The use of flexible packages for packing pasty liquids is well known. German utility model 9207385, for example, discloses a sausage like, flexible package for printing inks and a device for emptying such packages. While this is a very economic way for packaging liquids such as printing inks, there are some difficulties for emptying these pack- ages. The German utility model 9207385 discloses a caulking gun for holding and emptying such packages. The major disad- vantage of such a device is that, once the package is placed in the emptying device, the package must be completely emptied before another package can be inserted. If there are a number of different liquids to be used, an emptying device for each type of liquid (e. g. for each colour of ink) is necessary. Further, as packages must remain in the emptying device, the material in the dispensing opening may deterio- rate or harden.

DE 38 11 954 discloses a dispensing arrangement for emptying pasty liquids from flexible containers. The containers are placed in a cartridge which comprises an arrangement for displacing a piston. For each container which is in use, a separate cartridge is needed.

EP 248 278 discloses a dispenser for pasty liquids in a flexible container held in a cartridge. An arrangement for displacing the piston is associated with each cartridge.

It is an object of the present invention to overcome the drawbacks of the prior art, especially to provide a cartridge for a flexible container and a drive means for emptying such a cartridge which allow easy exchange of packages with dif- ferent liquids, which may be manufactured and filled in a simple and economic way and which allow easy handling.

According to the present invention, these objects are resolved with a cartridge and a drive means according to the features of the characterising portion of the independent patent claims.

The cartridge for a flexible package containing a pasty liquid, such as, for example, a printing ink, comprises a housing with a dispensing opening and a piston arranged displaceably along an axis within the housing. A flexible package may be placed within the housing. The piston is used for applying an axial force on the package. In response to the force, the liquid is dispensed through the dispensing opening. According to the present invention, the housing comprises at least one slit in its side wall, running approximately parallel to the axis of the housing. The piston is provided with at least one projection which extends outwardly from the piston. Through each slit arranged on the housing of the cartridge, there is one projection extending outwardly from the housing. By applying a force on the projection, the piston may be displaced and the content of the package may be dispensed. The projection (s) extending out of the housing of the cartridge are removably engageable with external drive means for moving the piston along the axis of the housing such that the cartridge is removably connected to the drive means.

In a preferred embodiment, the cartridge comprises two slits.

The slits are preferably arranged at a distance from each other corresponding to an angle of about 180°.

It is further preferred that the housing is substantially cylindrical or prismatic in form. Such a design is particu- larly simple for"sausage-like"cylindrical or prismatic packages.

The piston preferably has an outer diameter which corresponds to the inner diameter of the housing or which is slightly larger than the inner diameter of the housing and which may be slightly flexible or deformable. In this way, a friction force is created between the piston and the housing. Due to this friction force, the piston remains in an intermediate position within the housing when the package is partially emptied.

The simple and inexpensive design allows the use of a separ- ate cartridge for each package in use. When the package containing a specific liquid, e. g. an ink, is to be used, the corresponding cartridge may be placed in a drive means for creating a movement of the piston. Therefore, due to the projections extending outwardly of the housing, only one drive means is needed for any number of cartridges each containing a package with a specific type of liquid.

Preferably, the cylindrical housing comprises a tubular body which is closed at one end by the displaceable piston and which is closed at the other end by a cover which comprises the dispensing opening. The package is compressed between the cover and the piston when the piston is displaced. The slots are provided in the tubular body and the piston is moveable along the tubular body.

As the projections for displacing the piston extend out of the cartridge, the drive means for emptying the cartridge can be of a particularly simple design. The drive means accord- ing to the present invention comprises at least one screw means which is engageable with the projections of the piston for displacing the piston. Screw threads are selected in such a way (sufficiently deep and spaced) that engagement with the projections is possible. With such type of design, the two projections may be put simply in the helix of the screws without any firm engagement between the screw means and the projections. As soon as the screws are rotating, an axial pressure on the projections is created and the piston is displaced. The cartridge may be replaced without the need to loosen any fixing or connection between the cartridge and the drive means. An advantage of screw threads consists in that the projections of the piston may be engaged with the screw threads immediately, at any location on the screws, independent of the position of the piston, e. g. even if the cartridge is partially emptied and the piston is in an inter- mediate position, the cartridge can be placed into the drive means without changing the position or orientation of the drive means, i. e. screws.

