Machine and method for processing liquid or semi liquid food products

Abstract

A machine for processing liquid or semi-liquid food products including a containing element for containing the product to be dispensed; a stirrer for stirring the product to be dispensed; a heat exchanger fluid flowing in a circuit in a direction of circulation through an evaporator, a compressor, a condenser and a pressure reducing element; a fan rotating about an axis of rotation to force an air flow towards the condenser; a control unit connected to the fan to control the fan through a speed signal; a temperature sensor, located downstream of the condenser in the circulation direction to detect a condensation temperature and configured to send to the control unit a temperature signal as a function of which the control unit generates the speed signal.

Claims

1. A machine for processing liquid or semi-liquid food products, comprising: a container element for containing a product to be dispensed and including a mouth for dispensing the product; a stirrer mounted inside the container and rotatable about a stirring axis to stir the product; a first actuator, including an electric motor connected to the stirrer to rotate the stirrer about the stirring axis; a refrigeration system comprising a circuit configured to cause a heat exchanger fluid to circulate in a circulating direction and including an evaporator operatively connected to the container, a compressor located downstream of the evaporator in the circulation direction, a condenser located downstream of the compressor and a pressure reducing element located between the condenser and the evaporator; a fan rotatable about an axis of rotation to force an air flow towards the condenser of the refrigeration system; a controller connected to the fan to control the fan through a speed signal and also connected to the first actuator to drive the stirrer in rotation and to the compressor to drive the compressor; a temperature sensor, located downstream of the condenser in the circulation direction of the heat exchanger fluid to detect a condensation temperature and configured to send to the controller a temperature signal representing the condensation temperature, and wherein the controller is programmed to generate the speed signal as a function of the temperature signal; wherein the controller is configured, upon determination that the temperature sensor is not operating, to set a rotation speed of the fan to a maximum rotation speed.

2. The machine according to claim 1, wherein the controller is programmed to regulate the rotation speed of the fan through the speed signal.

3. The machine according to claim 2, wherein the controller is programmed to drive the fan at a first rotation speed for values of condensation temperature below a first threshold temperature, and at a second rotation speed, greater than the first rotation speed, for values of condensation temperature above the first threshold temperature.

4. The machine according to claim 3, wherein the controller is programmed to drive the fan at the second rotation speed for values of condensation temperature between the first threshold temperature, and a second threshold temperature, and at a third rotation speed, greater than the second rotation speed, for values of condensation temperature above the second threshold temperature.

5. The machine according to claim 1, wherein the controller is programmed to regulate the rotation speed of the fan steplessly between a minimum rotation speed and the maximum rotation speed.

6. The machine according to claim 1, wherein the temperature sensor is located along the circuit of the refrigeration system, between the condenser and the pressure reducing element.

7. The machine according to claim 1, wherein the circuit comprises a duct, configured to contain and cause the heat exchanger fluid to circulate, and wherein the temperature sensor is in contact with an outside surface of the duct of the circuit to determine the condensation temperature indirectly from a temperature of the outside surface of the duct.

8. The machine according to claim 1, wherein the temperature sensor is in direct contact with the heat exchanger fluid to determine the condensation temperature directly.

9. A method for processing liquid or semi-liquid food products, comprising the following steps: holding the product in a container from which it will be dispensed; stirring the product inside the container with a stirrer; cooling the product with a refrigeration system including a condenser, a pressure reducing element, a compressor and an evaporator operatively connected to the container and in which a heat exchange fluid circulates in a circulation direction; forcedly ventilating the condenser of the refrigeration system with air by a fan rotating at a variable rotation speed; driving the fan through a speed signal sent by a controller, detecting a condensation temperature of the heat exchanger fluid at a position downstream of the condenser of the refrigeration system, with a temperature sensor; sending to the controller a temperature signal representing the condensation temperature detected by the temperature sensor; generating the speed signal as a function of the temperature signal; wherein the controller is configured, upon determination that the temperature sensor is not operating, to set a rotation speed of the fan to a maximum rotation speed.

10. The method according to claim 9, wherein the step of driving the fan comprises a step of varying the rotation speed of the fan as a function of the temperature signal.

