8. In the present case, the inlet openings 6 are arranged along a circumference of a circle, with a circular plane of the circle being perpendicular to the axial direction Z.

[0066] In this case, the inlet openings 6 have different cross-sectional areas, specifically different diameters.

[0067] This design of the inlet openings 6 ensures that the flowable medium, in this case the adhesive, flows evenly into the cavity 4 and is thus evenly distributed over the entire circumference of the seal 11. In particular, no dead spaces arise in the cavity 4 in which the adhesive accumulates and is thus not supplied to the dispensing opening 5. This design of the inlet openings 6 also has the advantage of ensuring the most even flow of the adhesive into the cavity 4 and thus towards the seal 11, thereby achieving the most rotationally symmetrical loading of the seal 11 possible. This has a positive effect on the fatigue strength of the seal 11.

[0068] The device 1 further comprises an annular channel 15 for supplying the flowable medium to the plurality of inlet openings 6. This annular channel 15 circumferentially surrounds the rod 7, 8. In the present case, the circumferential channel 15 is formed by an annular gap between the base body portion 3, the head portion 2, and the second sealing portion 13.

[0069] The device 1 has a supply line 16 accessible from the outside, wherein the supply line 16 opens into the annular channel 15 and serves to supply adhesive or flowable medium from the outside into the device 1, specifically the channel 15.

[0070] A portion of the elastic region 14 of the seal 11 is arranged at a distance from the rod 7, 8 in a radial direction. The radial direction is oriented perpendicular to the axial direction Z.

[0071] In particular, the Fig. 2As can be seen, the elasticity region 14 has a curvature in a planar cross-section of the seal 11 extending through a central axis 34 of the rod 7, 8, which can be described by a center line 17 of the cross-section of the elasticity region 14. The curvature of the center line 17 is continuous, in this case, can be described by a section of a quadratic sine function.

[0072] The elastic region 14 has a first contact section 18 adjacent to the first sealing section 12, and the rod 7, 8 has a first sliding section 19, wherein the first contact section 18 contacts the first sliding section 19. With regard to the sliding section, it is considered particularly advantageous if the first sliding section 19 has a coating and / or a lower roughness than a region of the rod 7, 8 adjacent to the first sliding section 19.

[0073] The elastic region 14 furthermore also has a contact section 20 adjacent to the second sealing section 13, and the device 1 has a wall section 22 circumferentially enclosing the rod 7, 8, wherein the wall section 22 has a second sliding section 21, wherein the second contact section 20 contacts the second sliding section 21 on a side facing away from the rod 7, 8. It is also considered advantageous for the second sliding section 21 to have a coating and / or a lower roughness than a region of the wall section 22 adjacent to the second sliding section 21.

[0074] The device 1 has a guide sleeve 27, wherein the guide sleeve 27 is mounted in the base body section 3. The guide sleeve 27 serves to receive the second end section of the rod 7, 8, wherein the second end section of the rod 7, 8 passes through the guide sleeve 27. The guide sleeve 27 has a circumferential groove, wherein the base body section 3 has a bore adjacent to the groove, wherein for the purpose of stable mounting of the guide sleeve 27 in the base body section 3, a retaining pin 26 is inserted into the groove and the bore adjacent to the groove.

[0075] The guide sleeve 27 receives the second end section of the rod 7, 8 and serves to guide the movement of the rod 7, 8. The guide sleeve 27 has the second sliding section 21 in the region of the wall section 22.

[0076] The entirety of the inlet openings 6, the annular channel 15, the cavity 4, the seal 11 is, apart from the different diameters of the inlet openings 6, radially or rotationally symmetrical and in particular concentric to the rod 7, 8.

[0077] In order to seal the device 1 or components of the device 1 from one another, the device 1 has a sealing ring 32 between the head section 2 and the base body section 3, a sealing ring 32 between the cover 31 and the base body section 3, and a sealing ring 32 between the adjusting means 30 and an outer wall of the cover 31. Furthermore, a further seal 38 is arranged between the second rod part 8 and the base body section 3 in the area between the cylinder 23 and an overflow channel 37.

[0078] The overflow channel 37 is located downstream of the seal 11, which serves to seal the area of ​​the device 1 receiving the second end section of the rod 7, 8 from the cavity 4. The overflow channel 37 is formed in the area of ​​the device 1 receiving the second end section and serves to drain any misdirected hot melt adhesive that penetrates this area of ​​the device 1 despite the seal 11. The overflow channel 37 and the additional seal 38 prevent, in particular, misdirected hot melt adhesive from entering the area of ​​the actuator 10.

[0079] The seal 11 is manufactured such that, when installed, the rod 7, 8 is in the first end position without any external loads. Preferably, the seal 11 is installed without any preload on the elastic region 14.

[0080] Preferably, the device 1 is manufactured in such a way that, at the design point, stresses in the seal 11 in the axial direction largely disappear, i.e. the boundary conditions, such as the size of the stroke movement, temperature, adhesive pressure or medium pressure and viscosity, are selected in such a way that the applied stresses in the seal 11 in the axial direction Z largely disappear.

