Patent Publication Number: US-2016221700-A1

Title: Device for Controlling Flow Rate

Description:
The invention relates to a device for controlling the flow rate of flowable products, in particular of foodstuffs, comprising: a valve rod, a sealing element with at least one sealing lip connected to the valve rod, wherein the sealing element comprises a base plane and a contact plane, wherein the sealing lip is arranged on the contact plane and an outlet element with a stop plane and with at least one outlet channel, wherein the stop plane has at least one sealing region assigned to the sealing lip and at least one outlet region connected to the outlet channel. 
     The invention further relates to the use of a device of this kind for the filling of foodstuffs, in particular for the aseptic filling of foodstuffs. 
     When filling flowable products—for example foodstuffs such as fruit juices or milk—it is desirable and necessary to be able to regulate the flow rate. The flow rate is frequently controlled by the following sequence: A tank is initially filled with the flowable products, said tank comprising a plurality of outlets to different packaging lines. The flow rate at each of these outlets can be set by a reducing valve. Viewed in the flow direction, a dosing valve is arranged behind the reducing valve, with the help of which the flow rate can be increased or reduced or the through flow can be completely interrupted. For design reasons, it is often not possible, however, for the dosing valve to be arranged at the end of the flow path, in other words right in front of the outlet for flowable products from the filling machine. Instead of this, nozzles are customarily arranged at this point, said nozzles being adapted to the product being filled and the volume of the packing and being easily exchangeable. This arrangement of valve and nozzle means, however, that when the metering valve is shut off, there is still a residual amount of the product being filled in the section between the metering valve and the outlet nozzle. Because the metering valve is tightly closed, the residual amount does not flow out of the nozzle, but remains—as in the case of a pipette—in the flow section between the metering valve and the outlet of the nozzle. 
     There is a risk, however, that individual drops detach themselves from the nozzle and contaminate the packaging or the filling machine, for example. This may result in the packaging, for example a cardboard/plastic composite packaging, being contaminated in the region in which it is later to be sealed by heat-sealing. It is not possible, however, for a reliable heat-sealed joint to be produced between the walls of the packaging in the region of the contamination, which means that the packaging can no longer be tightly sealed and has to be rejected. If the leak is not immediately identified, the leaky packaging may contaminate parts of the filling machine or other packaging during subsequent processing steps or during transportation. Because many foodstuffs have to be filled under sterile, in other words germ-free, conditions, this kind of contamination of the filling machine may necessitate costly cleaning and also repeated sterilization of the entire filling machine. No filling can take place during this time, which results in production downtime. Contamination of other packaging, by contrast, can cause larger units or pallets of packaging to be unsaleable. 
     Even individual drops which escape from the nozzle of a filling machine unchecked can therefore cause significant problems. Different approaches have therefore been performed, in order to prevent drops from escaping from the nozzle of a filling plant. 
     It is known from EP 0 400 368 B1, for example, for the afterflow and dripping of product residues during the filling of flowable products to be prevented through the selective use of vibrations. It is proposed that the valve tappet should be connected to a vibration unit. The vibration unit can move the valve tappet up and down in an axial direction, so that a vibration is produced. The lift of the valve tappet during vibration is substantially smaller than the lift for opening and closing the valve tappet. 
     Moreover, structural measures ensure that the closing function of the valve tappet during vibration is retained. The vibrations are intended to shake off adhering product residues that have not already become detached during the closing process. 
     Several disadvantages are associated with the solution known from EP 0 400 368 B1. To begin with, the solution described requires high structural expenditure: Firstly, a drive must be provided to generate vibrations and secondly, it must be ensured that the closing function of the valve is not affected by the vibrations. A further disadvantage of the proposed solution lies in the fact that vibrations cause dynamic loads on the machine. This can result in increased maintenance expenditure and a shorter service life for the machine. Vibrations are undesirable for acoustic reasons too. In addition to this, the flow sections of the outlet channels of the outlet element connected in parallel empty to a varying degree with this kind of “shaking process”, which may be due to the arbitrary position of solid particles contained in the filling product, for example. This may give rise to unwanted differences in the filling level. 
