Method for automatic adjustment of the quantity of coffee and coffee machine using said method
The method for adjusting the quantity of coffee comprises the steps of: dispensing a predetermined quantity of coffee powder into an infusion chamber ( 36 ); by means of an electric actuator ( 19 ), closing said infusion chamber compressing the coffee powder in the infusion chamber. The method also provides for detection of at least one parameter of the electric actuator during at least a part of the step to close the infusion chamber and compress the coffee powder; and setting of the quantity of coffee powder dispensed in a subsequent dispensing cycle as a function of said parameter.
1. A machine for preparing coffee comprising:
a coffee powder doser;
an infusion chamber with at least two portions movable with respect to each other, said chamber in communication with said doser;
an electric actuator for opening and closing the infusion chamber;
a programmable control unit, interfaced with said doser and with said electric actuator, to:
dispense, through said doser, a predetermined quantity of coffee powder into said infusion chamber;
perform a cycle to close said infusion chamber;
deliver hot water into said infusion chamber,
detect at least one electrical operating parameter of said electric actuator during closing of the infusion chamber, said operating parameter being a function of a current absorbed by the electric actuator indicating a stress on said electric actuator to reach a closing position of the infusion chamber;
determine whether the determined electrical parameter is within known limits; and
adjust a quantity of coffee powder dispensed in a subsequent dispensing cycle as a function of said electrical operating parameter, when said determined electrical parameter is outside the known limits.
2. The machine as claimed in claim 1 , wherein said doser comprises:
a grinding unit to grind coffee beans and produce said coffee powder.
3. The machine as claimed in claim 2 , further comprising: a sensor associated with said grinding unit to determine a number of revolutions of the grinding unit, said predetermined quantity of coffee powder being defined in terms of the number of revolutions of said grinding unit.
4. The machine as claimed in claim 1 , wherein said doser comprises a powdered coffee dispenser.
5. The machine as claimed in claim 1 , wherein said control unit is programmed to:
decrease the quantity of coffee powder dispensed during the subsequent cycle with respect to said predetermined quantity, if said operating parameter exceeds a maximum set value;
increase the quantity of coffee powder dispensed during the subsequent cycle with respect to said predetermined quantity, if said operating parameter does not reach a minimum set value.
6. The machine as claimed in claim 1 , wherein said infusion chamber is controlled to reach a same closing position.
7. The machine as claimed in claim 1 , wherein said control unit causes opening of the infusion chamber and unloading of the powder from said infusion chamber without giving rise to an infusion step, if at least one operation parameter of the electric actuator reaches or exceeds an alarm value before said infusion chamber has reached the closed position.
8. The machine as claimed in claim 1 , wherein said infusion chamber comprises:
a plurality of closing positions.
9. The machine as claimed in claim 1 , wherein said operating parameter of the electric actuator is determined based on a power absorbed by said electric actuator.
10. The machine as claimed in claim 1 , wherein:
said operating parameter is determined as an average value of the current absorbed by the electric actuator in a time window during closing of the infusion chamber.
11. The machine as claimed in claim 10 , wherein said operating parameter is defined by a maximum of said average value of the current absorbed by the electric actuator.
12. The machine as claimed in claim 1 , wherein said known values are settable as a function of-qualitative properties of the coffee desired.
13. The machine as claimed in claim 1 , wherein said doser comprises a grinding unit to grind the coffee beans and produce a coffee powder.
14. The machine as claimed in claim 13 , wherein a sensor is associated with said grinding unit to determine a number of revolutions of the grinding unit said predetermined quantity of coffee powder being defined in terms of the number of revolutions of said grinding unit.
15. The machine as claimed in claim 1 , wherein closing the infusion chamber takes place in variable positions as a function of said operating parameter, the closing movement and consequently compression of the coffee powder being interrupted when said operating parameter reaches a preset value.
16. The machine of claim 1 , wherein the predetermined quantity of coffee power is defined in terms of number of revolutions of a grinding unit that grinds coffee beans to produce said coffee powder.
17. The machine of claim 1 , wherein:
the operating parameter depends on a power absorbed by said electric actuator.
18. The machine of claim 1 , wherein said operating parameter depends on a moving average value of the current absorbed by the electric actuator in a time window during closing of the infusion chamber.
19. The machine of claim 1 , wherein the control unit further:
compares said parameter with an interval of known values settable as a function of the qualitative properties of the coffee desired.
20. The machine of claim 1 , wherein the control unit closes the infusion chamber at variable positions as a function of said operating parameter, the closing movement and compression of the coffee powder being interrupted when said parameter reaches a present value.