11. The method according to claim 9, wherein, when the condensation temperature is below a first threshold temperature, the controller generates the speed signal to set the rotation speed of the fan at a first rotation speed, and wherein, when the condensation temperature is greater than a first threshold temperature, the controller generates the speed signal to set the rotation speed of the fan at a second rotation speed, which is greater than the first rotation speed.

12. The method according to claim 11, wherein, when the condensation temperature is between the first threshold temperature, and a second threshold temperature, the controller generates the speed signal to set the rotation speed of the fan at the second rotation speed, and wherein, when the condensation temperature is greater than the second threshold temperature, the controller generates the speed signal to set the rotation speed of the fan at a third rotation speed, which is greater than the second rotation speed.

13. The method according to claim 9, wherein, in the step of detecting, the temperature sensor detects the condensation temperature at a position downstream of the condenser and upstream of the pressure reducing element.

14. The method according to claim 9, wherein, in the step of driving, the controller regulates through the speed signal the rotation speed of the fan steplessly between a minimum rotation speed and a maximum rotation speed.

15. A machine for processing liquid or semi-liquid food products, comprising: a container element for containing a product to be dispensed and including a mouth for dispensing the product; a stirrer mounted inside the container and rotatable about a stirring axis to stir the product; a first actuator, including an electric motor connected to the stirrer to rotate the stirrer about the stirring axis; a refrigeration system comprising a circuit configured to cause a heat exchanger fluid to circulate in a circulating direction and including an evaporator operatively connected to the container, a compressor located downstream of the evaporator in the circulation direction, a condenser located downstream of the compressor and a pressure reducing element located between the condenser and the evaporator; a fan rotatable about an axis of rotation to force an air flow towards the condenser of the refrigeration system; a controller connected to the fan to control the fan through a speed signal and also connected to the first actuator to drive the stirrer in rotation and to the compressor to drive the compressor, wherein the controller is configured to measure working hours of the machine; a temperature sensor, located downstream of the condenser in the circulation direction of the heat exchanger fluid to detect a condensation temperature and configured to send to the controller a temperature signal representing the condensation temperature, and wherein the controller is programmed to generate the speed signal as a function of the temperature signal and of the working hours of the machine, wherein a rotation speed of the fan is increased with increased working hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other features will become more apparent from the following detailed description of a preferred embodiment, illustrated by way of non-limiting example in the accompanying drawings, in which:

(2) FIG. 1 illustrates an embodiment of a machine for processing liquid or semi-liquid food products;

(3) FIG. 2 illustrates another embodiment of a machine for processing liquid or semi-liquid food products;

(4) FIG. 3 illustrates another embodiment of a machine for processing liquid or semi-liquid food products;

(5) FIG. 4 illustrates a circuit of a refrigeration system of the machine of FIG. 1;

(6) FIGS. 5A and 5B illustrate two embodiments of a temperature sensor of the machine of FIG. 1;

(7) FIGS. 6A, 6B and 6C show, respectively, a first, a second and a third graph representing the modes of regulating a rotation speed of a fan of the machine of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) With reference to the accompanying drawings, the numeral 1 denotes a machine for processing liquid or semi-liquid food products. Alternatively, the products may also be cold or iced food products.

(9) The machine 1 comprises a frame 2. In an embodiment, the machine 1 comprises a containing element 3 for holding the product to be dispensed. The containing element 3 is designed to contain the product before the product is dispensed. The machine 1 comprises a dispensing mouth 4. The machine 1 comprises a dispenser 5. The dispensing mouth 4 is connected to the containing element 3. The dispenser 5 is connected to the dispensing mouth 4 to enable or inhibit the flow of fluid through the dispensing mouth 4 itself.

(10) The machine 1 comprises a stirrer 6. The stirrer 6 is mounted inside the containing element 3 to stir the product to be dispensed. In an embodiment, the stirrer 6 is an auger (or endless screw) which rotates about a stirring axis M.

(11) In an embodiment, the machine 1 comprises a first actuator 7. The first actuator 7 is connected to the stirrer 6 to set it in rotation about the stirring axis M. Preferably, the actuator 7 is an electric motor.