     An alternative solution for preventing afterflow and dripping of products to be filled is known from DE 32 29 162 A1. It is proposed that a liquid filling needle should be connected to a cylindrical space, in which a displaceable piston is disposed. By displacing the piston, the volume of the interior space can be increased or reduced. The idea involves displacing the piston after the valve has been shut, such that the interior space of the cylinder is increased. This means that part of the liquid remaining in the filling needle after shutting-off is drawn back into the cylindrical space and cannot therefore drip from the filling needle. 
     The solution known from DE 32 29 162 A1 also has the disadvantage of a complicated structural design. In particular, a separate piston and a drive assigned to said piston must be provided to draw back the liquid being filled. In addition, the relative movement between the piston and the cylindrical interior space requires a good seal on the one hand and, on the other hand, little friction between the two components; however these two things are difficult to reconcile with one another when filling liquid foodstuffs such as yoghurt, for example. A further disadvantage lies in the limited suitability for very quick filling processes. In the case of the filling outputs required today of 24,000 or more packaging units per hour, cycle times of roughly one second result in the case of 6 packing lines connected in parallel, for example. Consequently, only a few tenths of a second of time are available within a station in the respective packaging line, which means that a device according to DE 32 29 162 A1 is too slow. 
     The problem addressed by the invention is therefore that of configuring and developing the device referred to above and described previously in such a manner that the drip-free filling of flowable products is made possible in a cost-effective and structurally simple manner. 
     This problem is solved in the case of a device according to the preamble of claim  1 , in that the contact plane is spaced apart from the base plane, so that an offset is created between the sealing lip and the base plane. 
     A device according to the invention initially comprises a valve rod and a sealing element connected to the valve rod having at least one sealing lip. The valve rod may be connected to the sealing element directly or indirectly, in other words via other components. The sealing element can be actuated via the valve rod and raised or lowered onto the surface to be sealed, for example. The sealing element comprises a base plane and a contact plane. In the case of the contact plane, this is the plane on which the lowest edge of the sealing lip lies, in other words the region of the sealing lip which first makes contact with the surface to be sealed when mounted on top. Furthermore, a device according to the invention comprises an outlet element with a stop plane and with a plurality of outlet channels. The stop plane is the plane that is assigned to the sealing element. For sealing, the sealing lips of the sealing element are therefore pressed onto the stop plane of the outlet element. The outlet channels are used to as an outlet for the products to be filled; they lead from the stop plane in the direction of the underside of the outlet element. The stop plane may be divided into different regions: the sealing region and the outlet regions. The sealing region is assigned to the sealing lip and acts as a stop for it. On the other hand, the inlets of the outlet channels are located in the outlet regions. 
     According to the invention, the contact plane is spaced apart from the base plane, so that an offset is created between the sealing lip and the base plane. The invention has therefore recognized the use of a sealing element with a profiled underside rather than a sealing element with a smooth, flat underside. The projecting edge of the sealing lip in this case lies on the contact plane. Hollow cavities are formed between the sealing lips, the rear walls of which extend back to a plane referred to as the base plane. Because the contact plane and the base plane are not identical, but are arranged offset, a certain depth of the hollow cavities is guaranteed. 
     It is achieved through the embodiment of the sealing element according to the invention that the size of the offset, in other words the depth—and therefore also the volume—of the hollow cavities can be varied according to the contact pressure of the sealing element. For example, the sealing element can be pressed very firmly onto the outlet element in a first step, so that the flowable products to be filled can no longer flow through the device. Due to the high contact pressure and the elasticity of the sealing lips, said sealing lips become deformed such that the offset between the base plane and the contact plane diminishes. The consequence of this is that the volume of the hollow cavities lying between the sealing lips likewise diminishes. In this first position, a certain amount of flowable liquids to be filled remains in the outlet channels of the outlet element and therefore creates a flow front on the underside of the outlet element. The flow front typically projects beyond the underside of the outlet element, so that there is a risk of drop formation. The configuration of the sealing element according to the invention allows the sealing element to be pressed onto the outlet element slightly less firmly in a second step. In this second position, a sealing effect is still guaranteed, so that the flowable products being filled cannot flow through the device. However, the offset between the base plane and the contact plane—and therefore also the volume of the hollow cavities—has become slightly larger again in this position. It is thereby achieved that part of the flowable products being filled is drawn back into the—now enlarged—hollow cavities, so that a different flow front is created. The new flow front typically no longer projects beyond the underside of the outlet element, which means that the risk of drop formation is considerably reduced. Due to the embodiment of the sealing element according to the invention, a variation in volume between the sealing surface and the outlet of the filling nozzle can therefore be achieved, so that the residual amount of flowable products remaining in this region can be drawn back slightly. By drawing back the flowable products, blockages in the outlet channels which can occur with fibrous or lumpy filling materials can also be cleared. 