[0081] With a view to particularly simple and cost-effective production, it is considered advantageous if the seal 11 is first connected to the first sealing section 12 of the first rod part 7. Subsequently, the second rod part 8 is connected to the first rod part 7, in this case screwed and, if necessary, glued. Care must be taken to ensure that the seal 11 is not damaged when screwing the second rod part 8 into the first rod part 7. List of reference symbols

[0082] 1Device 2Head section 3Main body section 4Cavity 5Discharge opening 6Inlet opening 7First rod part 8Second rod part 9Sealing section 10Actuator 11Seal 12First sealing section 13Second sealing section 14Elasticity area 15Channel 16Supply line 17Center line 18First contact section 19First sliding section 20Second contact section 21Second sliding section 22Wall section 23Cylinder 24First connection 25Second connection 26Retaining pin 27Guide sleeve 28Stop 29Resetting means 30Adjusting means 31Cover 32Sealing ring 33Lock nut 34Center axis 35Screw 36Bead 37Transfer channel 38Additional seal 39Undercut 40Intermediate area ZAxial direction ΔStroke path

Claims

1. Device (1) for dispensing a fluid medium, in particular for dispensing an adhesive, preferably for dispensing a hot melt adhesive, wherein the device (1) comprises a head portion (2) and a base body portion (3), wherein the device (1) comprises a cavity (4) for receiving the fluid medium, wherein the head portion (2) comprises a dispensing opening (5), leading into the cavity (4), for dispensing the fluid medium, wherein the device (1) comprises a rod (7, 8), wherein the rod (7, 8) is displaceable in an axial direction (Z) between a first end position and a second end position, wherein a first end portion of the rod (7, 8) comprises a sealing portion (9), wherein the sealing portion (9), in the first end position, is arranged spaced from the dispensing opening (5) and, in the second end position, closes the dispensing opening (5) on a side facing the cavity (4), wherein a second end portion of the rod (7, 8) is guided out of the cavity (4) for coupling the rod (7, 8) to an actuator (10), wherein the device (1) comprises a seal (11) for sealing a region of the device (1) which receives the second end portion with respect to the cavity (4), wherein the seal (11) is arranged in the region of the cavity (4), wherein the seal (11) surrounds the rod (7, 8) circumferentially in the region of the cavity (4), wherein the seal (11) comprises a first seal portion (12) and a second seal portion (13), wherein the first seal portion (12) is connected to the rod (7, 8) such that it is stationary with respect to the rod (7, 8) and the second seal portion (13) abuts in a stationary manner against a wall delimiting the cavity (4), wherein the seal (11) comprises an area of elasticity (14) between the first seal portion (12) and the second seal portion (13), wherein the seal (11), in the second end position of the rod (7, 8), is stretched in the axial direction (Z) in relation to an initial state of the seal (11), characterized in that the area of elasticity (14) comprises a first contact portion (18) adjoining the first seal portion (12), and the rod (7, 8) comprises a first anti-friction portion (19), wherein the first contact portion (18) contacts the first anti-friction portion (19), and / or the area of elasticity (14) comprises a second contact portion (20) adjoining the second seal portion (13) and the device (1) comprises a wall portion (22) surrounding the rod (7, 8) circumferentially, wherein the wall portion (22) comprises a second anti-friction portion (21), wherein the second contact portion (20) contacts the second anti-friction portion (21) on a side remote from the rod (7, 8).

2. Device (1) according to Claim 1, wherein the first seal portion (12) is connected to the rod (7, 8) with material fit.

3. Device (1) according to Claim 1 or 2, wherein, without the effect of an external force on the rod (7, 8) and / or without the effect of an external force on the seal (11), the rod (7, 8) is located in the first end position, or, without the effect of an external force on the rod (7, 8) and / or without the effect of an external force on the seal (11), the rod (7, 8) is located between the first end position and the second end position.

4. Device (1) according to Claim 3, wherein the device (1) comprises means (28, 29), wherein the means (28, 29) exert an external force on the rod (7, 8) in the direction of the second end position.

5. Device (1) according to one of Claims 1 to 4, wherein the device (1) comprises a plurality of inlet openings (6) leading into the cavity (4), wherein the inlet openings (6) are arranged circumferentially around the rod (7, 8).

6. Device (1) according to Claim 5, wherein the inlet openings (6) are arranged along a circular circumference of a circle, wherein a circular plane of the circle is formed perpendicularly to the axial direction (Z).

7. Device (1) according to Claim 5 or 6, wherein the device (1) comprises an annular channel (15) for supplying the fluid medium to the plurality of inlet openings (6), in particular the annular channel (15) surrounds the rod (7, 8) circumferentially.

8. Device (1) according to one of Claims 1 to 7, wherein the second seal portion (13) is formed as a flange.

9. Device (1) according to one of Claims 1 to 8, wherein the seal (11) is formed as a bellows seal.

10. Device (1) according to one of Claims 1 to 9, wherein at least a segment of the area of elasticity (14) of the seal (11) is arranged spaced from the rod (7, 8) in a radial direction.

11. Device (1) according to one of Claims 1 to 10, wherein at least a segment of the area of elasticity (14) protrudes with respect to the first seal portion (12) in the radial direction.

12. Device (1) according to one of Claims 1 to 11, wherein the seal (11) has a constant wall thickness in the area of elasticity (14).

13. Device (1) according to one of Claims 1 to 12, wherein the area of elasticity (14) has a curvature in a planar cross section of the seal (11) formed parallel to the axial direction (Z), in particular the curvature of the area of elasticity (14) can be described by a centre line (17) of the cross section of the area of elasticity (14), wherein a curvature of the centre line (17) is constant, in particular the centre line (17) can be described by a segment of a quadratic sine function.

14. Device (1) according to one of Claims 1 to 13, wherein the rod (7, 8) is designed in at least two parts, wherein a first rod part (7) comprises the sealing portion (9), wherein the first seal portion (12) is connected to the first rod part (7) and / or the first seal portion (12) is mounted in a clamping manner between the first rod part (7) and the second rod part (8).