Abstract:
A mixing apparatus for producing a mixture of flowable components is provided. Two inlet channels for the components to be mixed open into a first mixing channel having at least one mixing element disposed therein. A second mixing channel having at least one mixing element disposed therein is connected downstream of the first mixing channel. A third inlet channel opens directly or indirectly into the second mixing channel in order to admix a third component. In further embodiments, three or more mixing channels are present. In addition, a discharge comprising such a mixing apparatus and corresponding containers and a method for mixing at least three components are provided.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a mixing device, to a discharge device equipped with such a mixing device, and to a method for producing a mixture of flowable components. 
       PRIOR ART 
       [0002]    An objective in many applications is to produce and discharge a mixture of several flowable components in a predefined mixing ratio. An example is the production of an adhesive for technical or medical uses, e.g. an epoxy resin adhesive or a medical glue based on fibrin, from two or more components. Another example is the production of a bone cement from several components. In systems of this kind, the curing time can be very short, and the product therefore has to be discharged immediately after being mixed. 
         [0003]    To this end, the prior art discloses discharge devices in which two components that are to be mixed are stored in a double syringe with two syringe containers, two outlets and two interconnected syringe pistons, or are sucked into such a double syringe shortly before application. A mixing device with two inlet channels is then fitted onto the double syringe, said inlet channels adjoining the outlets of the double syringe. The inlet channels open into a mixing channel, in which a static mixing element is located, in most cases in the form of a mixing helix with helically arranged mixing blades. When the interconnected syringe pistons are then pushed into the double syringe, the two components are fed from the syringe containers into the mixing device, where they are mixed with each other and discharged immediately thereafter. A discharge device of this kind is known, e.g., from WO 2006/005205. 
         [0004]    GB 1 423 933 discloses a mixing device for industrial applications, in which the mixing action for two components that are to be mixed is improved by means of two mixing channels, with mixing elements arranged therein, being routed in parallel in pairs. The outlets of the two mixing channels are brought together in a chamber. This chamber opens in turn into two parallel mixing channels which, with respect to the direction of flow, are offset by 90° in relation to the previous two mixing channels. This arrangement is repeated a number of times. 
         [0005]    In certain applications, however, instead of just two components it may be necessary for three or more components to be mixed and then immediately discharged. 
       SUMMARY OF THE INVENTION 
       [0006]    It is therefore an object of the present invention to make available a mixing device that permits the production and subsequent discharging of a mixture composed of at least three components. 
         [0007]    This object is achieved by a mixing device having the features of claim  1 . Preferred embodiments are set forth in the dependent claims. 
         [0008]    It is thus proposed to carry out a sequential or serial mixing procedure in which the first two components are first of all mixed and then other components (which can optionally be a mixture themselves) are admixed. To this end, a through-flow mixing device for producing a mixture of flowable components is proposed which comprises:
       at least a first and a second inlet channel for the components to be mixed;   an outlet channel for the mixture to be produced therefrom; and   a first mixing channel arranged, in the direction of flow, between the inlet channels and the outlet channel and accommodating at least one mixing element, wherein the first and second inlet channels open directly or indirectly into the first mixing channel;   a second mixing channel arranged, in the direction of flow, between the first mixing channel and the outlet channel and accommodating at least one mixing element, wherein the first mixing channel opens directly or indirectly into the second mixing channel, and   at least a third inlet channel, which opens directly or indirectly into the second mixing channel.       
 
         [0014]    The second mixing channel then opens directly or indirectly into the outlet channel of the mixing device. 
         [0015]    In other words, a through-flow mixing device is thus proposed which, viewed in the direction of flow, has at least two flow mixers connected in series. At least two components are delivered to the first flow mixer and are mixed together in this flow mixer. Thereafter, in the second flow mixer, the resulting intermediate product has added to it at least one further component (which itself can also be an intermediate product). The terms “directly” and “indirectly” are to be understood as follows. A channel opens “directly” into another channel when there is no further mixer located between these channels. A channel opens “indirectly” into another channel when a further mixer is located between the channels, and in particular if further components are admixed in the further mixer. 
