Sealed cartridge for making a beverage The present invention relates to a sealed cartridge, provided to be extracted under pressure, containing a substance for the preparation of a beverage chosen from ground roasted coffee, tea, instant coffee, a mixture of ground coffee and of instant coffee, a chocolate-based product or any other dehydrated edible substance, comprising a dish with a bottom and a side wall, having substantially the shape of a frustum of a cone, and a circular edge with a diameter greater than the bottom, and a cover welded to the periphery of the edge of the dish, in which the cover consists of a flexible material which is impermeable to oxygen, chosen from the group consisting of aluminium, an aluminium/plastic composite, an aluminium/plastic/paper composite, pure or multi-layer plastic, the said cartridge not comprising a filter or a weakening zone and the cover being intended to be torn only through the effect of the force of the extraction fluid when extraction starts.

The sealed cartridge described above is the subject of Patent EP 512,468, in the name of the applicant. This cartridge is extracted with the device forming the subject of Patent EP 512,470. This extraction takes place in the following manner: the cartridge is inserted into a cartridge holder and into an extraction cage. This extraction cage comprises a needle which will pierce the bottom of the dish and, when the pressure in the cartridge rises, the cover will bear on protruding and hollowed-out elements of the extraction device. When the pressure reaches a certain level, the cover reaches its rupture tension and it opens, allowing the coffee to flow into the cup.

At the end of extraction, it is possible to remove the cartridge from the extraction system in order to place the next one therein. When the said cartridge is removed, there is a hole in the bottom of the dish and this hole allows residual water and coffee grounds to

escape. This leakage of grounds causes a problem, because it soils part of the extraction machine.

The aim of the present invention is to perfect a cartridge provided for the same type of extraction as mentioned above and which does not lead to leaks of grounds or of any other solid substance when the said cartridge is changed.

The present invention relates to a sealed cartridge according to the preamble of Claim 1, which comprises, in the dish at the level of the bottom, a means guaranteeing the retention of solid substance when it is open. This involves arranging, in each cartridge, a non-return system for the coffee grounds or for any other solid substance extracted in the said cartridge. This system must suit the existing construction of the extraction head.

The means guaranteeing the retention of solid substance is chosen from the group consisting of a fabric, a valve and a foam, the said means being placed, adhesively bonded or sealed to the bottom of the said cartridge. The three aforesaid means are firstly acceptable in terms of cost and, secondly, are simple to produce, allow easy opening by the injection needle, are satisfactorily resistant to hot water and provide satisfactory closure after extraction, i. e. when the cartridge is removed.

The fabric used may be any type of fabric, woven or non-woven, made from plastic fibres, from vegetable fibres or from animal fibres. The fabric used is preferably fabric made from polypropylene, polyester or polyurethane having a thickness of between 15 and 100 microns. The fabric is hot-sealed in the bottom of the dish.

The valve used may be of any type, for example a flexible plastic disc with a cross-shaped cut-out, i. e. with four branches. It is also possible to have a valve with a three-branch or six-branch cut-out. The valve may be adhesively bonded or hot-sealed, but it is also possible simply to place it in the bottom of the

dish. This valve is preferably made from polypropylene or polyethylene.

The foam used is made from a flexible plastic, for example from PUR (polyurethane) or EVA (ethylene- vinyl acetate copolymer). It is hot-sealed in the bottom of the dish.

The cover is heat-welded or crimped to the periphery of the dish. A cartridge which can withstand the pressures which may range up to 15 bar in the extraction system is thereby obtained.

The cartridge is filled with a substance for the preparation of a beverage, as mentioned above. This substance is preferably ground roasted coffee.

"Dish"is understood to mean a frustoconical, hemispherical or frustopyramidal element. Naturally, the bottom 6f the dish does not have to be flat.

The principal body of the cartridge, namely the dish, of frustoconical shape and of semi-rigid nature, may consist of a material chosen from aluminium having a thickness of 20 to 100 ym, a pure or multi-layer plastic, a cardboard/aluminium/plastic composite and a cardboard/plastic composite.

The cover of the cartridge, of flexible nature, may be made from a material chosen from aluminium with a thickness of 15 to 60 Um and a multi-layer material comprising either paper of 20 to 60 g/m2, plastic of a thickness of 20 to 60 ym and aluminium of a thickness of 5 to 20 ym, or EVOH or PVDC of a thickness of 5 to 30 ym and plastic (PP, PE or PA) of 20 to 100 ym, or PET (5 to 30 Um) and plastic (PP, PE) of 20 to 100 ym, or PET that is metallized or equipped with a layer which forms an efficient barrier, such as SiO2.

The size of the cartridge according to the invention may vary according to the volume of coffee it is desired to prepare. The measure of coffee may vary between 5 and 20 g, the diameter of the cartridge is between 2.5 and 6 cm and the thickness of the bed of coffee between 10 and 40 mm.

The remainder of the description is given with reference to the drawings, in which: Fig. 1 is a diagrammatic representation of the cartridge according to the state of the art; Fig. 2 is a diagrammatic representation of the cartridge according to the invention, in a first embodiment; Fig. 3 is a diagrammatic representation of the cartridge according to the invention, in a second embodiment; and Fig. 4 is a diagrammatic representation of the cartridge according to the invention, in a third embodiment.

The cartridge (1) includes a dish (2) with a bottom (5) and a side wall of frustoconical shape (6).

The cartridge contains roasted coffee (3) and it is sealed by means of a cover (4) made from aluminium.

This cover is welded to the periphery (7) of the edge of the dish. When extraction takes place, the needle perforates the bottom of the cartridge in the zone A, allowing the extraction liquid to percolate into the coffee. At the end of extraction, the coffee grounds emerge from the opening in the zone A. The aim of the present invention is to prevent this emergence of grounds. To this end, there are at least three different solutions.

The solution of Fig. 2 is to provide a layer of fabric (13) made from polyester in the cartridge (8) having a dish (9) with a bottom (10) and a side wall (11) and a cover (12). This layer is welded to the shoulder (14) of the cartridge. The bed of coffee (15) is deposited on the fabric (13). The advantage of this fabric is that the needle perforates it easily and, at the end of extraction, its flexibility and its elasticity allow it to close again when the said needle is removed from the cartridge and the grounds do not exit via the opening (16). A cartridge guaranteeing satisfactory cleanliness of the extraction system is thus provided.

Fig. 3 provides a second solution in the form of a cartridge with a non-return device. The cartridge (17) comprises a dish (18) with a bottom (19) and side wall (20), together with a cover (21) welded to the periphery (22) of the dish. A valve (23) is adhesively bonded close to the bottom (19). The bed of coffee (24) is deposited on this valve. This valve has, for example, a cross-shaped cut-out, which allows satisfactory opening and satisfactory re-closing when the extraction needle is inserted and removed. It also allows satisfactory retention of the coffee grounds. It is also possible to arrange the valve of Figure 3 in the cartridge of Figure 2 and vice versa and it is possible to weld the layer of fabric of Figure 2 in the cartridge of Figure 3.

Fig'4, finally, shows a cartridge (25) comprising a dish (26) with a bottom (27) and a side wall (28) and a cover (29). The bottom of the cartridge includes an adhesively bonded layer of foam made from flexible plastic (30). The bed of coffee (31) is deposited on this foam. It is perforated easily and it has a satisfactory re-closing ability when the extraction needle is removed. The foam of Figure 4 may also be arranged in the cartridge according to Figure 3.