     Particularly good results are achieved when the offset is at least 1 mm and particularly lies in the region between 1 mm and 10 mm. An excessively small offset would cause an excessively small volume change in the hollow cavities and would not therefore generate an appreciable suction action. On the other hand, an excessively large offset would result in a reduced sealing effect due to the high elasticity of the sealing element. A particularly good compromise between sufficient volume change and reliable sealing effect can be achieved by an offset in the region of between 2 mm and 5 mm. 
     It is provided according to an embodiment of the invention that the sealing element, in particular the sealing lip, has a lesser hardness than the outlet element. The different hardness ensures that when there is contact between the sealing element and the outlet element, the sealing element and, in particular, the sealing lip thereof deform almost exclusively. The advantage of this is that the outlet element provides a rigid stop for the sealing element which is dimensionally stable even under pressure, as a result of which the seal between the sealing element and the outlet element is particularly reliable. So that the sealing lip is able to perform the desired sealing and reverse suction functions effectively, it is particularly advantageous for the sealing lip to exhibit a material thickness of 0.5 mm to 3.0 mm, preferably of 1.0 mm to 1.5 mm. 
     The profile of the sealing lip may take on different shapes. For example, its wall thickness may vary, it may be curved outwardly or inwardly, or tilted and it may be angular or curved, in particular bell-shaped, in design. If only a single sealing lip is provided, this may be annular in design and have a diameter that is suitable for completely enclosing the surface of the stop plane occupied by the outlet channel inlets. It is of particular advantage for a plurality of annular sealing lips to be provided, which are arranged concentrically for example. This improves the bearing and increases the service life of the seal, so that the maintenance interval for the seal can be adapted to that of the filling machine. 
     Additional sealing lips are used, moreover, to increase the resetting and therefore the suction forces that can be achieved. The sealing lips may be particularly flexibly configured, because the “spring forces” to be generated by them are distributed over two or more sealing lips. In addition, every further outwardly displaced sealing lip creates a kind of safety function in the event of possible damage or leakiness of a further inwardly lying sealing lip. 
     It is also possible for the second or other sealing lip to divide the hollow cavity formed by the first sealing lip into at least two chambers, wherein the volume of the chambers adjoining one another is influenced according to the embodiment or the profile of the sealing lips. It may therefore be desirable, for example, for the hollow cavity volume to be particularly greatly varied via particular inlets in the outlet channels during a filling cycle, while the volume changes in another region are smaller. 
     Sealing lip rings arranged concentrically to one another may be connected to one another. Web-shaped sealing lips running in a star-shaped or radial configuration from the centre are preferably provided. The web-shaped sealing lips may exhibit the same wall thickness as a sealing lip ring, but the wall thickness may also vary. The wall thicknesses of the individual sealing lip rings can vary. So that the first seal lip is constantly reliably deformed, it may also be provided that at least one part of the further sealing lip rings or else the sealing lip webs exhibits a smaller offset relative to the base plane than the first sealing lip. 
     A further teaching of the invention envisages that the sealing element, in particular the sealing lip, is made of an elastomer, in particular silicone. Elastomers and silicone in particular are characterized by a high elasticity and can therefore adapt particularly well to the surface of the outlet element which is never perfectly smooth. This property ensures a reliable seal between the sealing element and the outlet element. Further advantages of elastomers and silicone, in particular, lie in favourable producibility and also in variable forming. Finally, elastomers and silicone in particular also meet hygiene requirements which relate to the filling of foodstuffs, for example. 
     According to a further embodiment of the invention, the sealing element, in particular the sealing lip, has a hardness of 75 Shore-A or less. The hardness preferably falls within the range of between 55 Shore-A and 65 Shore-A. The Shore-A unit is measured by pressing a blunt-ended needle into the plastic being tested, in order to measure the penetration depth. The front face of the truncated cone has as standard a diameter of 0.79 mm, the opening angle is 35°, the bearing weight 1 kg and the holding time 15 s (DIN 53505 and DIN 7868). On a scale of 0 to 100, a higher number means a greater hardness. The hardness grades indicated mean that a high elasticity and at the same time an adequate dimensional stability of the sealing element and its sealing lip are guaranteed. 