         [0016]    The components should generally be flowable. This includes liquid, viscous and powdery components, if appropriate also gaseous components. The components can all be different, although it is also possible for two or more components to be identical. In particular, it is conceivable that the components delivered through the second and third inlet channels are identical, such that only the mixing ratio is changed between the first and second mixers. In this case, the third inlet channel can branch off from the second inlet channel. 
         [0017]    At least the first and second inlet channels, preferably also the third inlet channel, preferably each have a connector element for a container. This connector element can be designed in any known way, e.g. as a male or female Luer connector. It is also conceivable to design a common connector element for all three or more channels. In this case, each inlet channel has a connection portion designed for connection to a container. To make connection easier, at least the first and second inlet channels, preferably also the third inlet channel, can extend parallel to one another in the area of the connector elements. The first, second and third inlet channels can be arranged substantially in a common plane in the area of the connector elements, although they can also form a triangle, for example. The connectors can be coded, i.e. differently designed, such that each connector can only be connected to a corresponding complementary connector of a matching container, or they can be designed and arranged such that the mixing device can be connected only in a well-defined position to a matching container arrangement. 
         [0018]    The mixing elements in the mixing channels can be any desired static or dynamic mixing elements, as are known per se. In a preferred embodiment, the first and/or second mixing elements are static mixing elements. Mixing elements of this kind have long been known. They can, for example, comprise a helix with a plurality of helical blades or vanes arranged thereon. 
         [0019]    In a particular embodiment, the mixing device also comprises a third mixing channel accommodating at least one mixing element, and a fourth inlet channel. The third inlet channel and the fourth inlet channel then open into the third mixing channel, and the third mixing channel opens directly or indirectly into the second mixing channel. 
         [0020]    The invention also relates to a discharge device that comprises a mixing device of the type described above. The discharge device further comprises at least a first and a second container, wherein each container has a container outlet, and wherein the container outlet of the first container can be connected to the first inlet channel, and the container outlet of the second container can be connected to the second inlet channel. Preferably, a third container with a container outlet is also present, wherein this container outlet can be connected to the third inlet channel. Any desired containers can be used, e.g. syringes, carpules (i.e. containers that have a cylindrical wall portion and are closed at one end by a septum and at the other end by a movable piston), bags, tubes, etc. The containers can be accommodated in a common cartridge or can be connected to one another in some other way and form a single container unit. The container unit is then designed to be connected as a whole to the mixing device. 
         [0021]    For this purpose, the inlet channels of the mixing device and the container outlets of the containers preferably have mutually corresponding connector elements or connection portions, which are designed and/or arranged in such a way that the container outlet of the first container can be connected only to the first inlet channel, and the container outlet of the second container can be connected only to the second inlet channel. 
         [0022]    The discharge device preferably further comprises at least one discharge element in order to discharge the components from the containers and dispense said components through the container outlets. The discharge element can then usually be actuated manually. If the containers have a syringe-shaped or carpule-shaped design for example, the discharge element is, for example, a piston rod for each container. By contrast, if the containers are bag-shaped or collapsible tube-shaped for example, the discharge elements can also have completely different shapes. If several discharge elements are present, these are preferably connected to a common actuating element, so as to permit, by manual actuation of the actuating element, simultaneous dispensing of the components from the containers. 
         [0023]    In a simple embodiment, each of the containers has a syringe-shaped design, with a syringe body having a cylindrical wall portion, and with a piston movable in the syringe body. The syringe bodies can then be rigidly interconnected in order to form a multiple syringe, and the pistons can be rigidly interconnected in order to ensure joint discharging from the syringes. 
         [0024]    The quantities that are processed with a mixing and discharge device of this kind are normally small and vary within the range of about one to a few hundred milliliters. In other words, the containers normally have a volume of in each case less than about 300 ml. The sizes of the mixing device in each dimension usually reach at most about 30 cm, typically even less than 15 cm. The cross section of the mixing channels is typically less than about 5 cm 2 . 
