Machine for producing and dispensing liquid or semiliquid foodstuffs

A machine for producing and dispensing a liquid or semiliquid product for use as a foodstuff, comprising:

• a holding vat for a liquid base product;
• a treatment circuit for said liquid base product, in order to obtain a liquid or semiliquid foodstuff, said treatment circuit comprising at least one heat-adjustment system for adjusting at least one value associated with a temperature of at least one chosen from said base product, an intermediate product and a finished product;
• a dispensing mechanism for distributing said foodstuff;
• wherein said heat-adjustment system comprises:
• a thermal circuit within which a thermal fluid circulates, and including a compressor, a condenser, an electronic expansion valve, and an evaporator, an outlet of the compressor being fluidly connected to an inlet of the condenser, an outlet of the condenser being fluidly connected to an inlet of the evaporator, an outlet of the evaporator being fluidly connected to an inlet of the compressor and said electronic expansion valve being interposed between said condenser and evaporator;
• a control unit acting on said electronic expansion valve for adjusting a passage section of the electronic expansion valve through an electronic command signal (S), said control unit being configured for:
• determining a main parameter (SH) representative of an actual instantaneous overheating of the thermal fluid coming out of the evaporator, wherein said main parameter (SH)=(Tout)−(Tsat), where:
• (Tout) is a temperature of the fluid coming out of the evaporator, the temperature of the fluid taken between the outlet of the evaporator and the inlet of the compressor;
• (Tsat) is a saturation temperature of the fluid coming out of the evaporator;
• wherein (Tsat) is determined as a function of a pressure (Pout) of the fluid coming out of said evaporator, the pressure (Pout) of the fluid also taken between the outlet of the evaporator and the inlet of the compressor;
• determining a target reference parameter (SHset) for said overheating, a value thereof being a value that the instantaneous overheating should take to enable the foodstuff to at least one chosen from, reach a desired temperature and keep a desired temperature, said target reference parameter (SHset) being determined as a function of a predetermined value (SHmin), and of an auxiliary value (DT) calculated depending on a variation in time of the temperature (Tout) of the fluid coming out of the evaporator and of the saturation temperature (Tsat) of the fluid coming out of the evaporator such that the auxiliary value (DT) is calculated based on both 1) instantaneous values of (Tout) and (Tsat) taken at a current time and 2) values of (Tout) and (Tsat) taken at previous times;
• generating said electric command signal (S) as a function of a comparison between said main parameter (SH) and target reference parameter (SHset).