In the cases where two or more liquids are to be mixed and the mixed liquid volume must have a certain composition in respect of the volume of the liquids included, there are already inventions relating to the way in which a secondary liquid is added to a primary liquid which is conducted in a tube. Without separate mixing in a vessel, the liquids must be passed from their storage containers up to the packaging machine and, while being transported, they must be mixed with great accuracy so that none of the manufactured packages have too large or too small an amount of added liquids. As a rule, this is a problem particularly when adding exceedingly small amounts of a secondary liquid to a considerably larger volume of primary liquid. In the case here described, the secondary component liquid (or liquids) consists of added volumes which are 0.05-10% of the volume of the primary liquid, and the added volume of secondary liquid in the completed packages are only allowed to vary to a very small degree, of course depending on the intended use of the liquid. In medical technology the variables are generally very small whereas in food technology it is possible to apply slightly greater variations such as 5%.

A previously filed patent application concerning adding of small quantities of liquid to a flowing liquid is, for instance, Swedish Patent Application No. 9602179-5.

In the present case, the requirement that a small amount of secondary liquid be mixed with another liquid is not involved, but the invention relates to the way in

which this should be done under aseptic conditions. Thus the invention concerns the way of mixing sterile liquids with each other and packaging in a prior art manner the mixed liquid in aseptic containers. It is true that the invention is not completely directed to the liquids being uniform in respect of volume, but the practical applica- tions that have been made have, however, been limited in such manner that the invention concerns the way in which 0.05-10% of a secondary liquid can be mixed with a pri- mary liquid, thus enabling the result to be a closed package with a volume accuracy as intended, the mixed liquids supplied to the package being sterile.

As mentioned above, it is quite obvious that liquids can be sterilised and handled in a way that maintains sterility. It is also known that such sterile liquid can be mixed in tanks and that the contents of these tanks can later be discharged and poured into packages. How- ever, it has been found difficult to carry out these methods. They further necessitate large storage spaces and long mixing periods for the materials. However, by means of new packaging machines, for instance those sold by Tetra Pak AB under the trademark Tetra Brik, it is possible to continuously mix and package liquid material, such as liquids, in consumer packages. Such packaging machines can be intended for the manufacture of aseptic packages, and with a view to obtaining such an aseptic package containing several liquids, the liquids must be mixed in a preparatory operation during the transport of the sterile liquid material from their storage to the packaging machine, thereby achieving a liquid mixture which is correct in terms of volume. Examples of such products are juice or milk products, but it is worth noticing, and has already been pointed out, that the invention can also be used for medical products, cleaning products etc.

The invention is characterised in that the dosing apparatus for the product that is to be packaged

has a controllable valve with a movable closing sleeve for controlling the supply of secondary liquid to the flowing primary liquid, that the dosing apparatus has an outer valve member which in itself comprises an inner part which is displaceable in relation to the valve member and has a recess or duct whose end facing the closing sleeve is covered with a sealing protective wafer, that a supply tube for supplying secondary sterile liquid is arranged in said recess or duct, and that the dosing apparatus has a means for rupturing the protective wafer to allow injection of the secondary sterile liquid into the primary sterile liquid through the supply tube.

Embodiments of the invention, or more precisely of the inventive dosing apparatus, will be described below.

It is possible to use the dosing apparatus for many other packaging machines than the above-mentioned Tetra Pak machine, which is only mentioned as an example of a suit- able packaging machine, and it should be emphasised that the invention constitutes a suitable dosing valve for adding a sterile secondary liquid in the cases where mixing is to be carried out while the sterile liquids are being transported to the packaging machine and a well functioning mixing and an accurate mixing between the liquids are desirable.

In the following description of two different em- bodiments of the invention, Figs 1-6 illustrate the dosing apparatus in cross-section and how the apparatus is operated in the initial position and the shut-off position.

Fig. 1 shows how a primary conduit 1 is sterilised with vapour or gas. A first embodiment of the dosing apparatus is connected to the primary conduit 1. A closing sleeve or closing valve 16 of the dosing appa- ratus is open. En inner part of the dosing apparatus is raised to its upper position and covered with a pro- tective wafer 8.