(12) In an embodiment, the containing element 3 is a thermal processing cylinder 3A whose axis of symmetry coincides with the stirring axis M.

(13) In an embodiment, the containing element 3 is a thermal processing tank 3B which may have any of several shapes.

(14) In this embodiment, the machine 1 comprises a dispensing duct 3B. The dispensing duct 3B is configured to connect the thermal processing tank 3B to the dispensing mouth 4.

(15) In an embodiment, the machine 1 comprises a further containing element 3. The further containing element 3 is connected to the containing element 3 by a filling duct 3.

(16) In this embodiment, the machine 1 comprises a second actuator 7. In this embodiment, the machine 1 comprises an auxiliary stirrer 6. The second actuator 7 is connected to the auxiliary stirrer 6 to drive it in rotation and stir the product inside the further containing element 3.

(17) In this embodiment, the machine 1 preferably also comprises a pump for transferring the product from the further containing element 3 to the containing element 3.

(18) In an embodiment, the machine 1 comprises a refrigeration system 8. The refrigeration system 8 comprises a circuit 8. The refrigeration system 8 is configured to make a refrigerant fluid inside it flow in a circulation direction V. The circuit 8 comprises a plurality of ducts 8 configured to contain the fluid and to make it circulate in the circuit 8. Each duct of the plurality of ducts comprises an outside surface 8A and an inside surface 8B. The circuit 8 comprises a compressor 81. The compressor 81 is configured to increase the pressure of the refrigerant fluid. The circuit 8 comprises a condenser 82. The condenser 82 is configured to remove heat from the refrigerant fluid and to transfer it to the ambient surroundings. The circuit 8 comprises a pressure reducing element such as, for example, a throttle valve 83. The throttle valve 83 is configured to generate load losses in the refrigerant fluid, thereby reducing its pressure. The circuit 8 comprises an evaporator 84. The evaporator 84 is configured to draw heat from the product in order to cool it. The compressor 81, the condenser 82, the throttle valve 83 and the evaporator 84 are located along the circuit 8 in this order in the circulation direction V of the refrigerant fluid. More specifically, the compressor 81 is downstream of the evaporator 84 in the circulation direction V of the refrigerant fluid. The condenser 82 is downstream of the compressor 81 in the circulation direction V. The throttle valve 83 is located between the condenser 82 and the evaporator 84.

(19) In an embodiment, the evaporator 84 coincides with the containing element 3. More specifically, in an embodiment, the thermal processing cylinder 3A coincides with the evaporator 84. In an embodiment, the evaporator 84 and the containing element 3 have a partition wall 31 in common. In particular, the partition wall 31 is in contact with the refrigerant fluid at a first surface of it and with the product to be dispensed at a surface of it opposite to the first surface.

(20) The circuit 8 comprises an inlet duct 84, configured to channel refrigerant fluid into the evaporator 84. The circuit 8 comprises an outlet duct 84, configured to channel refrigerant fluid out of the evaporator 84 towards the compressor 81. The plurality of ducts 8 comprises the inlet duct 84 and the outlet duct 84.

(21) In an embodiment, the circuit 8 comprises a fan 85. The fan 85 is associated with the condenser 82. More specifically, the fan 85 is associated with the condenser 82 to force an air flow towards it. The fan 85 rotates at a rotation speed v. The forced air ventilation produces an air flow F proportional to the rotation speed v. The air flow F is configured to change the air that is in contact with the walls of the condenser 82, thus increasing the quantity of heat released to the ambient surroundings.

(22) In an embodiment, the machine 1 comprises a temperature sensor 86. In an embodiment, the temperature sensor 86 may be one of the following: a liquid sensor (liquid heat expansion), a bimetallic strip sensor (operating by heat expansion difference), an RTD (operating by change of resistance relative to change of temperature), a thermistor (operating by change of electrical conductivity relative to change of temperature), a thermocouple (operating by Seebeck effect), an integrated temperature sensor (based on the property of semiconductor couplingsdiodes and transistorsof having a voltage or current which is highly dependent on the temperature), or optical pyrometers for contactless measurements. Each of the above mentioned temperature sensors 86 corresponds to a different embodiment to be protected under this disclosure.

