COFFEE GRINDING MACHINE CONFIGURED TO PROVIDE DIFFERENT PARTICLE SIZE PROFILES AND ASSOCIATED METHOD

Abstract

A coffee grinding machine (10) and an espresso coffee machine are described. The coffee grinding machine comprises a first grinder and second grinder cooperating with each other so as to grind coffee beans, obtaining a first dose of ground coffee during a first grinding cycle. The coffee grinding machine comprises a motor which rotates one of the grinders relative to the other one at a rotation speed. The coffee grinder machine is configured to modify the rotation speed so as to perform a second grinding cycle in which a second dose of ground coffee is obtained. The rotation speed is modified depending on quantitative information received from the espresso coffee machine and based on a coffee preparation cycle performed with said first dose of ground coffee, wherein the quantitative information may be a flow value measured in the espresso coffee machine or a brew ratio value.

Claims

1. A coffee grinding machine and an espresso coffee machine, wherein the coffee grinding machine comprises a first grinder and a second grinder, wherein at least one of the first and second grinders is rotatable, wherein said grinders cooperate with each other so as to grind coffee beans, obtaining a first dose of ground coffee during a first grinding cycle, wherein said coffee grinding machine comprises a motor which rotates one of the grinders relative to the other grinder at a speed of rotation, wherein said coffee grinding machine is configured to modify a grinding parameter for performing a second grinding cycle in which a second dose of ground coffee is obtained, wherein said grinding parameter is modified depending on quantitative information received from said espresso coffee machine and based on a coffee preparation cycle performed with said first dose of ground coffee, wherein said grinding parameter comprises the rotation speed, wherein said quantitative information comprises at least one of the following: a flow value measured by a flowmeter of said espresso coffee machine and a brew ratio value.

2. The coffee grinding machine according to claim 1, wherein said first dose is ground during a grinding cycle immediately prior to the grinding of the second dose.

3. The coffee grinding machine according to claim 1, further comprising a connection module for connecting together said espresso coffee machine and said coffee grinding machine.

4. The coffee grinding machine according to claim 3, wherein said connection module is configured to connect wirelessly said coffee grinding machine to the espresso coffee machine.

5. The coffee grinding machine according to claim 1, comprising a comparator for comparing the flow value with a reference flow value and a speed variator device configured to (i) reduce the rotation speed of the motor if the flow value is greater than the reference flow value, (ii) increase the rotation speed of the motor if the flow value is less than the reference flow value, and (iii) maintain the rotation speed of the motor if the flow value is substantially the same as the reference flow value.

6. The coffee grinding machine according to claim 1, also comprising a first device for measuring the mass of said first dose of ground coffee, a second device for measuring the mass of the espresso coffee prepared, a processor device (CPU) for calculating a brew ratio corresponding to a ratio between said mass of the first dose and said mass of the espresso coffee prepared with said first dose.

7. The coffee grinding machine according to claim 6, comprising a comparator for comparing the brew ratio value with a reference brew ratio value and a speed variator device configured to (i) reduce the rotation speed of the motor if the brew ratio value is greater than the reference brew ratio value, (ii) increase the rotation speed of the motor if the brew ratio value is less than the reference flow value, and (iii) maintain the rotation speed of the motor if the brew ratio value is substantially the same as the reference brew ratio value.

8. A method for grinding coffee beans, the method comprising: providing a first and second grinder cooperating with each other, wherein at least one of the first and second grinders is rotatable, wherein said grinders cooperate with each other so as to grind coffee beans, obtaining a first dose of ground coffee during a first grinding cycle, providing a motor for rotating one of the grinders relative to the other one at a rotation speed, modifying a grinding parameter in order to perform a second grinding cycle in which a second dose of ground coffee is obtained, wherein said grinding parameter is modified depending on quantitative information received from a coffee machine and based on a coffee preparation cycle performed with said first dose of ground coffee, wherein said grinding parameter comprises the rotation speed, wherein said quantitative information comprises at least one of the following: a flow value and a brew ratio value.

9. The method according to claim 8, wherein said first dose is ground during a grinding cycle immediately prior to the grinding of the second dose.

10. The method according to claim 8, further comprising the step of comparing the flow value with a reference flow value and (i) reducing the rotation speed of the motor if the flow value is greater than the reference flow value, (ii) increasing the rotation speed of the motor if the flow value is less than the reference flow value, and (iii) maintaining the rotation speed of the motor if the flow value is substantially the same as the reference flow value.

11. The method according to claim 8, comprising the step of measuring the mass of said first dose of ground coffee, the step of measuring the mass of the espresso coffee prepared and calculating a brew ratio corresponding to a ratio between said mass of the first dose and said mass of the espresso coffee prepared with said first dose.