Fig. 2 shows how a valve member 18 of the dosing apparatus in Fig. 1 is internally sterilised with the closing sleeve 16 in its closed position and the inner part 17 lowered under the position of a groove 5. A sterilising agent, preferably in the form of a liquid, is supplied through connecting tubes 4.

Fig. 3 shows the dosing apparatus in Fig. 1 in its operating position. The closing sleeve 16 is raised and the inner part 17 is returned to its upper position. A longitudinally adjustable supply tube 12 is raised so that its front edge has penetrated the wafer 8, which means that secondary liquids discharged through the supply tube 12 are being mixed with the primary liquid in the primary conduit 1.

Fig. 4 shows how the dosing apparatus in Fig. 1 can be quickly shut off by the closing sleeve 16 closing the contact between the dosing apparatus and the primary conduit 1.

Fig 5 a-c illustrate a connecting device for con- necting the invention.

Fig. 6 shows a second embodiment of the inventive dosing apparatus.

Special embodiments of the invention will be de- scribed below by means of the accompanying drawings. It is worth noticing that the invention can be used with other types of connecting devices or dosing apparatus if these connecting devices satisfy the features as defined in the claims.

As mentioned above, the described apparatus can be used to mix and package liquids intended to be packaged in an aseptic packaging machine, for instance of the type sold under the trademark Tetra Brik. The liquids have been produced and sterilised in advance in some suitable manner and packaged or stored in aseptic storage tanks.

One or more of the dosing apparatus according to the invention are connected in the pipe connection between the aseptic storage tanks and the packaging machine. As

emphasised above, the connection is arranged in such manner that a dominating primary liquid is to be mixed with a secondary liquid whose volume in the mixture should be 0.05 to 10% of the total volume, but the mixing ratio should be constant in the packages produced. As is apparent from a previously filed patent application, this is achieved by measuring the flowing amount of primary liquid and letting the result of this measurement essen- tially control the supply of the secondary liquid so that the added amount of secondary liquid is always controlled by the amount of pumped primary liquid.

In the present case, the two mixed liquids have been sterilised and they are to be mixed and packaged in an aseptic packaging machine without their sterility being lost.

The enclosed Figs 1-5 illustrate the dosing appa- ratus according to a first preferred embodiment of the invention. With a view to elucidating the description, the dosing apparatus is shown in section.

First, the dosing apparatus is presented in its static design and the conduit, below referred to as primary conduit, for the primary liquid is designated 1.

In the primary conduit 1 there is arranged a seat for the dosing apparatus which essentially has two parts, viz. an upper movable closing sleeve 16 which is arranged to be moved upwards and downwards and be pressed against the upper part of the valve member 18 fixed in the primary conduit 1, the pressing being carried out by means of packing rings 2 mounted on the closing sleeve 16. The lower part of the dosing apparatus comprises the valve member 18 which has an inner cylindrical wall and a circumferential groove or annular gap 5, which is con- nected to connecting tubes 4, through which a sterilising material can be supplied. An inner part 17 is inserted into the cylindrical interior of the valve member 18. The inner part 17 has a central bore or duct 19, which at the top is covered with a rupturable protective wafer 8. The

inner part 17 also has two spaced-apart packing rings 6, which in the upper position of the inner part 17 surround and seal the circumferential groove 5 of the valve mem- ber 18. A supply tube 12 is arranged in the central duct 19 of the inner part 17. The supply tube 12 is movable in relation to the inner part 17 but also connected so as to accompany the inner part 17 as this is moved back and forth. The inner part 17 is moved by means of the guiding lug 7 while the supply tube 12 is displaced separately by means of the guiding lug 15. The lower portion of the inner part 17 is sealingly connected with a folded con- necting means or bellows 11 which can be moved without the tightness of the system being lost. The folded con- necting means 11 is kept in its position by the guiding lug 7, which can be moved up or down with the aid of means (not shown). As is evident from Fig. 5, the lower part of the folded connecting means 11 is fixed in a holder 14, which also holds the supply tube 12. The supply tube 12 can be raised with the aid of a further guide means 22 to a position above the protective wafer 8, which is then ruptured by the cutting edge 20 of the tube to form an opening 9.

