GB2104400A - Coffee maker - Google Patents

Abstract

In a coffee maker comprising a vessel of cylindrical cross-section and a plunger movable in the cylinder, the plunger 7 has a mesh of conical shape to increase its mechanical strength. <IMAGE>

Description

SPECIFICATION Coffee maker The invention relates to a coffee maker having a cylindrical vessel open at the top and, movable therein, a plunger disposed on a hand-operated rod.

Coffee filters of this kind have long been used for the extraction of coffee, the plunger being moved down the vessel upon completion of brewing so that the coffee grounds are separated from the coffee and the latter can be poured out by decanting.

The known coffee makers of this kind use a plane mesh foil made of a wire or nylon fabric. The disadvantage of these known coffee filters is that, more particularly when the coffee used has been ground to a very fine powder, the high pressure which then has to be applied to the plunger easily warps the filter fabric. The mesh size must therefore if at all possible not be less than a critical value in order to ensure that the filter fabric experiences only a reduced loading.

However, it is desirable to use fine-mesh filters, since it is precisely the fine particles of coffee which take the longest to drop and which, therefore, pass through the mesh when the plunger is depressed.

It is the object of the invention to provide a coffee maker of the kind described in which the mesh is not deformed as a result of a high pressure being applied to the plunger, even though the filter orifices are very fine. In accordance with the invention, therefore, the plunger has a conical mesh. The effect of the conical shape is that the mesh in shape is curved in a plane and therefore has much better mechanical strength and stability than a plane mesh.

Preferably, the conical mesh is secured, at least by of its radially outer edge, in a plastics ring which receives a lipped seal. This feature prevents coffee powder from passing through between the plunger and the vessel even though the vessel wall may not be dead cylindrial in shape.

To enable the loading of the plunger to be increased still further, a support cage can be disposed on the top of the conical mesh.

Preferably in this case, the support cage is rigidly secured to the conical mesh.

In accordance with a special feature, the support cage is formed by ribs which extend along generatrices of the conical mesh and terminate in the plastics ring and a hub.

To ensure, more particularly in the case of a very conical mesh, with the plunger depressed, coffee liquor as well as coffee powder still remains in the space below the plunger, the base of the vessel can have a shape corresponding to the conical mesh.

The invention will be described in greater detail hereinafter with reference to an embodiment shown in diagrammatic drawings wherein: Figure 1 is an axial section through a coffee maker along the line I-I of Fig. 2; Figure 2 is a plan view of the plunger, and Figure 3 is a cross-section through the plastics ring which extends around the outer edge of the mesh.

A coffee maker shown in the drawings comprises a cylindrical vessel 1 whose wall 2 is in cross-section circular and whose base 3 in shape resembles a shallow cone. Top edge 4 of the vessel 1 extends radially outwards and serves as support for a lid 5 formed with a central guide aperture 6. A plunger 7 is disposed for movement in the vessel 1 and is secured to the end of a rod 1 7 which extends through aperture 6.

The plunger 7, shown in plan view in Fig.

2, comprises a conical mesh 8 (only some of which is shown in Fig. 2) and a plastics ring 9 in which the mesh outer ring is clamped or secured in some other way.

Extending from ring 9 are a number of ribs 1 2 which extend along generatrices of the mesh 8 and terminate in a hub 1 3 in which the rod 17 is secured.

The ribs 1 2 are either in contact with or rigidly secured to the top of the mesh 8.

As can be gathered more particularly from Fig. 3, ring 9 is formed with an annular groove 10 receiving a resilient annular lipped seal 11.

The same can be removed from groove 10 and replaced.

To facilitate replacement of the seal 11, the ring 9 can be in two parts, as indicated by a division line 1 5.

In addition to the ribs 12, additional ribs 1 2a (shown in chain-dotted line) can be provided below the mesh 8, to clamp the same from both sides.

The coffee maker in accordance with the invention makes it possible to use very fine meshes, for instance, of mesh foils which are produced by electroplating and which are formed with perforations widening in the throughflow direction, since the mesh can withstand high pressures such as occur when fine ground coffee is used in conjunction with very fine mesh openings.

The construction can be used advantageously in association with lever mechanisms to move the rod 17, to enable a greater force to be applied thereto by a distance step-down.

The lipped seal has the advantage that the force with the same is pressed against the vessel wall 2 increases as the pressure on the plunger increases.

The opening angle of the conical mesh 8 can be greater than shown in the drawings or it can be less; in the latter case the conical mesh can be produced, for instance, in accordance with the disclosure of German patent application P 25 40 532.7 of 11 September 1975.

To ensure, when the vessel used has a base flatter than the conical mesh of the plungers 7, that with the plunger fully depressed coffee liquor as well as coffee grounds still remain in the space between the plunger and the base, the hub 1 3 can be extended towards the base, as indicated by a chain-dotted line 1 3a in Fig. 1. A hub 1 3 of this kind which is substantially frustrum-shaped and whose tip points downwards reduces the including volume and forces the coffee grounds radially outwards. Also, a hub of this kind can serve to protect the lipped seal 11 to prevent it from striking the base when the plunger is fully depressed.

Claims (8)

1. A coffee maker having a cylindrical vessel open at the top and, movable therein, a plunger disposed on a hand-operated rod, characterised in that the plunger (7) has a conical mesh (8)

2. A coffee maker according to claim 1, characterised in that the conical mesh (8) is secured, at least by way of its radially outer edge, in a plastics ring (9) which receives a lipped seal (11).

3. A coffee maker according to claim 1 or 2, characterised in that the support cage is disposed on the top of the conical mesh (8).

4. A coffee maker according to claim 3, characterised in that the support cage is rigidly secured to the conical mesh (8).

5. A coffee maker according to claim 3 or 4, characterised in that the support cage is formed by ribs which extend along generatrices of the conical mesh and terminate in the plastics ring (9) and hub (13).

6. A coffee maker according to claims 1 to 5, characterised in that the base (3) of the vessel has a shape corresponding to the coni cai mesh (8).

7. A coffee maker according to claims 1 to 6, characterised in that the plunger (7) has near its hub a bead (1 3a) which extends towards the base.

8. A coffee maker substantially as hereinbefore described with reference to the accompanying drawings.