(23) The temperature sensor 86 is configured to measure a condensation temperature Tc. The condensation temperature Tc is the temperature of the refrigerant downstream of (at the outlet of) the condenser 82. The condensation temperature Tc is defined as such because it is directly correlated with the temperature at which the refrigerant fluid condenses (in the condenser 82). In one embodiment, the temperature sensor 86 is configured to determine the condensation temperature Tc at a position downstream of the condenser 82 and upstream of the throttle valve 83. In other embodiments, it could be located at different positions in the circuit 8, provided that the value is suitably processed to determine the condensation temperature Tc.

(24) In an embodiment, the temperature sensor 86 is in direct contact with the refrigerant fluid so as to determine the condensation temperature Tc directly. In an embodiment, the temperature sensor 86 is in contact with the outside surface 8A of a duct of the plurality of ducts 8 of the circuit 8. In this embodiment, the temperature of the refrigerant fluid is determined by taking into due account the thermal resistance of the duct according to relations which are known to persons expert in the trade. In this embodiment, the temperature sensor comprises a probe 86A which is in direct contact with the refrigerant fluid.

(25) In an embodiment, the machine 1 comprises a control unit 9. The control unit 9 is preferably connected to one or more of the following parts of the machine 1:

(26) First actuator 7

(27) Second actuator 7

(28) Stirrer 6

(29) Auxiliary stirrer 6

(30) Dispenser 5

(31) Circuit 8 of the refrigeration system 8

(32) Compressor 81 of the circuit 8

(33) Throttle valve 83 of the circuit 8.

(34) The control unit 9 is programmed to receive control signals 901. The control unit 9 is programmed to process the control signals 901. The control unit 9 is programmed to generate drive signals 902 as a function of the control signals 901. The control unit 9 is programmed to send the drive signals 902 to the parts it is connected to and which it is responsible for controlling.

(35) The machine 1 comprises a user interface 9A. In an embodiment, the user interface 9A is configured to allow a user to send input signals 901A to the control unit 9. The temperature sensor 86 is configured to send a temperature signal 901B to the control unit 9. The temperature signal 901B represents the condensation temperature Tc.

(36) In an embodiment, the control signals 901 comprise the temperature signal 901B. In an embodiment, the control signals 901 comprise the input signals 901A.

(37) In an embodiment, the drive signals 902 comprise a speed signal 902A.

(38) The control unit 9 is configured to process the temperature signal 901B and to generate the speed signal 902A as a function of the temperature signal 901B.

(39) The control unit 9 is programmed to send the drive signals 902 to the fan 85 in order to control the fan. The control unit 9 is programmed to send the speed signal 902A to the fan 85. The control unit 9 is programmed to send the speed signal 902A to the fan 85 in order to control the rotation speed v of the fan.

(40) Described below are some aspects of the programming of the control unit 9 with regard to controlling the rotation speed v of the fan 85 as a function of the condensation temperature Tc. It should be noted that what is described below is provided purely by way of example and is not in any way intended to limit the programming of the control unit.

(41) In this regard, it is specified that in the graphs shown in FIGS. 6A, 6B and 6C, the values of the rotation speed v of the fan 85 are shown on the axis of ordinates and the values of the condensation temperature Tc on the axis of abscissas.

(42) In a first embodiment, the control unit 9 is programmed to vary the operating configuration of the fan 85 between a first operating configuration C1 and a second operating configuration C2.

(43) The control unit 9 is configured to set the first operating configuration C1 for values of condensation temperature Tc lower than a first threshold temperature Ts1.

(44) In the first operating configuration C1, the control unit 9 is configured to set the rotation speed v of the fan 85 at a first rotation speed v1.

(45) The control unit 9 is configured to keep the rotation speed v of the fan 85 constant at the value of the first rotation speed v1 for all values of condensation temperature lower than the first threshold temperature Ts1.

(46) The control unit 9 is configured to set the second operating configuration for values of condensation temperature Tc higher than the first threshold temperature Ts1.

