Method for controlling a coffee machine grinder

1. A method for controlling a coffee machine grinder comprising measuring an actual value of a physical quantity relating to a percolation process and modifying a ground coffee grain size at least for the subsequent percolation so as to compensate for a possible detected deviation between said actual value and a reference value for said physical quantity,

wherein as a consequence of user changes for the coffee machine, the control unit commands the execution of a preliminary coarse adjustment of a gap between grinding wheels by actuating an adjustment ring nut, and wherein when a rolling friction moment is created between the grinding wheels to block their reciprocal rotation, an activation signal is automatically generated for activation of an actuator of the adjustment ring nut to widen the gap between the grinding wheels so as to remove the source of the block.

2. The method for controlling a coffee machine grinder according to claim 1 , wherein said physical quantity is the percolation rate.

3. The method for controlling a coffee machine grinder according to claim 1 , wherein said physical quantity is the percolation time.

4. The method for controlling a coffee machine grinder according to claim 1 , wherein said physical quantity is the percolation hydraulic pressure.

5. The method for controlling a coffee machine grinder according to claim 2 , wherein said reference percolation rate is a fixed operational parameter that cannot be set by the user.

6. The method for controlling a coffee machine grinder according to claim 2 , wherein said reference percolation rate can be set by the user.

7. The method for controlling a coffee machine grinder according to claim 1 , wherein said deviation is compensated for through an algorithm which, based on said detected deviation, automatically commands a related rotation for the gap adjustment ring nut between the grinding wheels of said grinder.

8. The method for controlling a coffee machine grinder according to claim 7 , wherein rotation of said adjustment ring nut is performed at the beginning of at least one subsequent grinding for carrying out said at least one subsequent percolation.

9. The method for controlling a coffee machine grinder according to claim 7 , wherein rotation of said adjustment ring nut is divided into a sequence of small rotation steps performed for several successive grindings.

10. The method for controlling a coffee machine grinder according to claim 7 , wherein a current relative position between the grinding wheels of said grinder is read and said readout is used as input data for said algorithm in order to improve the precision of said rotation of said adjustment ring nut.

11. The method for controlling a coffee machine grinder according to claim 7 , wherein said algorithm commands said rotation of said adjustment ring nut without using as input data the readout of the current relative position between the grinding wheels of said grinder.

12. The method for controlling a coffee machine grinder according to claim 7 , wherein said rotation of said adjustment ring nut is automatically performed by a change in the setting of at least one of said reference value or a coffee powder amount.

13. A coffee machine comprising a grinder having an actuator for actuating a grinding wheel gap adjustment ring nut of said grinder, driven by an algorithm that compares an actual value for a physical quantity relating to a percolation process, measured by suitable measuring device, with a reference value for said physical quantity, and modifies a ground coffee grain size at least for a subsequent percolation so as to compensate for a possible detected deviation between said actual value and said reference value of said physical quantity,

wherein a control unit is responsive to user changes for coffee machine settings to command the execution of a preliminary coarse adjustment of a gap between grinding wheels by actuating an adjustment ring nut, and wherein the measuring device comprises a pressure sensor placed in a hydraulic circuit of the coffee machine.

14. The coffee machine according to claim 13 , wherein said measuring device comprises a flow meter placed in a hydraulic circuit of said machine.

15. The coffee machine according claim 13 , wherein said measuring device comprises a percolation timer.

16. The coffee machine according to claim 13 further comprising a detector that detects a current relative position between the grinding wheels of said grinder, in communication with a control unit of said coffee machine to improve control precision performed by an algorithm.

17. The coffee machine according to claim 16 , wherein said detector comprises a potentiometer or a position encoder or a strain gage.