1 Metering pump The invention relates to a metering pump for a metering device for metered dispensing of a liquid, which can be connected to a storage container, comprising a cylindrical pump body and an actuation body. Metering pumps for metered dispensing of liquids which can be connected to a storage container are known from the state of the art. Such a metering pump which consists of a cylindrical pump body, an actuation body and a closing cap is known from EP 0 473 892 A2 and from EP 1 466 668 Al. An essential element of the metering pump according to the above-mentioned European application is the construction in the form of a pump body in hollow cylinder form which has two portions, an inner hollow cylinder in which a piston is guided being mounted in the interior of the hollow cylindrical pump body portion. The seal relative to the storage container is achieved by a gasket disposed on the inside. A similar solution is known from WO 97/18902 in which a sealing ring is provided likewise for the seal between the storage container and the pump body in the form of a hollow cylinder. It has however been shown that such arrangements still display inadequate reliability with respect to the impermeability against air penetrating during the metering process. Furthermore, there are problems during the metering if a storage container with a high temporary counter-pressure is used. It is therefore the object of the present invention to indicate a metering pump for medical, pharmaceutical and cosmetic liquid and gel preparations and also in the foodstuff sphere (e.g. for food supplements, 2 herbs/spices, etc.) which can be connected to a storage container and in the case of which increased reliability of the impermeability against air penetrating during the metering process is achieved even under unfavourable circumstances. The object is achieved by the characterising features of patent claim 1. The sub-claims reveal preferred developments. According to the invention, it is proposed hence according to patent claim 1 that a metering pump which can be connected to a storage container, as is known already in the state of the art, e.g. from EP 0 473 892 A2, from EP 1 466 668 Al or from WO 97/18902, is improved such that a sealing ring for the seal is provided between the outside of the piston and the inside of the pump body on the pump body on the inside itself. Furthermore, the metering pump according to the invention is distinguished by a valve portion being provided on the open end in the direction of the storage container, in which valve portion an inlet valve cooperates, according to the invention, with a ball disposed in a valve seat. It is now achieved by the combination of these measures that even under unfavourable conditions during the metering process, i.e. at high temperatures and counter-pressure, extremely high impermeability is achieved. Furthermore, it has been shown that also a significantly simplified actuation of the metering pump is made possible by the configuration according to the invention such that the pumping process need not be implemented many times, as is normal in the state of the art, for the filling process, but rather that, even after a few pumping processes, generally after three to four times, reliable and perfect metering is possible. A particularly advantageous embodiment of the metering pump now provides that, in the interior of the valve portion, starting from the 3 inside, support elements which extend in the longitudinal direction are provided for upper path delimitation of the ball during actuation of the metering pump. As a result, extremely reliable guidance of the ball in the space spanned by the valve seat and by the support elements becomes possible. This measure in particular obviously leads to the fact that, as explained already above, an extremely reliable operation is possible with the metering pump according to the invention. For this embodiment, it has emerged as particularly favourable if at least one, preferably two, however particularly preferred three, support elements are provided. These support elements are preferably configured such that they are connected in one piece (monolithically) to the inside of the inner hollow cylinder which defines the valve portion. Preferably, these support elements are thereby produced in one piece together with the valve seat and the inner hollow cylinder, at least of the valve portion, preferably by an injection moulding process. The advantage of the thin configuration of the wall in this region is higher flexibility of this valve portion. This increased flexibility makes it possible to counteract the "suction force/restoring force" which is produced by the inner bag (disposed in the storage container) after actuation of the pump (tendency of the inner bag to return into a relaxed form instead of remaining in folded form). This means that the contact region of the valve wall with the ball seals even more tightly due to the increased flexibility and prevents the entrance of air in the direction of the bottle. In the case of a thicker wall, the result can be gaps in the region between the contact area of ball to valve so that air can enter. In particular, this is the case with balls which are not optimally round or with irregularly coated balls. In the case of the support elements, there are included all possibilities which are known per se in the state of the art and lead to stabilisation 4 of the ball. Preferred support elements are those which are configured in a wedge shape. Of further importance, it has emerged that at least the valve portion is configured such that the thickness of the walls of the valve portion is in the range of 0.2 to 1.0 mm, preferably in the range of 0.3 to 0.5 mm. The simplified production in the injection moulding process is thereby advantageous. The reproducibility of the shape of the support elements is increased as a result and hence allows precise function and mobility of the ball. An essential element in conjunction with this embodiment is hence the configuration in the form of thin walls within the indicated limits. If the upper