12. The method according to claim 11, further comprising the step of comparing the brew ratio value with a reference brew ratio value and (iv) reducing the rotation speed of the motor if the brew ratio value is greater than the reference brew ratio value, (v) increasing the rotation speed of the motor if the brew ratio value is less than the reference brew ratio value, and (vi) maintaining the rotation speed of the motor if the brew ratio value is substantially the same as the reference brew ratio value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] There now follows a detailed description of the invention, provided by way of a non-limiting example, to be read with reference to the attached drawings, in which:

[0057] FIG. 1 is graph showing an example of a particle size profile expressed on a logarithmic scale;

[0058] FIG. 2 is graph showing particle size profiles expressed on a logarithmic scale;

[0059] FIG. 3 is graph showing three particle size profiles expressed on a linear scale;

[0060] FIG. 4 is a schematic representation of the coffee grinding machine according to an embodiment of the present invention;

[0061] FIG. 5 is another schematic representation of the coffee grinding machine according to the present invention cooperating with an espresso coffee machine;

[0062] FIG. 6 is a flow diagram of an operating mode; and

[0063] FIG. 7 shows, by way of example, an espresso coffee machine with weighing and processing devices for calculating a brew ratio value.

DETAILED DESCRIPTION

[0064] FIG. 1, which has already been briefly referred to above, is a graph showing an example of a granulometric profile of a dose of coffee powder. The curve which shows the particle size profile is called a bimodal profile. The high peak (on the right, relating to the larger size particles) is referred to as “first modal” while the low peak (on the left, relating to the smaller size particles) is referred to as “second modal”.

[0065] FIGS. 2 and 3 show the influence of the rotation speed of the grinders in relation to the size of the particles. In particular, FIGS. 2 and 3 shows three particle size curves obtained by keeping a constant distance between the grinders and by varying the rotation speed. The two figures show the same profiles expressed on a logarithmic scale in order to emphasize the differences on the second modal and on a linear scale in order to emphasize the differences on the first modal.

[0066] As can be seen, at the slower speed (150 rpm), the first modal moves to the left and its relative amount is reduced to the advantage of the second modal.

[0067] At the higher speed (300 rpm), the first modal moves to the right and increases its relative amount.

[0068] In the case of FIG. 2 (which shows only an example), the first modal of the curve at 150 rpm is located at about 425 μm, while the first modal of curve at 300 rpm is located at about 475 μm.

[0069] The variation in speed is obtained by means of a suitable electronic speed regulator for electric motors. Many devices of this type, which vary depending on the type of motor used, are commercially available. According to an embodiment of the present invention, the coffee grinding machine comprises a three-phase asynchronous motor and, for the speed control, an inverter or any known frequency variator.

[0070] FIG. 4 shows in very schematic form the main components of a coffee grinding machine 10 according to embodiments of the present invention.

[0071] The machine 10 comprises a grinding chamber 12 with an upper inlet IN for the coffee to be ground, a first grinder 14A and a second grinder 14B cooperating with the first grinder 14A and an outlet conveyor 16 which receives the ground coffee from the grinders 14A and 14B and conveys it so as to be so as to be collected and used. For example, as shown in FIG. 4, the ground coffee may be conveyed towards a filter 21 supported by a portafilter 20 of any known type.

[0072] According to an embodiment of FIG. 4, the first grinder 14A is a fixed grinder while the second grinder 14B is movable, for example rotatable.

[0073] The coffee grinding machine comprises an electric motor 30 for rotating the second grinder 14B at a certain rotation speed. According to embodiments, the motor is a single-phase motor. For example, the motor is an electric motor comprising one of the following types: universal, DC, single-phase or three-phase AC, brushless, BLDC, stepper or other type of motor.

[0074] Preferably, the coffee grinding machine further comprises a frequency variator device 40 for controlling the rotation speed. For example, this frequency variator device comprises an inverter. This frequency variator device 40 is able to vary the grinding speed so as to allow grinding in a constant manner at a first speed or at a second speed.

[0075] According to embodiments, the coffee grinding machine further comprises an angular position transducer, for example an encoder 50, associated with the electric motor for measuring in a precise manner the rotation speed of the motor 30.

[0076] According to embodiments, the variation in the speed may be performed by the barista via a suitable interface 70 (FIG. 5). The interface 70 may for example comprise a pushbutton (or a plurality of pushbuttons) for selecting a predetermined rotation speed, a rotatable knob for selecting (continuously or discontinuously) a plurality of rotation speeds or a touch screen for choosing from among various available options/speeds. The interface 70 is connected to the inverter 40 (directly or via other devices, such as a processor 60, shown schematically in FIG. 5) for modifying the power supply frequency of the motor 30 and therefore the speed of the latter. Advantageously, it is possible to provide the option of selecting a rotation speed from among those offered by the manufacturer or a speed chosen by the user. Advantageously, a memory may be provided for storing values of rotation speeds.

[0077] According to other embodiments, a control unit (CPU 60) configured to set a rotation speed of the motor 30 depending on external signals, for example supplied by a coffee machine 90 connected to/associated with said coffee grinding machine 10, is provided. According to embodiments, the external signals which influence the rotation speed of the motor 30 are not environmental signals (pressure, humidity or temperature), but relate to operation of an espresso coffee machine.