         [0025]    According to a further aspect, the present invention relates to a method for producing a mixture of flowable components, said method comprising:
       feeding a first and a second component through a first mixing channel accommodating at least one mixing element, in order to mix the first and the second component with each other to form a first intermediate product;   feeding the first intermediate product, together with a further component, through a second mixing channel accommodating at least one mixing element, in order to mix the first intermediate product together with the further component.       
 
         [0028]    This method can be set up as an operating method for a device of the type described above, but it can also be carried out using other types of devices. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    Preferred embodiments of the invention are described below with reference to the drawings, which are provided only for illustration and are not to be interpreted as limiting the invention. In the drawings: 
           [0030]      FIG. 1   a  shows, in longitudinal section, a highly schematic view of a discharge device with mixing device according to a first embodiment; 
           [0031]      FIG. 1   b  shows an enlarged view of the mixing device from  FIG. 1   a;  and 
           [0032]      FIG. 2  shows a highly schematic view of a mixing device according to a second embodiment. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0033]      FIGS. 1   a  and  1   b  show highly schematic views of a discharge device in longitudinal section. The discharge device comprises a container unit in the form of a multiple syringe  200  (here a triple syringe) with three rigidly interconnected containers  210 ,  220  and  230  in the form of syringe bodies, which are closed by pistons  214 ,  224 ,  234 . In the present example, the containers are arranged next to one another in a common plane, but they can also have another arrangement. The containers can have identical cross sections or, as in the present example, different cross sections and, therefore, also different volumes. Each syringe body has a cylindrical jacket wall  211 ,  221 ,  231 , and a top wall  212 ,  222 ,  232  which delimits the syringe body in the distal direction and in each of which a container outlet  213 ,  223 ,  233  is formed. A piston  214 ,  224 ,  234  is inserted from the proximal direction into each syringe body and provides a seal with the jacket wall. A piston rod  215 ,  225 ,  235  is connected to each piston. At their proximal end, the piston rods are rigidly interconnected by a common actuating element  240 , here in the form of an actuating flange. 
         [0034]    A mixing device  100  is mounted on the container outlets  213 ,  223 ,  233 . The mixing device has three inlet channels  110 ,  120 ,  130 , of which the proximal end portions extend parallel to one another and, in the present example, are designed as connectors  111 ,  121 ,  131  ( FIG. 1   b ) for fitting onto the multiple syringe  200 . The connectors are only shown very schematically here. Many different types of connectors are conceivable here, e.g. standardized Luer connectors with the customary frustoconical contact surfaces and with or without a securing nut (Luer lock). The connectors are preferably coded, i.e. designed such that the mixing device can be fitted only in a well-defined position onto the multiple syringe, e.g. by choosing different diameters of the connectors or defined combinations of male and female connectors. Of course, completely different types of connectors and codings are also possible that permit a defined connection between the outlet of each container and the associated inlet channel. 
         [0035]    The first inlet channel  110  and the second inlet channel  120  open into a first mixing channel  141 . Before the inlet portion  143  of the mixing channel  141 , the two inlet channels  110 ,  120  run toward each other at an acute angle. However, it is also possible for the two inlet channels to be brought together in another way, e.g. parallel to each other or one surrounding the other in a ring shape, etc. The exact way in which the inlet channels are merged is not essential to the basic mode of operation of the mixing device. 
         [0036]    The mixing channel  141  accommodates a static mixing element  142  which, together with the mixing channel  141 , forms a first flow mixer  140 . The mixing element is designed in the usual way as a mixing helix, wherein the helix has a plurality of successively disposed helical mixing blades by means of which the volume flow passing through the mixing channel is divided up, diverted and recombined a number of times in order to achieve thorough and optimally homogeneous mixing together of the mixing material. Mixing helices of this kind have long been known per se, and the exact nature of the mixing element is not essential to the basic mode of operation of the mixing device. Instead of a static mixer, it is also possible in principle to consider using a movable, externally driven mixing element, e.g. a rotatable mixing element. 