The screws may be provided with a screw thread having a groove formed therein which is engageable with a protrusion arranged on the projection of the piston.

Other means or designs for avoiding separation of the screw means on the piston in a plane perpendicular to the axis of the screw means are conceivable.

Preferably, the screw means are driven by an electric motor operated by batteries. This permits a drive means which is easily removable and which can be used at any location within a fabrication facility.

In a further preferred embodiment, the screw means are coupled to the motor by a reduction gear. This allows the use of conventional electric motors having relatively high speeds. Due to the reduction gear, the content of the pack- age can be dispensed sufficiently slowly.

If the motor is battery-driven, the drive means can be formed as a hand-held drive means.

In a further preferred embodiment, the cartridge is held in the drive means in a space delimited by two screws. The screws are arranged distant from each other and form a space for the cartridge. The drive means further comprises holder means for holding the cartridge in a precisely defined posi- tion.

Of course, the screws may also be provided with additional elements displaceable along their axis, such as a nut.

In some cases, it may be easier to engage the projections of the piston with a nut on the screws rather than with the screw threads. Instead of a nut, an element comprising threads which are engageable with both screws and further comprising specifically designed engaging surfaces for the projection of the piston is conceivable.

The invention will be more clearly understood with reference to a preferred embodiment and to the following drawings which show: Figure 1 A schematic view of a cartridge according to the present invention Figure 2 A detailed view of the piston according the present invention Figure 3 A perspective view of the cartridge and a drive means according to the present invention Figure 4 A schematic view of a sausage like package Figure 5 A cross-section through a cartridge according to the invention comprising a sausage like package Figure 6 An enlarged view of the screw threads in enga- ging contact with the projections of the pis- ton Figure 1 shows a cartridge 2 consisting substantially of a housing 3 with a body 6, a cover 7 with a dispensing opening 4 and a piston 5 which is displaceable along an axis A of the cartridge 2.

The piston 5 (which is not shown in Figure 1) comprises projections 11 which extend outwardly from the piston 5 through slits 10 which are formed in the body 6 of the car- tridge 2. The piston 5 can be moved parallel the axis A along the slits 10.

Figure 2 shows piston 5 in more detail. The piston 5 com- prises an upper surface 14 for applying a force on a package 1 (Figure 5) which is contained in the cartridge 2. The piston 5 is further provided with an outer edge 15 having an outer diameter which is equal to or slightly larger than the inner diameter of the cartridge 2. Due to the friction created between the piston 5, especially its outer edge 15 and the inner surface of the body 6 of the cartridge 2, the piston may be held within the body 6 and remains at a speci- fic position without additional external force.

The projections 11 can be attached to the piston. A certain flexibility of the projections in a direction parallel to the axis of the cartridge allows easier insertion of the projec- tion 11 into the screw threads. Resilience can be achieved by a separate projection and by spring means, attaching the projection 11 to the piston 5.

Both the body 6 of the cartridge 2 and the piston are formed substantially cylindrical. It is, however, conceivable to use cartridges and pistons of other shapes, especially of any polygonal cross-section.

If the piston 5 is displaced along the axis A, a package 1 (not shown in Figure 1) can be compressed between the upper surface 14 of the piston and the cover 7 of the cartridge.

The content which is contained within package 1 is therefore dispensed through the dispensing opening 4. The piston 5 can be displaced along the axis A through action of force on the projections 11 which extend outwardly of the body 6.

Figure 3 shows a drive means 21 for holding the cartridge 2 and for displacing the projections 11 in the slits 10 of the body 6.