[0078] The connection between the coffee machine 90 and the coffee grinding machine 10 may be via a cable (for example a standard data cable or an optical fibre cable) or may be via a wireless connection, for example based on an industrial technical data transmission standard for WPANs (Wireless Personal Area Networks). For example the connection may be via the Bluetooth standard or the like. The connection could also be optical and based on a wireless network. FIG. 5 shows in schematic form a wireless connection between the coffee machine 90 and the coffee grinding machine 10 via a communication module (for example a receiver or a transceiver).

[0079] According to embodiments, the speed of the motor 30 is varied depending on information relating to a flow value measured in the espresso coffee machine 90. The flow information is preferably flow information obtained during a cycle for preparation of an espresso coffee with the machine 90 using a dose of coffee powder ground during a grinding step prior to the grinding operation in progress. Preferably, the prior grinding step is the grinding step immediately preceding the grinding step in progress. The flow may advantageously be measured using a flowmeter 91 of the espresso coffee machine 90. The flowmeter 91 may be in any position in the hydraulic circuit of the machine 90, for example in the vicinity of a dispensing unit of the machine 90.

[0080] FIG. 6 shows in schematic form a possible mode for implementing the steps by means of which the rotation speed of the motor 30 is varied depending on the flow information obtained from an associated coffee machine.

[0081] After receiving flow information from the espresso coffee machine (step 100), an evaluation is carried out to check whether the flow value measured is outside a predetermined tolerance range (step 101), namely differs from a (desired) reference value, plus or minus a threshold.

[0082] If the flow value measured, in relation to the reference dose, lies within the tolerance range, no variation of the rotation speed of the motor is performed (step 102) and therefore grinding of the dose is performed as for grinding of the reference dose, i.e. typically grinding of the previous dose.

[0083] If the flow value measured, in relation to the reference dose, is greater than the desired value (taking into account also the tolerance range) the rotation speed of the motor is increased (steps 103 and 105).

[0084] If the flow value measured, in relation to the reference dose, is smaller than the desired value (taking into account also the tolerance range) the rotation speed of the motor is decreased (steps 103 and 104).

[0085] According to other embodiments, the speed V of the motor 30 is varied depending on information relating to a brew ratio value measured in the espresso coffee machine 90. The brew ratio information is preferably brew ratio information obtained during a cycle for preparation of an espresso coffee with the machine 90 using a dose of coffee powder ground during a grinding step prior to the grinding operation in progress. Preferably, the prior grinding step is the grinding step immediately preceding the grinding step in progress.

[0086] According to embodiments, the machine 90, as shown in FIG. 7, comprises means for calculating the brew ratio between the mass (or weight) of a quantity of ground coffee used to prepare an espresso coffee and the mass (or weight) of the espresso coffee actually prepared. As is known, consumers require espresso coffee in amounts and/or diluted to different degrees depending on their particular habits and tastes and/or depending on the usual practice of the place where they are present. Thus, a consumer may require a short coffee, a normal coffee, a long coffee, etc. The consumer may also request a single, double, triple, etc., espresso coffee.

[0087] Said means for calculating the brew ratio may comprise a first weighing device 95 for measuring the mass of the ground coffee (for example directly in the filter supported by a portafilter 20), a second weighing device 96 for measuring (directly in the cup) the mass of the espresso coffee prepared and a processing device (CPU) configured at least to receive the measurement of the mass of ground coffee and the measurement of the mass of espresso coffee prepared and to obtain said brew ratio from the two mass measurements. FIG. 7 also shows in schematic form two dispensing units 99 configured for engagement with a portafilter 20.

[0088] Therefore, the speed of the motor is decided depending on the quantitative information received from a coffee machine for which the ground coffee is intended. Advantageously, the value obtained on the basis of a dose is used to decide whether to maintain or modify the grinding parameters (for example the grinding speed) of a next dose.

[0089] The system may function both in an open loop, i.e. without measuring the actual speed V of rotation of the motor, or in a closed loop, i.e. detecting the speed of the motor using a dedicated device, for example the speed sensor (encoder) 50.

[0090] Advantageously, according to the present invention, it is possible to solve the problem of defining a balance in the grinding particle size between a single-dose coffee and a double-dose coffee. For example it is possible to provide two pushbuttons, one for grinding a single dose and one for grinding a double dose. According to the present invention, in order to grind a single dose, it is possible to program the coffee grinding machine so that a specific speed V1 (for obtaining a certain particle size) and a first quantity W1 are associated with the corresponding pushbutton. Similarly, according to the present invention, in order to grind a double dose, it is possible to program the coffee grinding machine so that a specific speed V2 (for obtaining a certain particle size) and a second quantity W2 are associated with the corresponding pushbutton.

[0091] Even if a service requiring alternation of single coffees at a speed V1 and double coffees at a speed V2 should arise, the system would not suffer as a result.

[0092] This flexibility is very advantageous. In fact, at present, the particle size selected by the barista is necessarily a compromise between the single dose and the double dose. With the present invention this limitation is overcome.