         [0037]    At its outlet portion  144 , the first mixing channel  141  opens into the inlet portion  153  of a second mixing channel  151  with a static mixing element  152 . The second mixing channel  151  and the second mixing element  152  together form a second flow mixer  150 . The latter can be constructed in the same manner as or in a different manner than the first mixer  140  and have the same or different dimensions, in particular length; the exact structure is once again not essential to the basic mode of operation of the mixing device. 
         [0038]    The third inlet channel  130  extends, in a delivery section  132 , parallel to the first mixing channel  141  and opens with a distal mouth portion  133  likewise into the inlet portion  153  of the second mixing channel  151 . Once again, the outlet portion  144  of the first mixing channel  140  and the mouth portion  133  of the third inlet channel  130  can be brought together in any desired manner known per se. 
         [0039]    In the present example, the outlet portion  154  of the second mixing channel  151  is adjoined directly by the outlet channel  101  of the mixing device  100 , or this outlet channel is formed by the outlet portion  154 . The outlet channel  101  can be provided with fastening means for attachment of an accessory, e.g. with a Luer cone for attachment of a spray device or of another accessory, or can itself be designed in any desired form, e.g. fan-shaped for a planar discharging of the mixing product. The exact configuration of the outlet portion is also not essential to the basic mode of operation of the mixing device. 
         [0040]    In operation, the containers  210 ,  220 ,  230  are first of all filled with the components to be mixed and are vented, if this has not yet been done. Then the mixing device  100  is mounted on the multiple syringe. By manual pressure on the actuating element, the three pistons  214 ,  224  and  234  are pushed forward to the same extent, such that the components located in the containers pass through the outlets  213 ,  223 ,  233  of the containers into the inlet channels  110 ,  120 ,  130  of the mixing device. Here, the components from the first two containers  210 ,  220  are first of all brought together and mixed in the first mixer  140 . The resulting intermediate product emerges from the first mixer  140  and is brought together with the third component from the container  230  and mixed in the second mixer  150 . The resulting product is then discharged through the outlet channel  101 . The components thus undergo sequential or serial mixing. 
         [0041]    A mixing device of this kind can be advantageously used wherever a plurality of components are intended to be mixed together in succession. An example is the production of a bone cement from two components known per se, to which an active substance, e.g. a growth factor or an antibiotic, is to be admixed. The two cement components are in this case delivered through the first and second inlet channel and mixed in the first mixer, while the active substance is delivered through the second inlet channel and admixed in the second mixer. Another example involves two components of an adhesive system (e.g. two monomers), which are first of all mixed together in the first mixer and are then mixed together with a catalyst and/or promoter in the second mixer. Another possible application is one in which the viscosity of a mixture is intentionally influenced by admixture of a component through the third inlet channel. Many other applications are conceivable in which, for chemical or physical reasons, a defined sequence of mixing is necessary or desirable. 
         [0042]    Although the three components to be mixed will be different in many applications, it is nonetheless also conceivable that the components in the second container and third container are identical, such that the component from the first container is first of all mixed in the first mixer with a smaller quantity of the other component, before the final mixing ratio is fixed in the second mixer. In this case, embodiments are also conceivable in which, instead of the third inlet channel being connected to a separate container, the second container opens with its outlet both into the second inlet channel and also into the third inlet channel, and these inlet channels are thus connected in the area of their proximal ends or branch off from a common inlet. This results in some of the component from the second container bypassing the first mixer. 
         [0043]    It is also not strictly necessary for the components to be delivered from the three containers in a fixed and predetermined ratio, and instead the three pistons can also be advanced independently of one another or in an adjustable ratio of advance. 