(47) In the second operating configuration, the control unit 9 is configured to set the rotation speed v of the fan 85 at a second rotation speed v2.

(48) The control unit 9 is configured to keep the rotation speed v of the fan 85 constant at the value of the second rotation speed v2 for all values of condensation temperature higher than the first threshold temperature Ts1.

(49) In another embodiment, the control unit 9 is programmed to vary the operating configuration of the fan 85 between a first operating configuration C1, the second operating configuration and a third operating configuration C3.

(50) In this embodiment, the control unit 9 is configured to set the second operating configuration for values of condensation temperature Tc higher than the first threshold temperature Ts1 and lower than a second threshold temperature Ts2.

(51) The control unit 9 is configured to keep the rotation speed v of the fan 85 constant at the value of the second rotation speed v2 for all values of condensation temperature higher than the first threshold temperature Ts1 and lower than the second threshold temperature Ts2.

(52) The control unit 9 is configured to set the third operating configuration C3 for values of condensation temperature Tc higher than the second threshold temperature Ts2.

(53) In the third operating configuration C3, the control unit 9 is configured to set the rotation speed v of the fan 85 at a third rotation speed v3.

(54) The control unit 9 is configured to keep the rotation speed v of the fan 85 constant at the value of the third rotation speed v3 for all values of condensation temperature higher than the second threshold temperature Ts2.

(55) In an embodiment, the first rotation speed v1 is lower than the second rotation speed v2. In an embodiment, the second rotation speed v2 is lower than the third rotation speed v3.

(56) In an embodiment, the first threshold temperature Ts1 is preferably lower than the second threshold temperature Ts2.

(57) In a further embodiment to be protected, the control unit 9 is configured to generate speed signals in real time as a function of the temperature signal 901B received in real time. More specifically, for each value of condensation temperature it receives in real time, the control unit 9 generates a speed signal 902A corresponding to an optimum rotation speed v.

(58) In an embodiment, the control unit 9 is configured to vary the rotation speed v of the fan 85 steplessly. The control unit 9 is programmed to vary the rotation speed v of the fan 85 steplessly between a minimum rotation speed vmin and a maximum rotation speed vmax.

(59) In an embodiment, the minimum rotation speed vmin coincides with the first rotation speed v1. In one embodiment, the maximum rotation speed vmax coincides with the second rotation speed v2. In another embodiment, the maximum rotation speed vmax coincides with the third rotation speed v3.

(60) In this embodiment, the control unit 9 is configured to receive the temperature signal 901B, process it with a transfer function and generate the corresponding speed signal 902A. The transfer function is programmed to maximize the efficiency of heat exchange in the condenser 82.

(61) In an embodiment, the transfer function may be a linear function f1. In an embodiment, the transfer function may be an exponential function f2 or polynomial.

(62) In an embodiment, the control unit 9 is configured, when there is no temperature signal 901B, to set the rotation speed v of the fan 85 at the third rotation speed v3.

(63) In an embodiment, the control unit 9 is configured, when there is no temperature signal 901B, to set the rotation speed v of the fan 85 at the maximum rotation speed vmax.

(64) In an embodiment, the control unit 9 is configured to measure the working hours of the machine 1. In an embodiment, the control unit 9 is configured to calculate the working hours of the machine. The control unit 9 is programmed to set the first operating configuration C1 or the second operating configuration C2 as a function of the working hours of the machine 1. More specifically, the control unit 9 is programmed to increase the rotation speed v of the fan 85 with increasing operating hours. That means that in one embodiment, the control unit 9 is configured to determine a first, updated threshold temperature Ts1 determined as a function of the operating hours of the machine 1. The higher the number of operating hours of the machine 1, the lower the first, updated threshold temperature Ts1.

(65) What is set out above with regard to operation with one temperature threshold (first temperature threshold) also applies to operation with two temperature thresholds (first and second temperature thresholds). In effect, the control unit 9 is configured to determine a second, updated threshold temperature Ts2: the higher the number of operating hours, the lower this is than the first threshold temperature Ts1. The same applies to the embodiment with stepless speed variation. In that case, the transfer function is suitably adapted by considering as variable also the operating hours of the machine 1. More specifically, the increase in speed with temperature will be all the higher with the increase in the number of operating hours of the machine 1.

