Cartridge containing one serving of coffee powder for preparing a coffee beverage

1. A single cartridge containing one serving of coffee powder for preparing a coffee beverage, comprising a cartridge body and a lower filter element, the cartridge body having a cup-like shaped lower portion and a cover, the cup-like shaped lower portion having a bottom portion, an open top, a lateral wall and an upper region defined by the lateral wall, the open top being opposite the bottom portion, the cover being fixed to the open top and covering the open top, the cup-like shaped lower portion containing the coffee powder, the lower filter element being located within an interior volume of the cup-like shaped lower portion, the lower filter element having a peripheral edge portion and being located between the coffee powder and the bottom portion, the interior of the cup-like shaped lower portion being provided with an annular groove formed in the lateral wall, the annular groove being located at the inside of the cup-like shaped lower portion and providing a corresponding projection projecting outwardly, wherein the portion of the lateral wall which defines the annular groove also defines the corresponding projection projecting outwardly, the annular groove engaging the peripheral edge portion of the lower filter element and clampingly fixing the lower filter element to the cup-like shaped lower portion and preventing movement of the lower filter element towards the cover.

2. The cartridge according to claim 1 , wherein said peripheral edge portion is provided with a circumferential annular projection which engages the annular groove.

3. The cartridge according to claim 2 , wherein said circumferential annular projection enters the annular groove.

4. A single cartridge containing one serving of coffee powder for preparing a coffee beverage, comprising a cartridge body and a lower filter element, the cartridge body having a cup-like shaped lower portion and a cover, the cup-like shaped lower portion having a bottom portion, an open top, a lateral wall and an upper region defined by the lateral wall, the open top being opposite the bottom portion, the cover being fixed to the open top and covering the open top, the cup-like shaped lower portion containing the coffee powder, the lower filter element being located within an interior volume of the cup-like shaped lower portion, the lower filter element having a peripheral edge portion and being located between the coffee powder and the bottom portion, in which the lateral wall of said cup-like shaped lower portion of said cartridge is provided with an annular groove which is located at the outside of the cup-like shaped lower portion and provides a corresponding projection which projects inwardly, wherein the portion of the lateral wall which defines the annular groove also defines the corresponding projection which projects inwardly, said peripheral edge portion engaging the inward projection of the annular groove so that the lower filter element is clampingly fixed to the cup-like shaped lower portion, whereby a movement of the lower filter element towards the cover is prevented.

5. The cartridge according to claim 4 , wherein said peripheral edge portion is provided with a circumferential annular projection which engages the inward projection of the annular groove.

6. The cartridge according to claim 1 in which said lower filter element is dimensionally stable and comprises a plurality of apertures.

7. The cartridge according to claim 6 in which the total cross sectional area of all said apertures in said lower filter element amounts to at least three percent (3%) of the mean cross sectional area of said cartridge body, such that the prepared coffee beverage can flow through said lower filter element without substantial resistance to said passage and out of the cartridge.

8. The cartridge according to claim 1 in which said lower filter element is provided with a plurality of channels for collecting and discharging the coffee beverage escaping from the cartridge.

9. The cartridge according to claim 8 in which said lower filter element comprises stampings directed towards the interior of the cartridge for constituting said channels, and a plurality of apertures, whereby said apertures are located in said channels.

10. The cartridge according to claim 1 in which said lower filter element comprises at least one recess directed towards the interior of the cartridge.

11. The cartridge according to claim 6 in which the statistic mean value of the diameter of a single coffee powder particle amounts to between 400 and 600 μm, and in which the diameter of the apertures provided in the lower filter element is smaller than the statistic mean diameter of a single coffee powder particle.

12. The cartridge according to claim 1 in which said bottom portion of said cup-like shaped lower portion has a passage and a gas-tight foil member covers said passage.

13. The cartridge according to claim 12 in which said foil member is located at an inside of the cartridge body between said lower filter element and said bottom portion.

14. The cartridge according to claim 12 in which said foil member is attached to an outside of said bottom portion and is manually removable.

15. The cartridge according to claim 7 , wherein the total cross sectional area of all said apertures in said lower filter element amounts to at least five percent (5%) of the mean cross sectional area of said cartridge body.

16. The cartridge of claim 1 , wherein the lower filter element has a bottom portion (a) located lower than the peripheral edge portion and (b) extending towards the bottom portion of the cup-like shaped lower portion.

17. The cartridge of claim 1 , wherein the annular groove is located in an intermediate position between the open top and the bottom portion.

18. The cartridge of claim 1 , wherein the coffee powder fills a chamber which is delimited by the lateral wall and the lower filter element, the coffee powder being in contact with the lateral wall on a region between the open top and the annular groove.

19. The cartridge of claim 1 , wherein the lower filter element is dimensionally stable and has essentially a disc-like shape.

20. The cartridge of claim 4 , wherein the coffee powder fills a chamber which is delimited by the lateral wall and the lower filter element, the coffee powder being in contact with the lateral wall on a region between the cover and the inward projection of the annular groove.

21. The cartridge of claim 4 , wherein the lower filter element is dimensionally stable and has essentially a disc-like shape.

22. The cartridge according to claim 4 in which said lower filter element is dimensionally stable and comprises a plurality of apertures, the total cross sectional area of all said apertures in said lower filter element amounts to at least three percent (3%) of the mean cross sectional area of said cartridge body, such that the prepared coffee beverage can flow through said lower filter element without substantial resistance to said passage and out of the cartridge.

23. The cartridge according to claim 4 in which said bottom portion of said cup-like shaped lower portion has a passage and a gas-tight foil member covers said passage.

24. The cartridge of claim 4 , wherein the lower filter element has a bottom portion (a) located lower than the peripheral edge portion and (b) extending towards the bottom portion of the cup-like shaped lower portion.

25. The cartridge according to claim 4 in which said lower filter element comprises at least one recess directed towards the interior of the cartridge.

26. The cartridge according to claim 4 in which said lower filter element is provided with a plurality of channels for collecting and discharging the coffee beverage escaping from the cartridge, said lower filter element comprising stampings directed towards the interior of the cartridge for constituting said channels, and a plurality of apertures, whereby said apertures are located in said channels.