limit of 1.0 mm is exceeded, it has emerged that this can lead to a lack of seal in subsequent use. In addition, the rigidity is so high that the flexibility of the wall is reduced too far still to seal the ball reliably. With smaller thicknesses than 0.2 mm, adequate stabilisation cannot be achieved. In a further preferred embodiment, coating the ball is proposed. The coating of the ball is effected in a thin layer which is placed around the ball over the whole surface. Suitable materials for this are in particular LD-PE (Low-Density-Polyethylene). An improvement in the metering effect is achieved by this measure. Coating with this material which is authorised for medical applications enables the authorisation of a medical product in markets which have particularly strict regulations. The ball itself can consist for example of stainless steel or a ball coated with silver which is then germicidal. The gasket which is proposed according to the invention is a sealing ring in a preferred embodiment. The sealing ring, according to the present invention, is disposed on the inside of the hollow cylindrical pump body portion which points in the direction of the actuation body. The arrangement should thereby be 5 chosen such that as high a sealing effect as possible is achieved relative to the piston which is guided in the interior of the hollow cylinder. The sealing ring can also be present as an integral component in the corresponding pump body portion. In a favourable manner, the sealing ring is therefore configured such that it is at a spacing from the piston outer wall and has suitable sealing lips. The impermeability relative to the piston is then achieved by these sealing lips. The sealing lips can thereby be configured as individual separate lips and point in the direction of the actuation body. The sealing ring can thereby have at least one, preferably 3 to 5 lips. A development of the invention proposes that, for reliable mounting of the sealing ring in the interior of the hollow cylindrical pump body portion, the sealing ring is configured in profile in the shape of a U and one U-leg engages in a groove on the interior of the pump body portion. The second leg of the U is then used for the sealing effect. This second leg of the U can then also be configured such that it is at a spacing relative to the outside of the piston and produces the sealing effect via lips. From the point of view of choice of material, basically all materials can be used which are used in general for gaskets. The choice of material thereby depends upon the safety for the respective field of use. Thermoplastics and thermoplastic elastomers are possible. Examples are PTFE (polytetrafluoroethylene), PU (polyurethane), polyamide (PA), polyethyleneterephthalate (PET), LD-PE (low density polyethylene), HD PE (high density polyethylene) and PP (polypropylene). The metering pump according to the invention can even of course, as in the state of the art, also have an additional gasket for the seal relative to the storage container. It is thereby preferred that a gasket is disposed internally between, on the one hand, the inner hollow cylinder and the 6 cylindrical pump body portion and, on the other hand, the storage container, not illustrated. The cylindrical pump body is formed preferably from a plastic material, such as e.g. polypropylene (PP) or polyethylene (PE). Of importance for the choice of material are thereby the medical and pharmaceutical safety and also the material safety in the foodstuff sphere. The inner surface of the cylindrical pump body can therefore also have a coating for germicidal purposes. The invention also includes an embodiment analogous to EP 1 466 668 Al in which the inner hollow cylinder which forms the pressure chamber can be exchanged. The metering pump according to the invention has then of course also an actuation body which is connected to the piston and to the cylindrical pump body. The configuration of the actuation body is thereby likewise based upon the state of the art. Reference is made in this respect to EP 0 473 892 A2, EP 1 466 668 Al and also WO 97/18902. There are basically possible as storage container which can be connected to the metering pump, all storage containers of the state of the art. Reference is made in this respect to the documents mentioned in the preceding paragraph. These must enable operation without air equalisation, i.e. for example containers with a flexible inner bag or drag piston. In addition to cylindrical containers manufactured from stable plastic material, also plastic material bags which are integrated in a separate container are suitable. When using drag piston bottles, a lower pressure should be expected. The storage containers are favourably connected to the metering pump via a snap-on closure or via a thread.
7 The invention is described subsequently in more detail with reference to Figures. Figure 1 shows an embodiment with the sealing element according to the invention. Figure 2 shows the sealing element of Figure 1 according to the invention in enlarged form. Figure 3 shows an embodiment in which the sealing element is configured in the form of a U. Figure 4 shows the sealing element of Figure 3 according to the invention in enlarged form. Figure 5 shows, as a cut-out, the configuration of the valve region with the sequence of Figures 1, 2, 3 which show the different operating states. Figure 6 shows the dimensioning of the valve region. Figure 1 shows schematically the construction of a metering pump according to the invention, the cylindrical pump body 1 with the actuation body 20 being represented here for the metering pump. The actuation body 20 which can consist preferably of the same material as the cylindrical pump body, i.e. for example PE, is connected to the pump body 1, e.g. via a snap-on closure or a plug-in connection. In Figures 1, 2, 3 and 4, the storage container is not illustrated since it is not essential for understanding the invention. For this purpose, as also for the explanation of the actuation body 20, reference is made to EP 0 473 892 A2, EP 1 466 668 Al or WO 97/18902.
