Apparatus for brewing coffee

An apparatus for brewing coffee, in particular for a coffee machine (1), comprises a brewing chamber (19) which is enclosed by a housing (10) and has a base (12) with an outflow (40) provided on one side and a nozzle assembly (8, 9, 11) provided on the opposite side, the nozzle assembly (8, 9, 11) comprising a nozzle (11) for supplying a fluid. The base (12) can be moved within the housing (10) and, depending on the degree to which the brewing chamber (19) is filled, the base (12) can be fixed in different positions for the brewing operation. It is thus possible for the apparatus for brewing coffee, while being of straightforward construction, to be adapted in a flexible manner to the desired quantity of coffee.

FIELD OF THE INVENTION

The present invention relates to an apparatus for brewing coffee, in particular for a coffee machine, having a brewing chamber which is enclosed by a housing and has a base with an outflow provided on one side and a nozzle assembly provided on the opposite side, the nozzle assembly comprising a nozzle for supplying a fluid.

BACKGROUND OF THE INVENTION

There are coffee machines in which portion packs can be introduced into a holder, which can then be inserted into a closeable housing for a brewing operation. If a relatively large quantity of coffee is to be brewed, it is possible to insert another holder in order for two portion packs to be introduced. The disadvantage with this brewing apparatus is that different holders have to be used for different quantities of coffee or portion packs. This, on the one hand, involves laborious handling and, on the other hand, is inflexible since, depending on taste, finer apportioning of the quantity of coffee is desirable.

SUMMARY OF THE INVENTION

One of the objects of the present invention is thus to provide an apparatus for brewing coffee which is easy to handle and can flexibly accommodate different quantities of coffee or some other extraction substance.

This object is preferably achieved by an apparatus for brewing coffee which has the features of claim1. According to the invention, the base can preferably be moved within the housing for the brewing chamber and, depending on the degree to which the brewing chamber is filled, can be fixed in different positions for the brewing operation. It is thus possible to adjust the quantity of coffee in the brewing chamber in accordance with requirements or taste, and there is no need for different components in order to change the volume of the brewing chamber.

According to a preferred embodiment of the invention, the position of the base in the housing can be adjusted via a mechanism. This means that handling is easy since the mechanism can be used to predetermine the position from the outside without any manual movement of the base.

In order for it also to be possible to execute a brewing operation under pressure in the brewing chamber, an all-round seal is preferably arranged between the base and housing. The seal here may be retained in a brewing position with a contact pressure between the base and housing, and the contact pressure can be reduced, or done away with altogether, for the movement of the base within the housing. This is because, for the brewing operation with a certain pressure of, for example, between 2 and 5 bar, it is necessary for the brewing chamber to be sealed, for which purpose the seal is retained with contact pressure between the base and housing. For the movement of the base, in contrast, it is disadvantageous if the contact pressure is still present, since this would just lead to wear of the seal and to high frictional forces.

For the movement of the base, it is therefore advantageous if the seal is guided smoothly in the housing. The seal may thus be movable relative to the base, and it is possible to produce a contact pressure between the seal and housing via wedge surfaces. This ensures that a contact pressure prevails merely in the fixed position of the base or in the brewing position.

For mechanical shifting of the arrangement of the seal on the base, the base is preferably mounted in a displaceable manner on a holder and has a wedge-shaped protrusion on the side which is directed away from the brewing chamber, it being possible for the outer wedge surface of this protrusion to be positioned against a sealing lip of the seal in order to produce the contact pressure. It is thus possible for the brewing chamber to be sealed straightforwardly using only a small number of components. On the side which is directed away from the base, the seal may be accommodated in a cutout on the holder, this acting as a type of stop in order for it also to be possible for the seal to be secured with clamping action between the holder and the base.

For easy handling, the apparatus has a switch in order for it to be possible to adjust the volume of the brewing chamber with respect to the thickness and the number of portion packs which are to be inserted. For coordination which is as flexible as possible, it is also possible to provide a metering device in order for it to be possible to adjust the quantity of water for the brewing operation. The consumer can thus make an individual adjustment in accordance with the strength and quantity of the coffee desired.

DESCRIPTION OF EXAMPLE EMBODIMENTS

A coffee machine1has a storage container2for clean water, the storage container being connected to a pump5via an outlet valve3and a line4. By means of the pump5, the water can be led to a heating plate6which contains helical through-passages7in which the water can be heated. Provided alongside this is a plate8which forms part of a nozzle assembly and in which is provided a supply line30for the heated water. Installed on the plate8is a mount9for a sealing element20which is of essentially annular design and has a nozzle11provided in its center.

Via the nozzle11, the heated water can flow into a brewing chamber19which is enclosed by a housing10. Provided on the opposite side of the nozzle11is a base12which is intended for bounding the brewing chamber19and which contains an outflow, with the result that the fluid brewed flows through a funnel-like outlet13to an extension arm14, on which an outlet opening15is provided for the purpose of filling coffee cups.

The coffee machine1comprises a brewing chamber19in which it is possible to insert one or more portion packs with coffee. Provided for this purpose is a cylindrical covering16on which is formed a handle17, via which the housing10can be released from the nozzle assembly and pivoted via an actuating mechanism, with the result that the brewing chamber19is filled from above. The covering16is then closed and the housing10is moved into the position shown. Following the brewing operation, the portion packs are then emptied into a collecting container18in order for the brewing chamber19to be filled anew. For the coffee machine1shown, however, it is also possible to use other actuating mechanisms in order to fill the brewing apparatus with one or more portion packs.

FIG. 2illustrates the brewing apparatus of the coffee machine1in detail.

