WO2009128110A1

WO2009128110A1 - Coffee machine with a cooling system for cooling the grinding unit and relative method

Info

Publication number: WO2009128110A1
Application number: PCT/IT2009/000146
Authority: WO
Inventors: Marco Righetti
Original assignee: Saeco Ipr Limited
Priority date: 2008-04-16
Filing date: 2009-04-06
Publication date: 2009-10-22
Also published as: TW200946063A; ITFI20080079A1

Abstract

The machine (1) for preparing coffee comprises a boiler (13) for producing hot water, a pipe (11) to supply water to the boiler, a grinding unit (7) to grind coffee and supply ground coffee to a brewing unit (17). The pipe (11) to supply water to the boiler (13) passes through heat exchanger means to remove heat generated by the grinding unit.

Description

Coffee machine with a cooling system for cooling the grinding unit and relative method DESCRIPTION Technical Field The present invention relates to a coffee machine of the type comprising a boiler to produce hot water, a pipe to supply hot water to the boiler, a grinding unit to grind coffee and supply ground coffee to a brewing unit. The coffee machine can be intended for domestic or also professional use. The concept underlying the invention can also be adopted in a coffee machine forming a vending machine or part of a beverage vending machine. State of the art

In many automatic coffee machines coffee is extracted from coffee powder obtained by instantaneous grinding of coffee grains. Machines of this type - intended for professional or commercial use (vending machines) or for domestic use - are therefore provided with a grinding unit, usually comprising a pair of grinders, which produce coffee powder from grains or beans. The freshly ground coffee powder is then fed to a brewing unit.

When grinding grains of coffee a considerable amount of heat is generated as a result of friction between the grinders and the grains. This heat causes the coffee to heat up and consequently to degenerate. In fact, at high temperatures there is a deterioration of the organoleptic qualities of coffee.

For machines intended to grind large quantities of coffee, for packaging and subsequent sale of powdered coffee, cooling of the grinders of the grinding unit directly using jets of water has been suggested (see patent USA n. 2,834,552). For this purpose, water is pumped from a tank and sprayed through nozzles onto the surfaces of the grinders opposite to the grinding teeth. A complex sealing system prevents water leakage and contact of the water with the coffee. The water is recovered and recycled towards the tank.

Summary of the invention

According to one aspect, the invention relates to a new type of coffee machine, which entirely or partly solves the problem linked to the generation of heat in the grinding unit located upstream of the brewing unit. In substance, in an advantageous embodiment of the invention, the pipe to supply water to the boiler passes through heat exchanger means associated with the grinding unit, to remove heat generated by the grinding unit. In this manner, at least part of the heat generated by grinding coffee grains, besides being removed to prevent or reduce the damaging effect on the organoleptic qualities of the coffee, is recovered and increases the temperature of the water which supplies the boiler, with a consequent energy saving: a part of the thermal energy required to take the water to the brewing temperature is in fact supplied by the heat generated by grinding. In some embodiments the water supply pipe is connected to a water tank and comprises a pump to extract water from said tank and supply it to said boiler through said heat exchanger means.

In a know manner, the grinding unit can include a grinder and a counter-grinder, one rotating with respect to the other. In some preferred embodiments of the invention, the heat exchanger means are positioned around said grinder and counter-grinder. In some embodiments, a compartment for collecting the ground coffee is positioned around said grinder and counter-grinder, in thermal contact with the heat exchanger means. For example, these can surround the compartment for collecting the coffee powder.

Further advantageous embodiments of the invention are set forth in the appended claims and are described below with reference to the drawings.

According to a further aspect, the invention relates to a method for preparing coffee with a machine comprising a grinding unit to grind coffee grains and form coffee powder, characterized by removing heat generated by the grinding unit to preheat the brewing water to be used to prepare the coffee. Brief description of the drawings The invention will be better understood by following the description and accompanying drawing, which shows practical non-limiting embodiments of the invention. More in particular, in the drawing:

Fig.1 shows a diagram of an embodiment of the invention, arranged in a coffee machine of which only the components essential to understand the invention are shown;

Fig.2 shows a view according to H-Il of the grinding unit; Figs.3 and 4 show two axial sections of two embodiments of the grinding unit and of the heat exchanger means. Detailed description of embodiments of the invention

The present invention can be incorporated generically in a machine 1 which comprises a tank 3 for coffee grains, an auger 5 to feed the coffee grains to a grinding unit 7, a water tank 9, a pipe 11 to supply water to a boiler 13, a pump 15 which collects water from the tank 9 and supplies it at the required pressure to the boiler 13, and a brewing unit, indicated schematically with 17.

The various components described above can have any configuration compatible with the elements characterizing the present invention, which will be described in greater detail below. In particular, the brewing unit, the boiler, the pump and the water tank can be of any type. The boiler can be an instantaneous boiler or a storage boiler. Moreover, the tank 9 can be omitted and the pipe could be connected directly, for example, to a faucet of a water supply network.