     A further embodiment of the invention envisages that the valve rod is made of plastic and/or metal. Plastics are characterized by variable forming, low weight and low cost. In addition, many plastics meet hygiene requirements for the filling of foodstuffs. Due to its high strength, its temperature resistance and, above all, due to its high friction resistance, PEEK (polyether ether ketone) is a particularly suitable plastic. On the other hand, very high rigidity, strength and hardness grades can be achieved by metals. Certain high-grade steels can be used, in particular, which are especially corrosion-resistant and therefore suitable for use when filling foodstuffs. Also with regard to the outlet element, an embodiment of the invention envisages production from plastic and/or metal. The outlet element is therefore preferably made of metal, since in this case in particular high rigidity and hardness are required, so that the sealing element can be used as a stop. In the case of both the valve rod and also the outlet element, combinations of plastic and metal are possible, for example a metal core with a plastic coating. 
     It is provided according to an embodiment of the invention that the sealing element has a stiffening element made of metal. For example, the stiffening element made of metal may form a core which has a coating made of an elastomer, particularly silicone. The dimensional stability of the sealing element can be increased by a stiffening element. Particularly in the case of a sealing element made from very soft plastic, a stiffening element made of metal can perform a supporting function, holding the sealing element in its basic shape. The use of a stiffening element made of metal therefore allows the use of particularly soft, flexible sealing elements. A further advantage of a stiffening element made of metal is that the sealing element can be connected to the valve rod particularly reliably via a screw connection, for example. 
     The invention may be advantageously developed by an intermediate element which is arranged between the valve rod and the sealing element and connects the valve rod to the sealing element. Intermediate elements may exhibit different lengths and be interchangeable. In this way, the distance between the valve rod and the sealing element can be varied. In addition, the intermediate element may perform an adapter function, so that the same valve rod can be fitted with different sealing elements through the use of corresponding intermediate elements. 
     It is further proposed in this respect that the intermediate element comprises two opposite threads, wherein the one thread is assigned to the valve rod and wherein the other thread is assigned to the sealing element. By means of opposite threads, the valve rod and the sealing element can be particularly well aligned and connected to the intermediate element in the aligned position. The valve rod must, for example, be aligned in such a manner that a drive can be coupled on. The sealing element, on the other hand, must be aligned in such a manner that the position of the sealing lip and the hollow cavities corresponds to the position of the outlet channels in the outlet element. Through opposite threads, the intermediate element can be screwed through rotation in a direction simultaneously with the aligned valve rod and also with the aligned sealing element. The intermediate element preferably has at least two faces arranged parallel to one another, with which a combination wrench can engage. Assembly can be made easier by an assembly aid. For this purpose, the valve rod, the intermediate element and the sealing element are only screwed together loosely to begin with. Then both the valve rod and also the sealing element are fixed in the assembly aid in a rotation-proof manner. This may take place, for example, in that the assembly aid—such as a combination wrench—engages with two faces arranged in parallel to one another, said faces being provided for this purpose on the valve rod and the sealing element or else the pressure plate connected thereto. The screw connection finally takes place in that the intermediate element is rotated using a combination wrench for example, wherein both opposite threads are tightened at the same time. 
     According to one embodiment of the invention, the intermediate element comprises a threaded bolt and a spacer element. In this case, the threaded bolt may exhibit two opposing threads on its ends, one thread whereof being assigned to the valve rod and the other thread whereof being assigned to the sealing element. Between the two threads, the threaded bolt may exhibit a threadless profile, for example a four-sided profile, on which the spacer element can be mounted in a form-fitted manner. Although the threaded bolt and the spacer element may be moved in an axial direction relative to one another in this case, they are however connected to one another in a rotation-proof manner. The spacer element may exhibit at least two faces arranged in parallel to one another, with which an open-ended wrench can engage. 