The sealing element20is of annular design and has an outer section on which are formed sealing lips22which butt against a radially outwardly projecting flange21of the housing10. Also formed on the outer section of the seal20is a sealing surface23which ensures sealing between the holder9and the seal20. Provided on an inner section of the seal20is a further sealing lip25for forming a sealing surface which butts against an annular section26of the holder9. The holder9here is provided with an annular wall which is designed in a manner similar to the geometry of the seal20. A pressure chamber27is thus formed between the wall of the holder9and the seal20, and this pressure chamber is bounded by the sealing surface23on the outside and by the sealing surface25on the inside and can be subjected to pressure via a supply line38. The supply line38is connected to the supply line30for supplying the heated water into the brewing chamber19and, for pressure-reducing purposes, preferably likewise has a valve with a spring, as is the case with the supply line30.

Arranged on that side of the sealing element20which is directed toward the brewing chamber19is a plate-like pressure-exerting element28, which is aligned by two pins24formed on the sealing element20. The pressure-exerting element28has an inner cutout, in which the fixed nozzle11is accommodated. The pressure-exerting element28here has a protrusion29which can be moved maximally between the nozzle11and a stop37on the holder9. The pressure-exerting element28is arranged in a displaceable manner in this region and can be moved correspondingly into the brewing chamber19.

Once the fluid has been heated, it can flow through a supply line30which is closed by a prestressed valve31. For this purpose, a spring36is arranged between the valve body31and the nozzle11. The nozzle11is screw-connected to a sleeve-like protrusion of the plate8and has an opening32which opens out into the brewing chamber19.

On the opposite side of the nozzle11, a base12is15provided on the brewing chamber19, this base having a plurality of ribs44and a central outflow40. The outflow40is closed via a valve body41, which is prestressed into the closed position via a spring42. This ensures that, within the brewing chamber19, the fluid can be led away via an outflow channel43only when a certain pressure is exceeded.

The base12is mounted on a holder50which is coupled to a pin51. The pin51is retained in a curved element52of a curved guide53, with the result that, in the case of movement of the actuating element17, the curved guide53is moved and, via the pin51, the holder50is displaced together with the base12within the housing10. The holder50also has a slot56through which leads a further pin54as a fulcrum for the housing10and central mounting for the curved guide53, on which a further curved element55is formed. Pivoting of the actuating element17thus allows, on the one hand, pivoting of the base12in the housing10and, on the other hand, pivoting of the housing10itself for filling purposes, the brewing chamber19then having an upwardly directed opening into which one or more portion packs can be inserted. The actuating element17is then pivoted back again and the brewing chamber19assumes the position shown inFIG. 1or2, and the base12is adjusted automatically to the brewing-chamber height corresponding to the portion packs introduced.

Arranged alongside this on the base12is a seal45which has a sealing lip66which butts only lightly against the housing10, with the result that the base12can be displaced smoothly. For the brewing operation, however, the seal45has to be accommodated with a contact pressure in the housing10, in order for it to be possible for a pressure of, for example, between 2 and 5 bar to build up in the brewing chamber19. For this purpose, on the side which is directed away from the brewing chamber19, the base12has an all-round protrusion60which is of wedge-shaped design in cross section and has an outer wedge surface61which can be positioned against the sealing lip66. The sealing lip66likewise has, in the front region, a slope62, which can be positioned against the wedge surface61. The seal45is of cross-sectionally U-shaped design and has an accommodating means63for the protrusion60and, on the opposite side, butts against a ring64on a sleeve-like section65of the holder50.

As long as the spring-assisted spacing between the base12and seal45is present, the base12can be displaced smoothly in the housing10. For the brewing operation, the base12is positioned in a form-fitting manner against the portion packs, but may also be forced against the same with light contact pressure, with the result that the base12moves in relation to the seal45. By virtue of this movement, the wedge surface61forces the sealing lip66outward and ensures reliable sealing. The contact-pressure force is increased further if, upon initiation of the brewing operation, the pressure-exerting element28is forced, by the build-up of pressure in the pressure chamber27, against the portion packs, which then, in turn, force the base12against the seal45. This achieves, on the one hand, good sealing of the brewing chamber19and, on the other hand, a high level of tolerance in respect of the quantity of coffee.

FIG. 3shows the nozzle11in plan view, from which the cross-shaped outlet opening32is visible. The nozzle11is accommodated within the pressure-exerting element28, which is retained in a centered manner via pins24and butts against the seal20on the rear side. The sealing lips22are of circular design and butt against the housing10.

FIG. 4illustrates the base12of the brewing chamber19. The ribs44ensure a spacing between the portion packs within the brewing chamber19and a base surface, with the result that the fluid can be led to the outflow40. The base44is sealed on the periphery via a seal45.

FIG. 5shows the adjusting mechanism on the coffee machine1. A housing ring70is provided with markings72which indicate symbolically the quantity of water required. A lever71can be used to adjust the desired quantity of water by way of the markings72, with the result that the pump5correspondingly provides just the desired volume of water.

Furthermore, a marking74is located on the cylindrical covering16and, when the brewing assembly is closed by way of the actuating element17, this marking indicates, via markings73and the housing ring70, how many portion packs have been introduced. The markings73denote one or two portion packs. The user can thus freely select the quantity of coffee which is to be brewed in the brewing chamber19. It is, of course, also possible to provide for a finer adjustment of the size of the brewing chamber19, for example if there are portion packs of different thicknesses which, in accordance with the coffee taste, contain different quantities of coffee powder. In addition, it is also possible to introduce more than two portion packs into the brewing chamber19.

It is, of course, also possible for the adjusting mechanism for apportioning the quantity of coffee and for metering the water to be designed differently and to have, for example, stepless adjustment with a quantity indicator.