TEXT OF THE DESCRIPTION

The present invention relates to mach ines for the preparation of coffee, and in particular relates to machines for the preparation of espresso coffee. More particularly, the present invention relates to espresso coffee machines that use pre-packed ground coffee pods.

A typical problem in the use of these machines arises from the need to satisfy the d ifferent tastes of users, particularly according to geographical areas, with regard to drinks obtained by the infusion of g round coffee. Whereas in Italy the concept of coffee is strictly linked to the dual concept of coffee made in a coffee pot at home and an espresso at a bar, with a marked propensity for espresso, in many other countries coffee is available in very different strengths , and the small espresso cup does not fully satisfy the req u irements of those markets. Espresso is tru ly someth ing enjoyable and exotic, but not the drink that is usually consumed .

The coffee that is generally consumed in many Eu ropea n countries and in the U SA, the so-called "reg u lar coffee", is usually obtained th rough proced ures of preparation by percolation at atmospheric pressure or, in any event, by extraction at very low pressures, with the water supply having by contrast substantially high flow rates, otherwise waiting times wou ld be extremely long . By operating in this way, however, the ground coffee is "under-extracted", i.e . the extraction that it undergoes does not bring into the infusion all those substances conferring the major organoleptic properties of an "espresso type" coffee infusion .

Vice versa , if an attempt is made to prod uce an infusion having a considerably larger volume than a standard small coffee cup using an espresso coffee machine, the combination of a high extraction pressure and a fairly low pump flow rate, given the small quantity of liquid normally required for extraction , means that the infusion is "over-extracted", i.e. not only are the substances that provide the coffee with its aroma extracted , but so too are other substances, which are a legacy of roasti ng the coffee and may also have harmful effects, and in any event have an unpleasant taste.

I n espresso coffee mach ines using pre-packed pods, various exped ients have been adopted in order to achieve an optimum extraction of the infusion by making best use of the characteristics of the pre-packed pod . I n this regard , Document EP 1723047, belong ing to the present applicant, describes a delivery un it wherein the delivery of the infusion depends upon reaching a given pressure inside the pre-packed pod, which is perforated by an appropriate perforation means; the perforation enables the infusion to pass only when the pressure distorts the lips of the opening formed in the pre-packed pod. Clearly, in coffee machines of this type, it is not possible to consider reducing the supply pressure of the infusion liquid, given that the quality of the product would be reduced as well, precisely because the delivery could not take place in this way.

Therefore, one of the aims of the present invention is to provide a coffee machine that is capable of producing an infusion that has the same organoleptic characteristics as "Italian" espresso coffee, but in a much larger quantity.

A further aim of the present invention is to provide a machine that enables the preparation of a coffee of the type described above as well as the preparation of a normal espresso, in an alternative manner.

Another aim of the present invention is to provide pre-packed ground coffee pods suitable for use in the machine according to the present invention.

Therefore, the object of the present invention is a coffee machine of the type for pre-packed ground coffee pods, comprising a tank for the infusion liquid, usually water, means for feeding said liquid u nder pressure to a heater, a dispensing unit comprising filter-holder means in which the pre-packed pod has to be positioned , means for feed ing the pressurized hot water into said pre-packed pod , and means for delivering the coffee brew, characterized in that said means for feed ing said liquid u nder pressu re to said heater comprise at least two pumps operating in parallel between said tank and said heater, each of said pumps having a substantially high operating pressure ranging from 1 5 to 30 atmospheres , and preferably from 20 to 25 atmospheres, and a low flow rate ranging from 4 to 8 cm ³ /s.

Advantageously, said machine further comprises control means provided with suitable switch ing means that can be operated by the user, said switch ing means allowing both the pumps , or alternatively one pump or the other one, to be actuated .

I n a preferred embodiment, said control means comprise an electronic control un it wh ich allows to operate the pumps according to the operating program me chosen by the user; furthermore , in the case of an extraction using only one pump, the control unit can control the alternative switching-on of one of the two pumps accord ing to the last operation performed by each pump . Another object of the present invention is a series of pre-packed ground coffee pods adapted for the use in a coffee mach ine of the above-described type, comprising fi rst pods containing an amount of coffee powder which is double as compared to the usual amount employed for the preparation of an espresso coffee, and second pods containing said usual amount of coffee, said second pods being formed so as to be fitted in the same filter-holder as used for said first pods. Particu larly, said second pods have a container body which is sma ller than that of said first pods, and are provided of rad ially projecting members adapted for compensating said size reduction .

Other advantages a nd featu res will be apparent from the following detailed description of a preferred embodiment of the present invention wh ich is provided by way of illustration , and not by way of limitation , with reference to the accompanying drawings in which:

Figure 1 is a schematic block d iagram showing an embod iment of the coffee mach ine according to the present invention ;

Fig ures 2A and 2 B show said first pre-packed pod of the series of pre-packed pods accord ing to the present invention ;

Figures 3A and 3B show said first pre-packed pod of the series of pre-packed pods according to the present invention;

Figure 4 is a sectional view of the delivery unit of an embodiment of the coffee machine according to the present invention.