(66) According to one aspect of it, this disclosure is also intended to protect a method for processing liquid or semi-liquid food products.

(67) The method comprises a step of holding, in which the product is held in a containing element 3 from which it will be dispensed.

(68) The method comprises a step of preparing, in which a preparation is made in a further containing element 3 and then transferred into the containing element 3 to be thermally processed.

(69) The method comprises a step of stirring the product inside the containing element 3 by means of a stirrer 6.

(70) The method comprises a step of cooling the product by means of a refrigeration system 8 including a circuit 8 in which a refrigerant fluid circulates in a circulation direction V.

(71) The refrigerant fluid is subjected to one or more of the following steps:

(72) Compressing the refrigerant fluid inside a compressor 81. In this step, the refrigerant fluid may be saturated vapor or superheated vapor.

(73) Condensing the refrigerant fluid inside a condenser 82. In this step, condensation occurs at an effective condensation temperature Tc. The effective condensation temperature Tc is a function of the ambient temperature. In this step, the refrigerant fluid stops condensing and is in the supercooled liquid state, where supercooling is usually constant and not sensitive to ambient temperature changes.
Reducing the pressure of the fluid by means of a throttle valve 83. The pressure of the fluid is reduced by a concentrated load loss represented by the throttle valve 83.
Evaporating the refrigerant fluid. The refrigerant fluid receives heat from the ambient surroundings and evaporates until it once again reaches the state of saturated or superheated vapor entering the compressor 81.

(74) In an embodiment, the step of evaporating the refrigerant fluid coincides with the step of cooling the product to be dispensed. In effect, evaporation of the refrigerant fluid causes heat to be removed from the product.

(75) In an embodiment, the step of cooling comprises a step of forced ventilation. In the step of forced ventilation, a fan 85 produces an air flow F directed towards the condenser 82 of the refrigeration system 8. The step of forced ventilation increases the heat exchange performance of the condenser 82.

(76) In an embodiment, the method comprises a step of driving, in which a control unit 9 drives the fan 85. In the step of driving, the control unit 9 drives one or more of the following parts: the stirrer 6, an auxiliary stirrer 6, a plurality of actuators.

(77) In an embodiment, in the step of driving, the control unit 9 sends drive signals 902.

(78) In an embodiment, the method comprises a step of controlling.

(79) In the step of controlling, the control unit 9 can receive control signals 901 from the components it is connected to. In an embodiment, the control signals 901 comprise input signals 901A. The input signals 901A are entered by a user through a user interface 9A.

(80) In the step of controlling, a temperature sensor 86 measures a condensation temperature Tc. In the step of controlling, the temperature sensor 86 measures the temperature of the refrigerant fluid downstream of the condenser 82. The condensation temperature Tc is the temperature of the refrigerant downstream of the condenser 82. The effective condensation temperature Tc can be calculated from the condensation temperature Tc using suitable mathematical relations. In the step of controlling, the temperature sensor 86 sends a temperature signal 901B to the control unit 9. In an embodiment, the temperature signal 901B is part of the control signals 901. In an embodiment, the control unit 9 processes the control signals 901 and generates drive signals 902 as a function of the control signals 901. More specifically, the control unit 9 processes the temperature signal 901B and generates a speed signal 902A as a function of the temperature signal 901B. The speed signal 902A is part of the drive signals 902. The control unit 9 drives the fan 85 through the drive signals 902. In an embodiment, the control unit 9 controls a rotation speed v of the fan 85 through the speed signal 902A.

(81) Described below are some embodiments by which the control unit 9 regulates (controls or drives) the fan 85 and which differ in the control logic used (control unit programming).

(82) In an embodiment, the method comprises a step of controlling intermittently with the control unit 9. By controlling intermittently we mean a control mode where the control unit 9 is configured to vary the operating configurations (rotation speed v of the fan 85) discontinuously, by assigning a given operating configuration for a defined interval of condensation temperature Tc.

