Espresso coffee machine with improved system for regulating the temperature of the water and method for regulating the temperature of the water in an espresso coffee machine

1. A machine for preparing and dispensing espresso coffee comprising:

a water supply;

a dispensing group and a corresponding coffee boiler containing water under pressure;

a heater device for heating the water in the coffee boiler;

a temperature sensor for measuring the temperature of the water in the coffee boiler;

a processor connected to said temperature sensor and configured to drive said heater device so that said water in the coffee boiler is at a reference temperature,

wherein said processor comprises a feedback system; and

wherein the value of said reference temperature is varied as a function of a quantified time elapsed from a machine operating cycle or a frequency of use of the machine within a time interval.

2. The machine for preparing and dispensing espresso coffee according to claim 1 , wherein said processor is configured to control the switching on or switching off of the heater device on the basis of the temperature sensed by the temperature sensor.

3. The machine for preparing and dispensing espresso coffee according to claim 1 , wherein said heater device comprises an electrical resistance.

4. The machine for preparing and dispensing espresso coffee according to claim 1 , wherein said feedback system comprises a Proportional-Integral-Derivative or Proportional-Integrative-Derivative controller.

5. The machine for preparing and dispensing espresso coffee according to claim 1 , wherein said value of said reference temperature is varied as a function of time elapsed since a last machine operating cycle.

6. The machine for preparing and dispensing espresso coffee according to claim 5 , wherein a first parameter for varying said reference temperature (Trif, Trif_new) is the time elapsed since the last beverage extraction cycle, and if the last dispensing operation is termed to, Trif can be modified as follows:

t 0 <t 1 :Trif_new=Trif+Δ T 1;

t 1 <t 0 <t 2 :Trif_new=Trif+Δ T 2;

t 2 <t 0 <t 3 :Trif_new=Trif+Δ T 3;

. . .

t n-1 <t 0 <t n :Trif_new=Trif+Δ Tn;

where:

t 0 , t 1 , t 2 , t 3 , . . . t n-1 , t n are quantified times;

t 1 <t 2 < . . . <t n ;

ΔT1, ΔT2, . . . ΔTn are temperatures; and

n=1, 2, 3, . . . .

7. The machine for preparing and dispensing espresso coffee according to claim 1 , wherein the value of said reference temperature is further varied as a function of the temperature of a component of the machine which enters into contact with a flow of water from the coffee boiler during a beverage dispensing operation.

8. The machine for preparing and dispensing espresso coffee according to claim 1 , wherein the value of said reference temperature is further varied as a function of the temperature of the environment in which the machine is installed.

9. A method for preparing and dispensing espresso coffee comprising:

supplying water to a coffee boiler containing water under pressure;

providing a dispensing group;

heating the water in the coffee boiler;

measuring the temperature of the water in the coffee boiler;

controlling the heating of water in the coffee boiler so that said water in the coffee boiler is at a reference temperature;

providing a feedback system; and

varying said value of said reference temperature (Trif, Trif_new) as a function of a quantified time elapsed from a machine operating cycle or a frequency of use of the machine within a time interval.

10. The method according to claim 9 , wherein said value of said reference temperature is varied as a function of a time elapsed since a last machine operating cycle.

11. The method according to claim 9 , wherein the parameter for varying said reference temperature is the time elapsed since a last beverage extraction cycle, and if the time of the last dispensing operation is termed to, Trif can be modified as follows:

t 0 <t 1 :Trif_new=Trif+Δ T 1;

t 1 <t 0 <t 2 :Trif_new=Trif+Δ T 2;

t 2 <t 0 <t 3 :Trif_new=Trif+Δ T 3;

. . .

t n-1 <t 0 <t n :Trif_new=Trif+Δ Tn;

where:

t 0 , t 1 , t 2 , t 3 , t n-1 , t n are quantified times;

t 1 <t 2 < . . . <t n ;

ΔT1, ΔT2, . . . ΔTn are temperatures; and

n=1, 2, 3, . . . .

12. The method according to claim 9 , wherein the value of said reference temperature is further varied as a function of a second parameter which is a function of the temperature of a component of the machine which enters into contact with a flow of water from the coffee boiler during a dispensing operation.

13. A machine for preparing and dispensing espresso coffee comprising:

a dispensing group and a corresponding coffee boiler containing water under pressure;

a heater device for heating the water in the coffee boiler;

a temperature sensor for measuring the temperature of the water in the coffee boiler;

a processor connected to said temperature sensor and configured to drive said heater device so that said water in the coffee boiler is at a reference temperature, and to vary the value of said reference temperature according to a function in which a parameter is a quantified time elapsed from a machine operating cycle or a frequency of use of the machine within a time interval.

14. The machine for preparing and dispensing espresso coffee according to claim 13 , wherein said the value of said reference temperature is varied according to a function in which the parameter is a quantified time elapsed since a last machine operating cycle.

15. The machine for preparing and dispensing espresso coffee according to claim 14 , wherein the parameter for varying said reference temperature (Trif, Trif_new) is the quantified time elapsed since a last beverage extraction cycle, and if the last dispensing operation is termed t 0 , Trif can be modified as follows:

t 0 <t 1 :Trif_new=Trif+Δ T 1;

t 1 <t 0 <t 2 :Trif_new=Trif+Δ T 2;

t 2 <t 0 <t 3 :Trif_new=Trif+Δ T 3;

. . .

t n-1 <t 0 <t n :Trif_new=Trif+Δ Tn;

where:

t 0 , t 1 , t 2 , t 3 , t n-1 , t n are quantified times;

t 1 <t 2 < . . . <t n ;

ΔT1, ΔT2, . . . ΔTn; and

n=1, 2, 3, . . . .