Figure 1 is a schematic block diagram showing the coffee preparation machine according to the present invention; 1 denotes the boiler of the machine, which is connected to the water tank 2 by a supply line provided with two parallely arranged pumps 3. The pumps 3 are each provided with valve means 103. The boiler 1 is connected to the supply unit 4 in which the extraction of the pre-packed pod takes place, as shown in the Figure by dotted lines. The pumps 3 and the boiler 1 are connected to the control unit 6 provided with user interface means 7.

Figure 2A shows a side elevation of a first prepacked pod of the series of pre-packed pods suitable for use in the machine according to the present invention. The pod 5 has a substantially cup-shaped container body 105 which is both tapering convexly towards the bottom wall 205 and provided with an outwardly protruding radial flange 305. As can be seen from the section in Figure 2B, a closing surface 315 is positioned on the flange 305, while the bottom wall has, substantially at its centre, an axial cavity which is outwardly provided with a closing lid 225 whose structure has thin areas 235 at the edges of said cavity 215.

By contrast, Figure 3A shows a second pre-packed pod of the series of pre-packed pods suitable for use in the machine according to the present invention. The capsule 8 in question has a container body 108 of considerably smaller size than that of the pod 5 previously described, but made with a plurality of protruding equidistant radial fins 408, formed with a profile such as to enable the insertion of this prepackaged pod into the same filter-holder as used for the pod 5 of Figures 2A, 2B, as will become clearer below. Figure 3B clarifies the above-described concepts, showing the actual capacity of the container body 105 and the function of the fins 408. The bottom wall is made in an absolutely identical way to the bottom wall 205 of the pre-packed pod 8.

Figure 4 is a longitudinal sectional view of the delivery unit 4 of the coffee machine according to the present invention. The unit comprises a supply inlet 104 provided with a perforation head 114 which enables the opening of holes for the passage of water from the boiler into the pre-packed pod. As shown here, the pod 5 or the pod 8 are positioned alternatively inside a filter- holder 204 provided with a substantially cup-shaped cavity 214 having means 224 to perforate the bottom wall 205, 208 of the pre-packed pod on the bottom wall thereof. Around the perforation area there is arranged a seal 234 that places the area around the opening formed by the perforation means in communication with a membrane 304 provided with an axial through-hole 314, which effectively places the filter-holder 204 in communication with the delivery pipe 404 terminating in the delivery spout 414. As can be observed, the drawing shows both the pre-packed pod 5 and the pre-packed pod 8 in the filter-holder.

The operation of the machine according to the present invention will emerge clearly from the following description. As already stated in the introduction of the present description, the aim of this machine is to provide an infusion of a quality similar to that of an espresso coffee, i.e. made at the appropriate pressure so as to promote the extraction of all the aromatic substances from the ground coffee, but having a much larger volume, i.e. in the order of about 200 cm ³ , that is the so-called "regular coffee" of the United States. In order to both achieve this result and avoid structural, construction and operating complications such as not to justify said desig n , accord ing to the present invention , the pump supplying the water from the tank to the boiler is duplicated , so as to achieve an increase in the flow rate - i .e. to double it - without changing the operating pressure. The man ufactu re of a pump of new design that wou ld combine a greater flow rate at the same pressure would have been quite costly from the point of view of design time, manufacturing time and approval time. I n add ition to this, it is worth underlin ing that this pump, precisely because it is not in "common use" even in this specific field , would eventually have been much more expensive than the two pumps used herein from the industrial point of view.

Furthermore, the use of the two pumps allows a certain safety marg in in the machine's use, given that any failure of one of the two pumps does not hamper the operation of the other; thus, the machine would remain capable of operating , albeit in a no longer optimum way.

Advantageously, by means of the control unit 6, the programmes that are selected by the user via the user interface 7 , and wh ich may include either making a "regular coffee" or making an espresso, can be conveniently set. Clearly, by a simple expedient, i .e. with the delivery spout split into two separate pipes , the machine accord ing to the invention can prepare two espresso coffees instead of just one, provided that the complete pre-packed pod is inserted in the filter-holder.

I n fact, the exped ient whereby the pre-packed pods of the types shown in Figures 3A and 3B can be employed in the machine accord ing to the present invention means that this mach ine can be used in a very versatile and easy way. The user will insert the appropriate pod in the filter and will select the corresponding prog ramme. If a pre-packed pod 8 is inserted , the user's selection will ensu re that the logic of the control unit 6 will turn on the pump which was not used during the last operation of a similar type, i .e. during the preparation of the last "short" coffee, th us preserving the functionality of the system .