     According to a further teaching of the invention, the intermediate element is sealed on both sides with an O-ring, in particular with a coated O-ring. An O-ring is an annular sealing element, the cross section of which is roughly O-shaped. By means of O-rings, the transition between the intermediate element and the components connected thereto, for example the valve rod, can be reliably sealed. O-rings with a coating which reduces friction have proved particularly advantageous. This may be a nano-coating. O-rings of this kind are marketed under the registered trademark “RFN” (Reduced Friction by Nano-Technology) by the company Freudenberg. O-rings with particularly low friction have the advantage that they slip off when screwed onto the components screwed to one another and are not therefore damaged or lacerated. Because they are aligned concentrically to the axis running through the screw connection, they make assembly easier and in addition deprive germs of the opportunity to congregate due to their closed, smooth surface. 
     A further embodiment of the invention envisages a pressure plate which is arranged between the sealing element and the valve rod, in particular between the sealing element and the intermediate element. The pressure plate particularly satisfies the function of transferring the force emanating from the intermediate element onto the sealing element as uniformly as possible. For this purpose, a jump in diameter often has to be overcome, since the valve rod usually has a substantially smaller cross-sectional surface than the sealing element. In addition, an adapter function can be performed by the pressure plate, so that said valve rod can be fitted with different sealing elements through the use of corresponding pressure plates. 
     Finally, it is provided according to an embodiment of the invention that the sealing regions and the outlet regions are arranged on a common plane. Through the profiled embodiment of the sealing element, the sealing regions and the outlet regions of the outlet element can be configured in a planar manner. In this way, the formation of depressions—so-called “pockets”—between the sealing regions, which are traditionally raised in relation to the outlet regions, can be prevented. In this way, the risk of unwanted accumulations or deposits can be substantially reduced. In the case of known outlet elements, accumulations or deposits of this kind occur particularly in those depressions which are not assigned outlet openings. Alongside this, swirling may occur in the depressions when the valve is opened, since the depressions are often very flat and therefore exhibit unfavourable flow cross sections. These problems can be overcome through the arrangement of the sealing regions and the outlet regions on a common plane. 
     The previously described device may be used particularly effectively in all embodiments depicted for the filling of foodstuffs, in particular for the aseptic filling of foodstuffs. The foodstuffs may be fruit juices, milk, sauces, yoghurt or milk pudding. 
    
    
     
       The invention is described in greater detail below with the help of a drawing depicting only one preferred exemplary embodiment. In the drawing: 
         FIG. 1  shows a valve rod of a device according to the invention as a perspective view, 
         FIG. 2  shows the valve rod from  FIG. 1  as a perspective view, 
         FIG. 3  shows an outlet element of a device according to the invention as a perspective view, 
         FIG. 4  shows the outlet element from  FIG. 3  as a perspective view, 
         FIG. 5  shows a device according to the invention as a sectional view in an open position, 
         FIG. 6  shows the device from  FIG. 5  in a first closed position and 
         FIG. 7  shows the device from  FIG. 5  in a second closed position. 
     
    
    
       FIG. 1  shows a valve rod  1  of a device according to the invention as a perspective view. In its upper region, the valve rod  1  exhibits a coupling  2  by means of which the valve rod  1  can be moved up and down during operation by positively locking engagement of a drive. The valve rod  1  is connected to a sealing element  5  in its lower region via a spacer element  3  and a pressure plate  4 . The connection may be made by a threaded bolt  6  (not shown in  FIG. 1 ), which exhibits two opposing threads. One thread of the threaded bolt  6  is screwed into the valve rod  1 ; the other thread of the threaded bolt  6  is screwed into the sealing element  5 . The spacer element  3  and the pressure plate  4  are only mounted on the threaded bolt  6  but without being screwed thereto. In order to seal the transitions between the valve rod  1  and the spacer element  3  and also between the spacer element  3  and the pressure plate  4 , an O-ring  7  is provided in each case. In the case of the view shown in  FIG. 1 , the sealing element  5  stands on a planar base, so that the valve rod  1  stands upwards perpendicularly. A centre axis  8  runs centrally through the valve rod  1 , the spacer element  3 , the pressure plate  4  and the sealing element  5 . 
