Beverage dispensing machine and operating method

A beverage dispensing machine, comprising

• a brewing chamber housing ingredients;
• a water heater configured to heat water;
• a pump configured to pump and pressurize the heated water so as to feed the heated and pressurized water to the brewing chamber to brew the ingredients within the brewing chamber with the heated and pressurized water to form a beverage;
• a beverage delivery section for delivering the beverage;
• at least one electrovalve in fluid communication with and between said brewing chamber and said beverage delivery section, said at least one electrovalve having a valve body with a wall that has a discharge opening extending therethrough to form a valve seat, and a shutter movable relative to the valve seat within the valve body between an open position and a closed position, and
• a control unit that commands the at least one electrovalve to open into the open position and to close into the closed position and to adjust a flow rate of the beverage exiting the brewing chamber during brewing of the beverage, the control unit commanding the at least one electrovalve in a manner so as to:
• attain the closed position by causing a tip of the shutter to abut the valve seat to close the discharge opening, which blocks the beverage from exiting into the beverage delivery section, the tip terminating at a distal point so that as the pump continues to pump the heated water into the brewing chamber, there arises a pressure build-up within the brewing chamber;
• attain the open position by adjusting an extent to which the tip of the shutter retracts away from the valve seat into a relative position with respect to the discharge opening that opens the discharge opening sufficient to allow the beverage to exit the brewing chamber and flow into the beverage delivery section via the discharge opening and prevent further continuation of the pressure build-up within the brewing chamber as the pump continues to pump the heated water into the brewing chamber;
• and
• adjust the flow rate of the beverage during brewing of the beverage, the at least one electrovalve being responsive to the control unit to adjust the flow rate of the beverage by raising the shutter above the valve seat by a minimum extent that attains the adjusted flow rate as a minimum flow rate, and the at least one electrovalve being further responsive to the control unit to adjust the flow rate of the beverage by raising the shutter above the valve seat by a maximum extent that attains the adjusted flow rate as a maximum flow rate, the minimum flow rate being greater than a zero flow rate, the maximum flow rate being greater than the minimum flow rate,
• wherein the shutter is made of piezoelectric materials that expand to overcome a force of a spring element and to push the spring element in a direction opposite the valve seat, adjust the extent to which the tip of the shutter retracts away from the valve seat and move toward the spring element.