(83) In an embodiment, the method comprises a step of controlling with a single threshold. In an embodiment, the method comprises a step of controlling with two thresholds. In another embodiment, the method comprises a step of controlling with a plurality of thresholds.

(84) In a yet further embodiment, the method comprises a first step of regulating. In the first step of regulating, the control unit 9 sets the fan 85 to a first operating configuration C1. The control unit 9 sets the fan 85 to the first operating configuration C1 when the condensation temperature Tc is lower than a first threshold temperature Ts1. When the fan 85 is in the first operating configuration C1, it rotates at a rotation speed v equal to a first rotation speed v1 which remains constant for every temperature value lower than the first threshold temperature Ts1.

(85) In an embodiment, the method comprises a second step of regulating. In the second step of regulating, the control unit 9 sets the fan 85 to a second operating configuration C2. The control unit 9 sets the fan 85 to the second operating configuration when the condensation temperature Tc is higher than the first threshold temperature Ts1. When the fan 85 is in the second operating configuration, it rotates at a rotation speed v equal to a second rotation speed v2, which is higher than the first rotation speed v1 and which remains constant for every temperature value higher than the first threshold temperature Ts1.

(86) In the step of controlling with a single threshold, the control unit 9 changes the operating configuration of the fan only between the first operating configuration C1 and the second operating configuration C2.

(87) In an embodiment, the method comprises a third step of regulating. In the third step of regulating, the control unit 9 sets the fan 85 to a third operating configuration C3. The control unit 9 sets the fan 85 to the third operating configuration C3 when the condensation temperature Tc is higher than a second threshold temperature Ts2. When the fan 85 is in the third operating configuration C3, it rotates at a rotation speed v equal to a third rotation speed v3, which is higher than the second rotation speed v2 and which remains constant for every temperature value higher than the second threshold temperature Ts2.

(88) When the control unit 9 carries out the step of regulating with two thresholds, it sets the fan 85 to the second operating configuration when the condensation temperature Tc is higher than the first threshold temperature Ts1 and lower than the second threshold temperature Ts2.

(89) In the step of controlling with two thresholds, the control unit 9 changes the operating configuration of the fan only between the first operating configuration C1, the second operating configuration C2 and the third operating configuration C3.

(90) What is described above regarding regulation with a single threshold and regulation with two thresholds can be extended to regulation with a plurality of thresholds, with the necessary changes made, which are known to experts in the trade. Generally speaking, we may observe that in the case of control with a plurality of thresholds, where n is the number of thresholds, there are n+1 temperature intervals and n+1 corresponding rotation speeds of the fan.

(91) In an embodiment, the method comprises a step of controlling steplessly with the control unit 9. In the step of controlling steplessly, the control unit 9 varies the rotation speed v of the fan 85 steplessly between a minimum rotation speed vmin (corresponding to the first rotation speed v1 in intermittent control mode) and a maximum rotation speed vmax (corresponding to the second rotation speed v2 or the third rotation speed v3, depending on the embodiment of the intermittent control mode).

(92) By controlling steplessly we mean a control mode where the control unit 9 is configured to change the operating configurations (rotation speed v of the fan 85) in a continuously variable manner and to assign a given operating configuration for each value of condensation temperature Tc measured by the temperature sensor 86.

(93) In an embodiment, in the step of controlling, the control unit 9 is configured, when the temperature sensor 86 is not working, to set the rotation speed v of the fan 85 to the second rotation speed v2.

(94) In an embodiment, in the step of controlling, the control unit 9 is configured, when the temperature sensor 86 is not working, to set the rotation speed v of the fan 85 to the third rotation speed v3.

(95) In an embodiment, in the step of controlling, the control unit 9 is configured, when the temperature sensor 86 is not working, to set the rotation speed v of the fan 85 to the maximum rotation speed vmax.

(96) In an embodiment, the control unit 9 measures the working hours of the machine 1. The control unit 9 changes the operating configuration of the fan 85 as a function of the temperature signal 901B and of the working hours of the machine 1. The control unit 9 changes the rotation speed v of the fan 85 as a function of the temperature signal 901B and of the working hours of the machine 1. More specifically, the rotation speed v of the fan increases with increasing operating hours.