     The valve rod  1  from  FIG. 1  is depicted as a perspective view in  FIG. 2 . The essential difference compared with the view shown in  FIG. 1  is that the valve rod  1  lies laterally on a planar base, so that the underside of the sealing element  5  is visible. The regions already described in connection with  FIG. 1  are provided with corresponding reference numbers in  FIG. 2 . The sealing element  5  exhibits projecting sealing lips  9  on its underside which lie on a contact plane  10  (not depicted in  FIG. 2 ). The other regions of the sealing element  5  are arranged displaced backwardly in relation to the sealing lips  9 , in other words in the direction of the valve rod  1 , and extend back as far as a base plane  11  (likewise not shown in  FIG. 2 ). The consequence of this is that when the sealing element  5  is mounted onto a planar surface, hollow cavities  12  form in the regions between the sealing lips  9 . 
       FIG. 3  shows an outlet element  13  of a device according to the invention as a perspective view. The outlet element  13  comprises a stop plane  14 , the surface of which can be divided into sealing regions  15  and outlet regions  16 . The sealing regions  15  are intended for the sealing bearing of the sealing lips  9  of the sealing element  5 . In each of the sealing regions  16 , by contrast, at least one outlet channel  17  is provided in each case. Each outlet region  16  preferably combines a plurality of outlet channels  17 . A centre axis  8 ′ runs centrally through the outlet element  13 . In the case of the outlet element  13  shown in  FIG. 3 , the sealing regions  15  and the outlet regions  16  are arranged on a common plane. 
     The outlet element  13  from  FIG. 3  is depicted in  FIG. 4  in perspective view. The essential difference compared with the view shown in  FIG. 3  is that the outlet element  13  lies with its side assigned to the sealing element  5  on a planar base, so that the underside of the outlet element  13  is visible. The regions of the outlet element  13  already described in connection with  FIG. 3  are provided with corresponding reference numbers in  FIG. 4 . The outlets of the outlet channels  17  are visible on the underside of the outlet element  13 . A large part of the underside of the outlet element  13  is covered by the outlets of the outlet channels  17 , so that only narrow webs  18  are present between the outlets of the outlet channels  17 . 
       FIG. 5  shows a device  19  according to the invention as a sectional view in an open position. The device  19  shown by way of example in  FIG. 5  comprises among other things the valve rod  1  already known from  FIG. 1  and  FIG. 2  with the sealing element  5  and also the outlet element  13  already known from  FIG. 3  and  FIG. 4 . The regions of the device  19  already described in connection with  FIG. 1  to  FIG. 4  are provided with corresponding reference numbers in  FIG. 5 . The valve rod  1  and the sealing element  5  indirectly connected thereto are arranged relative to the outlet element  13  in such a manner that the centre axis  8  of the valve rod  1  and of the sealing element  5  and also the centre axis  8 ′ of the outlet element  13  are congruent, in other words they run collinearly. Due to the sectional view, it can be seen that the sealing element  5  exhibits a stiffening element  20  in its inside. In addition, the sectional view allows a view of the threaded bolt  6  concealed by the spacer element  3 , which threaded bolt connects the valve rod  1  to the sealing element  5  or else the stiffening element  20  thereof. 
     Likewise, the different planes already previously referred to are evident in  FIG. 5 . The sealing element  5  initially exhibits a contact plane  10  in which the lower edges of the protruding sealing lips  9  lie. The other regions of the sealing element  5  lie in the direction of the valve rod  1  displaced upwardly, so that hollow cavities  12  form between the sealing lips  9 , the rear walls of which extend back as far as a base plane  11 . Between the contact plane  10  and the base plane  11 —and therefore also between the sealing lips  9  and the base plane  11 —an offset  21  is therefore created which corresponds to the height of the hollow cavities  12  in the position shown in  FIG. 5 . Apart from the contact plane  10  and the base plane  11 , the stop plane  14  which is a plane of the outlet element  13  is also depicted in  FIG. 5 . 
     Both parts of the device  19  can be moved along the centre axes  8 ,  8 ′ towards one another and moved away from one another during operation. In this way, the sealing element  5  and the outlet element  13  are aligned in such a manner that in the event of contact between these two components, the sealing lips  9  of the sealing element  5  are pressed onto the sealing regions  15  of the outlet element  13 , in order to seal the outlet channels  17  securely. When the sealing lips  9  are lifted from the sealing regions  15  again, the outlet channels  17  can be released again. The position shown in  FIG. 5  is in an open position. In this position, there is no contact between the sealing lips  9  of the sealing element  5  and the stop plane  14  of the outlet element  13 , so that the products to be filled can flow through the device  19  in the direction of the arrows shown in  FIG. 5 , so as to be filled in packaging  22 . 