The drive means comprises a holder means for holding the cartridge 2 in a defined position. The holder means consist of a holder 24 and a recess 23 which is formed at the bottom of the drive means.

Two screws 22 are arranged distant with respect to each other and form a space S for the cartridge 2. The projections 11 are in engaging contact with the helix of the screws 22. The screws 22 are rotating in counter sense and displace the piston 5 along the axis A. The screws 22 are driven by a motor 25 which is not explicitly shown and are connected to the motor by a reduction gear which is not explicitly shown.

The drive means 21 is formed as a hand-held drive means and can be used at any location in a production facility if needed. A force of up to 180kg per screw may be exerted, which can create a pressure of up to 6 bar in a package con- taining ink.

Figure 4 shows schematically a flexible, cylindrical package 1 which can be used in a cartridge and a drive means accord- ing to the present invention. The package comprises a thin wall 20 in which a pasty liquid is enclosed. The package 1 is closed at two ends 8 by clips. An elongated end 9 on one side may be used to insert the end 8 in a dispensing opening 4 of a cartridge 2. The wall 20 is made from a flexible plastic sheet, such as PE or PET or laminates of aluminum and appropriate plastic material, at a thickness of about 10- 150pm. Depending on the context, other material, such as plastic having barrier properties or multi-layer foils or aluminium foils may be used.

For emptying a full package 1, the package 1 is placed into the cartridge 2. The piston 5 is displaced to the lower end of the housing, the package 1 is placed with one end 8 on the upper surface 14 of the piston, and the elongated end 9 of the package 1 is passed through the dispensing opening 4 of the cover 7. The cover is subsequently put on the housing 3 of the cartridge 2 containing the package 1. For each type of liquid, a corresponding package may be placed in a separ- ate cartridge 2 and may remain therein. Upon use, the car- tridge is placed in the drive means 21. As there are no firm engaging contacts between the drive means 21 and the car- tridge 2, exchange of different cartridges 2 is very easy.

The cartridge 2 may simply be put in the recess 23 of the drive means 21 and the projections 11 of the piston 5 are brought in contact with the helix of the screws 22.

If another type of liquid is to be used, the cartridge 2 may be removed from the drive means 21 and a new cartridge 2 may be placed therein. As the piston 5 is in a frictional con- tact with the inner surface of the body 6, the piston remains in its intermediate position and the package 1 remains par- tially compressed. The cartridge 2 may therefore be stored complete with the package 1 for future use.

Figure 5 shows a cross-section through a cartridge 2 com- prising a cylindrical package 1. The package is compressed between the upper surface 14 of a piston 15 displaceably arranged within the housing 3 especially in slits 10 of the body portion 6 of the housing. Two projections 11 extend outwardly through the slits 10. Each of the projections 11 is engageable with a screw 22. Action of these screws 22 displaces the piston 5 along the axis A and compresses the package 1 between the upper surface 14 of the piston and the cover 7 closing the housing 3 of the cartridge 2 at the other end. Upon compression of the package 1, the content of the package is displaced through an elongated end 9 of the pack- age which is passed through a dispensing opening 4 of the cover 7.

Figure 6 shows schematically a section of the thread of the screw 22 in engagement with the projection 11 of the piston 5. The threads are provided with a groove 30 which receives a protrusion 31 arranged on the lower surface of the projec- tion 11. Engagement between the groove 30 and the protrusion 31 avoids separation between the screws 22 and the piston even if high loads are created.

The present invention is particularly advantageous in combi- nation with pasty liquids such as printing inks. It is, however, understood that any type of pasty liquids, especial- ly glues, sealing material or food, can be packed in this type of package and can be used in cartridges according to the present invention.

While it is preferred that the cartridge and the packages are of a cylindrical shape, any form of a package is conceivable.

A major issue of the present invention is the projections of the piston which extend outwardly of the cartridge 2 and which are engageable with external drive means without creat- ing a firm contact.