The protective wafers 8 must have certain features.

They must not be too easily rupturable and they must withstand high temperatures as well as high pressures. As far as our experience goes, the wafer material should be plastic or rubber and the wafers should withstand a tem- perature of 140°C at an excess pressure of 2 bar.

Fig 1 shows how the dosing apparatus is connected in the primary conduit 1 which extends between a storage tank (not shown) for the primary liquid and the packaging machine (not shown). As shown in the figure, the closing sleeve 16 is raised and the lower part of the dosing appa- ratus is protected by the wafer 8. In this position, the primary conduit 1 is flushed with a hot sterilising liquid or with some sterilising gas so as to make the primary conduit 1 sterile and maintain its sterility. After steri-

lising of the primary conduit 1, as shown in Fig. 2, the closing sleeve 16 is closed, whereupon the inner part 17 is pulled backwards with the aid of said means 7 so that a free volume forms in the upper part of the valve member 18. Since in this position the circumferential groove 5 is uncovered, the upper part of the valve member 18 is steri- lised together with the circumferential groove 5 by using a sterilising agent in the form of liquid or gas supplied through the connecting tubes 4.

In Fig. 3, the closing sleeve 16 is again raised and the inner part 17 is once more in its upper position. To enable the secondary liquid to be supplied, the position of the supply tube 12 is raised so that the cutting edge 20 of the tube 12 ruptures the protective wafer 8. The apparatus is now ready to be used and the primary liquid is supplied through the primary conduit 1 while at the same time feeding the previously mentioned secondary liquid, which is controlled by the flowing amount of the primary liquid. By the sterilising liquid or gas being continuously supplied through the connecting tubes 4, it is possible to maintain sterility in the apparatus.

Fig. 4 shows how the apparatus is stopped without sterility being lost. The stopping occurs simply by the closing sleeve 16 being lowered towards the valve member 18 so that the supply of secondary and primary liquid is stopped. In this manner, the apparatus can be switched off for a long period without necessitating the starting of a new sterilising programme.

Fig. 5 shows how the connecting devices to the dos- ing apparatus can be arranged. Fig. a) shows the con- necting device before being fixed on the dosing appara- tus. The inner part 17 with its applied protective wafer 8 and its packing rings 6 has already been described. It is evident from the Figure that the inner part 17 with the supply tube 12 can be connected, by means of a screw connection 23, to a distribution tube 25 whose opposite end can also have a tight protective wafer to be con-

nected to a sterile tank for secondary liquid. Fig. b) shows a smaller type of connecting device intended to be used when adding very small amounts of secondary liquid, and Fig. c) shows protective sleeves which can be used to cover the contact surfaces of the not yet used connecting means.

It has been found convenient to pre-treat the dis- tribution tube 25 by sterilisation as shown in Fig. 5 in such manner that it is provided with its protective sleeves 10, and that the distribution tube 25 in its as- sembled state is then exposed to sterilising gamma radia- tion which sterilises the distribution tube 25, inside and outside, and the parts included in the distribution tube 25. If desired, the distribution tube 25 can, before the sterilising treatment, be packaged in a sealed plas- tic bag, but as a rule it is sufficient to use the pro- tective sleeves 10 shown in Fig. 5 as an aseptic seal of the distribution tube 25.

Fig. 6 shows a second preferred embodiment of the dosing apparatus according to the invention. What differs this embodiment from the above first embodiment of the present invention is that the means for rupturing the protective wafer 8 in this case consists of a projection 24 arranged on the closing sleeve 16.

By moving the closing sleeve 16 and the inner part 17 together, i. e. by arranging the closing sleeve 16 in its closed position and by displacing the inner part 17 in the direction of the closing sleeve 16, the projection 24 is made to engage the protective wafer 8 and, thus, penetrate the same. The supply tube 12 can then be in- serted through the thus formed opening 9 to allow injec- tion of the secondary sterile liquid into the primary sterile liquid flowing in the primary conduit 1.

It has been found that the preferred embodiments of the inventive dosing apparatus operate well and that ex- cellent results have been achieved when packaging aseptic liquid mixtures.