8 In Figure 1, the cylindrical pump body 1 of a metering pump with the actuation body 20, as known from state of the art, is illustrated. The cylindrical pump body 1 thereby consists of a hollow cylindrical pump body portion 2 which is open in the direction of the storage container (not illustrated) and a second hollow cylindrical pump body portion 3 which is open in the direction of the actuation body 20. A groove disposed on the inner wall of the portion 3 is thereby designated with 15. An inner hollow cylinder 4 is mounted between the pump body portions 2, 3. Mounting of the inner hollow cylinder 4 in the pump body portions 2 and 3 is effected, in the embodiment according to Figure 1, by engagement in a groove. As emerges further from Figure 1, a piston 5 is guided in the inner hollow cylinder 4. The piston 5, as known from the state of the art, is thereby supported in the interior of the hollow cylinder 4 via a spring 9. The inner hollow cylinder 4 here now has an inlet valve 6, the inlet valve 6 being configured with a ball 8 which cooperates with a valve seat 7. The valve region is thereby designated with 30. In order to ensure the air-tight seal between the storage container (not illustrated) and the surroundings, a gasket arrangement 10 is provided on the lower side in the drawing. The sealing element 11, which is essential to the invention, is thereby configured, as emerges in particular from Figure 2, in the shape of a ring and is mounted on the inside of the hollow cylindrical pump body portion 3 and preferably at a spacing relative to the outer wall of the piston 5. For improving the sealing effect, sealing lips 12, 12' which produce a reliable seal even against air penetrating during the pumping process are provided, as emerges from Figure 2. The invention thereby includes of course also embodiments in which at least one sealing lip is provided. In a modification of the embodiment, as was described in Figure 1 or Figure 2, Figure 3 now also shows that the sealing element 11 is configured in the shape of a U. In this embodiment, the sealing ring 11 9 is mounted by the one U-leg in a groove 15 on the inside of the pump body portion 3. The second U-leg functions as sealing element relative to the outer wall of the piston 5. In the embodiment according to Figure 3, sealing lips 12, 12' are also provided again in order to enable optimal guidance of the piston in the interior of the hollow cylinder 4 and a seal. In Figure 4, a partial region of the embodiment represented in Figure 3 is illustrated enlarged. The sealing lips 12, 12' are provided for improving the sealing effect. These enable reliable sealing also against air penetrating during the pumping process. The sealing ring 11 is present here in the shape of a U. Figure 5 shows, in a cut-out, the configuration of the valve region 30 with the sequence of Figures 1, 2 and 3 which illustrate the different operating states during actuation. In Figure 5, the support elements 31 are thereby illustrated in a wedge shape. The support elements 31 and also the valve seat 7 are thereby configured integrally with the inside of the inner hollow cylinder 4. Such a configuration is preferably achieved by producing at least the part of the inner piston which is defined by the valve region 30 in one piece made of a suitable plastic material by means of an injection moulding process. By means of the configuration of the valve region 30, as described above, it is now achieved that reliable closure of the valve 6, as illustrated in the sequence of Figures 1, 2 and 3, is achieved during actuation of the piston. The sequence of Figures 2 and 3 then shows the change in the position of the ball 8 during actuation of the metering pump and the mode of operation of the wedge-shaped support elements 31 which lead to reliable and defined securing of the ball 8. A further essential element of the invention resides, as illustrated in Figure 6, in the valve region 30 being formed by a relatively thin-walled inner hollow cylinder 4. The thickness of the wall of the valve portion 10 30 of the inner hollow cylinder 4 is thereby preferably in the range of 0.2 to 1.0, particularly preferred in the range of 0.3 to 0.5 mm. It was shown that, in the case of this thin material thickness, an optimum flexibility is achieved, yet with adequate stability in order that the valve seat achieves optimum adaptation of its shape to the ball but still holds it securely. As a result, the seal is achieved. According to the invention, the metering pump is therefore configured such that the above-mentioned dimensions of the walls of the inner hollow cylinder are maintained at least in the region of the valve region.