Sealed capsule for the preparation of a beverage, in particular coffee

Abstract

A capsule including a cup-shaped body with a protruding top flange, a lateral wall, a flexible bottom wall, and a flexible cover welded to the flange to define a sealed chamber containing ground roasted coffee. The coffee is compressed within the chamber to form a compact panel, and a vacuum is provided such that the cover moves towards the upper surface of the panel. Between the flange and the bottom wall, the lateral wall of the body has an annular step formation providing a local reduction in the cross-section of the chamber towards the bottom wall. This step formation is closer to the bottom wall than to the flange and provides a local reduction in the cross-section of the chamber of at least about 25%. The bottom wall of the body is deformable under the effect of the fluid introduced into the capsule, being displaced away from the cover.

1 . A sealed capsule for the preparation of a beverage including coffee, by introduction of fluid under pressure, comprising:
 a cup-shaped body having a substantially planar top flange, radially protruding towards the outside, a lateral wall and a flexible bottom wall, and   a flexible cover welded to the flange of the cup-shaped body so as to define therewith a sealed chamber containing a dose of a granular material, including ground roasted coffee, for the preparation of the beverage;   wherein the granular material is preliminarily compressed within said chamber in a direction perpendicular to the plane containing said flange, such as to form a compact panel of said material, and in said chamber a vacuum is provided to a degree such that the cover moves towards and at least tends to adhere to the upper surface of said panel;   wherein between the flange and the bottom wall the lateral wall of the cup-shaped body has an annular step formation which provides a local reduction in the cross-section of said chamber towards the bottom wall;   wherein the bottom wall of the cup-shaped body is deformable under the effect of the fluid introduced into the capsule, being displaced away from the cover; and   wherein said step-like formation is provided closer to the bottom wall of the cup-shaped body than to the flange and provides a local reduction in the cross-section of said chamber of at least about 25%.   
     
     
         2 . The sealed capsule according to  claim 1 , wherein said step-like formation provides a local reduction in the cross-section of said chamber of about 35%. 
     
     
         3 . The sealed capsule according to  claim 1 , wherein the step-like formation the cup-shaped body has a frusto-conical lateral wall portion which tapers toward said step-like formation. 
     
     
         4 . The sealed capsule according to  claim 3 , wherein said lateral wall portion has a tapering angle (α) between 0° and 8°. 
     
     
         5 . The sealed capsule according to  claim 3 , wherein between the frusto-conical lateral wall portion and said top flange the cup-shaped body has a cylindrical wall portion. 
     
     
         6 . The sealed capsule according to  claim 5 , wherein the cylindrical lateral wall portion has a height (h d ) smaller than the height (h e ) of said frusto-conical lateral wall portion. 
     
     
         7 . The sealed capsule according  claim 1 , wherein under the step-like formation the cup-shaped body has a lower lateral wall portion which tapers, in a frusto-conical manner, towards the bottom wall of said body. 
     
     
         8 . The sealed capsule according to  claim 3 , wherein said lower lateral wall portion has a height (h g,h ) at least approximately equal to or smaller than the height (h e ) of said lateral frusto-conical wall portion. 
     
     
         9 . The sealed capsule according to  claim 1 , wherein the bottom wall of the cup-shaped body is curved towards the inside of the capsule. 
     
     
         10 . The sealed capsule according to  claim 1 , wherein the bottom wall of the cup-shaped body is essentially flat.