Thanks to their special features, microwaves are being used more and more, in particular because of how quickly they perform a great many functions. The fact that their thermal excitation action is exerted mainly on water molecules makes them highly suitable for all activities that require the heating of water, as it is or contained in food. For some time now devices have been produced that make it possible to prepare coffee using a microwave oven; the apparatus in question makes it possible to prepare"mocha"coffee extremely quickly and easily. This is achieved with a device most of the characteristics of which are similar to those of an ordinary coffee- maker and most of the components of which are made of plastic, to take advantage of the transparency of this material to the radiation used. However, this type of device has a number of drawbacks, both structural-and functional, that hamper its effective use.

First, while the use of plastic makes it easier and cheaper to produce the device, the force that can be applied to the connection between the boiler and the container for collecting the coffee infusion, i. e. the force exerted on the seal that allows water to pass through the filter loaded with coffee, is much lower than that which can be applied to a connection made between metal parts. These possible sealing problems undoubtedly impair the quality of the infusion produced, may contribute to the diffusion of losses inside the oven cavity, and more generally make the use of this kind of device less efficient and attractive.

Another problem that is also due to the structural characteristics of this kind of

coffee-maker is linked to the fact that, once it reaches its collection container, the coffee infusion continues to be subjected to radiation and its temperature tends to rise to boiling point, considerably impairing the quality and aroma of said infusion.

The purpose of the present invention is therefore to provide a coffee-maker for microwave ovens that can overcome the above drawbacks, making it possible to prepare coffee efficiently, without problems of sealing, dripping or overheating of the infusion produced.

The subject of the present invention is therefore a coffee-maker, preferably for microwave ovens, comprising a boiler, a load-bearing funnel inserted in said boiler, and a container for holding the coffee infusion having means for delivering the coffee infusion coupled, with an end seal, to said boiler. The means for sealed coupling between said delivery means and said boiler comprise an annular seal that extends over a substantial radial portion of the coupling surface, and a plurality of concentric coaxial annular reliefs that bear on the surface of said seal.

In a preferred embodiment, said annular reliefs are formed on a radial flange projecting from the end edge of said filter-holder funnel, which is made of metal, such as aluminium.

Advantageously, the container for holding the coffee infusion delivered is provided with a lid, and a layer of material that reflects microwave radiation is provided on a substantial portion of its side wall and on the lid. This material is preferably a sheet of aluminium. It may be appropriate to make a window in the side wall of the container for viewing the level of the coffee infusion.

Further advantages and characteristics of the device according to the present invention will become clear from the following detailed description of an embodiment thereof, described by way of non-limiting example, with reference to the attached

drawing in which: Figure 1 is a view in longitudinal section of the coffee-maker according to the present invention.

Figure 1 shows the coffee-maker of the invention; the boiler of said coffee- maker bears the reference number 1. The boiler 1, of substantially cylindrical shape, is provided with a frustoconical apron 101, made as a single piece with said boiler 1, and is connected, as described below, to a container 3 for holding the coffee infusion.

A radial through hole 111 is made in said apron 101, level with the safety valve 201 of said boiler 1. A screw thread 301 is formed near the open end of the boiler 1 and, on the inner end edge of said boiler 1 there is a groove 401, in which is housed the periphery of the radial flange 102 projecting from the load-bearing funnel 2, where the load of coffee powder, either loose or enclosed in an appropriate capsule of determined quantity, is placed on the base 202 which is provided with holes 212. The flange 102 has two annular reliefs 112 projecting outwards from the boiler 1, which bear on the seal 803. Said seal 803 is placed in the area of the container 3 between the delivery filter 203 and the flange 703 for coupling between the container 3 and the boiler 1, and a radial annular relief 723 holds it in place.

The delivery filter 203, placed on the end wall of the container 3 located towards the boiler 1, is provided with holes 213, and controls the flow to the delivery nozzle 103, open at its free end via the mouth 113, which pours the coffee infusion into the internal chamber of the container 3. The container 3 is coupled to the boiler 1 by means of the axial flange 703 provided on its inner side wall with the screw thread 713 that cooperates with the screw thread 301 of the boiler 1.

On its outer wall the container 3 has the covering 403 of material that reflects microwave radiation, covered by the layer of plastic 303 whose only purpose is to prevent sparks from being generated inside the cavity of the microwave oven. The

covering 403, which covers a substantial portion of the container 3, has a window 413. Likewise, a layer 513 of material that reflects microwave radiation is also inserted in the lid 503, held between said lid and the insert 523, which are both made of plastic.

The following description will give a clear idea of how the coffee-maker according to the present invention works. As stated above, the seal for end coupling between the means for delivering the coffee, i. e. the filter 203 and spout 103 system, and the boiler is fundamental to guarantee correct, efficient operation of a coffee- maker. This kind of coupling, because of its end position, considerably depends on the forces applied by the mutual clamping of the two coupled parts. However, especially in the case of coffee-makers used in microwave ovens, the material used to make the coffee-maker can considerably limit the amount of force applied at said clamp.

To this end, the coffee-maker according to the invention has been designed with an alternative sealing system which, by making the sealing surface smaller, thereby improves the efficiency of the seal itself. The annular reliefs 112 formed on the radial flange 102 of the funnel 2 are in fact in contact with an extremely small area of the surface of the seal 803, and this kind of contact requires, as regards the clamping applied at the screw threads 713 and 302, a significantly lower force than normal. The seal 803 is, on the one hand, subjected to a considerable pressure load due to the much smaller contact surface and, on the other hand, protected from wear owing to the lower level of thermal stress, since the heating times for a coffee-maker used in a microwave oven and its overall conduction of heat are much lower than usually found in coffee-makers that heat up through contact with the walls of the boiler.

The boiler 1 is in fact"sui generis"since it is the liquid inside it, and not the boiler itself as the container for the liquid, that is heated. In addition, the fact that it is

made of a material with low thermal conductivity such as plastic, clearly limits the dispersion of heat. Advantageously, to prevent the user from being able to feel the heating-up of the contents of the boiler, said boiler has an apron 101 which insulates it from its surroundings. Said apron 101 has a radial hole 111 for the discharge, if necessary, of the safety valve 201, allowing it to be assembled at the time of manufacture of the coffee-maker. Note also that the boiler 1 itself does not constitute the support base of the coffee-maker, which rests only on the end edge of said apron.

The container 3 for holding the coffee infusion is provided with a layer 403 of material that reflects microwave radiation, to avoid an excessive increase in temperature of the infusion once it has been delivered into said container 3. The reflective material is preferably a sheet of aluminium on which is placed in turn a layer of plastic 303, to prevent discharges owing to direct exposure of the metal to said radiation. A similar layer 513 is inserted in the lid 503 and fulfils the same functions as described for the layer 403. Advantageously, the container 3 is made of transparent plastic, and the provision of a window 413 in the layer 403 of reflective material-enables the user to see the level of coffee infusion inside the container.

Naturally, if the plastic used to make the layer 303 were opaque, it would be appropriate to make a window in said layer, level with the window 413.