         [0044]    The mixing device can of course also be used with containers of other designs. Possible examples of such containers are: a cartridge which contains a plurality of containers and from which material is discharged via an integrated or independent actuating element; a tube arrangement; a bag system with flexible bags as containers, etc. The essential point is simply that each container has an outlet and that at least one discharge element is present that can be actuated in such a way that, upon actuation, the content is discharged from the container through the outlet. All the containers advantageously form a common unit. 
         [0045]    Another embodiment of a mixing device is shown in  FIG. 2 . Identical or corresponding parts are designated by the same reference numbers as in  FIGS. 1   a  and  1   b.  This mixing device  100 ′ has four inlet channels  110 ,  120 ,  130  and  170 . The first two channels  110 ,  120  open into a first mixer  140 . As in the previous illustrative embodiment, this mixer is followed downstream by a second mixer. The other two channels  130 ,  170  open into a third mixer  160  with mixing channel  161  and mixing element  162 . The outlet portions of the first and third mixers open jointly into the second mixer. 
         [0046]    In operation, the components from the first two inlet channels are fed through the first mixer  140 , in order to mix these components together to form a first intermediate product, while the components from the other two inlet channels are fed through the third mixer, in order to mix these components together to form a second intermediate product. The first and second intermediate products are then fed through the second mixer  150  and mixed with each other. As before in the first illustrative embodiment, each mixer comprises a mixing channel and a mixing element arranged in the latter. 
         [0047]    In the second illustrative embodiment too, many variations and modifications are once again possible. 
         [0048]    Thus, in this case too, it is once again possible for two components to be identical, e.g. the components that pass through the inlet channels  120  and  130 . These channels can accordingly also branch off from a common inlet. While a linear arrangement of the connectors of the mixing device is shown here, any other desired arrangement is also possible. Here too, the connectors can be designed such that they can be connected only in a very specific manner to a corresponding multiple container. 
         [0049]    It is clear from the abovementioned examples that there are also many possible variations in respect of the arrangement of the individual mixers in the mixing device. Thus, instead of a two-stage sequential mixing procedure, it is also possible to provide a three-stage sequential mixing procedure in which at least three mixers are present, arranged one after another in the direction of flow, and in which a further component (which itself can once again be the intermediate product from a preceding mixing procedure) is admixed after each mixer. Thus, individual mixers can be combined with one another in substantially any desired topologies. Each individual mixer can also be designed to mix together not just two components but also three or more components in a single step. 
       LIST OF REFERENCE SIGNS 
       [0050]      100 ,  100 ′ mixing device 
         [0051]      101  outlet channel 
         [0052]      110  first inlet channel 
         [0053]      111  first connector 
         [0054]      120  second inlet channel 
         [0055]      121  second connector 
         [0056]      130  third inlet channel 
         [0057]      131  third connector 
         [0058]      132  delivery section 
         [0059]      133  mouth portion 
         [0060]      140  first mixer 
         [0061]      141  first mixing channel 
         [0062]      142  first mixing element 
         [0063]      143  inlet portion 
         [0064]      144  outlet portion 
         [0065]      150  second mixer 
         [0066]      151  second mixing channel 
         [0067]      152  second mixing element 
         [0068]      153  inlet portion 
         [0069]      154  outlet portion 
         [0070]      160  third mixer 
         [0071]      161  third mixing channel 
         [0072]      162  third mixing element 
         [0073]      170  fourth inlet channel 
         [0074]      171  fourth connector 
         [0075]      200  multiple syringe 
         [0076]      210  first container 
         [0077]      211  jacket wall 
         [0078]      212  top wall 
         [0079]      213  outlet 
         [0080]      214  piston 
         [0081]      215  piston rod 
         [0082]      220  second container 
         [0083]      221  jacket wall 
         [0084]      222  top wall 
         [0085]      223  outlet 
         [0086]      224  piston 
         [0087]      225  piston rod 
         [0088]      230  third container 
         [0089]      231  jacket wall 
         [0090]      232  top wall 
         [0091]      233  outlet 
         [0092]      234  piston 
         [0093]      235  piston rod 
         [0094]      240  actuating element