In some embodiments, as shown in particular in Fig. 3, the grinding unit 7 comprises an electric motor 21 , which drives in rotation a motor shaft 23, on which the auger or helical screw 5 for coffee feed and a rotating grinder 25 are fitted. In the example shown, the grinder 25 is a disk grinder, but in other embodiments it could be a conical grinder. It cooperates with a second fixed grinder or counter-grinder 27, also disk-shaped in the example shown, but which could have a different shape, such as conical. Fixed grinder is intended as a grinder that does not rotate during grinding. However, in a known manner, the fixed grinder or counter-grinder 27 is in actual fact adjustable in axial direction to adjust the reciprocal distance between the grinders 25, 27 both in order to compensate any wear and in order to adjust the grinding fineness according to the consumer's taste. The counter-grinder 27 is for this purpose mounted on a block 29 threaded in 29A and engaged through the thread 29A in a female thread 31A of a fixed body 31 , to which the motor 21 is also fastened. With appropriate adjustment mechanisms, of known type and not shown, the distance between the active surfaces of the grinders 25, 27 is adjusted by rotating the block 29 with respect to the body 31.

A substantially annular compartment 33 extends around the grinders

25, 27, and into said compartment the coffee powder, obtained by grinding of the grains performed by the grinders 25, 27 is unloaded. The coffee powder is unloaded into the annular compartment 33 as a result of centrifugal force and from here is fed through an outlet 33A (Fig. 2) to the brewing unit 17.

According to some advantageous embodiments, a substantially cylindrical wall 31 B of the body 31 extends around the annular compartment 33, which as well as delimiting the compartment 33 also delimits a substantially annular volume 35 closed externally by a wall 37. Seals 39 can be provided to close the annular volume 35 off from the outside, in the coupling areas between the body 31 and the wall 37.

The annular volume 35 is in fluid connection with the pipe 11 to supply water to the boiler 13. The numbers 11A and 11B indicate fittings to feed water to and deliver water from the annular volume 35. In this manner the annular volume 35 in thermal contact with the compartment 33 forms a heat exchanger means which removes heat from the grinding unit 7 by means of the circulation of water through said annular volume 35. The heat removed increases the temperature of the water delivered through the fitting 11 B and then fed to the pump 15 and to the boiler 13. Consequently, as well as limiting the increase in temperature of coffee during grinding, the removal of heat obtained by water circulation allows a considerable saving of energy.

Fig.4 shows a modified embodiment of the heat exchanger means, in a section of the grinding unit 7 similar to that of Fig.3. The same numbers indicate the same or equivalent parts to those of the embodiment of Fig. 3.

In this embodiment, the fixed body 31 of the grinding unit 7 is co- molded with a coil 51 , inside which the water fed through the inlet fitting 11A circulates before being delivered through the outlet fitting 11 B. In some embodiments the coil 51 can be produced with a steel tube inserted in an aluminum block, which forms the remaining part of the body 31. The block 31 is manufactured by inserting the helical tube forming the coil 51 in a mold in which the aluminum is then die-cast. The shape of the pipe formed by the tube can differ from a helical coil 51. For example, it can have an undulated shape about the axis. This configuration allows simpler manufacture and greater thermal efficiency.

It is understood that the drawing only shows possible embodiments of the invention, which may vary in forms and arrangements, without however departing from the scope of the concept on which the invention is based. The presence of any reference numerals in the appended claims has the sole purpose of facilitating reading of the claims in the light of the preceding description and of the accompanying drawings and does not limit the scope of protection of the claims.

Claims

1. A machine for preparing coffee, comprising a boiler to produce hot water, a pipe to supply hot water to said boiler, a grinding unit to grind coffee and supply ground coffee to a brewing unit; characterized in that said pipe to supply water to said boiler passes through heat exchanger means to remove heat generated by said grinding unit.

2. Machine as claimed in claim 1 , characterized in that said pipe to supply water is connected to a water tank and comprises a pump to extract water from said tank and supply it to said boiler through said heat exchanger means.

3. Machine as claimed in claim 1 or 2, characterized in that said grinding unit comprises a grinder and a counter-grinder, one rotating in relation to the other.

4. Machine as claimed in claim 3, characterized in that said heat exchanger means are positioned around said grinder and counter-grinder.

5. Machine as claimed in claim 4, characterized in that a compartment for collecting the ground coffee is positioned around said grinder and counter-grinder, said compartment being in thermal contact with said heat exchanger means.

6. Machine as claimed in claim 5, characterized in that said compartment is surrounded by said heat exchanger means.

7. Machine as claimed in one or more of the preceding claims, characterized in that said heat exchanger means comprise an annular volume inside which water circulates.

8. Machine as claimed in one or more of the preceding claims, characterized in that said heat exchanger means comprise a pipe wound around the grinding unit.

9. Machine as claimed in claim 5 or 6, characterized in that said heat exchanger means comprise a pipe wound around the grinding unit produced by co-molding in a wall delimiting said compartment for collecting the coffee ground by said grinding unit.

10. Machine as claimed in one or more of the preceding claims, characterized in that said grinding unit comprises an auger to feed the coffee to be ground to the grinding unit, positioned substantially coaxial with the grinder and counter-grinder of the grinding unit.

11. A method for preparing coffee with a machine provided with a grinding unit for grinding coffee grains, characterized by removing heat generated by said grinding unit to preheat the brewing water to be used to prepare the coffee.