     The device  19  from  FIG. 5  is depicted in  FIG. 6  in a first closed position. The regions of the device  19  already described in connection with  FIG. 5  are provided with corresponding reference numbers in  FIG. 6 . The essential difference compared with the position shown in  FIG. 5  is that the sealing lips  9  are firmly pressed onto the stop plane  14  in the position depicted in  FIG. 6 , so that the flowable products being filled are no longer able to flow through the device  19 . The contact between the sealing lips  9  and the sealing regions  15  of the outlet element  13  means that the contact plane  10  lies on the stop plane  14 . Due to the high contact pressure and elasticity of the sealing lips  9 , the sealing lips  9  deform in such a manner that the distance between the contact plane  10  and the base plane  11  diminishes. In other words, an offset  21 ′ is created in the position shown in  FIG. 6  which is smaller than the offset  21  shown in  FIG. 5 . The result of this is that the volume of the hollow cavities  12  diminishes too. In the position depicted in  FIG. 6 , a given quantity of flowable products to be filled remains in the outlet channels  17  and therefore forms a flow front  23  on the underside of the outlet element  13 . The flow front  23  typically projects beyond the underside of the outlet element  13 , so that there is a risk of drop formation. 
       FIG. 7  shows the device  19  from  FIG. 5  in a second closed position. The regions of the device  19  already described in connection with  FIG. 5  and  FIG. 6  are provided with corresponding reference numbers in  FIG. 7 . The essential difference compared with the position shown in  FIG. 6  is that the sealing lips  9  are pressed onto the stop plane  14  less firmly. As in  FIG. 6 , there is also a sealing contact between the sealing lips  9  and the outlet element  13  in  FIG. 7 , so that the flowable products to be filled are no longer able to flow through the device  19 . The contact between the sealing lips  9  and the sealing regions  15  of the outlet element  13  means that the contact plane  10  also lies on the stop plane  14  in the position shown in  FIG. 7 . Due to the lower contact pressure and the elasticity of the sealing lips  9 , the distance between the contact plane  10  and the base plane  11  is admittedly still smaller than in the open position ( FIG. 5 ), but it is greater than in the first closed position ( FIG. 6 ). In other words, in the position shown in  FIG. 7  there is an offset  21 ″ that is smaller than the offset  21  shown in  FIG. 5  and greater than the offset  21 ′ shown in  FIG. 6 . The result of this is that the volume of the hollow cavities  12  is increased slightly in comparison with the position shown in  FIG. 6 . It is thereby achieved that part of the flowable products to be filled is drawn from the outlet channels  17  back into the now enlarged hollow cavities  12 , so that a different flow front  23 ′ is created. The new flow front  23 ′ typically no longer projects beyond the underside of the outlet element  13 , which means that the risk of drop formation is substantially reduced. 
     In practice, the device  19  can be moved into the position shown in  FIG. 7  in different ways to the position depicted in  FIG. 6 . One possibility involves the valve rod  1  being actively pulled slightly upwards again ( FIG. 7 ) from the maximum position ( FIG. 6 ). This may be achieved by a drive, for example, which moves the valve rod  1  via the coupling  2 . A further possibility involves only the contact pressure acting on the valve rod  1  and therefore also on the sealing element  5  being slightly reduced. The elasticity of the sealing element  5  and in particular of the sealing lips  9  means that a reduction in the contact pressure automatically results in a decompression of the sealing element  5  and therefore an enlargement of the offset  21  and of the hollow cavities  12 . 
     LIST OF REFERENCE NUMBERS 
       1 : Valve rod 
       2 : Coupling 
       3 : Spacer element 
       4 : Pressure plate 
       5 : Sealing element 
       6 : Threaded bolt 
       7 : O-ring 
       8 ,  8 ′: Centre axis 
       9 : Sealing lip 
       10 : Contact plane 
       11 : Base plane 
       12 : Hollow cavity 
       13 : Outlet element 
       14 : Stop plane 
       15 : Sealing region 
       16 : Outlet region 
       17 : Outlet channel 
       18 : Web 
       19 : Device 
       20 : Stiffening element 
       21 ,  21 ′,  21 ″: Offset 
       22 : Packaging 
       23 ,  23 ′: Flow front