Foods and beverages: apparatus – Beverage – Infusors
Patent
1993-03-25
1994-05-03
Jenkins, Robert W.
Foods and beverages: apparatus
Beverage
Infusors
99289R, 99302R, A47J 3100
Patent
active
053077342
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a brewing apparatus for a coffee machine comprising a brewing cylinder (1) having a cylindrical bore (2), a pair of pistons (3,4) mounted within and closing the cylinderical bore (2) to form a brewing chamber (5), the brewing cylinder (1) and the pistons (3, 4) being displaceable relative to one another along a brewing cylinder axis (16) and each of the pistons (3, 4) having on its outside surface (6, 7) a groove (8, 9) extending about the entire circumference with an inserted gasket (10, 11) for sealing the piston (3, 4) in relation to the cylindrical bore (2).
The preparation of coffee by means of coffee machines is carried out according to different processes which may be separated into two basic types. A first type of process, in which the hot water runs through the ground coffee in a filter solely owing to gravity, is distinguished from a second type of process, in which the hot water is conveyed through the ground coffee under pressure (espresso or pressure-brewing process). The present invention relates to the last-mentioned pressure-brewing process. For carrying out this process automatically, various coffee machines are already known. These customarily have a brewing cylinder with a cylindrical bore which is closable at both ends by means of one piston each for forming a brewing chamber, the brewing cylinder and the pistons being displaceable relative to one another in the brewing cylinder axis. Each of the pistons has moreover a fine-meshed strainer on its end face turned toward the brewing chamber formed. Through one strainer, there is conveyed into the brewing chamber hot water under pressure which flows around and scalds the ground coffee, the coffee thus produced being discharged through the strainer of the other piston. The said strainers are subjected both to fouling (clogging) and to wear and tear and must not only be regularly cleaned but also exchanged from time to time. They are relatively expensive during manufacture.
It is the task of the present invention to create a brewing apparatus for a coffee machine in which the above-mentioned drawbacks are no longer present. In particular, it is a matter of decreasing the number of wearing parts in a brewing apparatus, which also include the said strainers.
The solution of this problem takes place by means of a brewing apparatus for a coffee machine which has the features that at least one of the pistons (4) has a reduced diameter between an end face (13) and its gasket to provide an annular gap (14) between the piston (4) and the bore (2) whereby said gap provides an annular passage for the feeding and/or discharge of liquid to and/or from the brewing chamber (5).
In at least one of the pistons, the end face turned toward the brewing chamber does not have any more strainer. The feeding or discharge of liquid takes place via the annular gap provided. The formation of such a gap is substantially more cost-effective during manufacture than providing a piston end face with a fine-meshed strainer. The solution is particularly advantageous when at least that piston at which the water under pressure is fed to the brewing chamber, and which furthermore is intended for ejecting the leached-out ground coffee from the brewing chamber, the piston end face is designed without a strainer. Through the feeding of water under pressure to the annular gap, a self-cleaning effect of the latter occurs during each brewing operation, and upon stripping from the end face of the said piston the ground coffee customarily pressed into a cake, leached out, and ejected from the brewing chamber, no strainer fouling can be brought about.
Expediently, the wall of the brewing cylinder has, for the feeding and/or discharging of liquid via the said gaps to and/or from the brewing chamber, through bores running approximately at right angles to the brewing cylinder axis, which bores, in the brewing positions of the pistons, are disposed in the region of the gaps. The through bores may each be provided on the outside of the brewing cylinder with
REFERENCES:
patent: 3760712 (1973-09-01), Rossi
patent: 4457216 (1984-07-01), Dremmel
patent: 4797296 (1989-01-01), Meier
patent: 4852472 (1989-08-01), In-Albon
Lussi Andre
von Gunten Jurg
Zurbuchen Hans
Jenkins Robert W.
Sintra Holding AG
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